A 24-year-old female was hospitalized with a 10 day history ofincreasing fever, one or two severe shaking chills daily, andprogressive weakness. A chronic, nonproductive cough, which thepatient attributed to moderately heavy smoking, probably had becomemore prominent during the two or three weeks precedinghospitalization. A diagnosis of primary thrombocytopenia had beenestablished approximately one year previously, based on thepresence of splenomegaly. Initial physical findings included atemperature of 102 F orally, a pulse of 110 per minute,respiration’s 24 per minute, and a blood pressure of 110/70 mm Hg.The patient appeared acutely ill, dyspneic, and extremelyapprehensive. Conversation was difficult because of intermittentparoxysms of coughing, which produced no sputum. Several nontenderlymph nodes, up to 1 cm in diameter, were readily palpable in eachaxilla. The spleen was enlarged, with a firm, nontender edgedescending at least 6 cm below the left costal margin on deepinspiration. Initial lab data include a total leukocyte count of20,800 per cubic mm, a differential of 42% neutrophils, 25% bandforms, and 19% lymphocytes, and a hematocrit of 42; the plateletcount was 2,120,000 per cubic mm. Chest X-ray revealed a moderatelydense pulmonary infiltrate extending out from the right hilum intothe right lower lobe. One of the two blood cultures obtained at thetime of admission to the hospital and before any antimicrobialagents were administered yielded a slow growing gram-negativebacillary rod. It was identified as Pseudomonas aeruginosa. Theattending physician elected to initiate antimicrobial therapy withpenicillin G administered intravenously, 2.5 million units everysix hours. Because of the febrile course, with spiking feverranging as high as 105.6 F, evidence of an increase in the rightlower lobe infiltrate on a subsequent X-ray, and the report of agram-negative bacilli in one of the two blood cultures, penicillintherapy was discontinued and cephalothin therapy was initiated. Alung biopsy of the right lower lobe was performed and the specimenrevealed many focal granulomas consisting largely of histiocytesand epithelioid cells, with some areas of necrosis and caseation.Innumerable acid-fast bacilli were present.
What is the microbe?
