Al-Agamy Mohamed H, El Mahdy Taghrid S, Shibl Atef M
Department of Pharmaceutics, Microbiology Division, College of Pharmacy, King Saud University, P.O. Box 2457, Riyadh 11451, Saudi Arabia; Department of Microbiology and Immunology, Faculty of Pharmacy, Al-Azhar University, Cairo, Egypt.
Microbiology and Immunology Department, Faculty of Pharmacy, Helwan University, Cairo, Egypt.
Biomed Res Int. 2016;2016:3704150. doi: 10.1155/2016/3704150. Epub 2016 May 31.
Background. Extended-spectrum β-lactamases (ESβLs) and AmpC β-lactamases cause β-lactam resistance in Escherichia coli. Fecal colonization by ESβL- and/or AmpC-positive E. coli is a source of nosocomial infections. Methods. In order to investigate inpatient fecal colonization by ESβLs and AmpC, antibiotic sensitivity tests were conducted and minimum inhibitory concentrations (MICs) were determined using the disk diffusion method and E-test, respectively. Characterization of ESβL and AmpC was performed using E-test strips, and a set of PCRs and DNA sequence analyses were used to characterize the ESβL and AmpC genes. Results. The whole collection of E. coli isolates (n = 50) was sensitive to imipenem, tigecycline, colistin, and fosfomycin, while 26% of the isolates showed reduced susceptibility to ceftazidime (MIC ≥ 4 μg/mL). ESβL was phenotypically identified in 26% (13/50) of cases, while AmpC activity was detected in two ESβL-producing E. coli isolates. All ESβL-producing E. coli were positive for the CTX-M gene, eleven isolates carried bla CTX-M-15, and two isolates carried bla CTX-M-14 gene. Two CTX-M-positive E. coli isolates carried bla CMY-2. Conclusions. The alimentary tract is a significant reservoir for ESβL- and/or AmpC-producing E. coli, which may lead to nosocomial infection.
背景。超广谱β-内酰胺酶（ESβLs）和AmpCβ-内酰胺酶可导致大肠埃希菌对β-内酰胺类抗生素耐药。产ESβL和/或AmpC的大肠埃希菌在粪便中的定植是医院感染的一个来源。方法。为了调查住院患者粪便中产ESβLs和AmpC的情况，分别采用纸片扩散法和E-test法进行抗生素敏感性试验并测定最低抑菌浓度（MIC）。使用E-test试条对ESβL和AmpC进行鉴定，并通过一组聚合酶链反应（PCR）和DNA序列分析对ESβL和AmpC基因进行鉴定。结果。大肠埃希菌分离株的总体集合（n = 50）对亚胺培南、替加环素、黏菌素和磷霉素敏感，而26%的分离株对头孢他啶的敏感性降低（MIC≥4μg/mL）。26%（13/50）的病例在表型上鉴定出ESβL，而在两株产ESβL的大肠埃希菌分离株中检测到AmpC活性。所有产ESβL的大肠埃希菌的CTX-M基因均为阳性，11株携带bla CTX-M-15，2株携带bla CTX-M-14基因。两株CTX-M阳性的大肠埃希菌分离株携带bla CMY-2。结论。消化道是产ESβL和/或AmpC的大肠埃希菌的重要储存库，这可能导致医院感染。
