title: Rapid detection of pyrazinamide-resistant Mycobacterium tuberculosis by a PCR-based in vitro system.
abstract: Pyrazinamide (PZA), an analog of nicotinamide, is a prodrug for tuberculosis which requires conversion to the bactericidal compound pyrazinoic acid by bacterial pyrazinamidase activity. Mutations leading to a loss of pyrazinamidase activity cause PZA resistance in Mycobacterium tuberculosis. Thus, the detection of pyrazinamidase activity makes the discrimination of PZA-resistant tuberculosis possible. However, the detection of the pyrazinamidase activity of M. tuberculosis isolates needs a large amount of bacilli and is therefore time consuming. In this paper, we describe a new method for the detection of pyrazinamidase activity with a PCR-based system. The genes encoding pyrazinamidase (pncA genes) in 30 resistant clinical isolates were amplified by PCR by using forward primers containing bacteriophage T7 promoter sequences at their 5" ends. Then the PCR products were directly subjected to an in vitro transcription-translation coupled system. All of the PZA-resistant isolates tested showed reduced pyrazinamidase activity compared to susceptible M. tuberculosis type strain H37Rv. In contrast, all of the 15 susceptible clinical isolates exhibited pyrazinamidase activities similar to that of H37Rv. This fact suggested the possibility of the usefulness of this system for the rapid detection of PZA-resistant M. tuberculosis.
authors.affiliation: Department of Pathology, Osaka Prefectural Institute of Public Health, Higashinari-ku, Osaka 537-0025, Japan. suzuki@iph.pref.osaka.jp
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Aya
authors.initials: A
authors.lastname: Suzuki
authors.forename: Aki
authors.initials: A
authors.lastname: Tamaru
authors.forename: Chihiro
authors.initials: C
authors.lastname: Katsukawa
authors.forename: Hajime
authors.initials: H
authors.lastname: Oda
mesh_terms: D000581:Amidohydrolases / Q000235:genetics / Q000378:metabolism; D000995:Antitubercular Agents / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000201:enzymology / Q000302:isolation & purification; D016133:Polymerase Chain Reaction / Q000379:methods*; D011718:Pyrazinamide / Q000494:pharmacology*; D013997:Time Factors; D014397:Tuberculosis, Pulmonary / Q000382:microbiology
chemical_list: D000995:Antitubercular Agents; D011718:Pyrazinamide; D000581:Amidohydrolases; C022490:pyrazinamide deamidase