A medical technician is trying to isolate a pathogen from the sputum sample of a patient. The sample is heat fixed to a slide then covered with carbol fuchsin stain and heated again. After washing off the stain with clean water, the slide is covered with 1% sulfuric acid for decolorization. The sample is rinsed again and stained with methylene blue. Microscopic examination shows numerous red, branching filamentous organisms. Which of the following is the most likely isolated pathogen?
ACryptococcus neoformans
BTropheryma whipplei
CNocardia asteroides
DRickettsia rickettsii
EStaphylococcus aureus
A 28-year-old woman comes to the physician because of a two-month history of fatigue and low-grade fevers. Over the past 4 weeks, she has had increasing shortness of breath, a productive cough, and a 5.4-kg (11.9-lb) weight loss. Three months ago, the patient returned from a two-month trip to China. The patient appears thin. Her temperature is 37.9°C (100.2°F), pulse is 75/min, and blood pressure is 125/70 mm Hg. Examination shows lymphadenopathy of the anterior and posterior cervical chain. Rales are heard at the left lower lobe of the lung on auscultation. Laboratory studies show a leukocyte count of 11,300/mm3 and an erythrocyte sedimentation rate of 90 mm/h. An x-ray of the chest shows a patchy infiltrate in the left lower lobe and ipsilateral hilar enlargement. Microscopic examination of the sputum reveals acid-fast bacilli; polymerase chain reaction is positive. Sputum cultures are pending. After placing the patient in an airborne infection isolation room, which of the following is the most appropriate next step in management?
AAdminister only isoniazid for 9 months
BAdminister isoniazid, rifampin, pyrazinamide, and ethambutol for 2 months, followed by isoniazid and rifampin for 4 months
CAwait culture results before initiating treatment
DObtain CT scan of the chest
EPerform interferon-γ release assay
A 32-year-old man comes to the physician because of a 3-week history of cough, weight loss, and night sweats. He migrated from Sri Lanka 6 months ago. He appears emaciated. His temperature is 38.1°C (100.5°F). Physical examination shows enlargement of the right supraclavicular lymph node. Chest and abdominal examination show no abnormalities. An interferon-gamma assay is positive. A biopsy specimen of the cervical lymph node is most likely to show the causal organism in which of the following locations?
AMantle zone
BMedullary sinus
CGerminal center
DSubcapsular sinus
EParacortex
+ 7 more in the PDF
Browse all chapters