First Report of <i>aac(6′)-Ib</i> and <i>aac(6′)-Ib-cr</i> Variant Genes Associated with Mutations in <i>gyrA</i> Encoded Fluoroquinolone Resistance in Avian <i>Campylobacter coli</i> Strains Collected in Tunisia

Abstract

The aac(6′)-Ib gene is the most widespread gene encoding aminoglycoside-modifying enzyme and conferring resistance to tobramycin, streptomycin and kanamycin. The variant aac(6′)-Ib-cr gene confers resistance to both aminoglycosides and fluoroquinolones (FQ). A total of 132 Campylobacter isolates, including 91 C. jejuni and 41 C. coli, were selected from broiler hens isolates. The aac(6′)-Ib gene was amplified using PCR and was subsequently digested with the BtsCI restriction enzyme to identify aac(6′)-Ib-cr. Among these isolates, 31 out of 41 C. coli (75.6%) and 1 (0.98%) C. jejuni were positive for the aac(6′)-Ib gene, which was identified as the aac(6′)-Ib-cr variant in 10 (32.25%) C. coli isolates. This variant was correlated with mutations in gyrA (Thr-86-Ile), as well as resistance to FQs. This study is the first report in Tunisia on Campylobacter coli strains harboring both the aac(6′)-Ib and aac(6′)-Ib-cr variants. These genes were present in Campylobacter isolates exhibiting resistance to multiple antibiotics, which restricts the range of available treatments.

Keywords

• <i>Campylobacter</i>
• poultry
• fluoroquinolone-resistance
• phylogeny
• <i>aac(6′)-Ib-cr</i>