羊源粪肠球菌多位点序列分型及其耐药特性和毒力基因检测分析

Multilocus sequence typing, antibiotic resistance, and virulence genes of Enterococcus faecalis from sheep

摘要:

【背景】粪肠球菌(Enterococcus faecalis)作为一种普遍存在的条件致病菌，能引起严重感染，并能作为高耐药/毒力因子的储存和传播者对公共安全造成严重威胁。【目的】掌握安徽地区羊源粪肠球菌ST型分布特征及耐药、毒力特性，并分析其耐药基因、毒力基因与ST型之间的相关性，评估其潜在致病性及对公共卫生的危害性。【方法】以2021−2023年采集自安徽地区的64份羊直肠棉拭子为样本对粪肠球菌进行分离鉴定，采用多位点序列分型(multilocus sequence typing, MLST)方法对菌株进行分型鉴定，Kirby-Bauer (K-B)纸片扩散法测定粪肠球菌对16种抗菌药物的敏感性，并检测9种耐药基因及14种毒力基因的分布。【结果】共分离得到61株粪肠球菌，鉴定为24种ST型，其中9种为新发现ST型；奈替米星(72.13%)、丁胺卡那(75.41%)、四环素(55.74%)和红霉素(63.93%)的耐药比例最高，少数对万古霉素(9.84%)、利奈唑胺(11.48%)耐药，多重耐药(multi-drug resistance, MDR)率为57.38%；耐药基因ermB (77.05%)、aac(6')/aph(2') (52.46%)、tem (55.74%)的携带率最高，vanC (8.20%)、mefA (1.64%)的携带率最低；毒力基因cpd (100%)、efaA (98.36%)、ebp (95.08%)和fsr (81.97%)的携带率最高，hyl (11.48%)的携带率最低；部分耐药基因、毒力基因的分布在不同ST型之间具有显著差异(P<0.05)。【结论】羊源粪便粪肠球菌中携带高耐药和高水平毒力基因，且耐药特性及毒力的分布与ST型有着较高的相关性。

Abstract:

[Background] As a common opportunistic pathogen, Enterococcus faecalis can cause severe infections and pose a serious threat to public safety as a carrier of high resistance/virulence factors. [Objective] To master the sequence type (ST) distribution, antibiotic resistance, and virulence of sheep-derived E.faecalis strains in Anhui Province, analyze the correlations of antibiotic resistance and virulence genes with ST, and evaluate the potential threat to the public health. [Methods] E.faecalis was isolated from 64 sheep anal swab samples collected from Anhui during 2021−2023. Multilocus sequence typing (MLST) was employed to classify and identify the isolates. Kirby Bauer (K-B) test was carried out to determine the sensitivity of E.faecalis isolates to 16 antibiotics. Furthermore, the distribution of 9 resistance genes and 14 virulence genes was tested. [Results] A total of 61 strains of E.faecalis were isolated and identified as 24 STs, of which 9 were newly discovered STs. Most of the strains showed resistance to netilmicin (72.13%), amikacin (75.41%), tetracycline (55.74%), and erythromycin (63.93%). A few strains were resistant to vancomycin (9.84%) and linezolid (11.48%). with And the multi-drug resistance (MDR) rate was 57.38%. The carrier rates of resistance genes ermB (77.05%), aac(6')/aph(2') (52.46%), and tem (55.74%) were high, while those of vanC and mefA were low at 8.20% and 1.64%, respectively. The carrying rates of virulence genes cpd (100%), efaA (98.36%), ebp (95.08%), and fsr (81.97%) were high, while it was the lowest for hyl (11.48%). The distribution of some resistance and virulence genes showed differences among different STs (P<0.05). [Conclusion] Enterococcus faecalis from sheep feces carry high resistance and high virulence genes, and the distribution of resistance and virulence is highly correlated with STs.