A 30-year-old man with sickle cell anemia is admitted with cough, rusty sputum, and a single shaking chill. Physical examination reveals increased tactile fremitus and bronchial breath sounds in the left posterior chest. The patient is able to expectorate a purulent sample. Which of the following best describes the role of sputum Gram stain and culture?
The Infectious Disease Society of America’s guidelines on the treatment of community-acquired pneumonia still recommend the use of sputum Gram stain and culture. This is particularly important in the era of multiantibiotic-resistant S pneumoniae. Sputum culture and sensitivity can direct specific antibiotic therapy for the patient as well as provide epidemiologic information for the community as a whole. A good sputum sample showing many polymorphonuclear leukocytes and few squamous epithelial cells can give important clues to etiology. A Gram stain that shows gram-positive lancet-shaped diplococci intracellularly is good evidence for pneumococcal infection. Gram-positive cocci in clusters would suggest staphylococcal infection, which would be uncommon in this setting. Empirical antibiotic therapy becomes more difficult in community-acquired pneumonia as more pathogens are recognized and as the pneumococcus develops resistance to penicillin, macrolides, and even quinolones.
A family of four presents to the emergency room with sudden-onset abdominal cramps, nausea, and vomiting. None of them has fever or diarrhea. Four hours earlier, they had lunch at a road side restaurant. They ate a variety of grilled meats, fried rice, and seasoned vegetables. Symptoms resolved in 24 hours. Which organism is most likely responsible for this outbreak?
The symptoms and time of onset after consumption of contaminated food determine the agents likely responsible for foodborne illness. Nausea and vomiting within 1 to 6 hours of consumption of food are caused by preformed toxins of B cereus and S aureus or heavy metals like copper or zinc. Abdominal cramps and diarrhea that develop more than 8 hours after a meal are caused by C jejuni, E coli, Salmonella, Shigella, and Vibrio parahaemolyticus. It takes more than 8 hours for the bacteria to proliferate in the gut and initiate the infection. Watery diarrhea can also be caused by enterotoxigenic E coli, V cholerae, and Norovirus. Yersinia enterocolitica can cause fever and abdominal cramps without diarrhea—a presentation closely resembling acute appendicitis. Cryptosporidiosis, cyclosporiasis, and giardiasis cause diarrhea that can persist for 1 to 3 weeks. The onset of symptoms in these parasitic diseases is more gradual; fever and systemic toxicity are absent.
A 40-year-old female nurse was admitted to the hospital because of fever to 39.4°C (103°F). Despite a thorough workup in the hospital for over 3 weeks, no etiology has been found, and she continues to have temperature spikes greater than 38.9°C (102°F). Which of the following statements about diagnosis is correct?
Patients may develop fever as a result of infectious or noninfectious diseases. The term fever of unknown origin (FUO) is applied when significant fever (usually defined as > 38.3°C or > 101°F) persists without a known cause after an adequate evaluation. Several studies have found the leading causes of FUO to include infections, malignancies, collagen vascular diseases, and granulomatous diseases. As the ability to more rapidly diagnose some of these diseases increases, their likelihood of causing undiagnosed persistent fever lessens. Infections such as intra-abdominal abscesses, tuberculosis, hepatobiliary disease, endocarditis (especially if the patient had previously taken antibiotics), and osteomyelitis may cause FUO. In immunocompromised patients, such as those infected with HIV, a number of opportunistic infections or lymphomas may cause fever and escape early diagnosis. Self-limited infections such as influenza should not cause fever that persists for many weeks. Neoplastic diseases such as lymphomas and some solid tumors (eg, hypernephroma and primary or metastatic disease of the liver) are associated with FUO. A number of collagen vascular diseases may cause FUO. Since conditions such as systemic lupus erythematosus are more easily diagnosed today, they are less frequent causes of this syndrome. Adult Still disease, however, is often difficult to diagnose. Other causes of FUO include granulomatous diseases (ie, giant cell arteritis, regional enteritis, sarcoidosis, and granulomatous hepatitis), drug fever, and peripheral pulmonary emboli. Factitious fever is most common among young adults employed in health-related positions. A prior psychiatric history or multiple hospitalizations at other institutions may be difficult to obtain, since these patients often skirt around the truth. Such patients may induce infections by self-injection of nonsterile material, with resultant multiple abscesses or polymicrobial infections. Alternatively, some patients may manipulate their thermometers. In these cases, a discrepancy between temperature and pulse or between oral temperature and witnessed rectal temperature will be observed.
A 40-year-old school teacher develops nausea and vomiting at the beginning of the fall semester. Over the summer she had taught preschool children in a small town in Mexico. She is sexually active, but has not used intravenous drugs and has not received blood products. Physical examination reveals scleral icterus, right upper quadrant tenderness, and a palpable liver. Liver function tests show aspartate aminotransferase of 750 U/L (normal < 40) and alanine aminotransferase of 1020 U/L (normal < 45). The bilirubin is 13 mg/dL (normal < 1.4) and the alkaline phosphatase is normal. What further diagnostic test is most likely to be helpful?
This patient has evidence for acute hepatitis as is suggested by the history, physical examination, and laboratory data showing hepatocellular injury. The epidemiology favors acute hepatitis A; the patient’s history of travel to Mexico and work as a teacher are risk factors for hepatitis A. The incubation period of about 1 month is also typical. Hepatitis B and C are less likely without evidence for drug abuse or blood transfusion. Antibody to hepatitis B surface antigen would not be evidence for acute hepatitis B. HCV RNA is the appropriate test for acute hepatitis C infection, but this disease typically causes mild transaminase elevation and rarely presents with icterus. Liver biopsy is not indicated in acute hepatitis as the diagnosis is usually apparent from the examination, liver enzymes, and serological evidence of recent viral infection. Abdominal ultrasound would not be helpful as liver enzymes suggest hepatocellular damage, not biliary obstruction.
A previously healthy 25-year-old music teacher develops fever and a rash over her face and chest. The rash is itchy and, on examination, involves multiple papules and vesicles in varying stages of development. One week later, she complains of cough and is found to have an infiltrate on x-ray. Which of the following is the most likely etiology of the infection?
Varicella pneumonia develops in about 20% of adults with chickenpox. It occurs 3 to 7 days after the onset of the rash. The hallmarks of the chickenpox rash are papules, vesicles, and scabs in various stages of development. Fever, malaise, and itching are usually part of the clinical picture. The differential can include some coxsackievirus and echovirus infections, which might present with pneumonia and vesicular rash. Rickettsial pox, a rickettsial infection, has also been mistaken for chickenpox. Although the pneumococcus, Mycoplasma, and Chlamydia are common causes of community-acquired pneumonia in young adults, they would not account for the preceding vesicular rash. Histoplasmosis can cause acute pneumonitis after a large exposure but would not account for the rash.
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