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Journal of Clinical Microbiology, February 2001, p. 647-650, Vol. 39, No. 2
Division of Tuberculosis Elimination,
National Center for HIV, STD, and TB
Prevention,1 and National Center for
Infectious Diseases,4 Centers for Disease
Control and Prevention, Atlanta, Georgia 30333; California
Department of Health Services, Berkeley, California
947043; and Department of Infectious
Diseases and Microbiology, Imperial College School of Medicine,
London W2 1PG, United Kingdom2
Received 30 June 2000/Returned for modification 9 October
2000/Accepted 15 November 2000
Mycobacterium bovis is naturally resistant to the
antituberculosis drug pyrazinamide (PZA). To determine whether all
Mycobacterium tuberculosis complex isolates demonstrating
PZA monoresistance were truly M. bovis, we examined
the phenotype and genotype of isolates reported as PZA monoresistant in
five counties in California from January 1996 through June 1999. Isolates reported by local laboratories to be PZA monoresistant were
sent to the state reference laboratory for repeat susceptibility
testing using the BACTEC radiometric method and to the Centers for
Disease Control and Prevention for pncA sequencing and
PCR-restriction fragment length polymorphism (RFLP) analysis
of the oxyR gene. Of 1,916 isolates, 14 were reported as
PZA monoresistant and 11 were available for retesting. On repeat
testing, 6 of the 11 isolates were identified as
PZA-susceptible M. tuberculosis, 1 was
identified as PZA-monoresistant M. bovis, and 1 was
identified as M. bovis BCG. The three remaining isolates were identified as PZA-monoresistant M. tuberculosis. Sequencing of the pncA and
oxyR genes genotypically confirmed the two M. bovis and the six susceptible M. tuberculosis
species. Each of the three PZA-monoresistant M. tuberculosis isolates had different, previously unreported,
pncA gene mutations: a 24-bp deletion in frame after codon
88, a base substitution at codon 104 (Ser104Cys), and a
base substitution at codon 90 (Ile90Ser). This study
demonstrates that PZA monoresistance is not an absolute marker of
M. bovis species but may also occur in M. tuberculosis, associated with a number of different mutational
events in the pncA gene. It is the first report of
PZA-monoresistant M. tuberculosis in the United States.
0095-1137/01/$04.00+0 DOI: 10.1128/JCM.39.2.647-650.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Pyrazinamide-Monoresistant Mycobacterium
tuberculosis in the United States
*
Corresponding author. Mailing address: Surveillance and
Epidemiology Branch, Division of Tuberculosis Elimination, 1600 Clifton Rd., Mailstop E-10, Atlanta, GA 30333. Phone: (404) 639-5485. Fax:
(404) 639-1287. E-mail: mhannan{at}cdc.gov.
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