发布者：抗性基因网 时间：2020-04-23 浏览量：1607
摘要
目的：
非医院来源的高水平氨苄西林和氨基糖苷类耐药肠球菌越来越多。这项研究的目的是对尼日利亚非医院来源的这些菌株进行鉴定。
方法：
从蔬菜、土壤、农场动物和粪便中分离出一批粪肠球菌，观察其对氨苄西林（n=63）和庆大霉素（n=37）的耐药性，并用电子测试条筛选出对高浓度氨苄西林和氨基糖苷的耐药性。采用聚合酶链反应（PCR）技术，筛选出可能的氨苄西林和氨基糖苷类耐药菌株，分别检测其pbp5和氨基糖苷类修饰酶基因。对扩增的pbp5基因的C末端进行了测序。
结果：
根据MIC结果，5株（5/63）和35株（35/37）氨苄西林和氨基糖苷类耐药菌株分别被鉴定为高水平氨苄西林和氨基糖苷类耐药菌株。从高水平氨苄西林耐药菌株中扩增出的pbp5基因与参考菌株和3个新的氨基酸序列（500Glu→Leu、502Asp→Arg和614Ile→Phe）具有96-99%的核苷酸序列相似性。氨基糖苷类修饰酶基因aac（6’）-Ie aph（2〃）（100%），aph（2’）-Ic（88.8%），aph（3’）-iia（90%）和ant（4’）-Ia（40%）。
结论：
这是尼日利亚首次对动物和蔬菜中的高水平氨苄西林和氨基糖苷类耐药屎肠球菌进行鉴定。研究结果表明，非医院来源可以通过食物链或直接接触构成这些菌株和基因向人类传播的潜在库。
High level ampicillin- and aminoglycoside-resistant enterococci are being increasingly reported from non-hospital sources. This study was carried out to characterize these strains from non-hospital sources in Nigeria.
A collection of Enterococcus faecium isolated from vegetables, soil, farm animals and manure and observed to be resistant to ampicillin (n=63) and gentamicin (n=37) discs, were screened for resistance to high levels of ampicillin and aminoglycoside using E-test strips. Putative high level ampicillin- and aminoglycoside-resistant strains were screened for pbp5 and aminoglycoside modifying enzyme genes, respectively, by PCR. The C-terminal region of the amplified pbp5 gene was also sequenced.
Five (5/63) and thirty-five (35/37) of the ampicillin- and aminoglycoside-resistant strains were identified as high level ampicillin- and aminoglycoside-resistant E. faecium strains, respectively, based on the MIC results. The amplified pbp5 gene from the high level ampicillin-resistant isolates displayed 96-99 % nucleotide sequence similarity with the reference strains and three novel insertions (500Glu→Leu, 502Asp→Arg and 614Ile→Phe) in the amino acid sequence. Aminoglycoside modifying enzyme genes aac(6')-Ie-aph(2″) (100 %), aph(2')-Ic (88.8 %), aph(3')-IIIa (90 %) and ant(4')-Ia (40 %) were detected among the high level aminoglycoside-resistant isolates.
This is the first report on the characterization of high level ampicillin- and aminoglycoside-resistant Enterococcus faecium among animals and vegetables in Nigeria. The results show that non-hospital sources can constitute a reservoir for potential dissemination of these strains and genes to humans via the food chain or by direct contact.