Neisseria gonorrhoeae acquires mutations in analogous regions of gyrA and parC in fluoroquinolone‐resistant isolates

Abstract

Neisseria gonorrhoeae homologues of gyrA and parC have been identified using hybridization probes generated from conserved regions of diverse gyrA genes. These genes have been tentatively identified as gyrA and parC, based on predicted amino acid sequence homologies to known GyrA homologues from numerous bacterial species and to ParC from Escherichia coli and Salmonella typhimurium. The gyrA gene maps to a physical location distant from the gyrB locus on the gonococcal chromosome, which is similar to the situation found in E. coli. The parC gene is not closely linked (i.e. greater than 9 kb) to an identifiable parE gene in N. gonorrhoeae. The gonococcal GyrA is slightly larger than its E. coli homologue and contains several small insertions near the C-terminus of the predicted open reading frame. A series of ciprofloxacin-resistant mutants were selected by passage of N. gonorrhoeae on increasing concentrations of the antibiotic. Sequential passage resulted in the selection of isolates with minimum inhibitory concentrations approximately 10,000-fold higher than the parental strain. Mutations within gyrA resulted in low to moderate levels of resistance, while strains with high-level resistance acquired analogous mutations in both gyrA and parC. Resistance mutations were readily transferred between N. gonorrhoeae strains by transformation. The frequencies of transformation, resulting in different levels of ciprofloxacin resistance, further support the notion that both gyrA and parC genes are involved in the establishment of extreme levels of ciprofloxacin resistance.

Genotyping of two Neisseria gonorrhoeae fluroquinolone-resistant strains in the Brazilian Amazon Region

“…Residue substitutions were identified by comparing the predicted amino acid sequences of the isolates from this study with the wild-type GyrA and ParC sequences (Genbank accessions: AAA82128 and AAA82151, respectively). The sequencing analysis identified mutations in residues 91 and 95 (Ser91Phe and Asp95Gly) of GyrA and Ser87Arg of ParC, which have already been associated with the fluroquinolone resistance phenotype (Belland et al 1994, Tiejun et al 2009). …”

“…Fragments of gyrA (278 bp) and parC (254 bp) genes, which corresponded to the quinolone resistance-determining region (Belland 1994), were polymerase chain reaction (PCR)-amplified and sequenced in both directions using the BigDye Terminator Cycle Sequence kit 3.1 in an ABI 3130 genetic analyzer (Applied Biosystems). Residue substitutions were identified by comparing the predicted amino acid sequences of the isolates from this study with the wild-type GyrA and ParC sequences (Genbank accessions: AAA82128 and AAA82151, respectively).…”

Analysis of Neisseria gonorrhoeae in Ontario, Canada, with decreased susceptibility to quinolones by pulsed-field gel electrophoresis, auxotyping, serotyping and plasmid content

“…A study by Stein et al [29] has suggested that low level resistance was associated with the gyrB gene while high level resistance probably represents a mutation in gyrA. A recent study [30] also found mutations in the gyrA gene associated with quinolone resistance in clinical isolates of N gonorrhoeae and Belland et al [31] have indicated that alterations in topoisomerase Iy an enzyme related to DNA gyrase, have also been associated with quinolone resistance in gonococci.…”

The Role of the Transcription Factors MtrR and MtrA in the Fitness of the Pathogen Neisseria gonorrhoeae

“…Other noteworthy examples of N. gonorrhoeae modifying the targets of a drug are the gyrA and pare mutations, which alter the bacterial DNA binding proteins gyrase and topoisomerase, respectively (36). Such mutations In these DNA binding proteins make quinolone antibiotics less effective (15).…”