Tuberculosis Research Today is a free monthly online journal that collates and summarizes the latest research about Tuberculosis, including details on symptoms, causes, treatment, pulmonary, mycobacterium.

Recurrent tuberculosis in the United States and Canada: relapse or reinfection?

Jasmer RM, Bozeman L, Schwartzman K, Cave MD, Saukkonen JJ, Metchock B, Khan A, Burman WJ,

Division of Pulmonary and Critical Care Medicine, San Francisco General Hospital, San Francisco, CA 94110, USA. rjasmer@itsa.ucsf.edu

Recurrence of active tuberculosis after treatment can be due to relapse of infection with the same strain or reinfection with a new strain of Mycobacterium tuberculosis. The proportion of recurrent tuberculosis cases caused by reinfection has varied widely in previous studies. We evaluated cases of recurrent tuberculosis in two prospective clinical trials: a randomized study of two regimens for the last 4 months of treatment (n = 1,075) and a study of a twice-weekly rifabutin-containing regimen for human immunodeficiency virus-infected tuberculosis (n = 169). Isolates at diagnosis and from positive cultures after treatment completion underwent genotyping using IS6110 (with secondary genotyping for isolates with less than six copies of IS6110). Of 85 patients having a positive culture after completing treatment, 6 (7.1%) were classified as false-positive cultures by a review committee blinded to treatment assignment. Of the remaining 75 cases with recurrent tuberculosis and genotyping data available, 72 (96%; 95% confidence interval, 88.8-99.2%) paired isolates had the same genotype; only 3 (4%; 95% confidence interval, 0.8-11.2%) had a different genotype and were categorized as reinfection. We conclude that recurrent tuberculosis in the United States and Canada, countries with low rates of tuberculosis, is rarely due to reinfection with a new strain of M. tuberculosis.

Published 13 December 2004 in Am J Respir Crit Care Med, 170(12): 1360-6.
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