Analysis of the gyrA gene of clinical Yersinia ruckeri isolates with reduced susceptibility to quinolones

• Published in: Applied and Environmental Microbiology Vol. 70; no. 1; pp. 599 - 602
• Main Authors: Gibello, A, Porrero, M.C, Blanco, M.M, Vela, A.I, Liebana, P, Moreno, M.A, Fernandez-Garayzabal, J.F, Dominguez, L
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 2004
• Subjects: Amino Acid Sequence; Amino Acid Substitution; Animals; Anti-Infective Agents - pharmacology; bacterial infections; Biological and medical sciences; DNA Gyrase - chemistry; DNA Gyrase - genetics; DNA topoisomerase (ATP-hydrolysing); drug resistance; Drug Resistance, Bacterial - genetics; enteric redmouth disease; fish diseases; Fish Diseases - microbiology; Fundamental and applied biological sciences. Psychology; Genetics; Genetics and Molecular Biology; Microbial Sensitivity Tests; Microbiology; Molecular Sequence Data; mutants; Nalidixic Acid - pharmacology; nucleotide sequences; Oncorhynchus mykiss; Oxolinic Acid - pharmacology; quinolones; Quinolones - pharmacology; structural genes; Yersinia ruckeri; Yersinia ruckeri - drug effects; Yersinia ruckeri - genetics; Bacteria; Gene; Yersinia ruckeri; Clinical isolate; Enterobacteriaceae
• ISSN: 0099-2240; 1098-5336
• DOI: 10.1128/AEM.70.1.599-602.2004

Antimicrobial susceptibility of seven clinical strains of Yersinia ruckeri representative of those isolated between 1994 and 2002 from a fish farm with endemic enteric redmouth disease was studied. All isolates displayed indistinguishable pulsed-field gel electrophoresis restriction patterns, indicating that they represented a single strain. However, considering both inhibition zone diameters (IZD) and MICs, the isolates recovered in 2001-2002 formed a separate cluster with lower levels of susceptibility to all the quinolones tested, especially nalidixic acid (NA) and oxolinic acid (OA), compared with the isolates recovered between 1994 and 1998. Analysis of the PCR product of the quinolone resistance-determining region of the gyrA gene from clinical isolates of Y. ruckeri with reduced susceptibility to OA and NA revealed a single amino acid substitution, Ser-83 to Arg-83 (Escherichia coli numbering). Identical substitution was observed in induced OA-resistant mutant strains, which displayed IZD and MICs of quinolones similar to those of the clinical isolates of Y. ruckeri with reduced susceptibility to these antimicrobial agents. These data indicate in that for Y. ruckeri, the substitution of Ser by Arg at position 83 of the gyrA gene is associated with reduced susceptibility to quinolones.