title: Overexpression of an ABC transporter and mutations of GyrA, GyrB, and ParC in contributing to high-level ciprofloxacin resistance in Streptococcus suis type 2.
abstract: Streptococcus suis is a pathogen of zoonotic diseases. Moreover, the emergence of fluoro-quinolones (FQs) resistance in this pathogen has severe consequences for pigs and human health. In this study, the molecular mechanism of FQs resistance in S. suis type 2 (SS2) sensitive strains isolated from pigs was assessed after in vitro induction of resistance against the most frequently used FQs: ciprofloxacin, norfloxacin, and enrofloxacin. Proteome analysis, sequencing and real-time RT-PCR results strongly established an overexpression of an ABC transporter protein (other than SatAB) and topoisomerase mutations in GyrA (Ser81Arg), GyrB (Glu354Lys), and ParC (Ser79Phe) in contributing to high level ciprofloxacin resistance in SS2. Due to the overexpression of the ABC transporter, intracellular ciprofloxacin concentrations were significantly lower in the resistant strains than those of sensitive strains after 20, 35, and 60 min exposures to ciprofloxacin (p < 0.05). It was concluded that improper use of FQs is one of the main causes of the emergence of this zoonotic pathogen as a multiresistant organism against commonly used antibiotics. The existence of an efflux-like protein is an incentive to find new drug targets to avoid the spread of FQs-resistant S. suis isolates in pigs and the human population.
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University.
authors.forename: Jie
authors.initials: J
authors.lastname: Yao
authors.forename: Kexin
authors.initials: K
authors.lastname: Shang
authors.forename: Jinhu
authors.initials: J
authors.lastname: Huang
authors.forename: Wei
authors.initials: W
authors.lastname: Ran
authors.forename: Jam
authors.initials: J
authors.lastname: Kashif
authors.forename: Liping
authors.initials: L
authors.lastname: Wang
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002939:Ciprofloxacin / Q000494:pharmacology*; D027081:DNA Gyrase / Q000235:genetics; D027101:DNA Topoisomerase IV / Q000235:genetics; D006801:Humans; D009154:Mutation; D013290:Streptococcal Infections / Q000188:drug therapy; D017011:Streptococcus suis / Q000187:drug effects* / Q000235:genetics*; D013552:Swine
chemical_list: D018528:ATP-Binding Cassette Transporters; D000900:Anti-Bacterial Agents; D002939:Ciprofloxacin; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase