Pyrazinamide-monoresistant Mycobacterium tuberculosis in the United States.
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.
Hannan
M M
MM
Division of Tuberculosis Elimination, National Center for HIV, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA. mhannan@cdc.gov
Desmond
E P
EP
Morlock
G P
GP
Mazurek
G H
GH
Crawford
J T
JT
D000581:Amidohydrolases / Q000235:genetics; D000995:Antitubercular Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D002140:California; D002487:Centers for Disease Control and Prevention, U.S.; D004268:DNA-Binding Proteins; D004352:Drug Resistance, Microbial; D005838:Genotype; D006801:Humans; D009163:Mycobacterium bovis / Q000145:classification / Q000187:drug effects / Q000235:genetics; D009169:Mycobacterium tuberculosis / Q000145:classification / Q000187:drug effects* / Q000235:genetics; D010641:Phenotype; D016133:Polymerase Chain Reaction / Q000379:methods; D012150:Polymorphism, Restriction Fragment Length; D011718:Pyrazinamide / Q000494:pharmacology*; D012097:Repressor Proteins / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics; D014376:Tuberculosis / Q000382:microbiology*; D014481:United States
D000995:Antitubercular Agents; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D011718:Pyrazinamide; D000581:Amidohydrolases; C022490:pyrazinamide deamidase