USMLE : Microbiology Hardest Test! Trivia Quiz

25 Questions | Total Attempts: 703

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USMLE : Microbiology Hardest Test! Trivia Quiz

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Questions and Answers
  • 1. 
    A 28-year-old male intravenous drug user presents with a febrile illness that has lasted 2 weeks. He also complains of chills, weakness, dyspnea, cough, arthralgia, diarrhea, and abdominal pain. On examination, a heart murmur is present, and small, tender nodules are found on the finger and toe pads, along with small hemorrhages on the palms and soles. Three sets of blood cultures are obtained from different veins. While awaiting laboratory confirmation, an empiric antibiotic regimen should primarily be directed at which of the following organisms?
    • A. 

      Enterococci

    • B. 

      Pseudomonas aeruginosa

    • C. 

      Staphylococcus aureus

    • D. 

      Streptococcus pneumoniae

    • E. 

      Streptococcus pyrogenes

  • 2. 
    A 20-year-old female presents with a two day history of dysuria and increased urinary frequency. She states that she was recently married and was not sexually active prior to the marriage. Physical exam reveals a temperature of 100.7 °F with normal vital signs. Gynecological exam reveals no evidence of discharge, vaginitis, or cervicitis. Urinalysis reveals 14 white blood cells per high-powered field with many gram-negative rods. The most appropriate therapy would be
    • A. 

      Ampicillin

    • B. 

      Ceftriaxone

    • C. 

      Fluconazole

    • D. 

      Gentamicin

    • E. 

      Metronidazole

  • 3. 
    A 36-year-old mother of two children presents with a 4-day history of swollen, painful hands. Her wrists and metacarpophalangeal joints are boggy and inflamed bilaterally. Her 5-year-old son had been sent home from school approximately 3 weeks previously with red cheeks and a blotchy rash on his torso. What is the most likely diagnosis?
    • A. 

      Listeriosis

    • B. 

      Lyme disease

    • C. 

      Mumps

    • D. 

      Parvovirus

    • E. 

      Reiter's syndrome

  • 4. 
    A 28-year-old pregnant woman develops a flu-like illness with fever, headache, myalgia, and back pain. As a complication of the illness, she has a spontaneous abortion. Examination of the abortus demonstrates severe amnionitis. Which of the following organisms would most likely be isolated from the placental membranes?
    • A. 

      Borrelia burgdorferi

    • B. 

      Leptospira interrogans

    • C. 

      Listeria monocytogenes

    • D. 

      Spirillium minus

    • E. 

      Streptobacillus moniliformis

  • 5. 
    A 14-year-old boy has just moved with his family from Brazil to the U.S. He starts complaining of shortness of breath and palpitations. Chest x-ray films demonstrate pulmonary congestion, and ECG shows alterations in heart rhythm. Echocardiography reveals biventricular dilatation with massive cardiac enlargement. An endomyocardial biopsy shows diffuse interstitial fibrosis, myocyte necrosis, chronic inflammation, and the presence of intracellular protozoan parasites. The patient may also develop which of the following complications?
    • A. 

      Achalasia

    • B. 

      Chronic arthritis

    • C. 

      Cysts in the brain

    • D. 

      Pleuritis

    • E. 

      Splenomegaly

  • 6. 
    A debilitated 72-year-old woman develops dry cough, fever, headache, and muscular pains. She treats herself with aspirin and ampicillin without any improvement. Her children take her to a local hospital, where chest x-ray films reveal scattered opacities, suggestive of interstitial infiltration. Laboratory investigations demonstrate the presence of cold agglutinins. She is treated with erythromycin, and her symptoms rapidly improve. Which of the following is the most likely etiologic agent of this patient's condition?
    • A. 

      Influenza virus

    • B. 

      Mycoplasma pneumoniae

    • C. 

      Pneumocystis carinii

    • D. 

      Respiratory syncytial virus

    • E. 

      Streptococcus pneumoniae

  • 7. 
    A 25-year-old female presents with a confluent maculopapular rash that began on her face, then spread downward over her trunk. She states that 3 days ago she started having a fever and headache, with bilateral pain associated with the front and back of her neck. She also complains of joint pain. Which of the following diseases does she most likely have?
    • A. 

      Infectious mononucleosis

    • B. 

      Lyme disease

    • C. 

      Roseola

    • D. 

      Rubella

    • E. 

      Rubeola

  • 8. 
    A Michigan fisherman presents with complaints of chronic diarrhea and fatigue. His physician orders a complete blood count with differential, which reveals a megaloblastic anemia. Which of the following organisms is the most likely cause of this patient's problems?
    • A. 

      Clonorchis sinensis

    • B. 

      Diphyllobothrium latum

    • C. 

      Echinococcus granulosus

    • D. 

      Taenia saginata

    • E. 

      Taenia solium

  • 9. 
    A child with sickle cell anemia is seen in a hematology clinic. Her mother states that she has been feeling very tired lately, and may have "come down with a virus." On physical examination, the girl is very pale, and a complete blood count shows severe anemia. A bone marrow aspirate contains no erythroid precursor cells. The girl was probably infected with which of the following viruses?
    • A. 

      Coxsackie virus

    • B. 

      Echovirus

    • C. 

      Hepadnavirus

    • D. 

      Herpes virus

    • E. 

      Parvovirus

  • 10. 
    A 43-year-old executive presents to a physician with chronic, symmetric polyarthritis involving the knees. The man gives a history of having developed an extensive rash after a deer hunting trip in Connecticut several years earlier. He recalls that he felt "sick" at the time, and developed knee pain that prevented him from climbing stairs for several months, but then partially resolved. Which of the following organisms is most likely etiologically related to the patient's arthritis?
    • A. 

      Fungus

    • B. 

      Gram-negative cocci

    • C. 

      Gram-negative rod

    • D. 

      Gram-positive cocci

    • E. 

      Spirochete

  • 11. 
    A 39-year-old HIV-positive man is brought into the emergency room after experiencing a seizure witnessed by several friends. The observers relate that the patient suddenly lost consciousness and experienced both leg and arm jerking. The man's tongue has been severely bitten, and loss of bowel and bladder function is evident upon admission. On physical examination, the patient is lethargic, unable to answer simple questions, and has an obvious left-sided hemiparesis. An MRI of the head shows multiple ring-enhancing lesions. Infection with which of the following agents is most likely responsible for this presentation?
    • A. 

      Cryptococcus neoformans

    • B. 

      Herpes simplex

    • C. 

      Mycobacteria tuberculosis

    • D. 

      JC virus

    • E. 

      Toxoplasma gondii

  • 12. 
    Which of the following organisms would most likely cause infection after a sterilization procedure that killed vegetative cells but did not kill spores?
    • A. 

      Chlamydia

    • B. 

      Clostridium

    • C. 

      Escherichia

    • D. 

      Pseudomonas

    • E. 

      Streptococcus

  • 13. 
    A newborn in the neonatal intensive care unit becomes tachypneic and irritable. Blood cultures grow a gram-positive coccus in chains that is presumed to be a streptococcus. Which of the following characteristics would help to differentiate Streptococcus agalactiae from Streptococcus pneumoniae?
    • A. 

      Alpha-hemolysis

    • B. 

      Carbohydrate capsule

    • C. 

      Cytochrome enzyme system

    • D. 

      Growth in bile

    • E. 

      Oxacillin sensitivity

  • 14. 
    A 35-year-old man presents to the emergency room with intense back pain. He is hydrated and given pain medication. After several hours he passes a kidney stone. Laboratory analysis of the stone reveals that it is composed of struvite (magnesium ammonium phosphate). Infection with which of the following organisms promotes the production of such stones?
    • A. 

      Escherichia coli

    • B. 

      Proteus mirabilis

    • C. 

      Pseudomonas aeruginosa

    • D. 

      Staphylococcus saprophyticus

    • E. 

      Ureaplasma urealyticum

  • 15. 
    A 54-year-old truck driver in Oklahoma collides with a deer on the highway. He takes the deer home and butchers it. Five days later, he develops fever, non-productive cough, shortness of breath, and generalized lymphadenopathy. No skin lesions are noted. What is the most likely diagnosis?
    • A. 

      Anthrax

    • B. 

      Leptospirosis

    • C. 

      Pasteurella multocida infection

    • D. 

      Plague

    • E. 

      Tularemia

  • 16. 
    A 67-year-old black man with a history of glucose-6-phosphate dehydrogenase (G-6-PD) deficiency presents with fever, irritative voiding symptoms, and perineal pain. Rectal examination is remarkable for a boggy, exquisitely tender prostate. A urine Gram's stain is positive for gram-negative rods. The risk for development of hemolytic anemia is highest if he receives high-dose, 21-day therapy with
    • A. 

      Ampicillin

    • B. 

      Cefaclor

    • C. 

      Ciprofloxacin

    • D. 

      Sulfamethoxazole/trimethoprim

    • E. 

      Tetracycline

  • 17. 
    A 25-year-old man presents with a high fever and generalized malaise. His condition deteriorates so rapidly that his friends decide to take him to the emergency department 24 hours after the onset of symptoms. He has a history of intravenous drug abuse. A test for anti-HIV antibodies is negative. Physical examination reveals a systolic murmur, and echocardiography shows bulky vegetations attached to the tricuspid valve leaflets. Which of the following microorganisms will be most likely be isolated from this patient's blood cultures?
    • A. 

      Candida albicans

    • B. 

      Hemophilus influenzae

    • C. 

      Staphylococcus aureus

    • D. 

      Staphylococcus epidermidis

    • E. 

      Viridans (α-hemolytic) streptococci

  • 18. 
    A newborn infant develops respiratory distress shortly after delivery and is taken to the neonatal intensive care unit for observation. The next day she becomes febrile with persistent dyspnea and coughing. Sputum recovered by the respiratory therapist reveals numerous neutrophils and gram-negative rods that grow as pink colonies on MacConkey's agar. The infective organism most likely belongs to which of the following genera?
    • A. 

      Escherichia

    • B. 

      Proteus

    • C. 

      Pseudomonas

    • D. 

      Salmonella

    • E. 

      Shigella

  • 19. 
    Five days after returning to his military base in South Carolina after survival training in the nearby countryside, an 18-year-old recruit reports to the infirmary complaining of a headache. Physical examination reveals a fever, but no other abnormalities are noted. A few days later he returns to the infirmary with a maculopapular rash involving the hands and feet. The rash then spreads centripetally to involve the trunk. Which of the following diseases should be suspected?
    • A. 

      Chickenpox

    • B. 

      German measles

    • C. 

      Measles

    • D. 

      Mumps

    • E. 

      Rocky Mountain spotted fever

  • 20. 
    A 47-year-old grocer complains of diarrhea and painful arthritis. Physical examination is remarkable for lymphadenopathy and weight loss. Biopsy of his small bowel reveals PAS-positive macrophages within the lamina propria. Electron microscopic examination of the macrophages reveals small rod-shaped structures. These structures are most likely
    • A. 

      Clostridium

    • B. 

      Enterotoxigenic E. coli

    • C. 

      Isospora

    • D. 

      Salmonella

    • E. 

      Tropheryma

  • 21. 
    A 33-year-old G1P0 female at 6 months gestation returns from a visit to her parents house in Arizona. Approximately 7 days following her return, she develops axillary lymphadenopathy and a low-grade fever. Her physician notices a small papule and healing scratch on her arm on the affected side. The patient states that she has pet birds at home, and there was a new kitten at her mother's house. She does not remember receiving the scratch. Which of the following organisms is most likely responsible for this illness?
    • A. 

      Bartonella henselae

    • B. 

      Coccidioides immitis

    • C. 

      Cryptococcus neoformans

    • D. 

      Histoplasma capsulatum

    • E. 

      Pasteurella multocida

  • 22. 
    A 33-year-old woman begins seeing a new boyfriend. Several weeks later, a week after her menstrual period, the woman develops a painful, swollen right knee. The most likely causative organism has which of the following characteristics?
    • A. 

      Both hyphae and spores

    • B. 

      Can live within neutrophils

    • C. 

      Cannot make ATP

    • D. 

      No true cell wall

    • E. 

      Stains with silver stains

  • 23. 
    A 32-year-old man presents to the emergency room with a severe headache. Nuchal rigidity is found on physical examination. Lumbar puncture demonstrates cerebrospinal fluid with markedly increased lymphocytes. Other cell populations are not increased. Which of the following agents is the most likely cause of his symptoms?
    • A. 

      Escherichia coli

    • B. 

      Haemophilus influenzae

    • C. 

      Herpes virus

    • D. 

      Mycobacterium tuberculosis

    • E. 

      Treponema pallidum

  • 24. 
    A febrile 12-year-old child presents with severe right lower quadrant pain that is interpreted by the attending physician as acute appendicitis. The patient has also been complaining of joint pain. At laparotomy, the surgeon notes that the appendix is normal; however, the mesenteric lymph nodes are markedly enlarged and contain focal areas of microabscess formation on cut section. This patient is most likely
    • A. 

      An asthmatic

    • B. 

      Deficient in C1 esterase inhibitor activity

    • C. 

      HLA-B27 positive

    • D. 

      Leukopenic

    • E. 

      Serologically positive for toxoplasmosis

  • 25. 
    A 16-year-old girl presents to her physician complaining of redness and a yellowish discharge from her left eye for the past 2 days. She reports minimal crusting upon awakening and denies eye pain or previous trauma. Upon examination, there is diffuse conjunctival hyperemia associated with a mucoid discharge. The pupils dilate normally, although there is mild photophobia in the affected eye. Gram's stain of the exudate shows pleomorphic, gram-negative bacilli. To culture this organism with whole blood agar, which of the following must be used?
    • A. 

      Antibiotics to inhibit normal flora

    • B. 

      Cold temperature

    • C. 

      Egg yolk cholesterol

    • D. 

      Reduced oxygen tension

    • E. 

      Staphylococcus aureus