Costa Daniela, Vinué Laura, Poeta Patricia, Coelho Ana Cláudia, Matos Manuela, Sáenz Yolanda, Somalo Sergio, Zarazaga Myriam, Rodrigues Jorge, Torres Carmen
Universidade de Trás-os-Montes e Alto Douro, Departamento de Ciências Veterinárias, Vila Real, Portugal.
Vet Microbiol. 2009 Sep 18;138(3-4):339-44. doi: 10.1016/j.vetmic.2009.03.029. Epub 2009 Mar 28.
Seventy-six faecal samples were obtained from broilers at slaughterhouse level in Portugal. Samples were inoculated on cefotaxime-supplemented Levine agar plates. Cefotaxime-resistant Escherichia coli isolates were recovered from 32 samples (42.1%), obtaining a total of 34 E. coli 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 E. coli isolates. Twenty-six isolates harboured the bla(TEM-52) gene and two of them also harboured bla(TEM-1b). The bla(CTX-M-14) gene was identified in three isolates (in association with bla(TEM-1b) in one of them), and bla(CTX-M-32) 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 ampC gene. tet(A) and/or tet(B) genes were detected in all 34 tetracycline-resistant isolates, aadA in all 26 streptomycin-resistant isolates; cmlA in 3 of 6 chloramphenicol-resistant isolates, and aac(3)-II or aac(3)-I + aac(3)-IV genes in all 4 gentamicin-resistant isolates. Different combinations of sul1, sul2 and sul3 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 E. coli isolates.
从葡萄牙屠宰场的肉鸡中采集了76份粪便样本。将样本接种在添加头孢噻肟的莱文琼脂平板上。从32份样本（42.1%）中分离出对头孢噻肟耐药的大肠杆菌，共获得34株大肠杆菌分离株（每份样本1株或2株）。采用纸片扩散法研究了这些分离株对16种抗生素的敏感性，85%的分离株呈现多重耐药表型，包括至少四个不同家族的抗菌药物。在31株ESBL阳性大肠杆菌分离株中检测到TEM和CTX-M组的超广谱β-内酰胺酶（ESBL）。26株分离株携带bla(TEM-52)基因，其中2株还携带bla(TEM-1b)。在3株分离株中鉴定出bla(CTX-M-14)基因（其中1株与bla(TEM-1b)相关），另外2株分离株中证实存在bla(CTX-M-32)。34株对头孢噻肟耐药的分离株中有3株（9%）不产生ESBL，其中2株在ampC基因启动子/衰减子区域的-42（C→T）、-18（G→A）、-1（C→T）和+58（C→T）位置出现突变。在所有34株对四环素耐药的分离株中检测到tet(A)和/或tet(B)基因，在所有26株对链霉素耐药的分离株中检测到aadA；6株对氯霉素耐药的分离株中有3株检测到cmlA，所有4株对庆大霉素耐药的分离株中检测到aac(3)-II或aac(3)-I + aac(3)-IV基因。在22株对甲氧苄啶-磺胺甲恶唑耐药的分离株中证实了sul1、sul2和sul3基因的不同组合。在所有18株对环丙沙星耐药的分离株中鉴定出GyrA和ParC蛋白的氨基酸变化。本研究结果表明，健康家禽的肠道是ESBL阳性大肠杆菌分离株的储存库。
