Mutations in gyrA, gyrB, parC, and parE in quinolone‐resistant strains of Neisseria gonorrhoeae

Abstract

Mutations in the genes for the subunits GyrA and ParC of the target enzymes DNA gyrase and topoisomerase IV are important mechanisms of resistance in quinolone-resistant bacteria, including Neisseria gonorrhoeae. The target enzymes also consist of the subunits GyrB and ParE, respectively, though their role in quinolone-resistance has not been fully investigated. We sequenced the quinolone-resistance-determining regions (QRDR) of gyrA, gyrB, parC, and parE in 25 ciprofloxacin-resistant strains from Bangladesh (MIC 4-->32 mg/l) and 5 susceptible strains of N. gonorrhoeae. All the resistant strains had three or four mutations. Two of these were at positions 91 and 95 of gyrA. Fourteen strains had an additional mutation in parC at position 91, and 17 strains had an additional mutation in parE in position 439. No alterations were found in gyrB. The five susceptible strains had identical DNA sequences. Data indicate that the mutations detected in the QRDR of gyrA and parC may be important in the development of quinolone resistance. According to transformation experiments we assume that the alteration in parE is not related to a high degree of quinolone resistance. There was no correlation between ciprofloxacin MICs and pattern or number of mutations in the target genes.

Molecular characterization of Neisseria gonorrhoeae identifies transmission and resistance of one ciprofloxacin‐resistant strain

“…All phenotypically determined ciprofloxacin-resistant isolates comprised SNPs that are highly correlated with ciprofloxacin resistance, i.e. in the Ser91 and the Asp95 codons of the wild-type gyrA gene sequence (14)(15)(16)(17)(18)(19)21,22). This method basedon Pyrosequencing technology is rapid, high-throughput, sensitive, accurate, and costeffective for identification of ciprofloxacin resistance in N. gonorrhoeae.…”

“…Since the mid-1990s, the prevalence of isolates resistant to ciprofloxacin, previously the drug of first choice for treatment of uncomplicated gonorrhoea, has been increasing in Sweden and in many other countries (SWEDRES 2004 http://www.strama.se (2)(3)(4)(5)13)). In N. gonorrhoeae, the ciprofloxacin resistance is mainly due to single nucleotide polymorphisms (SNPs) in the gyrA gene and the parC gene, which code for the target enzymes DNA gyrase and topoisomerase IV, respectively (14)(15)(16)(17)(18)(19). The level of resistance appears to be correlated with the location and number of mutations in these genes.…”

“…However, treatment failures with fluoroquinolones have been shown to be due to mutations primarily in the gyrA gene, and especially substitutions in a short quinolone resistance determining region (QRDR) of this gene (14,19,20). Consequently, it may be sufficient to analyze a short QRDR of the gyrA gene for identification of N. gonorrhoeae isolates with decreased susceptibility and resistance to ciprofloxacin (14)(15)(16)(17)(18)(19)21,22).In 2003, a presumed epidemiological core group comprising domestic cases of mainly young (<25 years of age) heterosexuals with urogenital gonorrhoea was identified in one Swedish county. All preserved N. gonorrhoeae isolates from these cases were assigned to serovar IB-10 and showed a high level of resistance to ciprofloxacin.…”

Comparison of Mismatch Amplification Mutation Assay with DNA Sequencing for Characterization of Fluoroquinolone Resistance in Neisseria gonorrhoeae

“…In laboratory mutants and in clinical isolates of fluoroquinolone-resistant N. gonorrhoeae, amino acid changes have been identified in GyrA and GyrB of DNA gyrase and in ParC and ParE of topoisomerase IV (1,12). Both clinical isolates and laboratory mutants showed identical mutations in gyrA.…”

“…The principal mechanisms of resistance are alterations in the target enzymes and a reduced cytoplasmic quinolone concentration due to overexpression of multidrug efflux systems (7). The most prevalent mechanism contributing to fluoroquinolone resistance in the gonococcus involves mutations in the quinolone resistance-determining region (QRDR) of gyrA and possibly in the analogous region of the parC locus on the chromosome (12).…”