USMLE USMLE Certifications USMLE-STEP-2 Questions & Answers

• Question 421:

  A 20-year-old student asks to have his vaccinations updated. You recommend that he be vaccinated for typhoid fever under which of the following circumstances?

  A. Natural disasters destroy the local water and sewage systems.

  B. He takes a rural vacation in the southwestern United States.

  C. He travels in countries with endemic typhoid.

  D. He eats organic foods fertilized with raw cow manure.

  E. He lives in a community in which carriers are found.

  Correct Answer: C

  Vaccination against typhoid fever (caused by Salmonella typhi) is less effective than antibiotic treatment, with only 6575% effectiveness. Transmission is via fecal-oral route, with humans as the reservoir. Most cases (62%) are contracted as a result of overseas travel to certain areas of the world where the incidence remains high. It is in such endemic areas that vaccine is still advised. There has been no indication that immunization after earthquakes or other cataclysmic disasters is either necessary or effective.

• Question 422:

  You participate in the global effort to eradicate poliomyelitis. A poliomyelitis outbreak has been identified in a community in Africa. You advise your outbreak investigation team that they must focus on transmission from which one of the following sources?

  A. green monkeys

  B. mosquitoes of the species Aedes aegypti

  C. contaminated vaccine

  D. polluted water sources

  E. poorly cooked food

  Correct Answer: D

  The poliovirus is excreted in stools and pharyngeal secretions. Transmission occurs mainly by the fecal-oral route, particularly where sanitation and personal hygiene are poor, as in developing countries. The WHO, with the assistance of Rotary International, is progressing toward global eradication. There is no known reservoir for poliovirus except humans. By 2000, the Americas were polio free.

• Question 423:

  As a health officer, you have identified blindness among the elderly in your state as a cause of falls and resultant inability to perform activities of daily living. You try to prevent this by improving access to which of the following?

  A. residence in nursing homes

  B. corneal surgery for near vision

  C. cataract surgery

  D. treatment of glaucoma

  E. refractive correction

  Correct Answer: C

  There is a markedly higher frequency of impaired vision of the elderly in nursing homes than in the community. While it is not frequently recorded as a reason for nursing home admission, people with impaired vision experience any other limitations. Cataract is the leading cause of blindness in both communities. Maximizing visual acuity by appropriate refraction obviously improves mobility and ability to function but is not effective if the patient has cataracts.

• Question 424:

  Apreviously healthy male postal worker complains of fever, headache, myalgia, and cough for the past 3 days. He reports that several of his coworkers have also been ill with similar complaints. His leukocyte count is normal with a relative lymphopenia. Achest x-ray shows only enlarged hilar shadows. Which of the following is the most likely cause of this infection?

  A. Influenza A virus

  B. Bacillus anthracis

  C. Francisella tularensis

  D. Yersinia pestis

  E. Clostridium botulinum

  Correct Answer: A

  Onset of influenza usually is abrupt, with fever, chills, fatigue, headache, myalgias, malaise, anorexia, scratchy throat, and nonproductive cough. Fever appears early and may reach 40°C (104°F). Myalgias affecting the back and legs, and retrobulbar headache are worse with high fever. There is a normal leukocyte count with relative lymphopenia. Chest x-ray may show enlarged hilar shadows. Fever lasts a few days. Upper and then lower respiratory symptoms become more prominent, and cough may persist for weeks. Respiratory anthrax is exceedingly rare. Initial symptoms may resemble influenza, but rhinorrhea is rare. X-rays generally show patchy lung infiltrate and mediastinal widening (due to enlarged hemorrhagic lymph nodes). Early treatment with antibiotics such as ciprofloxacin sometimes prevents death.

• Question 425:

  An athletic 12-year-old boy complains of left knee pain when he runs and plays sports. The pain resolves

  when he rests. He has otherwise been well. His physical examination is normal, except for swelling and

  increased prominence over the left tibial tubercle. Aradiograph of the left knee is normal.

  Which of the following is the most likely diagnosis?

  A. Legg-Calv?Perthes disease

  B. Osgood-Schlatter disease

  C. patellar subluxation

  D. popliteal cyst

  E. slipped capital femoral epiphysis

  Correct Answer: B

  Osgood-Schlatter results from microfractures and inflammation of the tibial tubercle where the patellar tendon inserts. It is most commonly seen in young adolescents who are involved in athletics. Legg- Calv? Perthes disease is idiopathic avascular necrosis of the capital femoral epiphysis and presents between the ages of 2 and 12 with a painless limp. Patellar subluxation is usually due to a congenital deficiency within the patellofemoral joint. On examination, these patients have tenderness over the inferior surface of the patella and terminal subluxation of the patella when the knee is fully extended. Popliteal cysts are usually asymptomatic and present with a fluidfilled mass in the popliteal fossa. The symptoms of slipped capital femoral epiphysis are variable but typically involve hip pain and limp. On examination, patients have limitation of motion in the hip. It is most common in obese adolescents

• Question 426:

  An 18-month-old boy presents with a history of fever to 39.0°C for 5 days. He has also been irritable and has not been drinking well. Associated symptoms include red eyes, a rash, and some trouble walking. On physical examination, he has a temperature of 39.5°C. He has bilateral bulbar conjunctivitis, a strawberry tongue, an inflamed oral pharynx, edema of the hands and feet, a morbilliform rash, and cervical lymphadenopathy. He is very irritable. His CBC shows a WBC of 15,000/mm3 with 60% neutrophils, 35% lymphocytes, and 5% monocytes. His hemoglobin is 12.0 g/dL and platelet count is 500,000/ mm3.

  Which of the following is the most likely diagnosis?

  A. erythema infectiosum (fifth disease)

  B. Kawasaki disease

  C. rubella

  D. rubeola (measles)

  E. rheumatic fever

  Correct Answer: B

  Kawasaki disease is an acute febrile illness of unknown etiology that typically affects young children, usually those under 5 years of age. There are six clinical criteria used for diagnosing this disease. The presence of 5 days or more of fever, in addition to four of the five additional criteria, establishes the diagnosis. The five additional criteria are bilateral bulbar nonexudative conjunctivitis, rash, hand and foot changes (edema followed by desquamation), oral changes such as strawberry tongue and erythema, and cervical lymphadenopathy. Erythema infectiosum presents with a prodrome of malaise and myalgia and then with local erythema of the cheeks (slapped cheeks). Rubella and rubeola are unusual because of the MMR vaccination. Rubeola presents with the three "Cs"--cough, coryza, and conjunctivitis-- followed by the oral inflammation and the pathognomonic Koplik spots, rash, and fever. Rubella is typically a mild disease characterized by low-grade fever and a maculopapular rash. Rheumatic fever is also unusual. It tends to present in children over 3 years of age after an infection with group A Streptococci, with transient migratory arthritis, carditis, chorea, rash, and nodules. Diagnosis is made according to the Jones criteria.

• Question 427:

  A 12-year-old girl has had a sore throat over 2 days. She now has a fever of 39.5°C and has difficulty opening her mouth, swallowing, or speaking. Her throat can be visualized with difficulty, the right tonsil is significantly more enlarged than the left, and the uvula is displaced to the left side. Which of the following is the most likely diagnosis?

  A. retropharyngeal abscess

  B. acute uvulitis

  C. peritonsillar abscess

  D. acute pharyngitis

  E. lateral pharyngeal abscess

  Correct Answer: C

  This is a classic presentation for a peritonsillar abscess. Development of a peritonsillar abscess is usually preceded by acute pharyngotonsillitis, followed by development of severe throat pain and trismus. It is usually caused by group A hemolytic Streptococci or oral anaerobes in preadolescent or adolescent patients. Speech is often with a "hot potato" voice. The affected tonsil is enlarged causing the uvula to be pushed to the other side. Antibiotics (penicillin) and incision and drainage are usually required. Retropharyngeal abscess is usually a complication of bacterial pharyngitis in younger children under age 34 years. It is caused by infection and further suppuration of nodes in the retropharyngeal area. Symptoms include high fever, difficulty swallowing, feeding refusal, hyperextension of the head, and drooling. There is bulging of the posterior pharyngeal wall; diagnosis can be confirmed by widening of the retropharyngeal space on x-ray. With lateral pharyngeal abscess there is bulging of the lateral pharyngeal wall. Acute uvulitis is caused by group Ahemolytic Streptococci and H. influenzae type B, often in association with tonsillitis and uvulitis.

• Question 428:

  A 10-year-old boy presents with red discoloration of the urine since the morning. He is healthy and otherwise asymptomatic. He denies dysuria, frequency, urgency, flank, or abdominal pain. His BP is normal. His examination is within normal limits including abdomen and genitourinary system. There is no rash or edema. His urine is pink in color; urinalysis is negative for hemoglobin or protein. No white cells, red cells, or bacteria are noted. Which of the following is the most appropriate next step?

  A. obtain a recent dietary and drug history

  B. obtain a urine culture

  C. test for myoglobin in the urine

  D. obtain a renal ultrasound

  E. obtain antistreptococcal antibodies

  Correct Answer: A

  There are many drugs and foods that cause red urine. These include azo dyes, beets, blackberries, ibuprofen, methyldopa, red food color, rifampin, phenolphthalein, pyridium, sulfasalazine, and many others. Dark brown or black urine can be associated with alanine, cascara, resocinol, and thymol. If the diet or drug history as well as dipstick are negative, porphyrinuria should be considered. A positive reagent strip (dipstick) indicates hemoglobin or myoglobin. Negative dipstick and normal urinalysis makes renal pathology unlikely. Because the urinalysis is negative, and the patient is asymptomatic, urine culture is not indicated at this time. Test for antistreptococcal antibodies should be done if poststreptococcal glomerulonephritis is suspected; it is characterized by proteinuria, hematuria, edema, and hypertension.

• Question 429:

  A 12-year-old girl presents with chest pain when she plays basketball. The pain is substernal, is associated with dyspnea, and occurs after she has been playing vigorously. The pain does not radiate. The pain and dyspnea resolve with rest. She does not have palpitations or any lightheadedness associated with the pain. She does not have pain or dyspnea at other times. There is no history of early cardiac deaths or unexplained deaths of young people in her family. Her physical examination is normal, except for a grade 2/6 systolic vibratory murmur heard at the left lower sternal border.

  The same patient now complains of palpitations and dizziness with the chest pain. Which of the following tests should be ordered for this patient?

  A. chest x-ray

  B. echocardiogram

  C. pulmonary function tests

  D. 24-hour Holter monitoring

  E. cardiac enzymes

  Correct Answer: E

  In a patient with symptoms and signs consistent with exercise-induced asthma, a therapeutic trial of inhaled albuterol is the first line of therapy and diagnosis. If there is evidence of cardiac disease on history or physical examination, then one should proceed with the indicated tests. Pulmonary function tests could be used to confirm the diagnosis and are used in cases in which the diagnosis is uncertain or if patients fail the therapeutic trial.

• Question 430:

  A 12-year-old girl presents with chest pain when she plays basketball. The pain is substernal, is associated with dyspnea, and occurs after she has been playing vigorously. The pain does not radiate. The pain and dyspnea resolve with rest. She does not have palpitations or any lightheadedness associated with the pain. She does not have pain or dyspnea at other times. There is no history of early cardiac deaths or unexplained deaths of young people in her family. Her physical examination is normal, except for a grade 2/6 systolic vibratory murmur heard at the left lower sternal border.

  Which of the following is the most likely cause of her symptoms?

  A. angina

  B. asthma

  C. costochondritis

  D. esophagitis

  E. mitral valve prolapse

  Correct Answer: B

  Chest pain in adolescents is a common problem. It is rarely associated with serious illness. In this patient, the onset with exercise, resolution with rest, and a family history of asthma, exercise-induced asthma is the most likely cause. Angina is a rare cause of chest pain in adolescents, and with a normal cardiac examination and no family history of cardiac disease, this is unlikely. Costochondritis is a common cause of chest pain but typically has an insidious onset and does not resolve with rest. Esophagitis is a common cause of chest pain but is typically impacted by eating, not exercise. Mitral valve prolapse can cause chest pain, although most pediatric patients with mitral valve prolapse are asymptomatic. On examination, they often have a systolic click.