Antimicrobial resistance profiling and fla-typing of Irish thermophillic Campylobacter spp. of human and poultry origin

Aims: To determine the genetic relationship between a random collection of Irish human and poultry Campylobacter isolates and to determine the frequency of antibiotic resistance. Methods and Results: Sixty-six Campylobacter isolates (34 human and 32 poultry) were typed by restriction fragment length polymorphism of flagellin-A (flaA) PCR products (flaA-RFLP) and by sequencing of the short variable region of flaA (flaA-SVR). FlaA-RFLP identified 58 distinct profiles, while flaA-SVR identified 28 different alleles. The highest level of antibiotic resistance was found for ampicillin (48.5%) followed by nalidixic acid (42.2%) and ciprofloxacin (31.8%). In general, poultry isolates displayed a higher incidence of resistance to the antimicrobials tested than the human isolates. Conclusions: A high level of genetic diversity existed among the Campylobacter strains confirming the weak clonality of this species. There was no relationship between antimicrobial resistance and specific genotypes determined by flaA typing suggesting that resistance was due to pressures of antimicrobial therapy. Significance and Impact of the Study:This study emphasizes the need for increased surveillance of antimicrobial susceptibility among Campylobacter isolates in Ireland and the implementation of more stringent control policies relating to the use of antimicrobials in the poultry industry.