Infectious Disease — MCQs

A 2-year-old boy is brought to the physician by his mother for evaluation of recurrent infections and easy bruising. He has been hospitalized 3 times for severe skin and respiratory infections, which responded to treatment with antibiotics. Examination shows sparse silvery hair. The skin is hypopigmented and there are diffuse petechiae. Laboratory studies show a hemoglobin concentration of 8 g/dL, leukocyte count of 3000/mm3, and platelet count of 45,000/mm3. A peripheral blood smear shows giant cytoplasmic granules in granulocytes and platelets. Which of the following is the most likely underlying cause of this patient's symptoms?

A 9-year-old boy is brought to the emergency department for the evaluation of diarrhea and vomiting for the last 2 days. During this period, he has had about 12 watery, non-bloody bowel movements and has vomited three times. He came back from a trip to India 3 days ago, where he and his family were visiting relatives. He has not been able to eat anything since the symptoms started. The patient has not urinated since yesterday. He appears pale. His temperature is 38°C (100.4°F), pulse is 106/min, and blood pressure is 96/60 mm Hg. Examination shows dry mucous membranes. The abdomen is soft with no organomegaly. Bowel sounds are hyperactive. Laboratory studies show: Hemoglobin 13 g/dL Serum Na+ 148 mEq/L Cl- 103 mEq/L K+ 3.7 mEq/L HCO3- 19 mEq/L Urea nitrogen 80 mg/dL Glucose 90 mg/dL Creatinine 2 mg/dL Intravenous fluid resuscitation is begun. Which of the following is the most likely cause of this patient's abnormal renal laboratory findings?

A 13-month-old boy with sickle cell anemia is brought to the emergency department because of continuous crying and severe left-hand swelling. His condition started 2 hours earlier without any preceding trauma. The child was given diclofenac syrup at home with no relief. The temperature is 37°C (98.6°F), blood pressure is 100/60 mm Hg, and pulse is 100/min. The physical examination reveals swelling and tenderness to palpation of the left hand. The hemoglobin level is 10.4 g/dL. Which of the following is the best initial step in management of this patient condition?

A 2-year-old boy is brought to the physician by his mother because of fever and left ear pain for the past 3 days. He has also been frequently rubbing his left ear since he woke up in the morning. He has a history of atopic dermatitis, and his mother is concerned that his symptoms may be caused by him itching at night. She says that he has not been having many flare-ups lately; the latest flare-up subsided in time for his second birthday party, which he celebrated at a swimming pool 1 week ago. Six months ago, he had an episode of urticaria following antibiotic treatment for pharyngitis. He takes no medications. His temperature is 38.5°C (101.3°F), pulse is 110/min, respirations are 25/min, and blood pressure is 90/50 mm Hg. Otoscopy shows an opaque, bulging tympanic membrane. Which of the following is the most appropriate next step in management?

A 7-year-old boy is brought to a new pediatrician to establish care. He presents with a history of extensive eczema, recurrent respiratory, skin, and gastrointestinal infections, and significant thrombocytopenia. The boy was born at 39 weeks gestation via spontaneous vaginal delivery. He is up to date on all vaccines and is meeting all developmental milestones. Given this classic grouping of clinical symptoms in a patient of this age, which of the following represents the most likely underlying medical condition?

A 2-year-old boy is brought to the physician by his parents for the evaluation of an unusual cough, a raspy voice, and noisy breathing for the last 2 days. During this time, the symptoms have always occurred in the late evening. The parents also report that prior to the onset of these symptoms, their son had a low-grade fever and a runny nose for 2 days. He attends daycare. His immunizations are up-to-date. His temperature is 37.8°C (100°F) and respirations are 33/min. Physical examination shows supraclavicular retractions. There is a high-pitched breath sound on inspiration. Which of the following is the most likely location of the abnormality?

A father brings in his 7-year-old twin sons because they have a diffuse rash. They have several papules, vesicles, pustules, and crusts on their scalps, torso, and limbs. The skin lesions are pruritic. Other than that, the boys appear to be well. The father reports that several children in school have a similar rash. The family recently returned from a beach vacation but have not traveled internationally. Both boys have stable vital signs within normal limits. What is the most common complication of the infection the boys appear to have?

An 8-month-old boy is brought to the emergency department by his mother. She is concerned that her son has had intermittent periods of severe abdominal pain over the past several days that has been associated with emesis and "currant jelly" stool. Of note, the family lives in a rural part of the state, requiring a 2 hour drive to the nearest hospital. He currently appears to be in significant pain and has vomited twice in the past hour. On physical examination, a sausage-shaped mass is noted on palpation of the right upper quadrant of the abdomen. Ultrasound of the abdomen was consistent with a diagnosis of intussusception. An air-contrast barium enema was performed, which confirmed the diagnosis and also successfully reduced the intussusception. Which of the following is the next best step in the management of this patient?

A 3-year-old girl is brought to the emergency department by her parents with sudden onset shortness of breath. They tell the emergency physician that their daughter was lying on the bed watching television when she suddenly began gasping for air. They observed a bowl of peanuts lying next to her when they grabbed her up and brought her to the emergency department. Her respirations are 25/min, the pulse is 100/min and the blood pressure is 90/65 mm Hg. The physical findings as of now are apparently normal. She is started on oxygen and is sent in for a chest X-ray. Based on her history and physical exam findings, the cause of her current symptoms would be seen on the X-ray at which of the following sites?

A previously healthy 9-year-old, Caucasian girl presents to your office with severe abdominal pain. Her mother also mentions that she has been urinating significantly less lately. History from the mother reveals that the girl suffers from acne vulgaris, mild scoliosis, and had a bout of diarrhea 3 days ago after a family barbecue. Lab work is done and is notable for a platelet count of 97,000 with a normal PT and PTT. The young girl appears dehydrated, yet her serum electrolyte levels are normal. What is the most likely etiology of this girl's urinary symptoms?