Phenotypic and Molecular Patterns of Resistance among Campylobacter coli and Campylobacter jejuni Isolates, from Pig Farms

Abstract

The purpose of this research was to characterize the antibiotic resistance patterns of <i>Campylobacter</i> spp. isolated from commercial farrow to finish farms in Greece, and analyze the relevant molecular resistance mechanisms among the resistant <i>Campylobacter</i> isolates. Susceptibility testing to five different classes of antibiotics was performed in 100 <i>C. coli</i> and 100 <i>C. jejuni</i>, previously isolated and identified. All isolates were found susceptible to meropenem. Very high rates of resistance were recorded for tetracyclines (84.5%), medium rates of resistance were recorded regarding quinolones (23%), and low and very low rates of resistance were identified for macrolides such as erythromycin and aminoglycosides (12% and 4%, respectively). Only 12.5% of the <i>Campylobacter</i> isolates displayed MDR. Regarding the molecular mechanisms of resistance, all ciprofloxacin resistant isolates hosted the mutant type <i>Thr-86-Ile</i> region of the quinolone resistance-determining region (QRDR) of the <i>gyrA</i> gene. In all erythromycin resistant isolates, the transitional mutations A2075G and A2074C in the <i>23S rRNA</i> gene were only amplified. Molecular screening of tetracycline resistance genes indicated that the vast majority of <i>Campylobacter</i> isolates (92.3%) were positive for the <i>tet(O)</i> gene. In summary, these findings and especially the very high and medium rates of resistance for tetracyclines and fluroquinolones, respectively recommend that a continuous monitoring of <i>Campylobacter</i> isolates susceptibility in combination with the proper use of antimicrobials in livestock production is of great importance for public health.