USMLE USMLE-STEP-2 Exam Questions & Answers

Correct Answer: A

Hepatic encephalopathy is a syndrome of declining intellectual function, altered state of consciousness, and neurologic abnormalities in the setting of advanced liver disease. Other findings include hyperactivity, delirium, agitation, and personality changes, progressing to confusion, somnolence, and coma. Asterixis (lapses of sustained muscle contraction) or "flapping tremor" is common. Jaundice, spider angiomas, and ascites can be present in alcoholic liver disease without the presence of encephalopathy. Precipitating factors must be looked for and reversed if possible. GI bleeding (due to esophageal varices, gastritis, ulcer, and so forth) increases the nitrogen load in the gut and reduces cerebral perfusion. Excessive diuresis with prerenal azotemia increases extrahepatic circulation of urea and ammonia production, so noncompliance with diuretics would decrease ammonia levels. Lactulose acidifies the stool, traps ammonia and other nitrogenous substances, and decreases their absorption from the gut so excessive lactulose would decrease ammonia levels. Excessive protein intake is a common precipitant.

Correct Answer: C

Hypocalcemia is not a cause of constipation. On the contrary, it increases irritability of nerve cells and may result in diarrhea. Hypothyroidism, lead poisoning, and Hirschsprung disease all may be associated with constipation. Congenital hypothyroidism and Hirschsprung disease (a congenital disorder characterized by regional absence of ganglion cells from the myenteric plexus of the colon) present at birth. Lead poisoning is more common after the child becomes mobile. Functional constipation is the most common cause of constipation at this age. It is usually due to dietary factors.

Correct Answer: I

Giardiasis may cause cramping and a chronic diarrheal syndrome, with malabsorption and weight loss. Its distribution is worldwide, particularly where hygienic standards are not high. It also occurs sporadically in high-risk individuals. Streptococcal pyoderma, including erysipelas and impetigo, has been demonstrated to precede acute glomerulonephritis. Even when appropriate antibiotics are given in adequate dosage and duration for these conditions, renal damage may still result. Prevention thus consists of wound care, including cleaning wounds well and removal of crust. Mycoplasma infections are particularly common in families with younger children. They are frequently imported to the family by school-aged children, leading to a low-grade fever and persisting tracheobronchitis in the parents, or more acutely, an atypical pneumonia. G. lamblia is found in up to 20% of homosexual males, and may cause chronic diarrhea, although in these patients it tends to be asymptomatic. E. coli was first reported as a cause of watery diarrhea in nurseries in the 1940s. Although nursery epidemics with enteropathogenic serotypes had decreased in recent years in the United States, the increase of infant- child day care centers has resulted in their relatively frequent occurrence. Furunculosis is most frequently caused by coagulase-positive staphylococcal infections. The public health significance of this largely relates to the hazards of skin infections in food handlers and subsequent staphylococcal toxin in the food, leading to staphylococcal intoxication food-borne disease. H. pylori has been associated with gastric ulcers, but not with duodenal ulcers. Otitis media, whether acute or with effusion, commonly results from viral infection, such as by RSV. Various other organisms may be responsible including Streptococcu pneumoniae, H. influenzae, and others. C. perfringens, with rare exceptions, is transmitted in a meat dish prepared in bulk. Under propitious circumstances for the organism, especially on cooling of the food, bacterial multiplication can be very rapid. Symptoms begin to occur in the affected population in about 12 hours. Epidemic typhus is a rickettsial illness. Man is the host and long-term reservoir. The vectors are body lice (P. humanus corporis). The rickettsia are not present in human excretions and cannot be transmitted by person-toperson contact.