Biomedical subjects
Publications and source records attributed to L Mosher.
White-tailed deer in Michigan are now recognized as a reservoir host of bovine tuberculosis (TB). It has been determined that the most likely cause of bovine TB infection in the deer is from congregating in artificially high numbers at feed sites. The presence of a wildlife reservoir of TB in Michigan poses a serious threat to the control and eradication programs that are now in their final stages in the United States.
Cross-contamination during sequential processing of sputum specimens from different patients causes false-positive growth of Mycobacterium tuberculosis in culture. We describe an unusual case of cross-contamination in a 36-year-old man with acquired immunodeficiency syndrome and possible persistent tuberculosis. Culture with 1 of 3 sputum specimens was positive for rifampin-susceptible M tuberculosis. Review of processing revealed that his single culture-positive sputum specimen had followed a sputum specimen from another patient with active pulmonary tuberculosis that was positive in culture for M tuberculosis resistant to rifampin. Molecular strain typing by restriction fragment length polymorphism demonstrated the 2 isolates to be an identical strain of M tuberculosis. Agar proportion susceptibility testing of the rifampin-resistant isolate revealed low numbers of resistant organisms in a range of 1.5% to 3.3%. It was concluded that rifampin-susceptible organisms that constituted approximately 98% of the resistant isolate contaminated sputum from the patient with possible persistent tuberculosis. His culture result was, therefore, considered false positive, not an indication of tuberculosis.
At the Veterans Affairs Lakeside Medical Center, two episodes of specimen cross-contamination with Mycobacterium tuberculosis were detected during a 54-month period by molecular strain typing using DNA restriction fragment length polymorphism for 3 patients without clinical or radiologic signs of tuberculosis (TB). A cross-contaminated specimen was the only culture-positive specimen for each of the 3 patients. Laboratory features of cross-contamination included acid-fast smear negativity, growth only in broth or solid medium, and growth in solid medium with 5 or fewer colonies. Retrospective analysis demonstrated identical features for occasional culture-positive specimens from 54 patients with TB during the same period. However, productive cough, pleural pain, weight loss, night sweats, chest radiograph results suggestive of TB, positive tuberculin skin testing, and/or multiple culture-positive specimens were invariably present in patients with TB with such specimens. Most patients with TB (50/54; 93%) had multiple specimens positive in culture for M. tuberculosis, and the few patients with TB with single culture-positive specimens were symptomatic. These results indicate that correlation with clinical manifestations is necessary to determine the significance of isolated, acid-fast smear negative, and/or low-yield culture-positive specimens. Although the prevalence of specimen cross-contamination is low (0.1%), possible sources (especially the use of single-reagent delivery systems for multiple specimens) should be eliminated by mycobacteriology laboratories.
A cluster of multidrug-resistant tuberculosis sputum isolates led to the detection of specimen contamination in a hospital mycobacteriology laboratory. Thirteen specimens were smear negative but culture positive from one specimen only; 12 appeared to be contaminated. Each of these specimens was processed in the same batch as one or more smear- and culture-positive isolates. Molecular analysis confirmed the traditional epidemiologic, laboratory, and clinical methods of evaluating presumed mycobacterial contamination.
In 1978 a revolutionary mental health act was passed in Italy. By closing large mental hospitals and replacing them with community programs, it required a radical shift in psychiatric practice. The authors discuss the background philosophy, principles, and practical implications of this change. They describe a model program and training design of a 4-year residency in which psychiatrists learn the skills for community work while actually working in the community. The residency differs from most U.S. residencies in having trainees responsible for patients wherever they are being treated (residents are not rotated between services), its strong team orientation, and the value placed on community work.
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