title: 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.
abstract: Parachlamydia acanthamoebae has been shown to be resistant to fluoroquinolones. In this study, we determined the susceptibility of Neochlamydia hartmannellae and Simkania negevensis to quinolones using amoebal co-culture in the presence of serial dilutions of ciprofloxacin. The gyrA and parC quinoline resistance-determining regions (QRDRs) were amplified and sequenced, and amino acid substitutions that may explain the observed quinolone resistance were investigated. Neochlamydia and Simkania were resistant to 16 microg/mL ciprofloxacin. Substitution at positions 83 and 70 of GyrA QRDR were present in Neochlamydia and in both Parachlamydia strains studied. For Simkania, substitutions at positions 99 and 101 in the GyrA QRDR and at positions 81 and 84 in the ParC QRDR were observed. Resistance of Parachlamydia, Neochlamydia and Simkania to quinolones is likely due to these mutations.
authors.affiliation: Center for Research on Intracellular Bacteria, Microbiology Institute, Faculty of Biology and Medicine, University of Lausanne, 1011 Lausanne, Switzerland.
authors.forename: Nicola
authors.initials: N
authors.lastname: Casson
authors.forename: Gilbert
authors.initials: G
authors.lastname: Greub
mesh_terms: D000595:Amino Acid Sequence; D000890:Anti-Infective Agents / Q000494:pharmacology*; D002689:Chlamydia / Q000187:drug effects* / Q000235:genetics; D002939:Ciprofloxacin / Q000494:pharmacology*; D027081:DNA Gyrase / Q000737:chemistry / Q000235:genetics*; D027101:DNA Topoisomerase IV / Q000737:chemistry / Q000235:genetics*; D024881:Drug Resistance, Bacterial; D008969:Molecular Sequence Data; D013329:Structure-Activity Relationship
chemical_list: D000890:Anti-Infective Agents; D002939:Ciprofloxacin; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase