Multiple Choice Questions Database

 

Key Code: B

A 42-year-old woman develops a severe bacterial pneumonia. Culture of the sputum yields gram positive diplococci that are alpha hemolytic on blood agar, catalase negative and sensitive to optochin (bile soluble). Which of the following statements concerning this infection is TRUE:

A) A conjugated vaccine to immunize against this infection is now available for children under the age of 2
B) The carriage rate of this organism as normal flora in the general population is less than 1%
C) The patient is protected from future infections with all strains of this organism since she has antibodies to the capsule as a result of her infection
D) This organism rarely causes community acquired pneumonia
E) Treatment of this infection with penicillin is uniformly effective in treating disease caused by this organism

Answer: A

 

(Year Posted:  UI  801)

 

Key Code: B

A 65-year-old male complains of fever, diarrhea, cough and chest pain. Evidence of pneumonia is seen on a chest X-ray. Due to the inability of the patient to produce a suitable sputum specimen, a transtrachial aspirate is obtained. Culture of the aspirate on blood agar is negative for respiratory pathogens. However, growth of the organism on media containing high levels of cysteine and iron shows the presence of weakly staining gram negative rods. The source of the organism responsible for the patient's pneumonia is most likely:

A) Aerosol of drift from a contaminated cooling tower
B) Aspiration of his own normal flora
C) Contaminated food
D) Droplet infection from a close contact

Answer: A

 

(Year Posted:UI  802)

 

Key Code: B

A 6-year old male presents to your office for evaluation of fever, migratory joint swelling and jerking movements of his arms. The mother reports that her son has had several bouts with "strep throat" the past year with the most recent about 1 month ago. On exam the child has a temperature of 1010F with a normal blood pressure and pulse. His heart exam reveals a new mitral regurgitant murmur, and there is swelling and tenderness of the right knee. Skin exam reveals subcutaneous nodules of the upper extremities. The preliminary diagnosis is rheumatic fever. Confirmation of the diagnosis in this child could be done by:

A) Assay the child's serum for antibodies to hyaluronic acid
B) Assay the child's serum for levels of protein A
C) Culturing the child's throat for the causative agent
D) Detection of antibodies to streptolysin O in the child's serum
E) Detection of antibodies to streptolysin S in the child's serum

Answer: D

 

(Year Posted: UI  803)

 

Key Code: B

Which one of the following statement concerning anthrax toxin is FALSE:

A) It consists of three parts, protective antigen, edema factor and lethal factor
B) It is encoded by a plasmid
C) The lethal factor is antiphagocytic and prevents phagocytosis of the organism
D) The Protective antigen is responsible for the binding of the toxin to the susceptible cell

Answer: C

 

(Year Posted:  UI  804)

 

Key Code: B

A 24-year old sexually active female presents with dysuria and a purulent discharge from the cervical canal. The gram stain of the discharge shows the presence of gram negative diplococci and numerous PMN's. The lab reports the isolation of non-hemolytic, gram negative, oxidase positive diplococci that ferment glucose. A deletion of the genes responsible for the synthesis of which one of the following would make the organism unable to initially attach to male urethral epithelial cells and endocervical cells:

A) Capsular polysaccharide
B) C-carbohydrate
C) O-side chain of lipooligsaccharide
D) Pili
E) Spore coat protein

Answer: D

 

(Year Posted:  UI  805)

 

Key Code: M

Two component regulatory systems are used by many pathogens to regulate the production of virulence factors. These systems require all of the following EXCEPT:

A) Environmental signal
B) Response regulator
C) Membrane sensor
D) Plasmid encoded repressor

Answer: D

 

(Year Posted:  UI  806)

 

Key Code: V

A 52 year-old man presented with a two-week history of progressive neurological abnormalities. The illness began with fever and sensory disturbances and later involved emotional lability and gait abnormality. While hospitalized, his illness progressed to coma. He then suffered cardiopulmonary arrest and died. Post-mortem examination of the brain revealed neuronal cell bodies containing negri bodies. On the basis of these findings, you conclude that the patient had:

A) Rabies
B) Herpes encephalitis
C) Spongioform encephalopathy
D) Progressive multifocal leukoencephalopathy (PML)
E) Alzheimer's disease

Answer: A

 

(Year Posted:  UI  807)

 

Key Code: V

A 25 year-old woman with advanced AIDS (CD4+ count, 3 cells /(ul) and history of recurrent herpes involving nose, right third finger, and anogenital region complained of a nonhealing genital lesion. Physical examination revealed molluscum contagiosum lesions involving the right arm antecubital fossa and inner aspect of both thighs. A superficial, slightly tender, 0.5 x 2.0 cm linear ulcer involved the vulva. A culture of the ulcer grew herpes simplex type 2. A biopsy of the lesion showed carcinoma in situ and koilocytes, as well acute and chronic inflammation. The finding of koilocytosis is a result of:

A) Molluscum contagiosum virus
B) Papillomavirus
C) Herpes simplex virus
D) Epstein-Barr virus
E) Human immunodeficiency virus

Answer: B

 

(Year Posted: UI  808)

 

Key Code: V

Lamivudine, a nucleoside analogue, is used to treat chronic infection with either HIV or hepatitis B virus. However, both HIV and hepatitis B virus can develop resistance to this antiviral agent, especially if the lamivudine is not used in combination with other antiviral drugs. Based on your understanding of the lifecycle of these two viruses and the mechanism of action of this nucleoside analogue, you deduce that the resistance to lamivudine is most likely the result of mutation in the viral:

A) Kinase
B) Protease
C) DNA-dependent DNA polymerase
D) RNA-dependent RNA polymerase
E) Reverse transcriptase

Answer: E

 

(Year Posted:  UI  809)

 

Key Code: V

Cytomegalovirus (CMV) infects 40 to 60% of persons living in the United States. CMV is the leading infectious cause of birth defects and is a major cause of life-threatening illness in persons with compromised immune systems. CMV infection is characterized by:

A) Increase in cellular MHC class I molecule expression on infected cells
B) Lack of asymptomatic viral shedding
C) Production of heterophile antibody
D) Viral replication using a viral nucleoside kinase
E) Establishment of viral latency in B lymphocytes

Answer: D

 

(Year Posted:  UI  810)

 

Key Code: I

Southern blot analysis of immunoglobulin DNA hybridized with the same J region probe showed a 6 kb band and a 1.5 kb band from a committed B cell clone and a 6 kb band only from a nonlymphoid cell. The 6 kb band represents a(n)

A) constant region gene rearrangement
B) D to J gene rearrangement
C) unrearranged Ig gene
D) V to D gene rearrangement
E) V to J gene rearrangement

Answer: C

 

(Year Posted: UI  811)

 

Key Code: I

Which immunoassay would most likely be used to determine the percentage of mature B cells in a peripheral blood lymphocyte sample from a patient?

A) ELISA
B) Flow cytometry
C) Immunohistochemistry
D) Radioimmunoassay
E) Western Blot

Answer: B

 

(Year Posted: UI  812)

 

Key Code: M, Key Code: B

A 74-year-old woman is hospitalized for heart failure and weakness. After 7 days in the hospital, she develops fever, increased cough and shortness of breath. A chest x-ray suggests pneumonia, and a gram stain of a sputum sample shows numerous gram-negative rods. She is placed on ceftazadime, a third-generation cephalosporin. The patient does not respond as expected and a sputum culture yields Enterobacter cloacae that is resistant to ceftazadime. Which one of the following is the most likely mechanism for this organism's resistance?

A) Active efflux of drug from the cell
B) Altered penicillin-binding protein
C) Decreased cell membrane permeability
D) Mutation in 23s ribosomal RNA
E) Synthesis of b-lactamase

Answer: E

 

(Year Posted:  UI  813)

 

Key Code: M

The mechanism most responsible for the spread of antibiotic resistance in nature is

A) conjugation between bacteria of different species
B) specialized transduction by bacteriophage lambda
C) spontaneous mutation
D) transduction of antibiotic resistance genes
E) transformation of transposable elements into competent bacteria

Answer: A

 

(Year Posted: UI  814)

 

Key Code: B

Which one of the following can infect the joints via hematogenous spread from the upper reproductive tract?

A) Chlamydia trachomatis, serovars D-K
B) Chlamydia trachomatis, serovars L1, L2, L2a and L3
C) Haemophilus ducreyi
D) Mycoplasma genitalium
E) Neisseria gonorrhoeae

Answer: E

 

(Year Posted: UI  815)

 

Key Code: B, Key Code: M

Selective media are used to isolate suspected pathogens from which one of the following sites?

A) Blood
B) Central nervous system
C) Colon
D) Lower respiratory tract
E) Stomach

Answer: C

 

(Year Posted:  UI  816)

 

Key Code: B

An endocervical swab taken from a patient suspected to be infected with Chlamydia trachomatis is processed by the microbiology laboratory. Which one of the following test results is consistent with infection by Chlamydia trachomatis?

A) Gram negative diplococci
B) Growth on cysteine tellurite agar
C) Inclusion formation within tissue culture cells
D) Luxuriant growth on chocolate agar
E) Positive Schick test

Answer: C

 

(Year Posted: UI  817)

 

Key Code: B

A college freshman who lives in a dormitory develops fever, a stiff neck, and a headache. Three hours later, he notices small hemorrhagic lesions developing on his trunk. His roommate takes him to the emergency room where the ER physician orders blood culture and a spinal tap to obtain cerebral spinal fluid (CSF) for analysis and culture. Both the blood and CSF cultures are positive for growth. The organism responsible for the infection is MOST LIKELY

A) A Gram negative rod
B) A Gram positive rod
C) Gram negative diplococci
D) Gram positive cocci in chains
E) Gram positive cocci in clusters

Answer: C

 

(Year Posted: UI  818)

 

Key Code: B, Key Code: F, Key Code: P

In a 25-year old patient, a vaginal discharge in which epithelial cells with numerous adherent bacteria predominate is characteristic of

A) bacterial vaginosis
B) normal flora
C) physiologic leukorrhea
D) trichomoniasis
E) vaginal yeast infection

Answer: A

 

(Year Posted:  UI  819)

 

Key Code: B

A hospitalized man who is taking b-lactam antibiotics following bowel surgery develops fever, cramps, and bloody diarrhea. A cytotoxin is detected in his stools. Which one of the following pathogens is the most likely cause of his symptoms?

A) Bacillus anthracis
B) Bacteroides fragilis
C) Clostridium difficile
D) Clostridium perfringens
E) Clostridium tetani

Answer: C

 

(Year Posted: UI  820)

 

Key Code: B

A child is taken to his pediatrician with lymphadenopathy and fever. On examination, the physician notes several bites on the child's ankles and arms that are consistent with flea bites. The mother notes that their pet dog and cat have fleas. Which one of the following pathogens is the most likely cause of his symptoms?

A) Bartonella henselae
B) Borrelia burgdorferi
C) Ehrlichia chaffeensis
D) Rickettsia prowazekii
E) Rickettsia rickettsii

Answer: A

 

(Year Posted: UI  821)

 

Key Code: B

A newly arrived 13-month-old adoptee from Russia develops signs and symptoms of bacterial meningitis. The toddler has recently received a DTP vaccination in her native country but no other immunization. A few small Gram-negative rods and white cells are observed in a Gram stain of the child's spinal fluid. Which one of the following pathogens is the most likely cause of her symptoms?

A) Bordetella pertussis
B) Haemophilus ducreyi
C) Haemophilus influenzae, non typeable
D) Haemophilus influenzae type b
E) Moraxella catarrhalis


Answer: D

 

(Year Posted:  UI  822)

 

Key Code: V

It is mid-January. A one-year-old child is brought to the emergency room by his mother because of severe diarrhea over the past two days. The child has a mild fever, and has vomited twice. The child has been in day care where a similar illness has been affecting other children. A pediatrician has ruled out bacterial and parasitic causes of illness in several other children in the day care center. The most likely cause for this infection is

A) enteric adenovirus
B) hantavirus
C) influenza virus
D) Norwalk virus
E) rotavirus

Answer: E

 

(Year Posted:  UI  823)

 

Key Code: V

Serological analysis of the blood sample of a 25-year old male Chinese immigrant detects the presence of anti-hepatitis B surface antigen (anti-HBs) antibody but absence of anti-hepatitis core antigen (anti-HBc) antibody. This person is

A) a chronic HBV carrier
B) an asymptomatic HBV carrier
C) previously immunized with the recombinant HBV surface antigen vaccine
D) previously infected by HBV but has resolved the infection
E) suffering from an early acute infection of HBV

Answer: C

 

(Year Posted:UI  824)

 

Key Code: V

Eight fraternity brothers report to your infirmary on a Wednesday morning complaining of mild fever, nausea, vomiting and, in some individuals, diarrhea the previous night. They all ate together at a sports bar to watch Monday night football, and all had a salad from the salad bar. Their symptoms abate approximately 24 hours after you see them. Which viral agent is the most likely cause of this episode?

A) Adenovirus type 40
B) Hepatitis A
C) Human Torovirus
D) Norwalk virus
E) Rotavirus

Answer: D

 

(Year Posted:UI  825)

Key Code: V

Smallpox was eradicated in 1977 following a successful vaccination and surveillance program. Today, vaccination against smallpox is no longer performed because of the risk of

A) non-response in immunosuppressed individuals
B) post-vaccination encephalitis
C) reassortment with other poxviruses
D) release of wild-type virus
E) reversion of the attenuated strain to the virulent form

Answer: B

 

(Year Posted: UI  826)

 

Key Code: F, Key Code: V

A 22-year-old woman reports to the clinic suffering from shortness of breath and a nonproductive cough. A personal history reveals that the woman is in the high-risk category for HIV-1 infection. Extracellular cysts are seen in the stained aspirate fluid from a bronchoalveolar lavage. The most likely diagnosis is

A) aspergillosis
B) blastomycosis
C) coccidiomycosis
D) histoplasmosis
E) pneumocystosis

Answer: E

 

(Year Posted: UI  827)

 

Key Code: F

Several patients with acute pneumonia (that has not responded to antibacterial therapy) have been admitted to your hospital in Terre Haute, Indiana in the past week. You discover that all of them had participated in a community project: the razing and cleanup of a blackbird roost on the edge of their subdivision. Some patients required antifungal therapy, while others recovered without further treatment. Which is the most likely diagnosis?

A) blastomycosis
B) coccidioidomycosis
C) cryptococcosis
D) histoplasmosis
E) paracoccidioidomycosis

Answer: D

 

(Year Posted: UI  828)

 

Key Code: F

A Washington, DC postal worker presents with an erythematous, scaly, pruritic plaque on the instep of his right foot. He expresses concern about cutaneous anthrax. The first test that should be performed is

A) a chest X-ray
B) a skin biopsy
C) cultures (bacterial, fungal and mycobacterial)
D) polymerase chain reaction (PCR) testing of scale
E) potassium hydroxide preparation of scale

Answer: E

 

(Year Posted: 2002 UI  829)

 

Key Code: P

A missionary, who has been working in the Papua New Guinea for the past year, develops fever, lymphangitis, and lymphadenitis. The most likely cause of his symptoms is

A) filariasis
B) loiasis
C) malaria
D) onchocerciasis
E) schistosomiasis

Answer: A

 

(Year Posted: UI  830)

 

Key Code: P

Which event in the pathophysiology of malaria occurs only with Plasmodium falciparum?

A) conversion of heme to hemozoin by heme polymerase
B) cytoadherence of schizont-infected erythrocytes to capillary endothelium
C) dyserythropoiesis
D) insertion of parasite proteins into infected erythrocyte cytoskeleton
E) release of toxic malarial antigens

Answer: B

 

(Year Posted: UI  831)

 

Key Code: P

A 25-year old African-American male comes to the emergency room because of a sudden onset of high fever, shaking chills, severe headache, and myalgia. He informs you that he returned from a vacation in East Africa a week ago and that he is still taking chloroquine prophylaxis. Laboratory test results include low hematocrit (35%), slight hypoglycemia, and an intraerythrocytic pathogen on Giemsa-stained blood films. The most likely cause of his symptoms is

A) babesiosis
B) falciparum malaria
C) kala azar
D) trypanosomiasis
E) vivax malaria

Answer: B

 

(Year Posted: UI  832)

 

Key Code: P

PATIENT 1

A 53-year old male, who lives in Arizona, is under treatment, by I.V. injections of blood products from human donors, for classic hemophilia (factor VIII deficiency). The patient reports that he is a cat owner, and further that he is inordinately fond of very rare steaks, believing that the nearly raw meat "will help build up his blood."

SCENARIO A: Patient 1 presents with nausea, vomiting, and increasing headache. A CT scan of the head demonstrated ring-enhancing lesions. The neurosurgical service obtained biopsies of some of the brain lesions. Bacterial, fungal, and viral cultures were all negative, but special stains of the brain tissue showed cyst-like structures containing numerous parasites.

What is the etiological agent of this disease?

A) Candida albicans
B) Cryptococcus neoformans
C) Cryptosporidium parvum
D) Pneumocystis carinii
E) Toxoplasma gondii

Answer: E

 

(Year Posted: UI  833)

 

Key Code: F

SCENARIO B:  Patient 1 presents with the same complaints. Suppose that the CT scan had been unremarkable, but that a negative stain (India ink) of Cerebrospinal Fluid (CSF) obtained by lumbar puncture showed heavily encapsulated yeast forms. Culture of CSF on Sabouraud Dextrose Agar at 30?C grew a white mucoid yeast that was inhibited on Sabouraud Dextrose Agar containing cycloheximide and chloramphenicol.

What etiological agent do you suspect?

A) Candida albicans
B) Cryptococcus neoformans
C) Cryptosporidium parvum
D) Pneumocystis carinii
E) Toxoplasma gondii

Answer: B

 

(Year Posted: UI  834)

 

Key Code: F

SCENARIO C:  Patient 1 presents with white, exudative lesions involving the tongue, uvula, palate, and buccal mucosa. Scrapings of oropharyngeal lesions were cultured and examined by KOH and Gram-stained preparations. Microscopic examination showed budding yeast cells, pseudohyphae and hyphal elements.

What is the most frequent cause of this type of infection?

A) Candida albicans
B) Coccidioides immitis
C) Cryptosporidium parvum
D) Pneumocystis carinii
E) Toxoplasma gondii

Answer: A

 

(Year Posted:  UI  835)

 

Key Code: F

SCENARIO D:  Patient 1 presents with symptoms suggestive of pneumonia. Bacterial and viral cultures were negative. However, fungal culture of bronchoalveolar lavage fluid was positive. Cytological examination of stained material from the lavage fluid yielded findings of relatively large spherules containing endospores. Within 4 days, a white, fluffy mold grew on plain Sabouraud Dextrose Agar (SDA) as well as SDA containing cycloheximide and chloramphenicol. Stained material from this culture showed hyphae which appeared fragmented into barrel-shaped structures. Had a transbronchial biopsy been performed, tissues stained with haematoxylin and eosin might have shown forms similar to those seen in the lavage fluid.

What etiological agent do you suspect?

A) Candida albicans
B) Coccidioides immitis
C) Cryptococcus neoformans
D) Pneumocystis carinii
E) Toxoplasma gondii

Answer: B

 

(Year Posted: 2002 UI  836)

 

Key Code: F

What property of this agent makes it so infectious?

A) Arthrospores are easily aerosolized by coughing
B) Arthrospores are easily aerosolized in the environment
C) Arthrospores are disseminated by macrophages
D) Endospores are easily aerosolized by coughing
E) Endospores are easily aerosolized in the environment

Answer: B

 

(Year Posted: 2002 UI  837)

 

Key Code: P, Key Code: F, depending on whom you believe

SCENARIO E:  Patient 1 presents with symptoms suggestive of pneumonia. Bacterial, fungal, and viral cultures were negative. Acid fast stains of bronchial washings showed RBC-sized (<10 um), round, partially acid-fast bodies. Methenamine silver stains of bronchial washings were more definitive.

What is the etiological agent?

A) Candida albicans
B) Coccidioides immitis
C) Cryptosporidium parvum
D) Pneumocystis carinii
E) Toxoplasma gondii

Answer: D

 

(Year Posted: UI  838)

 

Key Code: P

SCENARIO F:  Patient 1 presents with a complaint of diarrhea for more than 2 months. He describes having more than 50 "attacks" per day and says he has lost about 20 lb (~9 kg) over this time period. Stool cultures are negative for bacterial enteric pathogens and for Clostridium difficile toxin. O&P examination of stool shows acid-fast oocysts.

What is the etiological agent?

A) Candida albicans
B) Coccidioides immitis
C) Cryptosporidium parvum
D) Pneumocystis carinii
E) Toxoplasma gondii

Answer: C

 

(Year Posted: 2002 UI  839)

 

Key Code: P, Key Code: V

SCENARIO G:  Patient 1 complains of visual difficulty. Fundoscopic examination reveals severe retinal damage.

Which pair of organism types comprises the MOST LIKELY differential diagnosis?

A) A bacterium and a parasite
B) A virus and a parasite
C) A fungus and a parasite
D) A fungus and a virus
E) A fungus and a bacterium

Answer: B

 

(Year Posted:  UI  840)

 

Key Code: V

Given Patient 1's history, any of these presentations should result in your suggesting that the patient be examined for an underlying disease.

Which of the following groups of studies would be MOST APPROPRIATE for this situation?

A) CD4+ count, RT-PCR for viral load, Anti-CMV antibody
B) CD4+ count, RT-PCR for viral load, Anti-EVB antibody
C) CD4+ count, RT-PCR for viral load, Anti-HIV antibody
D) CD4+ count, RT-PCR for viral load, Anti-HBs antibody
E) CD4+ count, RT-PCR for viral load, HBs antigen

Answer: C

 

(Year Posted: 2002 UI  841)

 

Key Code: F

PATIENT 2

A 47-year-old male presents with respiratory symptoms (coughing, chest pain, hemoptysis), fever, and weight loss, as well as skin lesions. As part of the history, the patient indicates that he supplements his income by cutting firewood from "down timber" in the nearby National Forest. Stained preparations of purulent material from the skin lesions showed large (8 to 15 um) double walled yeasts with single, broad-based buds. Cultures on Sabouraud Dextrose Agar (room temperature) from skin samples finally (after 3 weeks of incubation) yielded white cottony mycelial growth which gradually darkened with age.

What is the etiological agent of this disease?

A) Blastomyces dermatitidis
B) Coccidioides immitis
C) Histoplasma capsulatum
D) Paracoccidioides brasiliensis
E) Sporothrix schenckii

Answer: A

 

(Year Posted: 2002 UI  842)

 

Key Code: F

PATIENT 3

A six-year-old girl from a farm town in Kentucky was admitted to the regional hospital for suspected tuberculosis. She possessed a chronic cough with productive sputum, and she complained of breathlessness, tiredness, and weight loss over the last several months. Multiple sputum specimens showed no acid-fast bacilli; her tuberculin skin test was negative. Abnormal hematologic findings were anemia, a low white blood cell count, and some monocytes containing intracellular yeasts with a narrow isthmus between mother and daughter cells. Blood specimens were processed through a membrane filter and placed on brain heart infusion agar with blood at room temperature. After three weeks, tan, fluffy colonies formed. Microscopically, the fungus produced microconidia along the sides of the hyphae, and tuberculate chlamydospores.

What is the etiological agent of this disease?

A) Blastomyces dermatitidis
B) Coccidioides immitis
C) Histoplasma capsulatum
D) Paracoccidioides brasiliensis
E) Sporothrix schenckii

Answer: C

 

(Year Posted: UI  843)

 

Key Code: F

PATIENT 4

A 40-year-old gardener, who had been working with sphagnum moss and orchids, noticed a hard, unmovable lump under the skin of his hand, but decided to ignore it. A month later, the lump ulcerated to present a black, necrotic appearance, and two more lesions developed further up the hand and wrist. At this point, he visited his physician. A histologic stain of material from deep in the lesions showed rare, elongated yeast cells resembling cigars. On Sabouraud dextrose agar at room temperature, a cream-colored, leathery colony grew relatively rapidly, and after 9 days it started to turn black.

What is the etiological agent of this disease?

A) Blastomyces dermatitidis
B) Coccidioides immitis
C) Histoplasma capsulatum
D) Paracoccidioides brasiliensis
E) Sporothrix schenckii

Answer: E

 

(Year Posted: UI  844)

 

Key Code: F

PATIENT 5

A 25-year-old man was hospitalized for treatment of acute lymphocytic leukemia. He was treated with anticancer drugs that produced remission. One year later he suffered a relapse of leukemia. He was treated again with large doses of anticancer drugs. A chest X-ray showed nodular lesions in both of his lungs. Blood cultures were negative. Microscopic examination of sputum specimens and a biopsy revealed septate, branching hyphae, 7 to 10 micrometers in diameter and several hundred micrometers in length. Cultures resulted in colonies of a white mold that quickly developed a smoky-gray color.

What is the etiological agent of this disease?

A) Aspergillus flavus
B) Aspergillus fumigatus
C) Aspergillus niger
D) Mucor racemosus
E) Rhizopus arrhizus

Answer: B

 

(Year Posted: UI  845)

 

Key Code: P

PATIENT 6

A late-30s male presents complaining of episodes of chills and fever, which seem to come "every 2 or 3 days," along with headaches and myalgia. He also reports that in recent days his urine seems to be getting darker in color. The patient says he works as a freight handler at the International Airport in Atlanta. A blood smear shows erythrocytes containing banana-shaped forms.

What is the etiological agent of this disease?

A) Babesia microti
B) Plasmodium falciparum
C) Plasmodium malariae
D) Plasmodium ovale
E) Plasmodium vivax

Answer: B

 

(Year Posted: UI  846)

 

Key Code: B

PATIENT 7

After a tooth extraction, a patient developed a draining sinus tract filled with yellowish granules. A crushed, Gram-stained granule (under oil immersion) shows delicate "stringy" Gram-positive organisms. Microbiological culture of these microorganisms grew only anaerobically.

Which type of antimicrobial agent should be used to treat this case?

A) an antibacterial agent
B) an antifungal agent
C) an antiparasitic agent
D) an antirickettsial agent
E) an antiviral agent

Answer: A

 

(Year Posted:  UI  847)

 

Key Code: P

PATIENT 8

Patient 8 is a 14-year old. She baby sits fairly often for a neighbor family with 4 children: an infant of <1 year, a 3-year old (who goes to day care), and "the twins" who are 4th graders.

SCENARIO A: Patient 8 is brought to her pediatrician complaining of intermittent attacks of diarrhea over the past several months. She reports that during these attacks, the stool is foul smelling and "foamy," but not bloody. She further reports loss of appetite. A stool specimen is examined for O&P, but is negative. A 'string test' was performed with positive results.

Which of the following would BEST describe the "positive result" from the string test.

A) Cysts containing four nuclei
B) Cysts containing eight nuclei
C) Trophozoites with one large nucleus
D) Trophozoites with two large nuclei
E) Trophozoites with ingested erythrocytes

Answer: D

 

(Year Posted:  UI  848)

 

Key Code: P

SCENARIO B:  Patient 8 is brought to a child psychiatrist for what her mother calls "inappropriate sexual behavior." On questioning, it turns out that what is meant is that the child tends to tug at her clothing, grope and scratch at her genital and perineal areas. (Note: rock stars, professional baseball players, and other famous personalities are often paid great sums of money to do this.) The alert psychiatrist refers them back to their pediatrician who recommends that a "scotch tape test" be performed on the patient.

The MOST LIKELY etiological agent of this disease is:

A) Ascaris lumbricoides
B) Enterobius vermicularis
C) Necator americanus
D) Strongyloides stercoralis
E) Trichuris trichiura

Answer: B

 

(Year Posted:UI  849)

 

Key Code: P

PATIENT 9

A 40-something-year-old woman presents for her annual gynecological examination. Almost as an afterthought, she mentions that she has experienced some vaginal itching along with some "smelly", frothy exudate.

What is the MOST LIKELY cause of this conditon?

A) Candida albicans
B) Gardnerella vaginalis
C) Trichomonas hominis
D) Trichomonas tenax
E) Trichomonas vaginalis

Answer: E

 

(Year Posted:UI  850)

Key Code: P

A 5-year-old girl was transported from Nuevo Laredo, Mexico to a hospital in the United States with "heart problems." She showed severe edema around the forehead and eyes. A blood smear showed elongate parasites in "S" and "C" configurations.
What is the MOST LIKELY etiological agent of this disease?

A) Leishmania braziliensis
B) Leishmania major
C) Leishmania mexicana
D) Trypanosoma brucei
E) Trypanosoma cruzi

Answer: E

 

(Year Posted: UI  851)

 

Key Code: P

A 55-year old female presented, complaining of nausea, vomiting, diarrhea, abdominal pain and severe muscle cramping. On examination, she appeared febrile and was hospitalized. On hospital day 19 she developed bronchopneumonia, pulmonary edema, and motor paralysis; she died later that day. Family members reported that they had received some home-made pork sausages from a neighbor "about a month ago" and that most family members had eaten portions, lightly fried. Blood and serum samples were obtained from the other family members who had developed symptoms of fever, periorbital edema, and muscle pain. All showed eosinophilia between 50% and 60% (normal is <5%) and had high titers of antibody specific for the suspected agent.
The MOST LIKELY etiological agent in this situation is

A) Trichinella spiralis
B) Trichomonas hominis
C) Trichophyton mentagrophytes
D) Trichosporon beigelii
E) Trichuris trichiura

Answer: A

 

(Year Posted: 2002 UI  852)

 

Key Code: F

Your patient complains of an "itching rash" on her abdomen. On examination, you find that the lesions are red, circular, with a vesiculated border and a healing central area. You suspect tinea corporis. 
Of the following, the MOST APPROPRIATE laboratory procedure to confirm the diagnosis is:

A) potassium hydroxide mount of skin scrapings
B) Giemsa stain for multinucleated giant cells
C) fluorescent-antibody stain of the vesicle fluid
D) 4-fold rise in antibody titer against the organism
E) RT-PCR for fungal DNA

Answer: A

 

(Year Posted: 2002 UI  853)

 

Key Code: F

Fungal cells that reproduce by budding are seen in the infected tissues of patients with which of the following groups of diseases:

A) blastomycosis, sporotrichosis, and coccidiomycosis
B) candidiasis, cryptococcosis, and sporotrichosis
C) mycetoma, candidiasis, and mucormycosis
D) tinea corporis, tinea unguium, and tinea versicolor
E) sporotrichosis, mycetoma, and aspergillosis

Answer: B

 

(Year Posted: 2002 UI  854)

 

Key Code: B

A 37 year old insulin dependent diabetic male presents to your primary care clinic complaining of a 6 week history of pain and ulceration in his right heel. In the last 2 weeks he has noticed a foul smelling discharge that is increasing in quantity. He is unable to weight-bear on that leg. Apart from his diabetes he has previously been well. He keeps a dog and 4 rabbits, works as an accountant, has no known allergies and takes no medication apart from insulin. On examination, he is afebrile (no fever), hemodynamically stable, with a 2x3cm ulcer covered with a purulent (pus filled) exudate. The ulcer appears to extend into the soft tissues of his heel. There are no other abnormal physical findings.
A Gram stain of the discharge reveals:

>25 PMNs per high power field
3+ Gram positive rods
3+ Gram negative rods
3+ Gram positive cocci, in pairs, chains and clusters

This is

A) unlikely to be an anaerobic infection because only Gram negative rods grow anaerobically
B) likely to be a mixed anaerobic and aerobic infection
C) likely to be an anaerobic infection because only anaerobes infect the feet
D) unlikely to be an anaerobic infection because such infections usually give off a characteristic grape-like smell
E) unlikely to be an anaerobic infection because the history is too long

Answer: B

 

(Year Posted: 2002 UI  855)

 

Key Code: B

The most efficient way to manage this man's problem is to:

A) send a wound swab for culture, and prescribe antibiotics to treat all organisms that grow
B) prescribe cephalexin (1st generation cephalosporin), orally
C) prescribe metronidazole, orally
D) arrange for surgical debridement (remove affected tissue), with collection of a bone biopsy for aerobic and anaerobic culture (if exposed bone is found at the ulcer base)
E) clean the wound and ask him to come back for re-assessment in one month

Answer: D

 

(Year Posted: 2002 UI  856)

 

Key Code: B

In which of the following clinical situations is continuous bacteremia common:

A) Occult, un-drained abdominal abscesses
B) Endoscopic manipulation of inflamed mucosal tissues
C) Diabetes
D) Infective endocarditis
E) Long term steroid use

Answer: D

 

(Year Posted: 2002 UI  857)

 

Key Code: B

The isolation of Clostridium septicum from the blood is highly associated with:

A) Long term antibiotic use resulting in selection for this highly resistant organism
B) Extended stays in the intensive care unit
C) IV drug abuse (shooters syndrome)
D) Porcine heart valve
E) Malignancy

Answer: E

 

(Year Posted: 2002 UI  858)

 

Key Code: V

You are asked to see a newborn baby delivered to an HIV infected woman. All of the following could be expected to be associated with an increase in the likelihood of maternal-fetal transmission EXCEPT:

A) High maternal viral load
B) Low maternal CD4 count
C) Duration of membrane rupture greater than 4 hours
D) Caesarian section delivery
E) Maternal acute seroconversion during pregnancy

Answer: D

 

(Year Posted: 2002 UI  859)

 

Key Code: V

Individuals have been identified who have been infected with HIV-1 for 10-15 years but who show no evidence of disease progression. Some of these so-called long-term non-progressors express elevated levels of MIP-1a, MIP-1b, and RANTES. These chemokines inhibit which step in virus replication?

A) Reverse transcription
B) Receptor binding
C) Transcription
D) Virus entry
E) Virus assembly

Answer: B

 

(Year Posted: 2002 UI  860)

 

Key Code: B

A 58 year old British man develops progressive cerebellar ataxia, profound cognitive loss and myoclonus (muscle contractions) over a period of weeks. There is no evidence of systemic infection or neoplasia. CT scan reveals mild cerebral atrophy and an EEG shows bilaterally synchronous sharp waves. The 14-3-3 immunoassay is positive. He dies 4 months after the onset of the illness. The most likely diagnosis is:

A) New variant CJD
B) Sporadic CJD
C) Iatrogenic CJD
D) Kuru
E) Fatal Familial Insomnia

Answer: B

 

(Year Posted: 2002 UI  861)

 

Key Code: F

A 23 year old female from Haiti is admitted with fever and decreased vision in her right eye. She had been diagnosed with AIDS one month ago, but was lost to follow up. She had a CD4 count of 3 and viral load of 197,000. She is currently on no medications. On physical exam she has retinal exudates in her right eye, heavy thrush and a large liver and spleen. He blood count demonstrates neutropenia, anemia, elevations of her alkaline phosphatase. The opthalmologist exam demonstrates retinitis, probably due to cytomegalovirus and suggests treatment. The bone marrow biopsy demonsrates acid fast bacilli. Which of the following should be done for this patient?

A) Therapy started with ganciclovir IV with close monitoring of neutropenia and abosolute neutrophil count
B) A skin test placed for tuberculosis (PPD), sputum cultures for acid fast bacilli
C) Treatment started for TB and MAC
D) Treatment for histoplasmosis
E) Discussion of a beginning highly active antiretroviral therapy (HAART) regiment

Answer: D

 

(Year Posted: 2002 UI  862)

 

Key Code: B

Which of the following predisposes to Pseudomonas aeruginosa infection?

A) Immunosuppression
B) Dehydration
C) Unprotected sex
D) Smoking
E) Anemia

Answer: A

 

(Year Posted: 2002 UI  863)

 

Key Code: M

Lysozyme treatment of bacteria which are suspended in a high osmotic pressure medium can be associated with all of the following, EXCEPT which one?

A) Rod shaped bacteria can round up to spheres
B) Protoplasts derived from Gram-positive organisms show most of the metabolic activities of the untreated cells
C) Addition of distilled water to the suspension results in cell death
D) Spheroplasts resulting from Gram-negative organisms will contain high Na+ and low K+ concentrations, like untreated bacteria
E) Lysozyme is an important defense mechanism produced by mammalian hosts

Answer: D

 

(Year Posted: 2002 UI  864)

 

Key Code: N

A 31-year old male presents to the clinic with burning urination and urethral pain. He admits to having had unprotected sexual contact with a prostitute before his return from a business trip to Thailand. Examination shows mucopurulent and slightly blood-tinged urethral discharge; normal testes and epididymis; no urinary retention. The discharge on gram smear revealed many intracellular diplococci associated with PMNs. How should this patient be treated?

A) Ampicillin & gentamicin
B) Trimethoprim & sulfamethoxzole
C) Penicillin V & doxycycline
D) Ceftriaxone & doxycyline
E) Penicillin G & erythromycin

Answer: D

 

(Year Posted: 2002 UI  865)

 

Key Code: B

A 59-year-old Caucasian male presents with a one-day history of high fever with rigors, pleuritic chest pain, and coughs producing green blood-flecked sputum. The patient lives in Minnesota, and has a history of congestive heart disease (CHD). Examination shows T: 39.9oC, R: 41/min, P: 118 beats/min, and BP: 88/53 mm Hg. His chest radiograph is remarkable with consolidation in the right middle lobe. Gram smear of sputum reveals lancet-shaped gram-positive cocci; sputum and blood cultures yields a significant (-hemolytic organism, sensitive to optochin. Which of the following microbial factors is the MOST LIKELY to have contributed to the pathogenesis of the disease?

A) Cell wall
B) Polysaccharide capsule
C) M-protein
D) Teichoic acid
E) Hemolysin

Answer: B

 

(Year Posted: 2002 UI  866)

 

Key Code: B

A 65-year-old male presents with a three-week history of fever, coughs, and weight loss. The patient, who resides in a nursing home, has poor oral hygiene and poorly controlled cough reflex due to head injury several months ago. Examination shows a sick-looking man with a foul-smelling breath; vital signs are: T: 39.9oC, P: 101/minute, R: 36/minute, and BP: 98/60. A chest x-ray shows a large cavity in the left mid lung with extensive surrounding inflammation. An anaerobic culture of sputum yields a filamentous gram-positive bacterium that is non-reactive to acid-fast stain. What is the most likely mode of this patient's infection?

A) inhalation of respiratory droplets from a sick room mate with similar disease
B) direct contact with discharges from a sick room mate with similar disease
C) inhalation of airborne organism from a sick room mate with similar disease
D) inhalation of airborne aerosol from the air entry duct in the room
E) aspiration of oral bacteria colonizing the upper respiratory tract

Answer: E

 

(Year Posted: 2002 UI  867)

 

Key Code: B

A 27-year-old man presents with chest pain, chills, fever, and dry cough of 10 days' duration. The patient has a history of bronchitis. Examination is remarkable with T: 39oC and R: 32/minute. Chest x-ray shows patchy infiltrates in the middle and lower lobes of the right lung. A Gram stain of the sputum shows very few polymorphonuclear white cells and no bacteria. A cold agglutinin test performed at the bedside turns positive. Which of the following is the most likely cause?

A) Mycoplasma pneumoniae
B) Bacillus anthracis
C) Francisella tularensis
D) Chlamydia pneumoniae
E) Legionella pneumophila

Answer: A

 

(Year Posted: 2002 UI  868)

 

Key Code: B

A 55-year-old male presents to the ER of a city hospital with high fever, chest pain, and shortness of breath. The patient is homeless and alcoholic. Examination shows T: 39.4oC, P: 95, R: 36, and BP: 100/58. Chest x-ray shows consolidation of the middle lobe of the right lung. A gram stain of suctioned sputum shows many PMNs, and predominantly gram-negative rods with a mixture of oral bacteria. Culture of sputum yields significant mucoid colonies that are oxidase-negative and lactose fermenting. What is the MOST LIKELY cause of this man's illness?

A) Pseudomonas aeruginosa
B) Klebsiella pneumoniae
C) Neisseria meningitidis
D) Moraxella catarrhalis
E) Haemophilus influenzae

Answer: B

 

(Year Posted: 2002 UI  869)

 

Key Code: B

A 4-month-old-girl has been gaining weight very slowly. On examination, the only other clinical abnormality is the finding of cloudy urine. The urine contains many white cells and serum protein. Radiological studies shows that the infant had reflux of urine from the bladder into the ureter and scarring of the pelvis of the left kidney. No obstruction is seen. What should be done to confirm the clinical diagnosis, and to initiate an appropriate therapy?

A) Urinalysis
B) Leukocyte esterase test of urine
C) Culture of urine and sensitivity
D) Urine antigen test
E) Gram stain of urine

Answer: C

 

(Year Posted: 2002 UI  870)

 

Key Code: N

A 9-week-old baby boy presents with a 5-day history of repetitive cough, choking spells, and vomiting of clear fluid. The patient's family lived in poor conditions in Chicago with six other young children. The vaccination schedule had been delayed due to febrile illness. Examination shows T: 38.3oC, P: 160/min and R: 32/min. Chest x-ray is clear. His white cell count is 15,000/mm3 with 70% lymphocytes. A selective culture of nasopharyngeal secretion is confirmed by direct immunofluorescence test. How should this patient be managed?

A) immediately administer antitoxin and vaccination
B) suction mucus and supportive care with pressurized oxygen
C) immediately administer aerosolised ribavirin
D) provide supportive care with humidified air
E) administer intravenous erythromycin

Answer: B

 

(Year Posted: 2002 UI  871)

 

Key Code: F

A 31-year-old African American male presents with a three-week history of headache, muscle ache, prolonged fever, mouth ulcers, increasing fatigue and weight loss. The patient moved recently from Seattle, Washington, to a small town beside the Ohio river, and spent one week cleaning a small hobby farm and cages that housed pigeons. Examination shows fever of 38.9oC, pallor, enlarged liver and spleen, generalized lymphadenopathy, and crackles throughout his lungs. His chest x-ray reveals infiltrates with nodular lesions over all lung fields. A punch biopsy of mouth lesion on silver stain shows small budding yeast. Which of the following is the MOST LIKELY cause of this man's illness?

A) Candida albicans
B) Blastomyces dermatidis
C) Coccidioides immitis
D) Histoplasma capsulatum
E) Cryptococccus neoformans

Answer: D

 

(Year Posted: 2002 UI  872)

 

Key Code: B

A 7-year-old female presents with itchy throat with pain, difficulty swallowing food, and moderate fever. The fully immunized patient has always been in good health. Examination is unremarkable except for a temperature of 38.4oC. A tonsillar aspirate yields positive direct antigen test, and on blood agar culture yields a significant bacterial isolate. Which of the following is the MOST LIKELY microbiological characteristic of the etiologic agent?

A) b-hemolytic gram-positive cocci in cluster, catalase-positive, penicillin sensitive
B) b-hemolytic gram-positive cocci in chains, catalase-negative, bacitracin sensitive
C) a-hemolytic gram-positive diplococci, catalase-negative, bile salt sensitive
D) a-hemolytic gram-positive cocci in chains, catalase-negative, optochin sensitive
E) g-hemolytic gram-positive cocci in chains, catalase-negative, high salt sensitive

Answer: B

 

(Year Posted: 2002 UI  873)

 

Key Code: V

A 15-year-old male presented with anxiety, difficulty breathing while speaking, left lower-quadrant abdominal pain, left leg pain, lower back pain, vague abdominal discomfort and an inability to eat. The patient was a citizen of Mexico who entered the United States three weeks before the current illness. He had a history of unprovoked dog attack in Mexico 40 days before the onset of illness. Examination showed conjunctivitis with vital signs: T: 35.7oC, P: 112/min. When offered water, he became anxious and hyperventilated. A head CT was normal. The patient died a few days later. How was the disease prevented in the contacts that included physicians, nurses, family, and friends?

A) oral acyclovir to all contacts
B) enhanced inactivated polio (eIPV) vaccine
C) rabies immunoglobulin and HDCV to all contacts
D) oral rifampin to all contacts
E) aerosolised ribavirin to all contacts

Answer: C

 

(Year Posted:UI  874)

 

Key Code: P

A 38-year-old male presents with a 3-day history of bloody diarrhea with mucus, tenesmus, and moderate fever. He returned from a trip to India a week prior to the onset of his illness. Examination is remarkable for a fever of 39.6oC. A CBC reveals leukocytosis with eosinophilic cells predominating. The ova & parasite test was positive for amebic trophozoites with internal RBCs. How should the patient be treated?

A) Metronidazole & iodoquinol
B) Sulfadiazine & pyrimethamine
C) Albendazole
D) Praziquantel
E) Trimethoprim & sulfamethoxazole

Answer: A

 

(Year Posted:UI  875)

Key Code: P

A 29-year old man, who was diagnosed with AIDS, presents with chronic, recurrent profuse, nonbloody, watery diarrhea. The diarrhea has recurred over the past two months with intermittent moderate cramping, and previous treatments have not been effective. The patient is moderately dehydrated. The patient has no travel history for the last two years. Lab test reveals 5um oocysts in the acid-fast stain of the stool sample. Which of the following is the MOST LIKELY cause of the man's illness?

A) Isospora belli
B) Giardia lamblia
C) Blastocystis hominis
D) Cyclospora cayetanensis
E) Cryptosporidium parvum

Answer: E

 

(Year Posted: 2002 UI  876)

 

Key Code: B

A 21 year-old female came to her physician complaining of a burning sensation upon urination. The urinalysis contained 3+ white cells with many bacteria seen. The urine culture revealed >100,000 colonies of a gram positive, catalase positive, coagulase negative cocci showing resistance to novobiocin. The etiologic agent of this UTI was:

A) Staph aureus
B) Staph epidermidis
C) Staph saprophyticus
D) Strep pyogenes
E) Enterococcus faecalis

Answer: C

 

(Year Posted: 2002 UI  877)

 

Key Code: B

A 25 year old man came to the clinic complaining of vomiting, diarrhea, and cramps. He had been to a picnic all afternoon in which food had set on the picnic table for several hours. He had eaten around 4 pm and symptoms appeared 5 hours later. Several other people attending the picnic also became ill. The only food eaten by all of those who became ill was ham. The MOST LIKELY cause of his food poisoning:

A) E. coli
B) S. aureus
C) C. jejuni
D) Salmonella
E) Clostridium perfringens

Answer: B

 

(Year Posted: 2002 UI  878)

 

Key Code: B

The vaginal culture of a pregnant woman revealed weakly beta hemolytic catalase negative gram positive cocci. The organism was resistant to bacitracin disk and had a positive CAMP test. The organism was:

A) Group A Strep
B) Group B Strep
C) Group C Strep
D) Group D Strep enterococcus
E) Group D Strep nonenterococcus

Answer: B

 

(Year Posted: 2002 UI  879)

 

Key Code: B

A dairy farmer ate whipped cream made from unpasteurized cream. Two days later he presented with foul-smelling diarrhea tinged with blood. The culture revealed curved gram-negative rods that grew under microaerophilic conditions at 42 degrees C. Name the organism:

A) E. coli
B) Shigella
C) Salmonella
D) Campylobacter jejuni
E) Staph aureus

Answer: D

 

(Year Posted: 2002 UI  880)

 

Key Code: B

A 27 year old man had an emergency appendectomy. After 3 days he spiked a 101 degree C fever and blood cultures were drawn. A gram positive coccus, catalase negative, bile esculin positive, 6.5% NaCl positive grew upon culture. The organism was:

A) Group A Strep
B) Group B Strep
C) Group C Strep
D) Group D Strep enterococcus
E) Group D Strep nonenterococcus

Answer: D

 

(Year Posted: 2002 UI  881)

 

Key Code: B

A 6 year-old boy was bitten by the family dog. His mother wasn't aware he had been bitten until the boy developed pain, erythema and swelling around the bitten area. The wound was gram-stained and cultured. The organism was a gram negative coccobacilli, oxidase positive, catalase positive. The organism did not grow on EMB. The organism MOST LIKELY belongs to this genus:

A) Hemophilus
B) Salmonella
C) Proteus
D) Neisseria
E) Pasteurella

Answer: E

 

(Year Posted: 2002 UI  882)

 

Key Code: B

A 3 year-old girl was admitted to the hospital with acute obstructive laryngeal edema. Her life was save by nasopharyngeal innntubation and aggressive antimicrobial therapy. Her diagnosis was epiglotitis. Blood cultures revealed a tiny pleomorphic gram negative rod that grew on chocolate agar. This organism was MOST LIKELY:

A) E. coli 0157:H7
B) Hemophilus influenzae type b
C) Pasteurella multocida
D) Virbio cholerae
E) Aeromonas hydrophilia

Answer: B

 

(Year Posted: 2002 UI  883)

 

Key Code: B

A 56 year-old alcoholic male came in with pneumonia. His pneumonia was destructive with extensive necrosis and hemorrhage. His sputum was a brick-red color. Culture revealed a non-motile gram-negative rod with a capsule, which formed pink colonies on MacConkeys medium. The MOST LIKELY organism would be:

A) E. coli
B) Enterobacter cloacae
C) Klebsiella pneumoniae
D) Proteus vulgaris
E) Hemophilus influenzae

Answer: C

 

(Year Posted: 2002 UI  884)

 

Key Code: B

A 40 year-old man was admitted with second and third degree burns on 20% of his body. On post-burn day 10 he developed a fever of 101 degrees C and his CBC showed marked leukocytosis. The burn wound was cultured revealing a pigmented gram-negative rod, oxidase positive, with a fruity odor. The genus and species of this organism was:

A) Pseudomonas aeruginosa
B) E. coli
C) Klebsiella pneumoniae
D) Proteus vulgaris
E) Helicobacter pylori

Answer: A

 

(Year Posted: 2002 UI  885)

 

Key Code: B

A 60 year-old cattleman came to the clinic with a black lesion on his forearm. The lesion began as a non-painful papule before it changed color. Culture revealed an aerobic gram-positive rod with endospores. The MOST LIKELY organism causing this infection:

A) Listeria monocytogenes
B) Clostridium perfringens
C) Clostridium tetani
D) Bacillus anthracis
E) Bacillus cereus

Answer: D

 

(Year Posted: 2002 UI  886)

 

Key Code: F

An archeologist who recently returned from excavations of ancient Indian ruins in Arizona presents with malaise, fever and a persistent productive cough. Examination of sputum reveals the presence of large (30 to 60 micron), thick-walled circular structures containing endospores. No hyphae or yeast cells are present in the sputum. Subsequent culture of the sputum results in the growth of an easily aerosolized fragmented mold. Based on these observations, you diagnose the disease as:

A) histoplasmosis
B) coccidioidomycosis
C) cryptococcosis
D) blastomycosis
E) sporotrichosis

Answer: B

 

(Year Posted: 2002 UI  887)

 

Key Code: F

Your patient complains of an "itching rash" on her abdomen. On examination, you find that the lesions are red, circular, with a vesiculated border and a healing central area. You suspect tinea corporis. Of the following choices, the MOST appropriate laboratory procedure to make the diagnosis is a:

A) Giemsa stain for multinucleated giant cells
B) potassium hydroxide mount of skin scrapings
C) fluorescent antibody stain of the vesicle fluid
D) four-fold rise in antibody titer against the organism
E) India Ink stain of cerebrospinal fluid

Answer: B

 

(Year Posted: 2002 UI  888)

 

Key Code: V

Each of the following statements correctly describes a distinctive characteristic of viruses EXCEPT:

A) Viruses are termed "filterable agents" because they pass through filters that retard bacteria and other cells
B) Viruses require living cells for replication
C) The viral genome may be comprised of DNA or RNA
D) Viruses provide their own ribosomes for protein synthesis
E) Viral infections are generally not sensitive to treatment with antibiotics

Answer: D

 

(Year Posted: 2002 UI  889)

 

Key Code: V

A 35-year-old man addicted to intravenous drugs has been a carrier of HBs antigen (HBsAg) for 10 years. He suddenly develops acute, fulminant hepatitis and dies within 10 days. A laboratory test for which of the following markers would contribute MOST to determining the cause of death?

A) antibody to HbsAg
B) HBe antigen
C) antibody to HbcAg
D) antibody to hepatitis delta virus antigen
E) antibody to HbgAg

Answer: D

 

(Year Posted: 2002 UI  890)

 

Key Code: V

A 20-year old college student presents with sore throat and lymphadenopathy accompanied by peripheral blood lymphocytosis with atypical cells and an increase in heterophile antibody. The MOST LIKELY diagnosis is:

A) influenza
B) infectious mononucleosis caused by Epstein-Barr virus
C) infectious mononucleosis caused by cytomegalovirus
D) infectious hepatitis caused by hepatitis A virus
E) an immunodeficiency disease of retroviral origin

Answer: B

 

(Year Posted: 2002 UI  891)

 

Key Code: N

You are donating blood to the local blood bank. The nurse screener asks you to complete a form indicating your possible risk factors for transmissible infectious agents. You answer all the questions in the negative, are approved, and then are relieved of 400 cc of whole blood. Your blood is later tested to assure that you have no detectable subclinical infections. Your blood will be screened for each of the following agents EXCEPT:

A) A lymphotropic agent with strong geographical and ethnic propensities, and with disease manifestations of spasms and/or malignancy after a long incubation period
B) An agent capable of transplacental transfer which produces a disease affecting in utero development of bones, teeth and cartilage
C) An agent with selective cell tropism, which during its in vivo progression may affect the central nervous system, causing distinctive pathological findings which are very different in brain and spinal cord, and produce clinical findings of dementia and lower extremity spasticity
D) Neurotropic agents that are resistant to treatment with DNase, RNase and boiling
E) Agents which are spread by blood and body fluids but are not concentrated in the bivalve mollusks

Answer: D

 

(Year Posted: 2002 UI  892)

 

Key Code: F

Pneumocystis carinii pneumonia is most classically characterized by

A) Fever, cough, dyspnea, and a dense lobar infiltrate
B) Acute onset of shortness of breath and a purulent cough
C) Cough, hypoxia, and an interstitial infiltrate on chest radiograph
D) Pleuritic chest pain, shortness of breath, and an elevated alkaline phosphatase
E) Fever, cough, dyspnea, and a CD4 count of 400

Answer: C

 

(Year Posted: 2002 UI  893)

 

Key Code: M

Causative organisms are initially introduced into hosts in the form of spores in all of the following diseases EXCEPT which one?

A) tetanus
B) gas gangrene
C) infant botulism
D) diphtheria
E) anaerobic cellulitis

Answer: D

 

(Year Posted: 2002 UI  894)

 

Key Code: B

An outbreak was reported in a day-care center where 60% of the children experienced bloody diarrhea, fever and nausea that lasted 2-6 days. White blood cells and mucus were seen in the stool specimens. An enteric Gram-negative bacillus was isolated from 80% of the stool specimens which was characterized as being lactose negative, non-gas producing, and non-motile. Which of the following organisms is the most likely cause?

A) Shigella sonnei
B) Salmonella enteritidis
C) Bacillus cereus
D) Vibrio cholerae
E) Escherichia coli

Answer: A

 

(Year Posted: 2002 UI  895)

 

Key Code: B

A 14 year-old boy who had been diagnosed with cystic fibrosis developed pneumonia. His sputum was positive for small Gram-negative pleomorphic organisms which grew on a chocolate agar plate, but failed to grow on blood agar. Which of the following is the most likely cause?

A) Pseudomonas aeruginosa
B) Neisseria meningitides
C) Pseudomonas cepacia
D) Haemophilus influenzae
E) Staphylococcus aureus

Answer: D

 

(Year Posted: 2002 UI  896)

 

Key Code: I

A three-year-old girl presents with persistent oral candida infection; she has a history of frequent bouts of diarrhea and she is in the bottom 5% of the weight range for her age. Based on these clinical findings, which of the following laboratory studies would be MOST useful in making a diagnosis?

A) T cell subpopulation enumeration and functional T cell tests
B) Serum Ig levels by class, plus measuring response to tetanus toxoid
C) Complement assessment by CH50 plus assessment of C3 level
D) Neutrophil studies (number and function)
E) Complete white blood cell count

Answer: A

 

(Year Posted: 2002 UI  897)

 

Key Code: I

A 10-year-old boy with a history of recurrent skin infections and 2 bouts of staphylococcal pneumonia is hospitalized for a staphylococcal abdominal abscess. Based on the clinical findings, which of the following laboratory studies would be MOST useful?

A) T cell numbers and function
B) Antibody studies
C) Complement assessment (CH50)
D) Neutrophil studies
E) IgA level

Answer: D

 

(Year Posted:UI  898)

 

Key Code: I

Which of the following reactions is most consistent with Type I (IgE-mediated) hypersensitivity to food?

A) Five minutes after drinking cows milk, a one-year-old boy vomits repeatedly, wheezes and develops an itchy skin rash.
B) A ten-year-old girl eats a fast food hamburger and develops shock 48 hours later
C) A 16-year-old male reproducibly develops diarrhea and bloating 4-6 hours after drinking milk
D) A 6-year-old starts vomiting within 3 hours of eating potato salad at the summer family reunion
E) A 3-year-old in daycare becomes repeatedly unruly and aggressive after snack time of graham crackers and milk.

Answer: A

 

(Year Posted:UI  899)

 

Key Code: I

An immediate hypersensitivity reaction to a given allergen involves all of the following EXCEPT?

A) Mast cells and/or basophils bearing IgE (Fc (R1) receptors
B) Release of pharmacologically active mediators
C) Antigen attachment to mast cell-bound IgE
D) Non-specific IgE bound to mast cells
E) Biologic responses including congestion, sneezing and urticaria

Answer: D

 

(Year Posted:UI  900)