Uncommon occurrence of fluoroquinolone resistance-associated alterations in GyrA and ParC in clinical strains of Chlamydia trachomatis

Global Fluoroquinolone Resistance Epidemiology and Implictions for Clinical Use

“…Quinolone resistance in C. pneumoniae has not been described clinically or even in vitro; however, high-level resistance to ofloxacin, sparfloxacin, and ciprofloxacin occurred in C. trachomatis upon serial exposure to subinhibitory quinolone-concentrations [445–449]. However, spontaneous mutation frequencies resulting in moxifloacin resistance were very low or even nonexistent; exposure of C. trachomatis serovars L 2 and D resulted in emergence of quinolone resistance at a frequency of 2.0–2.2 × 10 −8 in serovar L 2 only, whereas no resistant clones could be elicited in serovar D [450].…”

“…2.7 × 10 9 inclusion forming units) was exposed to the drug, whereas the bacterial load at the focus of infection is much lower thus reducing the likelihood of drug-induced resistance selection. Nevertheless, fluoroquinolone-resistant strains of C. trachomatis have been isolated occasionally [449, 450]. Fluoroquinolone resistance elicited in vitro in C. trachomatis serovar L 2 was due to a single nucleotide point mutation in gyrA , while no mutations were found in gyrB , parC , or parE genes; no QRDR mutations could be detected in the fluoroquinolone-resistant clinical isolates [451].…”

Clinical and microbiological outcomes in treatment of men with non-gonococcal urethritis with a 100-mg twice-daily dose regimen of sitafloxacin

“…They also recommend an erythromycin, levofloxacin, or ofloxacin regimen as alternative treatments. The emergence of drug-resistant C. trachomatis has been rare, so these regimens have been highly effective in the treatment of chlamydia-positive NGU [4]. For M. genitalium infections, however, treatment with the doxycycline regimen has not been so effective [5].…”

Resistance of different Chlamydia-like organisms to quinolones and mutations in the quinoline resistance-determining region of the DNA gyrase A- and topoisomerase-encoding genes

“…Partial amino acid sequence of ParC of Protochlamydia amoebophila strain UWE25, Parachlamydia acanthamoebae strain BN9, P. acanthamoebae strain Hall's coccus, Chlamydia caviae, Chlamydia pneumoniae, Chlamydia trachomatis[18], Simkania negevensis and Escherichia coli. The ParC QRDR (Ala-64 to Gln-103; E. coli numbering) is delimited by vertical black lines.…”