Characterization of pyrazinamide and ofloxacin resistance among drug-resistant Mycobacterium tuberculosis isolates from Singapore

Abstract

In Singapore, genotypic analysis of resistance to PZA and ofloxacin is inadequate and should be complemented by conventional methods.

Rapid Detection of Ofloxacin Resistance in Mycobacterium tuberculosis by Two Low-Cost Colorimetric Methods: Resazurin and Nitrate Reductase Assays

“…However, it is well known that DST on Löwenstein Jensen (LJ) medium or Middlebrook agar is very slow, requiring at least 4 to 6 weeks to produce the first results (5, 6). The development of rapid DST that is simple to use and affordable for low-resource countries is a priority (20, 24), since there are already reports of OFX-resistant strains of M. tuberculosis or the creation of OFX resistance during treatment (14,15,16,18,31,34,38). Some efforts have already been made to perform second-line DST by the radiometric BACTEC TB-460 system (Becton Dickinson Diagnostic Instrument Systems, Sparks, Md.)…”

Review: The Molecular Basis of Resistance in <i>Mycobaterium tuberculosis</i>

“…These are points of interaction of FQ and gyrase [108], and mutations in gyrA are associated with high-level resistance while gyrB mutations have been just identified in laboratory mutants of M. tuberculosis [84]. However, the percentage of FQs resistants M. tuberculosis clinical isolates with detectable gyr mutations may vary from 2% to 100% among different studies [109][110][111][112]. This variance can be explained by the differences in the extension of coverage of the genome [108]; the definition of MICs [111]; and maybe, others mechanisms responsible for the mycobacterial resistance to FQs, such as decrease in cell-wall permeability to drug, drug efflux pump, drug sequestration, or perhaps even drug activation [6,107].…”

Schneller Nachweis von Mutationen im gyrA-Gen von Mycobacterium tuberculosis mit Relevanz für die Entstehung von Medikamentenresistenzen gegen Chinolone mittels der Real-Time PCR auf dem LightCycler® System

“…Mutation identifiziert werden (Lee, Tang et al 2002). Mehrfachmutationen in den beiden Gyrasegenen wurden bisher in klinischen Stämmen nicht beschrieben.…”

“…Über die entscheidende Frage, in wie vielen phänotypisch resistenten Stämmen Gyrasemutationen hierfür verantwortlich gemacht werden können, finden sich häufig widersprüchliche Angaben. So wurden in einer Studie aus Hongkong (Williams, Chan et al 1996) in allen untersuchten resistenten Stämmen gyrA-Mutationen gefunden, wohingegen in einer Studie aus Singapur in keinem der untersuchten Stämme eine gyrA-Mutation identifiziert werden konnte (Lee, Tang et al 2002). Mehrere Reviews (Ramaswamy and Musser 1998;Ginsburg, Grosset et al 2003) Isolat mit einer Mutation Asp505→Ala identifiziert werden (Lee, Tang et al 2002).…”

“…In (Jacobs 1999;Piddock 1999;Bryskier and Lowther 2002;Victor, van Helden et al 2002;Jacobs 2004) (Takiff, Salazar et al 1994;Cambau, Sougakoff et al 1994 (2); Alangaden, Manavathu et al 1995;Sullivan, Kreiswirth et al 1995;Kocagoz, Hackbarth et al 1996;Takiff, Cimino et al 1996;Williams, Chan et al 1996;Xu, Kreiswirth et al 1996;Perlman, El Sadr et al 1997;Sougakoff, Lemaitre et al 1997;Zhou, Dong et al 2000;Lee, Tang et al 2002;Siddiqi, Shamim et al 2002;Yew, Chan et al 2002;Johansen, Larsen et al 2003;Cheng, Yew et al 2004;Post, Willcox et al 2004;Giannoni, Iona et al 2005) (Ginsburg, Grosset et al 2003;Wade and Zhang 2004) …”