Microbial Forensics

Notice: Because of current public health concern, this article is being published early (on November 8, 2001). It will appear in the IEF R EPOR T 29 issue of the Journal. November BR
he had been in good health. His only regular medications were daily metoprolol and aspirin. The patient was a nonsmoker and an avid outdoorsman whose pastimes were gardening and fishing. Four days before he wasadmitted to the hospital, the patient had been in good health and had left for a brief recreational trip to North Carolina. Immediately on his arrival in North Carolina, the first symptoms of illness developed; these included muscle aches, nausea, and fever. The symptoms waxed and waned for the duration of the three-day trip. The day after he returned home, he was taken to the hospital for medicalevaluation. During the trip, he had spent time outdoors, but he could identify no unusual exposure, including exposure to animals or animal hides. The patient was employed as a photo editor for a major tabloid newspaper and had been working until the day he departed for North Carolina. His duties usually kept him in a large office building in Florida, where he spent most of the day reviewingphotographs submitted by mail or over the Internet. On physical examination, he was found to be lethargic and disoriented. His temperature was 39°C (102.5°F), the blood pressure was 150/80 mm Hg, the pulse was 110, and the respirations were 18. No respiratory distress was noted; his arterial hemoglobin saturation, as indicated by pulse oximetry while he was breathing ambient air, was 97 percent. Noevidence of trauma was noted on examination of the head. Funduscopic examination was normal, as were the conjunctiva. Examination of the ear, nose, and throat detected no discharge or signs of inflammation. There was no discernable nuchal rigidity; Kernig’s and Brudzinski's signs were absent. The trachea was at midline, and there was no edema of the cervical or thoracic region. Chest examinationrevealed bibasilar rhonchi without rales. No murmurs, rubs, or gallops were heard on cardiac auscultation. The abdomen was soft, without rebound tenderness or organomegaly. Examination of the joints, legs, and arms was essentially normal. No lesions or rashes were noted on the skin. No focal deficits were noted on neurologic examination; there were no cranial-nerve palsies. The results of the patient’slaboratory tests on hospital admission are shown in Table 1. The initial chest radiograph (Fig. 1) was interpreted as showing basilar infiltrates and a widened mediastinum. The results of computed tomography of the head, performed without intravenous contrast medium, were normal. A spinal tap was performed under fluoroscopic guidance within hours after presentation at the hospital and yieldedcloudy cerebrospinal fluid (Table 1). Gram’s staining of cerebrospinal fluid revealed many polymorphonuclear white cells and many large gram-positive bacilli, both singly and in chains (Fig. 2). On the basis of the cerebrospinal fluid appearance, a diagnosis of anthrax was considered, and high-dose intravenous penicillin G was added to the antibiotic regimen. Within six hours after plating onsheep’s-blood agar, the cultures of cerebrospinal fluid yielded colonies of gram-positive bacilli (Fig. 3). The clinical laboratory of the medical center presumptively identified the organism as B. anthracis within 18 hours after plating; this identification was confirmed by the Florida Department of Health laboratory on the following day (Table 2).4 Multiple blood cultures obtained on admission were alsoultimately positive for B. anthracis. Within hours after admission, the patient had a generalized grand mal seizure and was intubated to protect his airway and so that ventilatory assistance could be provided. After intubation, the arterial blood gas values while the patient was receiving supplemental oxygen (fraction of inspired oxygen, 50 percent) were as follows: a pH of 7.31, a partial...