USMLE USMLE Certifications USMLE-STEP-2 Questions & Answers

• Question 31:

  A 36-year-old female complains of 5 days of fever, nasal congestion, sinus pressure, and postnasal drip. On examination, nasal discharge is yellow and the posterior pharynx is slightly erythematous. Tapping over the maxillary sinuses elicits mild pain. Which of the following is the most appropriate treatment for this patient?

  A. treatment of symptoms (analgesics, antipyretics, decongestants)

  B. a 7-day course of amoxicillin

  C. a 10-day course of amoxicillin clavulanic acid

  D. a 14-day course of clarithromycin

  Correct Answer: A

  The Clinical Practice Guidelines of the American College of Physicians (endorsed by Centers for Disease Control [CDC], American Academy of Family Physicians, and the Infectious Diseases Society of America) state that most cases of acute sinusitis in the ambulatory setting are due to viral infection and do not require antibiotic treatment or radiography. Therapy should be targeted toward symptoms and often include decongestants, antipyretics, and analgesics. Antibiotic treatment should be reserved for patients who have symptoms that persist or worsen (generally for more than 7 days)

• Question 32:

  A dentist asks you to evaluate a 42-year-old woman before tooth extraction. Which of the following is the prophylactic antibiotic of choice for dental procedures?

  A. amoxicillin

  B. vancomycin

  C. cephalexin

  D. penicillin

  E. clindamycin

  Correct Answer: A

  Guidelines for antibiotic prophylaxis of infective endocarditis (IE) underwent a major revision in 2007. Prophylaxis is now only recommended for those patients at highest risk of IE including patients with a prosthetic valve, history of IE, cardiac transplant patients that develop valvulopathy, cyanotic congenital heart disease that remains unrepaired, cyanotic congenital heart disease that has been repaired with a prosthesis during the first 6 months after the procedure or if a defect remains at the site of the prosthesis after 6 months. Congestive heart failure, an S4 gallop, and diabetes do not increase risk. Recommended antibiotic coverage for high-risk patients before dental procedures is amoxicillin 2 g PO 1 hour before the procedures. Penicillin-allergic patients can receive clarithromycin, cephalexin, cefadroxil, or clindamycin as prophylaxis. Streptococci and S. aureus are responsible for the majority of community- acquired native valve endocarditis cases. In IV drug abusers, S. aureus is responsible for more than 50% of cases, and Candida and Pseudomonas for about 6% each. Patients with prior endocarditis are at high risk. Bacterial endocarditis carries a mortality rate of about 25%, and prevention is of paramount importance. In S. aureus endocarditis in injection drug users, mortality is only 1015%. As many as 40% of cases occur without underlying heart disease. VSD, patent ductus arteriosus, and tetralogy of Fallot are most commonly associated; whereas, ASD is rarely a predisposing factor.

• Question 33:

  A dentist asks you to evaluate a 42-year-old woman before tooth extraction. Which of the following would prompt you to prescribe prophylactic antibiotics?

  A. midsystolic click at the left sternal border

  B. insulin-dependent diabetes

  C. a prior history of infective endocarditis

  D. a history of congestive heart failure

  E. S4 gallop

  Correct Answer: C

  Guidelines for antibiotic prophylaxis of infective endocarditis (IE) underwent a major revision in 2007. Prophylaxis is now only recommended for those patients at highest risk of IE including patients with a prosthetic valve, history of IE, cardiac transplant patients that develop valvulopathy, cyanotic congenital heart disease that remains unrepaired, cyanotic congenital heart disease that has been repaired with a prosthesis during the first 6 months after the procedure or if a defect remains at the site of the prosthesis after 6 months. Congestive heart failure, an S4 gallop, and diabetes do not increase risk. Recommended antibiotic coverage for high-risk patients before dental procedures is amoxicillin 2 g PO 1 hour before the procedures. Penicillin-allergic patients can receive clarithromycin, cephalexin, cefadroxil, or clindamycin as prophylaxis. Streptococci and S. aureus are responsible for the majority of community- acquired native valve endocarditis cases.

  In IV drug abusers, S. aureus is responsible for more than 50% of cases, and Candida and Pseudomonas for about 6% each. Patients with prior endocarditis are at high risk. Bacterial endocarditis carries a mortality rate of about 25%, and prevention is of paramount importance. In S. aureus endocarditis in injection drug users, mortality is only 1015%. As many as 40% of cases occur without underlying heart disease. VSD, patent ductus arteriosus, and tetralogy of Fallot are most commonly associated; whereas, ASD is rarely a predisposing factor.

• Question 34:

  Which of the following is the most likely diagnosis for the ulcerated lesion on the person's cheek shown in figure below?

  

  A. squamous cell carcinoma

  B. malignant melanoma

  C. benign ulcerated nevus

  D. basal cell carcinoma

  E. hemangioma

  Correct Answer: D

  Basal cell carcinoma is the most common form of skin cancer and can present as an isolated papule or nodule or with ulceration. Although locally aggressive and destructive, they rarely metastasize. Figure shows a large ulcer with a rodent-like appearance with nodules at the border. Squamous cell carcinoma would be in the differential, but it does not ulcerate as often and is characterized by being hard nodules. Malignant melanomas are usually nodular and pigmented. It would be highly unusual for a benign nevus to ulcerate and have this appearance. A hemangioma is a red vascular lesion.

• Question 35:

  You evaluate a 38-year-old man who complains of muscle weakness. Her appearance is remarkable for a periorbital heliotrope rash with edema and erythema on his upper chest, neck, and face. Which of the following is the most likely diagnosis?

  

  Which of the following blood parameters is likely to be elevated?

  A. serum creatinine B. serum potassium

  C. serum sodium

  D. rheumatoid factor

  E. creatinine phosphokinase

  Correct Answer: E

  The heliotrope, purple periorbital rash is seen with dermatomyositis and may even precede the muscle involvement. On examination, these patients will usually show proximal muscle weakness and may complain of difficulty getting up from a chair, climbing stairs, and raising the arms over the head. Ataxia may be present with cerebellar lesions. Deep tendon reflexes should be normal and there is no joint inflammation. Polymyalgia rheumatica generally occurs in older people but is not associated with muscle weakness. Spinocerebellar degeneration, vasculitis, and rheumatoid arthritis are not associated with this rash. Creatine phosphokinase is usually markedly elevated and muscle biopsy will confirm the diagnosis. Serum creatinine, sodium, and potassium should be normal, and the rheumatoid factor should not be elevated.

• Question 36:

  Doing a retrospective chart review of unmatched cases and controls, you calculate an OR to make an initial assessment of whether women who have had induced abortions are more likely to develop breast cancer. Twenty of 100 women with breast cancer reported a history of induced abortion. Ten of 200 women without breast cancer reported a history of induced abortion. What are the exposure odds among controls?

  A. 3.973

  B. 1.682

  C. 0.184

  D. 0.053

  E. 0.009

  Correct Answer: D

  The odds of exposure among controls are calculated by dividing the probability that a control was exposed by the probability that a control was not exposed: (10/200)/(190/200) = 10/190 = 0.053.

• Question 37:

  When making recommendations to a state general assembly against routine premarital screening, the State Health Commissioner used the following data to arrive at his conclusions. The state had a young adult population of 100,000. Their actual prevalence of human immunodeficiency virus (HIV) infection was 1 per 1000. The best screening test available had a sensitivity of 98% and a specificity of 95%. How many people would have screened as false negative?

  A. 4995

  B. 98

  C. 2

  D. 100

  E. 5000

  Correct Answer: C

  The following table was constructed using the data in the question. There would be 4995 FPs, 98 TPs, and 2 FNs.

  

• Question 38:

  A 30-year-old asymptomatic male presents to your office because his father just had a heart attack. He is concerned that he may have inherited his father's condition because a cholesterol level test done at his work site last year was 220 mg/dL. You review his history and find that he smokes 25 cigarettes a day, eats mostly at fast food restaurants, sits at a desk job, and has no regular moderate intensity physical activities. His blood pressure is 130/85 mmHg and his body mass index (BMI) is 26.

  Which of the following is the best first recommendation?

  A. electrocardiography (ECG)

  B. ECG and an exercise treadmill test (ETT)

  C. a diet for weight loss

  D. commencement of a daily exercise routine

  E. antihypertensive medication

  Correct Answer: D

  The USPSTF does not recommend ECG or ETT in asymptomatic patients. A BMI greater than 27 is associated with increased mortality. The U.S. Surgeon General recommends a program of moderate exercise most days of the week.

• Question 39:

  Schedules for the routine immunization of young children are developed jointly by the Advisory Commission on Immunization Practices (a federal commission) and the American Academy of Pediatrics. Which of the following vaccines is recommended for routine vaccination for all children in the United States?

  A. anthrax vaccine

  B. rabies vaccine

  C. Haemophilus influenzae b (Hib) vaccine

  D. hepatitis A vaccine

  E. typhoid vaccine

  Correct Answer: C

  Hib vaccine is recommended for routine immunization of children. Introduction of the Hib conjugate vaccine in the late 1980s was followed by a spectacular decrease in the incidence of H. influenzae meningitis. Anthrax vaccine is used to vaccinate military troops in selected overseas deployment. Rabies vaccine is used for postexposure prophylaxis when children are bitten by potentially rabid mammals. Hepatitis Avaccine is used for children at special risk of such infection. Typhoid vaccine is not routinely recommended for use in the United States but may be indicated for travelers to areas in the developing world where typhoid fever is endemic.

• Question 40:

  An 18-month-old boy is brought to the clinic for a checkup. As part of his routine care, a serum lead level is obtained. It is 25 g/mL. Which of the following is the most appropriate next step in his management?

  A. chelation with CaEDTA

  B. chelation with succimer

  C. investigation of his home for lead hazards

  D. reassurance that this level is not a problem

  E. repeating the level in 6 months

  Correct Answer: C

  The CDC has identified lead poisoning as one of the most common and preventable childhood health problems in the United States. Recent data indicate that undesirable behavioral and cognitive deficits can occur at levels previously thought to be "safe." Screening all children aged 672 months, by questionnaire or blood-lead level, is suggested. Children at greatest risk for lead poisoning include young inner-city children who live in housing constructed before 1960; children living near lead processing smelters, battery recycling plants, or other industries that release lead; or children with siblings or playmates diagnosed with lead poisoning. Eliminating the lead source is the cornerstone of treatment. Chelation therapy generally is reserved for those children with blood-lead levels greater than 45 g/dL.