Abodakpi Henrietta, Chang Kai-Tai, Sánchez Díaz Ana María, Cantón Rafael, Lasco Todd M, Chan Katrina, Sofjan Amelia K, Tam Vincent H
a Department of Pharmacological and Pharmaceutical Sciences , University of Houston College of Pharmacy , Houston , TX , USA.
b Department of Pharmacy Practice and Translational Research , University of Houston College of Pharmacy , Houston , TX , USA.
J Chemother. 2018 Apr;30(2):115-119. doi: 10.1080/1120009X.2017.1399233. Epub 2017 Nov 10.
To improve prescribing of empiric therapy, the local molecular epidemiology of extended-spectrum beta-lactamases (ESBLs) and Klebsiella pneumoniae carbapenemases (KPCs) in bloodstream isolates of K. pneumoniae were evaluated. Isolates resistant to third generation cephalosporins were screened phenotypically for ESBLs and carbapenemases, and subsequently confirmed by PCR for the presence of ESBL (bla, bla and bla) and carbapenemase (bla, bla, bla and bla) genes. Hydrolytic activity (functional gene expression) was quantified using a nitrocefin degradation assay and correlated to ceftazidime or meropenem MIC. Clonality was assessed by repetitive element-based PCR. Beta-lactamases were functionally expressed in 13 isolates (15.5%); 7 (53.8%) harboured bla and 6 (46.2%) carried the bla gene. Correlation of hydrolytic activity to MIC yielded a coefficient of 98% for isolates expressing ESBLs alone and 56% for carbapenemase producers. Four unique ESBL-expressing clones and five carbapenem-resistant clones were identified. All 13 resistant isolates were susceptible to ceftazidime/avibactam (MIC ≤ 8/4 mg/L).
为改善经验性治疗的用药情况，对肺炎克雷伯菌血流分离株中广谱β-内酰胺酶（ESBLs）和肺炎克雷伯菌碳青霉烯酶（KPCs）的局部分子流行病学进行了评估。对耐第三代头孢菌素的分离株进行ESBLs和碳青霉烯酶的表型筛选，随后通过PCR确认ESBL（bla、bla和bla）和碳青霉烯酶（bla、bla、bla和bla）基因的存在。使用硝基头孢菌素降解试验对水解活性（功能基因表达）进行定量，并与头孢他啶或美罗培南的最低抑菌浓度（MIC）相关联。通过基于重复元件的PCR评估克隆性。13株分离株（15.5%）功能性表达β-内酰胺酶；7株（53.8%）携带bla，6株（46.2%）携带bla基因。水解活性与MIC的相关性显示，仅表达ESBLs的分离株系数为98%，碳青霉烯酶产生菌为56%。鉴定出4个独特的表达ESBLs的克隆和5个耐碳青霉烯的克隆。所有13株耐药分离株对头孢他啶/阿维巴坦敏感（MIC≤8/4 mg/L）。
