Final Micro Flashcards by Andrea Whitley

1.	A 55-year-old man who is being treated for adenocarcinoma of the lung is admitted to a hospital because of a temperature of 38.9°C (102°F), chest pain, and a dry cough. Sputum is collected. Gram's stain of the sputum is unremarkable and culture reveals many small Gram-negative rods able to grow only on a charcoal yeast extract agar. Which of the following is the most likely organism?
A.  	Klebsiella pneumoniae
B. 	Mycoplasma pneumoniae
C. 	Legionella pneumophila
D. 	Chlamydia trachomatis
E. 	S. aureus

Legionella pneumophila

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Pathogenic mechanisms involved in tuberculosis can be primarily attributed to which of the following?
A. Toxin production by the mycobacteria
B. Specific cell adhesion sites
C. Cell-mediated hypersensitivity
D. Humoral immunity
E. Clogging of alveoli by large numbers of acid-fast mycobacteria

Cell-mediated hypersensitivity

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Parvovirus infection, the cause of a mild exanthem in children, is characterized by which of the following?
A.  	Epidemic acute respiratory disease
B. 	Gastroenteritis
C. 	Whooping cough–like disease
D. 	Keratoconjunctivitis
E. 	Acute hemolytic anemia

Acute hemolytic anemia

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Several antiviral compounds have been developed during the last decade. One such compound is ribavirin, a synthetic nucleoside structurally related to guanosine. Ribavirin therapy has been successfully used against which of the following?
A.  	Respiratory syncytial virus
B. 	Herpes simplex virus
D. 	Group A coxsackievirus
E. 	Parvovirus 
C. 	Hepatitis B

Respiratory syncytial virus

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5.	A patient presents with keratoconjunctivitis. The differential diagnosis should include infection with which of the following viruses?
A. 	Parvovirus
B. 	Adenovirus
C. 	Epstein-Barr virus
D. 	Respiratory syncytial virus
E. 	Varicella-zoster virus

Adenovirus

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A 21-year-old college student complained of malaise, low-grade fever, and a harsh cough, but not of muscle aches and pains. An x-ray revealed a diffuse interstitial pneumonia in the left lobes of the lung. The WBC count was normal. The student has been ill for a week.
Based on the information given, which of the following is the most likely diagnosis?
A. Mycoplasma pneumonia
B. Pneumococcal pneumonia
C. Staphylococcal pneumonia
D. Influenza
E. Legionellosis

Mycoplasma pneumonia

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A 34-year-old male patient visits a physician with complaints of fatigue, weight loss, night sweats, and “swollen glands.” The physician also observes that he has an oral yeast infection. Which of the following tests would most likely reveal the cause of his problems?
A. A test for CD8 lymphocytes
B. A human T-lymphotropic virus type I (HTLV-I) test
C. An HIV ELISA test
D. A test for infectious mononucleosis

An HIV ELISA test

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Which one of the following fungi is often isolated from blood, urine, and sputum in invasive disease? It is difficult to determine whether isolation from one body site or body fluid is suggestive of colonization or infection.
A.  	A. fumigatus
B. 	C. albicans
C. 	C. immitis
D. 	H. capsulatum
E. 	B. ranarum

C. albicans

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An ill patient denied being bitten by insects. However, he had spent some time in a milking barn and indicated that it was dusty. Of the following rickettsial diseases, which one has he most likely contracted?
A.  	Scrub typhus
B. 	Rickettsialpox
C. 	Brill-Zinsser disease
D. 	Q fever
E. 	Rocky Mountain spotted fever (RMSF)

Q fever

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Reverse transcriptase is an enzyme unique to the retroviruses. Which one of the following is a function of the enzyme reverse transcriptase?
A. DNase activity
B. RNA-dependent RNA polymerase activity
C. RNA isomerase activity
D. RNA-dependent DNA polymerase activity
E. Integration activity

RNA-dependent DNA polymerase activity

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Which of the following is the therapy of choice for pseudomembranous enterocolitis?
 A.  	Penicillin
B. 	Ampicillin
C. 	Erythromycin
D. 	Vancomycin
E. 	Ceftriaxone

Vancomycin

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A patient appeared in the emergency room with a submandibular mass. A smear was made of the drainage and a bewildering variety of bacteria were seen, including branched, Gram-positive rods. Which of the following is the most clinically appropriate action?
A. Do no further clinical workup
B. Suggest to the laboratory that low colony counts may reflect infection
C. Determine if fluorescent microscopy is available for the diagnosis of actinomycosis
D. Consider vancomycin as an alternative drug
E. Suggest a repeat antibiotic susceptibility test

Determine if fluorescent microscopy is available for the diagnosis of actinomycosis

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Recently, there have been sensational media reports of patients infected with invasive, "flesh-eating" bacteria that spread rapidly through the tissues. This necrotizing fasciitis is usually caused by which of the following?
 A.  	S. aureus
B. 	Group A streptococci
C. 	Micrococcus
D. 	Bacillus cereus
E. 	Clostridium tetani

Group A streptococci

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Acute hematogenous osteomyelitis is often diagnosed by isolation of the organism from the blood and is most often caused by which of the following?
 A.  	Proteus mirabilis
B. 	Streptococcus faecalis
C. 	Staphylococcus epidermidis
D. 	S. aureus
E. 	salmonella

S. aureus

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Cholera is a toxicogenic dysenteric disease common in many parts of the world. In the treatment of patients who have cholera, the use of a drug that inhibits adenyl cyclase would be expected to do which of the following?
 A.  	Kill the patient immediately
B. 	Eradicate the organism
C. 	Increase fluid secretion
D. 	Reduce intestinal motility
E. 	Block the action of cholera toxin

Block the action of cholera toxin

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A child comes to an emergency room because of an infected dog bite. The wound is found to contain small Gram-negative rods. Which of the following is the most likely cause of infection?
 A.  	E. coli
B. 	H. influenzae
C. 	Pasteurella multocida
D. 	Brucella canis
E. 	Klebsiella rhinoscleromatis

Pasteurella multocida

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An isolate from a wound culture is a Gram-negative rod identified as Bacteroides fragilis. Anaerobic infection with B. fragilis is characterized by which of the following?
A. A foul-smelling discharge
B. A black exudate in the wound
C. An exquisite susceptibility to penicillin
D. A heme-pigmented colony formation
E. Severe neurologic symptoms

A foul-smelling discharge

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There are millions of cases of Hansen’s disease worldwide, but predominately in Asia and Africa. The clinical spectrum of Hansen’s disease is best characterized by which of the following?
A. Immunologic anergy
B. Chronic pneumonitis
C. Peripheral neuritis
D. Bacilli in lesions that digest tissues
E. Erythematous lesions resembling concentric circles

Peripheral neuritis

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Which of the following is a double-stranded DNA virus and is responsible for 15% of pediatric respiratory infections and 10 to 15% of acute diarrhea in children?
 A.  	Measles virus
B. 	Influenza virus
C. 	Respiratory syncytial virus
D. 	Parainfluenza virus
E. 	Adenovirus

Adenovirus

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Eastern equine encephalitis virus is associated with a high fatality rate. Control of the disease could be possible by eradication of which of the following species?
 A.  	Horses
B. 	Birds
C. 	Mosquitoes
D. 	Fleas
E. 	Ticks

Mosquitoes

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Infection with hepatitis D virus (HDV; delta agent) can occur simultaneously with infection with hepatitis B virus (HBV) or in a carrier of hepatitis B virus because HDV is a defective virus that requires HBV for its replicative function. What serologic test can be used to determine whether a patient with HDV is an HBV carrier?
A.  	HBsAg
B. 	HBc IgM
C. 	HBeAg
D. 	HBs IgM
E. 	HBs IgG

HBc IgM

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A 3-year-old child presents at the physician’s office with symptoms of coryza, conjunctivitis, low-grade fever, and Koplik’s spots. The causative agent of this disease belongs to which group of viruses?
 A.  	Adenovirus
B. 	Herpesvirus
C. 	Picornavirus
D. 	Orthomyxovirus
E. 	Paramyxovirus

Paramyxovirus

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A 28-year-old menstruating woman appeared in the emergency room with the following signs and symptoms: fever, 104°F (40°C); WBC, 16,000/ L; blood pressure, 90/65 mmHg; a scarlatiniform rash on her trunk, palms, and soles; extreme fatigue; vomiting; and diarrhea.
Which of the following is the most likely diagnosis?
A. Scalded skin syndrome
B. Toxic shock syndrome
C. Guillain-Barré syndrome
D. Chicken pox
E. Staphylococcal food poisoning

Toxic shock syndrome

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A 70-year-old female patient was readmitted to a local hospital with fever and chills following cardiac surgery at a major teaching institution. Blood cultures were taken and a Gram-positive coccus grew from the blood cultures within 24 hours. Initial tests indicated that this isolate was resistant to penicillin. Which of the following is the most likely identification?
 A.  	Streptococcus pneumoniae
B. 	Neisseria
C. 	Group A streptococcus
D. 	Enterococcus
E. 	Group B streptococcus

Enterococcus

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``` Reactive cold agglutinins suggests which one of the following diseases? A. Chronic infectious mononucleosis B. Primary syphilis C. Scarlet fever D. Primary atypical pneumonia E. Immunity to rubella (German measles) ```

Primary atypical pneumonia

The mechanism of mucosal invasion by C. albicans is at least partially understood. Which one of the following modifications in the structure or function of this yeast would be most likely to affect its invasive ability? A. Loss of ability to produce ethanol from glucose B. Loss of ability to produce germ tubes or hyphae C. Reduced ability to grow at 37°C D. Loss of ability to produce a polysaccharide capsule E. Replacement of mannans in the cell wall with glucan

Loss of ability to produce germ tubes or hyphae

``` A 6-year-old girl presents to the clinic with scaly patches on the scalp. Primary smears and culture of the skin and hair were negative. A few weeks later, she returned and was found to have inflammatory lesions. The hair fluoresced under Wood's light and primary smears of skin and hair contained septate hyphae. On speaking with the parents, it was discovered that there were several pets in the household. Which of the following is the most likely agent? A. Microsporum audouinii B. Microsporum canis C. Trichophyton tonsurans D. Trichophyton rubrum E. Epidermophyton floccosum ```

Microsporum canis

``` Which of the following is the causative agent of lymphogranuloma venereum? A. B. (Rochalimaea) henselae B. E. chaffeensis C. C. trachomatis D. R. rickettsii E. C. burneti ```

C. trachomatis

``` A man with chills, fever, and headache is thought to have "atypical" pneumonia. History reveals that he raises chickens and that approximately 2 weeks ago he lost a large number of them to an undiagnosed disease. Which of the following is the most likely diagnosis of this man's condition? A. Anthrax B. Q fever C. Relapsing fever D. Leptospirosis E. Ornithosis ```

Ornithosis

``` Certain enzymes catalyze the cross-linking of peptidoglycan, a unique constituent of bacterial cell walls. Which of the following may be a factor in antibiotic resistance, the target of which is cell-wall synthesis? A. Bactoprenol B. Reverse transcriptase C. RNA polymerase D. DNA gyrase E. Penicillin-binding proteins (PBPs) ```

Penicillin-binding proteins (PBPs)

``` A 2-year-old infant is brought to the emergency room with hemolytic uremic syndrome and thrombocytopenia. Which one of the following bacteria would most likely be isolated from a stool specimen? A. Shigella B. Salmonella C. Aeromonas D. E. coli 0157/H7 E. Enterobacter ```

E. coli 0157/H7

``` An inhibitor was designed to block a biologic function in H. influenzae. If the goal of the experiment was to reduce the virulence of H. influenzae, which of the following would be the most likely target? A. Exotoxin liberator B. Endotoxin assembly C. Flagella synthesis D. Capsule formation E. IgA protease synthesis ```

Capsule formation

A man who has a penile chancre appears in a hospital's emergency service. The VDRL test is negative. Which of the following is the most appropriate course of action? A. Send the patient home untreated B. Repeat the VDRL test in 10 days C. Perform dark-field microscopy for treponemes D. Swab the chancre and culture on Thayer-Martin agar E. Perform a Gram stain on the chancre fluid

Perform dark-field microscopy for treponemes

``` A patient with a peptic ulcer was admitted to the hospital and a gastric biopsy was performed. The tissue was cultured on chocolate agar incubated in a microaerophilic environment at 37°C for 5 to 7 days. At 5 days of incubation, colonies appeared on the plate and were curved, Gram-negative rods, oxidase-positive. Which of the following is the most likely identity of this organism? A. Campylobacter jejuni B. Vibrio parahaemolyticus C. Haemophilus influenzae D. Helicobacter pylori E. Campylobacter fetus ```

Helicobacter pylori

``` An infant, seen in the ER, presents with a fever and persistent cough. Physical examination and a chest x-ray suggest pneumonia. Which of the following is most likely the cause of this infection? A. Rotavirus B. Adenovirus C. Coxsackievirus D. Respiratory syncytial virus E. Rhinovirus ```

Respiratory syncytial virus

``` Which marker or markers is present on cells which belong to lymphoid series that are important in innate immunity and could be used to specifically identify such cells in a flow cytometric analyzer? A. CD 3 and CD4 B. CD 3 and CD8 C. CD 14 and CD 38 D. CD 16 and CD 56 E. CD 19 and CD 20 ```

CD 16 and CD 56

A superantigen is a bacterial product that A. binds to B7 and CD28 costimulatory molecules B. binds to the beta chain of TCR and MHC class II molecules of APC stimulating T cell activation C. binds to the CD4 + molecule causing T cell activation D. is presented by macrophages to a larger-than-normal number of T helper CD4 + lymphocytes E. stimulates massive amounts of IgG synthesis because of its large size

binds to the beta chain of TCR and MHC class II molecules of APC stimulating T cell activation

Cytotoxic T cells induced by infection with virus A will kill target cells A. from the same host infected with any virus B. infected by virus A and identical at class I MHC loci to the cytotoxic T cells C. infected by virus A and identical at class II MHC loci to the cytotoxic T cells D. infected with any virus and identical at class I MHC loci to the cytotoxic cells E. infected with any virus and identical at class II MHC loci to the cytotoxic cells

infected by virus A and identical at class I MHC loci to the cytotoxic T cells

Antigen recognition by the helper T-cell antigen receptor occurs after A. Interaction with the CD8 molecule on the T cell B. Peptide binding to the HLA-DQ molecule C. Carbohydrate binding to the HLA-B27molecule D. Carbohydrate binding to the HLA-DP molecule E. Peptide binding to the HLA-B27molecule

Peptide binding to the HLA-DQ molecule

``` Functions of the thymus include all the following except A. Elimination of T cells that have low affinity for MHC class I molecules. B. Elimination of T cells that have high affinity for MHC class II molecules. C. Stimulation of T cells that have low affinity for MHC class I molecules. D. Stimulation of T cells that have low affinity for MHC class II molecules. ```

Elimination of T cells that have high affinity for MHC class II molecules.

``` IgG2 and IgA2 are examples of different A. Idiotypes B. Allotypes C. Genotypes D. Isotypes ```

Isotypes

``` A 12-year-old child is diagnosed with a T-cell lymphoma. The phenotype of the malignant cell matches that of normal progenitor cells that leave the bone marrow to enter the thymus. What cell surface molecules would you expect to find on the malignant cells? A. CD4-,CD8-, TCR-,CD3+ B. CD4-,CD8-, TCR+,CD3- C. CD4+,CD8+, TCR+,CD3+ D. CD4-,CD8-, TCR-,CD3- E. CD4+,CD8+, TCR+,CD3- ```

CD4-,CD8-, TCR-,CD3-

Which one of the following is correct about an IgG immunoglobulin molecule? A. The constant heavy 2 domain binds to Cl complement molecules. B. The constant heavy 1domain binds to antigen epitopes. C. The variable light domain binds to cell receptors on cell membranes. D. The constant heavy 3 domain binds to antigen epitopes. E. The variable light domain binds to J chains

The constant heavy 2 domain binds to Cl complement molecules.

``` An active inflammatory reaction is occurring, and large numbers of neutrophils are being attracted to the inflammation site. Which one of the following is a major chemotactic factor involved in this reaction? A. IL-2 B. IgM C. C5a D. C3b E. Lysozyme ```

C5a

``` Complement binding site A. A B. B C. C D. D E. E ```

A 34-year-old kidney transplant patient currently on immunosuppressants complains of shortness of breath and coughing. Physical exam reveals fever and abnormal lung sounds while chest x-ray indicates interstitial infiltrates in the lungs. No cysts are detected on silver stain of bronchoalveolar lavage fluid, ruling out Pneumocysitic carinii infection. The doctor makes a diagnosis after viewing a sample of the patient’s lung tissue, which shows abnormal giant cells. Which of the following is the mostly likely cause? a) Herpes simplex type 1 (HSV-1) b) Herpes simplex type 2 (HSV-2) c) Varicella-zoster virus (VZV) d) Epstein-Barr virus (EBV) e) Cytomegalovirus (CMV) f) Herpes lymphotropic virus (HHV-6) and Human herpesvirus 7 (HHV-7) g) Kaposi sarcoma-related virus (HHV-8)

Cytomegalovirus (CMV)

A 55-year-old man is hospitalized for a recent onset of high fever, headaches, and sporadic sensations of smelling sausages. Physical exam reveals neck stiffness, prompting the physician to perform a lumbar puncture. CSF values indicate elevated lymphocytes, elevated proteins, and normal glucose. A CT image confirms encephalitis localized to the temporal lobes. A diagnosis is confirmed by PCR of the CSF. The physician begins treatment with acyclovir and informs the patient that he may suffer permanent neurological abnormalities from the infection. Which of the following is the mostly likely cause? a) Herpes simplex type 1 (HSV-1) b) Herpes simplex type 2 (HSV-2) c) Varicella-zoster virus (VZV) d) Epstein-Barr virus (EBV) e) Cytomegalovirus (CMV) f) Herpes lymphotropic virus (HHV-6) and Human herpesvirus 7 (HHV-7) g) Kaposi sarcoma-related virus (HHV-8)

Herpes simplex type 1 (HSV-1)

The influenza vaccine (killed, formulin-inactived) is available annually and contains the most likely strain(s) to be present for the upcoming season. How many strains of influenza are included in common vaccinations? a) 1 b) 3 c) 5 d) Tens e) Hundreds

``` A 26-year-old HIV-positive woman is brought into the emergency room after she is found lying unresponsive in the street. She has no recollection of what had occurred. She reports sensing a smell "like burning hair" and then blacking out. A medical history reveals that she has had a fever and a headache for the past week. An MRI of the brain shows multiple ring-enhancing lesions. Which of the following is the most likely cause of her symptoms? A. Cryptococcus neoformans B. Cryptosporidium C. Cytomegalovirus D. Pneumocystis carinii E. Toxoplasma gondii ```

Toxoplasma gondii

A student cuts short an extended backpacking trip in Yosemite Park after developing diarrhea. He explains to his doctor that the diarrhea is non-bloody but smells very bad. On further questioning, the student tells his doctor that he has been drinking water from a fresh water spring. The patient appears malnourished on physical exam. A diarrhea sample reveals 2-nuclei motile ameba with tear-drop shape and 4 pairs of flagella. The patient is given metronidazole. Which of the following is most likely? a) Isospora belli b) Cryptosporidium parvum c) Cyclospora cayetanensis d) Entamoeba histolytica e) Giardia lamblia f) Balantidium coli

Giardia lamblia

An 18-year-old male patient appeared at the emergency room with a 3-day history of fever, dry cough, difficulty breathing, and muscle aches and pains. His chest x-ray showed a diffuse left upper lobe infiltrate. Which of the following is the most sensitive method for diagnosis of Legionnaires' disease? A.Detection of specific antigen in urine B.Cold agglutinin test C.Electron microscopy of sputum D.Detection of antigen in respiratory secretions E.Culture of respiratory secretions on a charcoal-based nutrient agar

E.Culture of respiratory secretions on a charcoal-based nutrient agar

An AIDS patient becomes ill days after a picnic in a park. The patient remembers moving to a new picnic location after finding several pigeon droppings. Amphotericin B is started after completing a hospital-required process for administering the drug. Which of the following is the most likely cause? a) Cryptococcus neoformans b) Haemophilus influenzae c) Mycobacterium tuberculosis d) Aspergillus species e) Histoplasma capsulatum

a) Cryptococcus neoformans

A patient has fever, malaise, rhinorrhea, and conjunctivitis for several days and thinks he has come down with the common cold. A few days later, he develops small, punctate, bluish-white dots on a red base on his tongue and this is followed by a maculopapular rash starting on face and spreading to torso and limbs. Which of the following is the most likely diagnosis? A. Infection with a highly contagious, single-stranded RNA paramyxovirus B. Infection with a tick-borne disease caused by Rickettsia rickettsii C. Infection with a togavirus with an inner icosahedral capsid of RNA with an outer lipid envelope D. Infection with a double-stranded DNA variola virus E. Infection with Staphylococcus aureus and secondary relase of toxins

A. Infection with a highly contagious, single-stranded RNA paramyxovirus

An ill patient denied being bitten by insects. However, he had spent some time in a milking barn and indicated that it was dusty. Of the following rickettsial diseases, which one has he most likely contracted? A. Scrub typhus (mite larvae, rats, shrew, mongooses, birds) B. Rickettsialpox C. Brill-Zinsser disease (rickettsia prowzeki) D. Q fever (get it from cattle, sheep and goats) E. Rocky Mountain spotted fever (RMSF)

D. Q fever (get it from cattle, sheep and goats)

A Mexican man complains to his doctor of worsening constipation and stomach pains. On physical exam, the doctor is surprised to find an enlarged heart on auscultation and moderate arrhythmia. An abdominal x-ray reveals megacolon. Head exam reveals unilateral periorbital swelling (Romaña sign, chagoma). The clinician explains there is no chronic treatment. What is the transmission vector involved (American trypanosomiasis)? a) Reduviid bug b) Aedes aegypti mosquito c) Phlebotomous sand fly d) Lutzomyia sand fly e) Tsetse fly

a) Reduviid bug

``` A one-month-old infant with no past medical history, normal gestation and delivery is brought to the hospital in cardiogenic shock. A viral infection is suspected for the acute heart failure. Which of the following viruses is the most likely culprit? A. Coxsackie Virus B B. Herpes Simplex Virus 2 C. Respiratory Syncytial Virus D. Rotavirus E. Rubella ```

E. Rubella

``` A 21-year-old college student complained of malaise, low-grade fever, and a harsh cough, but not of muscle aches and pains. An x-ray revealed a diffuse interstitial pneumonia in the left lobes of the lung. The WBC count was normal. The student has been ill for a week. Based on the information given, which of the following is the most likely diagnosis? A. Mycoplasma pneumonia B. Pneumococcal pneumonia C. Staphylococcal pneumonia D. Influenza E. Legionellosis ```

A. Mycoplasma pneumonia

After a camping trip to Mexico, a patient visits her doctor complaining of loose stools and abdominal cramps. The patient describes the stools as having flecks of blood and lots of mucus. The doctor orders a stool specimen in which she finds motile ameba with ingested RBCs. She starts the patient on metronidazole and considers a CT scan to detect any liver abscesses. Which of the following is most likely? a) Isospora belli b) Cryptosporidium parvum c) Cyclospora cayetanensis d) Entamoeba histolytica e) Giardia lamblia f) Balantidium coli

d) Entamoeba histolytica

``` A 42 year old woman who was complaining of shaking chills and fever went to the Salt Lake City Homeless clinic. She had enlarged lymph nodes in the right axilla. "Upstream" from the enlarged nodes was an ulcer on the top of the patient's right hand. When carefully questioned, the patient said she remembered being bitten there by an insect resembling a horsefly, but with yellow stripes on its abdomen; "Its what we used to call a deerfly," she added laconically. The patient denied any contact with rats or fleas. The patient's disease was most likely to be: A. Brucellosis B. Ulcero-glandular tularemia C. Pneumonic plague D. Relapsing fever ```

B. Ulcero-glandular tularemia

A 2-year-old child experiences a rapid onset of high fever that lasts for 3 days and then suddenly returns to normal. Two days later, a maculopapular rash appears on the trunk and spreads to other parts of the body. Which of the following is the most likely cause? a) Herpes simplex type 1 (HSV-1) b) Herpes simplex type 2 (HSV-2) c) Varicella-zoster virus (VZV) d) Epstein-Barr virus (EBV) e) Cytomegalovirus (CMV) f) Herpes lymphotropic virus (HHV-6) g) Kaposi sarcoma-related virus (HHV-8)

f) Herpes lymphotropic virus (HHV-6)

``` A 16-year-old girl was admitted to a New Mexico hospital because of hypotension, cyanosis, high fever (39.9°C), and bilateral, nonfluctuant, inguinal, and axillary lymphadenopathy. The patient died the same day. Blood cultures obtained on admission were positive for bipolar-staining, short, gram-negative bacilli. What is the most probable etiologic agent? A. Yersinia pestis B. Brucella abortus C. Klebsiella rhinoscleromatis D. Francisella tularensis ```

A. Yersinia pestis

15. A student cuts short an extended backpacking trip in Yosemite Park after developing diarrhea. He explains to his doctor that the diarrhea is non-bloody but smells very bad. On further questioning, the student tells his doctor that he has been drinking water from a fresh water spring. The patient appears malnourished on physical exam. A diarrhea sample reveals 2-nuclei motile ameba with tear-drop shape and 4 pairs of flagella. The patient is given metronidazole. Which of the following is most likely? a) Isospora belli b) Cryptosporidium parvum c) Cyclospora cayetanensis d) Entamoeba histolytica e) Giardia lamblia f) Balantidium coli

e) Giardia lamblia

16. A sexually active woman develops dysuria, pyuria, and fever suggestive of urinary tract infection. Urine cultures show G+ bacteria in clusters that are catalase positive and coagulase negative. E. Coli is ruled out as a cause of the cystitis. Which of the following would be the most likely cause of the cystitis? a) Viridans Streptococci b) Streptococcus pyogenes c) Staphylococcus aureus d) Staphylococcus epidermidis e) Staphylococcus saprophyticus

e) Staphylococcus saprophyticus

17. A man with fever, muscle pains, and headache feels no need to go to the doctor until about 1 day later, when he develops bloody diarrhea and abdominal pain as well. The abdominal pain is so severe that his physician fears appendicitis until learning that the man may have had unpasteurized milk in the past week. A definitive diagnosis is made by growth on stool cultures at 42ºC, microaerophilic conditions. Which of the following is the most likely cause? a) ETEC b) C. jejuni c) Rotovirus d) H. pylori e) S. aureus

b) C. jejuni

e) Cytomegalovirus (CMV)

a) Herpes simplex type 1 (HSV-1)

``` A 30-year-old female stored her contact lenses in tap water. She noticed deterioration of vision and visited an ophthalmologist who diagnosed her with severe retinitis. Culture of the water as well as vitreous fluid would most likely reveal which of the following organisms? A. Naegleria B. Pneumocystis C. Acanthamoeba D. Babesia E. Entamoeba coli ```

C. Acanthamoeba

``` A 9 year old girl presents with 2 days of sore throat and fevers of 102ºF. Physical exam reveals an erythematous pharynx with a white, creamy exudate covering the left tonsil. Palpation of the neck reveals an extremely tender left submandibular lymph node. Throat cultures were taken and reveal beta-hemolytic colonies on blood agar. Susceptibility analysis show growth is not inhibited by amoxicillin, and erythromycin. Growth is inhibited by bacitracin. Which of the following is the mostly likely causal organism? A. Rhinovirus B. Streptococcus pyogenes C. Streptococcus agalactiae D. Epstein-Barr virus E. Candida albicans ```

B. Streptococcus pyogenes

``` A 23 year old sexually active woman presents with a right upper quadrant pain of one day duration. Her pelvic exam is remarkable for purulent vaginal discharge and cervical motion tenderness. Speculum exam reveals a greening material coming out of a reddened cervix. What is the explanation of her RUQ pain? A. peri hepatitis B. Choledocholithiasis C. Cholelithiasis D. Pyelonephritis E. Bacterial vaginosis ```

A. peri hepatitis

``` A 24-year-old male with a history of Sickle Cell disease presents to your office complaining of pain in his arms and legs of 12 hours duration. Laboratory tests identify that this patient is experiencing severe anemia. PCR tests demonstrate infection by a single stranded small DNA virus. This virus may also cause which of the following syndromes: A. Burkitt’s Lymphoma B. Erythema Infectiosum C. Molluscum Contagiosum D. Smallpox E. Yellow Fever ```

B. Erythema Infectiosum

``` A 16-year-old boy presents to you complaining of throat pain and malaise for the last week. His exam is significant for multiple palpable anterior cervical lymph nodes and tonsillar swelling. Three days ago his mother gave him leftover amoxicillin from a previous bacterial infection, and he subsequently developed a morbilliform, papular rash over his face, neck and trunk. Which of the following is the most likely cause of his symptoms? A. Coxsackie A virus B. Epstein-Barr virus C. Group A streptococcus D. Group B streptococcus E. Measles virus ```

E. Measles virus

A neonate presents with classic signs of meningitis. Lumbar puncture is clear and shows increased lymphocytes, slightly increased protein, and normal glucose. Which of the following is most likely? a) Streptococcus agalactiae b) Respiratory synceseal virus c) Listeria monocytogenes d) HSV-1 e) HSV-2

a) Streptococcus agalactiae

A 2-year-old boy has surgery to correct a urinary tract obstruction. Post-operatively, with an indwelling urinary catheter in place, he develops a urinary tract infection. Urine culture grows out a lactose-negative, oxidase-negative, gram-negative rod. Which of the following agents is the most likely cause of this boy's urinary tract infection? A. Candida albicans B. Enterococcus faecalis C. Escherichia coli D. Klebsiella pneumoniae E. Proteus mirabilis F. Pseudomonas aeruginosa G. Staphylococcus saprophyticus

F. Pseudomonas aeruginosa

A previously healthy, 24-year-old Mexican immigrant is brought to an emergency room in Los Angeles because of seizures. A CAT scan reveals a solitary calcified lesion, 2 cm in diameter, in the right cerebral hemisphere. What is the most probable diagnosis? A. Central nervous system coccidioidomycosis B. Cerebral cysticercosis C. Cerebral echinococcosis D. Extraintestinal amebiasis

B. Cerebral cysticercosis

``` A previously healthy 18-month-old girl is brought to the office with 2 days of irritability, poor appetite, and pulling at her left ear. She has no known allergies, and her vaccinations are up-to-date. On examination, the child's temperature is 102.8 F. She is easily consoled by the mother and moves her neck spontaneously without discomfort. There is a clear discharge from the nares. The left tympanic membrane is erythematous, dull, and bulging. Which of the following virulence factors is generally absent in the strains of the causative organism tha produce otitis media, compared with those that produce epiglottitis or meningitis? A. β-Lactamase B. IgA protease C. Lipopolysaccharide D. Nonpilus adhesins E. Pili F. Pneumolysin G. Polyribitol phosphate ```

G. Polyribitol phosphate

A box of ham sandwiches with mayonnaise prepared by a person with a boil on his neck was left out of the refrigerator for the on-call interns. Three doctors became violently ill approximately 2 h after eating the sandwiches. Which of the following is the most likely cause? A. S. aureus enterotoxin B. Coagulase from S. aureus in the ham C. S. aureus leukocidin D. C. perfringens toxin E. Penicillinase given to inactivate penicillin in the pork

A. S. aureus enterotoxin

Taenia saginata and Taenia solium are similar in many ways, but Taenia solium is more dangerous. Which of the following makes T. solium more dangerous? A. It has an armed scolex B. It has fewer uterine branches than T. saginata C. Man can be infected as an intermediate host by eating the eggs from T. solium D. The cyst or larvae form ingested from pork is more potent than the cyst from beef E. It produces more eggs than T. saginata

C. Man can be infected as an intermediate host by eating the eggs from T. solium

``` A 42-year-old wig manufacturer returned 5 days ago from Iran where he was inspecting herds for raw material. He had initially experienced only mild upper respiratory tract symptoms, but 2 days later was brought to the emergency room with fever, severe dyspnea, cyanosis, and tachycardia. Blood cultures were drawn and after 16 hours of incubation, the smears revealed large, gram-positive rods with subterminal spores. The organism was nonhemolytic on blood agar and nonmotile. What is the most probable identity of this organism? A. Clostridium dificilli B. Bacillus anthracis C. Clostridium perfringens D. Bacillus subtilis ```

B. Bacillus anthracis

An old man and his great-grandson visit Death Valley National Park in the deserts of southern California. Upon returning from their visit, the man develops breathing difficulties along with arthralgias, periarticular swellings, and erythema nodosum. X-rays reveal a pneumonic infiltrate as well as granulomas. A diagnosis is confirmed by observing spherules containing individual endospores in tissue specimens. As expected, the child remains unaffected but several weeks later tests positive for a fungal antigen DTH reaction. Which of the following is most likely? a) Histoplasma capsulatum b) Coccidioides immitis c) Paracoccidioides brasiliensis d) Blastomyces dermatitidis e) Cryptococcus neoformans

b) Coccidioides immitis

``` A 30-year-old patient comes to clinic complaining of a three-week history of cough. He started with a runny nose, fever and sneezing for a few days followed by a dramatic cough that keeps him up at night. He complains of episodes of coughing where he will have "fits" of coughing with 10-15 coughs during one exhalation to the point that he is afraid that he will never be able to take in a breath. These coughing episodes are so severe that his ribs are extremely sore. An organism you should consider would be: A. Staph aureus B. Tuberculosis C. Bordetella pertussis D. Haemophilus influenza ```

C. Bordetella pertussis

A patient presents with “eye problems” several days after swimming in a lake. Satellite lesions are seen in the left eye. Culture reveals filamentous fungi that branch at 45-degree angles. Which of the following is the most likely? a) Coccidioides immitis b) Fusarium species c) Aspergillus species d) Naegleria fowleria e) Acanthamoeba species

c) Aspergillus species

``` A 30 year old male comes to the hospital complaining of "stiffness". He was fine until 2 days ago when he started to have trouble opening his mouth. Later the same day his neck became stiff, and since then he has had increasing trouble with respirations. On exam he has a temperature of 101 degrees, his pulse is 110, his respirations are shallow and at 24/minute. His blood pressure the first time taken by a nurse was 90/50, but now is 120/80. He appears flushed and is sweating profusely. He does appear quite rigid and his face appears to be in a grimace. His reflexes are all hyperactive. You should be worried that this patient has: A. Food borne botulism B. Tetanus C. Gram negative sepsis D. Toxin mediated food poisoning ```

B. Tetanus

A 65-year-old Laotian immigrant has developed thick, erythematous nodules on her ears and nose with significant associated sensory loss. The nodules have grown slowly over the course of many years. Biopsy of the lesions shows dermal granulomas with giant cells but no acid-fast bacteria. Culture on blood agar and Lowenstein-Jensen medium shows no growth. These findings are most consistent with which of the following diagnoses? A. Cutaneous leishmaniasis B. cuteneous nocardiasis C. scaled skin syndrome D. Smallpox E. Tuberculoid leprosy

E. Tuberculoid leprosy

Which of the following would be transmitted mainly by cats (e.g. litter boxes) but can also be caused by undercooked meat and is associated with ring-enhancing lesions on CT scan of the head? a) Malaria b) Babesiosis c) Lyme disease d) Toxoplasmosis e) Aspergillosis

d) Toxoplasmosis

``` A 70-year-old female patient was readmitted to a local hospital with fever and chills following cardiac surgery at a major teaching institution. Blood cultures were taken and a Gram-positive coccus grew from the blood cultures within 24 hours. Initial tests indicated that this isolate was resistant to penicillin.Which of the following is themost likely identification? A. Streptococcus pneumoniae B. Neisseria C. Group A streptococcus D. Enterococcus E. Group B streptococcus ```

D. Enterococcus

An 18-year-old male patient appeared at the emergency room with a 3-day history of fever, dry cough, difficulty breathing, and muscle aches and pains. His chest x-ray showed a diffuse left upper lobe infiltrate. Mycoplasma pneumoniae pneumonia (walking pneumonia) may be rapidly identified by which of the following procedures? A. Detection of specific antigen in urine B. Cold agglutinin test C. Electron microscopy of sputum D. Culture of respiratory secretions in HeLa cells after centrifugation of the inoculated tubes E. Culture of respiratory secretions on monkey kidney cells

D. Culture of respiratory secretions in HeLa cells after centrifugation of the inoculated tubes

An active intravenous drug abuser presents to the emergency department with fever of 5 days' duration, a cough occasionally productive of blood, and pleuritic chest pain with heart murmur. Petechiae are present in his mouth and skin ,and splinter hemorrhages are visible under the fingernails. Which of the following test results would most likely confirm the identity of the causative agent? A. Antibodies to p24 capsid antigen B. Antibodies to Trichinella spiralis antigen C. Blood culture of a catalase-positive, novobiocin-sensitive, gram-positive coccus D. Blood culture of a coagulase-positive, catalase positive, gram-positive coccus E. Blood culture of a gamma-hemolytic, gram-positive coccus on bile-esculin agar F. Blood culture of an alpha-hemolytic, optochin-resistant, gram-positive coccus G. Blood culture of an alpha-hemolytic, optochin-sensitive, gram-positive coccus

D. Blood culture of a coagulase-positive, catalase positive, gram-positive coccus

Final Micro Flashcards

(87 cards)