First description of the qnrS-like (qnrS5) gene and analysis of quinolone resistance-determining regions in motile Aeromonas spp. from diseased fish and water.
Antimicrobial resistance patterns in a collection of 33 motile Aeromonas species were described in this study. Quinolone has been frequently employed for treatment of Aeromonas-related diseases, and prolonged use of antimicrobial compounds has led to development of resistant strains. In a sample of diseased fish and environmental water, we evaluated nalidixic acid (n = 19) and ciprofloxacin (n = 4) resistance via minimum inhibitory concentration (MIC) assays and the genetic basis was also investigated. Among the isolated Aeromonas spp., 17 strains encoded for chromosomal mutations of quinolone resistance-determining regions (QRDRs) in gyrA, 11 strains encoded for mutations of QRDRs in parC, 1 strain harbored plasmid-mediated quinolone resistance (PMQR) qnrS1-like gene and 4 strains harbored the PMQR qnrS2 gene. In particular, the new variant (qnrS1-like) differed from qnrS1 by 6 amino acid substitutions at positions 5 (Asn(5)→Arg(5)), 120 (Ser(120)→Thr(120)), 148 (Asn(148)→His(148)), 206 (Leu(206)→Glu(206)), 207 (Ile(207)→ Leu(207)), and 216 (Tyr(216)→Phe(216)), and the gene was designated qnrS5. These resistant strains may function as reservoirs of quinolone resistance.
Laboratory of Aquatic Animal Medicine, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 151-742, Republic of Korea.
Jee Eun
JE
Han
Ji Hyung
JH
Kim
Casiano H
CH
Cheresca
Sang Phil
SP
Shin
Jin Woo
JW
Jun
Ji Young
JY
Chai
Sang Yoon
SY
Han
Se Chang
SC
Park
D000333:Aeromonas / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D024881:Drug Resistance, Bacterial; D005393:Fish Diseases / Q000382:microbiology*; D005399:Fishes; D005618:Fresh Water / Q000382:microbiology*; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology / Q000662:veterinary*; D008969:Molecular Sequence Data; D010802:Phylogeny; D015363:Quinolones / Q000494:pharmacology*
D001426:Bacterial Proteins; D015363:Quinolones