Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
PLoS One. 2010 Feb 26;5(2):e9440. doi: 10.1371/journal.pone.0009440.
The objective was to investigate the phenotypic and genotypic resistance and the horizontal transfer of resistance determinants from Salmonella isolates from humans and animals in Vietnam.
METHODOLOGY/PRINCIPAL FINDINGS: The susceptibility of 297 epidemiologically unrelated non-typhoid Salmonella isolates was investigated by disk diffusion assay. The isolates were screened for the presence of class 1 integrons and Salmonella genomic island 1 by PCR. The potential for the transfer of resistance determinants was investigated by conjugation experiments. Resistance to gentamicin, kanamycin, chloramphenicol, streptomycin, trimethoprim, ampicillin, nalidixic acid, sulphonamides, and tetracycline was found in 13 to 50% of the isolates. Nine distinct integron types were detected in 28% of the isolates belonging to 11 Salmonella serovars including S. Tallahassee. Gene cassettes identified were aadA1, aadA2, aadA5, bla(PSE-1), bla(OXA-30), dfrA1, dfrA12, dfrA17, and sat, as well as open reading frames with unknown functions. Most integrons were located on conjugative plasmids, which can transfer their antimicrobial resistance determinants to Escherichia coli or Salmonella Enteritidis, or with Salmonella Genomic Island 1 or its variants. The resistance gene cluster in serovar Emek identified by PCR mapping and nucleotide sequencing contained SGI1-J3 which is integrated in SGI1 at another position than the majority of SGI1. This is the second report on the insertion of SGI1 at this position. High-level resistance to fluoroquinolones was found in 3 multiresistant S. Typhimurium isolates and was associated with mutations in the gyrA gene leading to the amino acid changes Ser83Phe and Asp87Asn.
Resistance was common among Vietnamese Salmonella isolates from different sources. Legislation to enforce a more prudent use of antibiotics in both human and veterinary medicine should be implemented by the authorities in Vietnam.
本研究旨在调查越南人源和动物源非伤寒沙门氏菌分离株的表型和基因型耐药性以及耐药决定因子的水平转移。
方法/主要发现：采用纸片扩散法检测 297 株流行病学上无关的非伤寒沙门氏菌分离株的药敏性。通过 PCR 筛选这些分离株中是否存在 1 类整合子和沙门氏菌基因组岛 1。通过接合实验研究耐药决定因子的转移潜能。13%至 50%的分离株对庆大霉素、卡那霉素、氯霉素、链霉素、甲氧苄啶、氨苄西林、萘啶酸、磺胺类药物和四环素耐药。在属于 11 种沙门氏菌血清型（包括 S. Tallahassee）的 28%的分离株中检测到 9 种不同的整合子类型，鉴定的基因盒为 aadA1、aadA2、aadA5、bla(PSE-1)、bla(OXA-30)、dfrA1、dfrA12、dfrA17 和 sat 以及具有未知功能的开放阅读框。大多数整合子位于可将其抗菌药物耐药决定因子转移至大肠杆菌或肠炎沙门氏菌的接合质粒上，或位于沙门氏菌基因组岛 1 或其变体上。通过 PCR 图谱和核苷酸测序确定的血清型 Emek 中的耐药基因簇含有 SGI1-J3，该基因簇整合在 SGI1 上的位置与大多数 SGI1 不同。这是 SGI1 插入该位置的第二份报告。3 株多重耐药性鼠伤寒沙门氏菌分离株对氟喹诺酮类药物表现出高水平耐药性，与 gyrA 基因的突变有关，导致氨基酸变化为 Ser83Phe 和 Asp87Asn。
来自不同来源的越南沙门氏菌分离株耐药性普遍存在。越南当局应立法，在人类和兽医学中更审慎地使用抗生素。
