The Risk for Transmission of Mycobacterium tuberculosis at the Bedside and during Autopsy

Tuberculosis is generally not considered highly communicable. A recent experience shows the great variation in the infectiousness of a patient with tuberculosis. Case Report A 57-year-old man was hospitalized for increasing dizziness, decreased oral intake, and a weight loss of 11 kg within 6 months. His medical history included anemia and adenocarcinoma of the prostate that was treated with radical prostatectomy and radiation. He had abused alcohol and tobacco for many years but denied exposure to tuberculosis. The patient was cachectic but alert and cooperative. His temperature was 36.4 C, his pulse was 126 beats/min, his respiration rate was 20 breaths/min, and his blood pressure was 110/70 mm Hg when he was supine and sitting but 90/60 mm Hg when he was standing. Percussion and auscultation indicated that his lungs were clear and that his abdomen was soft and nontender with normal bowel sounds. A chest radiograph showed no abnormality of the heart or lungs. Laboratory findings were as follows: hematocrit, 24.7%; leukocyte count, 5.7 109/L; and hemoglobin level, 8.2 g/dL. Admission diagnosis was postural hypotension secondary to autonomic dysfunction, with dehydration playing a contributory role. Comorbid conditions included a normochromic, normocytic anemia. No recognizable infection was present, nor was there evidence for recurrent malignancy. On the sixth hospital day, a urinary tract infection developed that was caused by Streptococcus faecalis and that responded promptly to intravenous antibiotics. On hospital day 16, the patient gradually became dyspneic and less responsive. Moderate ascites was noted, and a chest radiograph showed cephalization of the pulmonary vasculature and diffuse bilateral pulmonary infiltration with bilateral pleural effusions. Examination of the ascitic fluid showed a leukocyte count of 1 109/L, an erythrocyte count of 120 cells/mm3, an amylase level of 0.32 kat/L, a glucose level of 6.4 mmol/L, a protein level of 24 g/L, and a lactate dehydrogenase level of 5.23 kat/L. Gram, fluorochrome, and Ziehl-Neelson stains of the ascitic fluid were negative. Intradermal skin tests with 5 tuberculin units of purified protein derivative and two control antigens gave no reaction at 48 hours. The serum was negative for antibody to human immunodeficiency virus. The ascites, pulmonary infiltration, and pleural effusions were thought to be caused by congestive heart failure or hepatic cirrhosis. The patient continued to deteriorate and died on hospital day 21. An autopsy was then done. Postmortem Examination Examination of the lungs showed extensive pneumonia with large areas of necrosis, but no granulomas were noted. Hundreds of tubercle bacilli were seen in every oil immersion field of the lung, hilar lymph nodes, spleen, peritoneum, kidneys, testes, brain, and vertebral bodies. Culture of all tissues showed heavy growth of Mycobacterium tuberculosis. Cultures of blood and ascitic fluid obtained 5 days before death were positive for M. tuberculosis and were sensitive to all drugs tested. Epidemiologic Investigation When it was realized that the patient had died of tuberculosis, an epidemiologic investigation was initiated. Fortunately, for several years our medical center has tested all new clinical personnel with the two-step Mantoux method using 5 tuberculin units of purified protein derivative. Nonreactors are retested annually. An induration of greater than 10 mm 48 hours after the test is considered a positive result. During the patient's 21-day hospital stay, 47 health care workers participated in his care. Of these, 7 (14.9%) were known positive tuberculin reactors and 40 were nonreactors. Because the diagnosis of tuberculosis had not been suspected, no respiratory precautions had been taken. The patient was in a single room with ventilation that provided five fresh-air changes per hour but no upper-air sterilization with ultraviolet irradiation. On repeat tuberculin testing 8 weeks after the patient's death, none of the 40 nonreactors had converted to positive, and none was treated. The findings for personnel in the autopsy room differed from the findings for the personnel who had cared for the patient (Table 1). Of the 10 persons in the room, 5 were already k Table 1. Duration of Exposure and Results of Clinical Evaluation and Treatment for Staff and Students Present at Autopsy*