Cavicchio Lara, Dotto Giorgia, Giacomelli Martina, Giovanardi Davide, Grilli Guido, Franciosini Maria Pia, Trocino Angela, Piccirillo Alessandra
Department of Comparative Biomedicine and Food Science, University of Padova, 35020 Legnaro (PD), Italy.
Laboratorio Tre Valli, 37132 San Michele Extra (VR), Italy.
Poult Sci. 2015 Jun;94(6):1202-8. doi: 10.3382/ps/pev095. Epub 2015 Apr 3.
The aim of this study was to investigate the occurrence of class 1 and 2 integrons in avian pathogenic Escherichia coli (APEC) from poultry in northern Italy. Strains were tested for phenotypic resistance to aminoglycosides and sulphonamides, and the association between the presence of integrons and the resistance to these antimicrobials was evaluated. A total of 299 isolates (158 from turkeys, 110 from broilers, and 31 from layer hens) were collected from 200 industrial farms. Antimicrobial susceptibility test by the disk diffusion method was performed in accordance with the Clinical and Laboratory Standards Institute (CLSI) guidelines. All strains were screened for the presence of class 1 and 2 integrons by PCR and sequencing. About 55% of APEC contained integrons (class 1, 49.8%; class 2, 10.4%). Different variants of the aadA (5 variants) and the dfrA (4 variants) genes, encoding for streptomycin and trimethoprim resistance respectively, were detected in integron-positive isolates. Less common gene cassettes, such as sat, estX, and orfF, were also identified. Fifteen and 4 gene cassette arrays were found among class 1 and 2 integrons, respectively. High levels of resistance were observed for triple sulphonamides (79.3%), streptomycin (67.2%), and sulfamethoxazole combined with trimethoprim (62.2%), whereas resistance against gentamycin (16.7%), kanamycin (14.7%), and apramycin 3.0%) was low. Integron positivity was significantly higher in isolates phenotypically resistant to aminoglycosides (63.6% vs. 37.8%, P<0.001) and sulfonamides (64.1% vs. 21.1%, P<0.001) than in susceptible ones. Integron-borne aminoglycoside and sulfonamide resistance in APEC represents a concern for the poultry industry in Italy, since they are among the most commonly used antimicrobials in poultry therapy.
本研究的目的是调查意大利北部家禽中禽致病性大肠杆菌（APEC）1类和2类整合子的发生情况。对菌株进行了对氨基糖苷类和磺胺类药物的表型耐药性测试，并评估了整合子的存在与对这些抗菌药物耐药性之间的关联。从200个工业化养殖场共收集了299株分离株（158株来自火鸡，110株来自肉鸡，31株来自蛋鸡）。按照临床和实验室标准协会（CLSI）指南，采用纸片扩散法进行抗菌药物敏感性试验。通过PCR和测序对所有菌株进行1类和2类整合子存在情况的筛查。约55%的APEC含有整合子（1类，49.8%；2类，10.4%）。在整合子阳性分离株中检测到分别编码链霉素和甲氧苄啶耐药性的aadA（5种变体）和dfrA（4种变体）基因的不同变体。还鉴定出了不太常见的基因盒，如sat、estX和orfF。在1类和2类整合子中分别发现了15种和4种基因盒阵列。对三联磺胺类药物（79.3%）、链霉素（67.2%）以及磺胺甲恶唑联合甲氧苄啶（62.2%）观察到高水平耐药，而对庆大霉素（16.7%）、卡那霉素（14.7%）和安普霉素（3.0%）的耐药率较低。表型上对氨基糖苷类（63.6%对37.8%，P<0.001）和磺胺类药物（64.1%对21.1%，P<0.001）耐药的分离株中整合子阳性率显著高于敏感分离株。APEC中整合子携带的氨基糖苷类和磺胺类药物耐药性是意大利家禽业的一个担忧，因为它们是家禽治疗中最常用的抗菌药物之一。
