Microbiology assessment #1 – Virology

These microbiology questions are exceedingly HY for the USMLE Step 1. It’s not a matter of if they will increase your score; they will increase your score.

They are presented in tutor-mode fashion, with a succinct explanation appearing instantly after selecting an answer.

Questions are heavily cited from the literature.

All material is copyrighted and the property of mehlmanmedical.

Copyright © mehlmanmedical

Privacy Policy and Terms and Conditions

1. A 22-year-old female presents to the physician with a painful vesicular eruption on her left labium majus. She describes the pain as burning and stinging. She has a fever of 101F and left-sided inguinal lymphadenopathy. Which of the following best describes the viral etiology?

 
 
 
 
 
 
 
 

2.

A 9-year-old boy presents with the above lesions on his trunk after returning home from a one-month-long summer camp. Which of the following might be seen under light microscopy if a biopsy is taken of one of the lesions?

 
 
 
 

3. A 3-year-old boy is brought in to the GP by his mother for severe watery diarrhea the past two days. He appears pale and his orbits are sunken. His history is significant for not having received childhood vaccinations. Which of the following best describes the most likely viral etiology?

 
 
 
 
 
 
 
 

4. A 6-year-old girl has a fever of 101F, malaise, and anorexia for two days. As the fever abates, a maculopapular rash starts on her face and spreads downward to involve her entire body; it lasts three days. On examination she has tenderness to palpation of the suboccipital and postauricular areas. Which of the following is the most likely diagnosis?

 
 
 
 
 

5. A 4-year-old who attends a daycare five days a week is brought to the GP by his mom for itchy, watery eyes. The conjunctivae are injected. The most likely causative virus is also known to cause which of the following?

 
 
 
 
 

6. A 40-year-old IV drug user is admitted to hospital after experiencing a first-time focal epileptic seizure. He has a two-day history of headache, confusion, sensory aphasia, and right-sided hemiparesis. CD4 count is 135/μL. He is on highly active antiretroviral therapy (HAART). Other medications include trimethoprim-sulfamethoxazole (TMP-SMX). CSF analysis detects a DNA virus. Which of the following is most likely to be seen in this patient?

 
 
 
 

7. A researcher is doing a study on a virus specifically associated with renal transplants. It demonstrates an organ tropism largely limited to the reno-urinary tract and is known to cause a tubulointerstitial inflammatory response, ureteral stenosis, and hemorrhagic cystitis. Which of the following best describes the virus the researcher is studying?

 
 
 
 
 
 
 
 

8.

A 42-year-old male presents with two-year history of a diffusely erythematous scaly rash over the trunk and extremities. He describes the rash as so intensely pruritic that he bathes several times a day in cold water to relieve the burning. On physical examination, he has multiple erythrodermic patches over his face and body. Abdomen is soft, non-tender, with no organomegaly. There is no lymphadenopathy. His vitals are within normal limits. A complete blood count is as follows:

Hb: 14 g/dL (NR for males: 13.5-17.5)
WBC: 23,000/mm3 (NR 4000-11,000)
–     Polymorphonuclear cells: ~10%
–     Lymphocytes: ~90%

Peripheral smear examination reveals large lymphoid cells with prominent nuclear indentations and grooving. Bone marrow examination is unremarkable. Transmission electron microscopy (TEM) reveals characteristic cells with cerebriform nuclei. Which of the following is the most likely diagnosis?

 
 
 
 
 

9. An 18-year-old man presents to hospital with fever, increasing confusion, and aphasia. A CT scan of the head is unremarkable. EEG shows temporal complexes and patterns of slowing. A lumbar puncture is performed. Cerebral spinal fluid (CSF) findings are as follows:

Glucose: 70 mg/dL (normal range 50-80)
Protein: 75 mg/dL (normal range 15-60)
WBC: 220 cells/mm3; lymphocyte predominance
RBC: 45 cells/mm3
Opening pressure: 180 mm H2O

Which of the following is the most likely diagnosis?

 
 
 
 
 

10. A 12-year-old girl has a three-day history of fever, sore throat, chills, myalgias, and general malaise. Her condition may have been prevented by receiving a yearly vaccine designed to induce an antibody response to a protein capable of binding sialic acid residues. Which of the following best describes the causative virus?

 
 
 
 
 
 
 
 

11.

A 15-year-old boy is biking through a wooded area in Vermont when he encounters a raccoon on the path. He runs it over, causing him to fall off his bike and scratch his hands. He proceeds to move the injured animal off the path and it bites him. Two months later, he experiences severe headache, paresthesia, and severe pain of his left hand. He presents to hospital febrile, with hypersalivation, hydrophobia, and aerophobia. He dies later the same day. Which of the following best describes the causative organism?

 
 
 
 
 
 
 
 

12. A 30-year-old male presents to the physician for a one-week history of fever, generalized body pain, and vomiting. He appears pale and fatigued. A complete blood count is ordered and is unremarkable. He is recommended to take acetaminophen and drink copious fluids. One week later the fever persists. He reluctantly discloses to the physician that he recently tried IV drugs and had unprotected sex at a party. Hepatitis B, C, and HIV tests are ordered. Antibody testing comes back positive for hepatitis C. Polymerase chain reaction test (PCR) detects HCV RNA genotype 3. Which of the following is the most likely mechanism of hepatocellular injury in this patient?

 
 
 
 

13. A 4-month old girl is brought to the GP by her mother for a two-day history of fever of 101F. On examination she appears healthy. There is no rash present. Soft expiratory crackles are auscultated diffusely across both lung fields. What is the most appropriate treatment for this patient?

 
 
 
 
 
 
 

14. A 26-year-old woman at 34 weeks gestation presents to hospital with a two-day history of severe fatigue, loss of appetite, and abdominal pain. She is febrile at 102F. Blood pressure is 90/60 mm Hg. Physical examination shows scleral icterus. Abdomen is soft. There is voluntary guarding. Liver edge is palpable 4 cm below the right costal margin. Her history is significant for having returned to the United States from India two weeks ago. She is admitted to hospital for further investigation and her condition continues to deteriorate. She dies the following morning. Which of the following is the most likely causative pathogen?

 
 
 
 
 
 
 
 
 
 
 
 

15. A 16-year-old girl has had increasing frontal headaches over the past four days that have become unbearable and associated with fevers and rigor. She reports having vomited once, as well as neck pain/stiffness and photophobia. A lumbar puncture is performed. Her cerebral spinal fluid (CSF) findings are as follows:

Glucose: 55 mg/dL (normal range 50-80)
Protein: 65 mg/dL (normal range 15-60)
WBC: 90 cells/mm3; lymphocyte predominance
RBC: 0-1 cells/mm3
Opening pressure: 180 mm H2O

Which of the following is the most likely diagnosis?

 
 
 
 
 

16.

A 6-year-old boy presents with the above rash. He has no prior dermatologic history. What is the most likely diagnosis?

 
 
 
 
 

17. A 3-year-old girl has a two-day history of dyspnea with feeding, vomiting, and pallor. On arrival, she is tachypneic, tachycardic, hypotensive, and febrile. Physical examination shows eyelid puffiness, hepatomegaly, and generalized edema. Her mother reports that she recently had a runny nose for a few days and a low-grade fever that self-resolved. The most likely pathogen responsible for this patient’s condition is also known to be associated with which of the following?

 
 
 
 
 

18.

A 21-year-old woman presents with the above skin findings on her back. She says the lesions are itchy and have gradually increased in number over the past couple of weeks. She is sexually active and infrequently uses barrier contraception. Her palms and soles show no abnormalities. Which of the following is the most likely diagnosis?

 
 
 
 
 
 
 

19. A 45-year-old man who recently arrived in the US from China has various screening tests performed as part of a routine immigration physical. His serum studies for hepatitis B are as follows:

Anti-HBcAb IgM: Positive
Anti-HBcAb IgG: Negative
HBsAg: Negative
HBsAb: Negative
HBeAg: Negative

Which of the following is the most accurate interpretation of these findings?

 
 
 
 
 

20.

A 52-year-old HIV-positive male who not taken his highly active antiretroviral therapy (HAART) for the past three months presents with new-onset violaceous lesions of his back, trunk, lower extremities. Which of the following best describes the histologic findings of these lesions?