Detection of mutations involved in fluoroquinolone resistance in Mycoplasma gallisepticum positive field samples from broiler chicken flocks in Ecuador

Abstract

The aim of this study was to determine the occurrence of mutations in the quinolone resistance-determining regions (QRDRs) of the genes gyrA and parC in M. gallisepticum positive field samples from broiler flocks in Ecuador. DNA was extracted from 24 M. gallisepticum PCR-positive samples from 22 commercial broiler flocks. The genes gyrA and parC were amplified by PCR. PCR products were sequenced by Sanger technology to analyze the genetic characteristics. To identify the mutations involved in fluoroquinolone resistance (FQR), the sequences obtained were processed and analyzed using the tools Geneious R11, BLASTn, MAFFT, ExPASy MBWS, and BioEdit. All samples had mutations in both gyrA and parC genes, resulting in changes at amino acid positions Ser-83→Ile and Ile-157→Val in GyrA, and Ser-80→Trp in ParC. In addition, a change at position His-59→Tyr in GyrA was also found in one sample. The results showed that alterations in both genes have been commonly linked to FQR in mutants of other Mycoplasma species, including M. gallisepticum. This is the first study on M. gallisepticum positive samples from chickens in Ecuador which revealed the occurrence of mutations resulting in amino acid changes previously linked to FQR.