Prevalence of extended-spectrum beta-lactamase-producing isolates in faecal samples of broilers

Daniela Costa , Laura Vinué , Patricia Poeta , Ana Cláudia Coelho , Manuela Matos , Yolanda Sáenz , Sergio Somalo , Myriam Zarazaga , Jorge Rodrigues , Carmen Torres

Seventy-six faecal samples were obtained from broilers at slaughterhouse level in Portugal. Samples were inoculated on cefotaxime-supplemented Levine agar plates. Cefotaxime-resistant isolates were recovered from 32 samples (42.1%), obtaining a total of 34 isolates (one or two isolates per sample). Susceptibility to 16 antibiotics was studied by disk diffusion method, and 85% of the isolates presented a phenotype of multi-resistance that included antimicrobial agents of at least four different families. Extended-spectrum-beta-lactamases (ESBL) of the TEM and CTX-M groups were detected in 31 ESBL-positive isolates. Twenty-six isolates harboured the gene and two of them also harboured . The gene was identified in 3 isolates (in association with in one of them), and was demonstrated in two additional isolates. Three of the 34 cefotaxime-resistant isolates (9%) did not produce ESBLs, and two of them presented mutations at positions -42 (C→T), -18 (G→A), -1 (C→T), and +58(C→T) of the promoter/attenuator region of gene. (A) and/or (B) genes were detected in all 34 tetracycline-resistant isolates, in all 26 streptomycin-resistant isolates; in 3 of 6 chloramphenicol-resistant isolates, and (3)-II or (3)-I + (3)-IV genes in all 4 gentamicin-resistant isolates. Different combinations of , and genes were demonstrated among the 22 trimethoprim-sulfamethoxazole-resistant isolates. Amino acid changes in GyrA and ParC proteins were identified in all 18 ciprofloxacin-resistant isolates. The results of this study indicate that the intestinal tract of healthy poultry is a reservoir of ESBL-positive isolates.

Mots clés: TEM-52; CTX-M-14; CTX-M-32; Broilers

Daniela Costa, Laura Vinué, Patricia Poeta, Ana Cláudia Coelho, Manuela Matos, et al.. Prevalence of extended-spectrum beta-lactamase-producing isolates in faecal samples of broilers. Veterinary Microbiology, 2009, 138 (3-4), pp.339. ⟨10.1016/j.vetmic.2009.03.029⟩. ⟨hal-00514603⟩