背景:产生碳青霉烯酶的肠杆菌(CPE)可以定植于肠道,是主要的临床问题。CPE定植的鉴定存在问题;没有金标准检测方法,抗生素暴露和微生物群菌群失调对检测的影响尚不清楚。
目的:根据一项全国调查,我们选择了四种常用的CPE筛查方法。我们使用人类肠道微生物群的临床反射体外模型来研究每种测试在不同条件下检测三种不同CPE菌株的性能。临床相关抗生素暴露。
方法:在12个肠道模型之前,用混合的粪便浆液接种并暴露于CPE,之后,伴随着,或在不存在哌拉西林-他唑巴坦(358mg/L,每天3×,七天)。每天计数肠杆菌和CPE总数。使用CepheidXpert®Carba-R分子测试对CPE进行定期筛选,和华晨™CRE,Colorex™mSuperCARBA和CHROMID®CARBASMARTagars。
结果:当微生物群完好无损时,检测CPE是有问题的。抗生素暴露会破坏微生物群,并允许CPE增殖,增加检测。化验的性能各不相同,特别是对于不同的CPE菌株。造父变菌试验比三种琼脂方法更好地检测完整微生物群中的低水平CPE,尽管当破坏的微生物群中CPE种群增加时,所有筛选方法的性能都相当。
结论:CPE菌株在体外肠道模型中的定植动力学以及随后对抗生素暴露的反应方面存在差异。这影响了分子检测和筛选方法,这对医疗机构中CPE筛查的敏感性有影响。
BACKGROUND: Carbapenemase-producing Enterobacterales (CPE) can colonize the gut and are of major clinical concern. Identification of CPE colonization is problematic; there is no gold-standard detection method, and the effects of antibiotic exposure and microbiota dysbiosis on detection are unknown.
OBJECTIVE: Based on a national survey we selected four CPE screening assays in common use. We used a clinically reflective in vitro model of human gut microbiota to investigate the performance of each test to detect three different CPE strains under different, clinically relevant antibiotic exposures.
METHODS: Twelve gut models were seeded with a pooled faecal slurry and exposed to CPE either before, after, concomitant with, or in the absence of piperacillin-tazobactam (358 mg/L, 3 × daily, seven days). Total Enterobacterales and CPE populations were enumerated daily. Regular screening for CPE was performed using Cepheid Xpert® Carba-R molecular test, and with Brilliance™ CRE, Colorex™ mSuperCARBA and CHROMID® CARBA SMART agars.
RESULTS: Detection of CPE when the microbiota are intact is problematic. Antibiotic exposure disrupts microbiota populations and allows CPE proliferation, increasing detection. The performances of assays varied, particularly with respect to different CPE strains. The Cepheid assay performed better than the three agar methods for detecting a low level of CPE within an intact microbiota, although performance of all screening methods was comparable when CPE populations increased in a disrupted microbiota.
CONCLUSIONS: CPE strains differed in their dynamics of colonization in an in vitro gut model and in their subsequent response to antibiotic exposure. This affected detection by molecular and screening methods, which has implications for the sensitivity of CPE screening in healthcare settings.