Fourth Department of Internal Medicine, Infectious Diseases Laboratory, Molecular Biology Section, National and Kapodistrian University of Athens, School of Medicine, Athens, Greece.
Fourth Department of Internal Medicine, Infectious Diseases Laboratory, Molecular Biology Section, National and Kapodistrian University of Athens, School of Medicine, Athens, Greece.
Clin Microbiol Infect. 2019 Jun;25(6):763.e5-763.e8. doi: 10.1016/j.cmi.2019.03.011. Epub 2019 Mar 28.
We characterized the first ceftazidime-avibactam-resistant KPC-producing-Klebsiella pneumoniae clinical isolate detected in Greece, before the introduction of ceftazidime-avibactam in clinical practice.
K. pneumoniae KP-90 was isolated from a hospitalized patient in Thessaloniki during a nationwide surveillance study conducted between 2014 and 2016. Antimicrobial susceptibility was tested against a panel of agents. Whole-genome sequencing (Ion Torrent TM platform) of the isolate was carried out to identify the acquired resistance genes and mutations that were associated with ceftazidime-avibactam resistance.
The K. pneumoniae isolate belonged to multilocus sequence type ST258 and harboured bla as the only carbapenemase gene. The isolate had a minimum inhibitory concentration (MIC) of 16 mg/L to ceftazidime-avibactam and was highly resistant to imipenem, meropenem (MICs, 512 mg/L) and ceftazidime (MIC, >1024 mg/L). bla was detected on a Tn4401a transposon, located on a pKPQIL-type plasmid. A non-functional outer membrane protein OmpK35 and an OmpK36 variant that had been previously associated with K. pneumoniae isolates of ST258 were detected. Transformation studies with Escherichia coli TOP10 showed that KPC-23 offered similar carbapenem MICs as KPC-2 and KPC-3. However, KPC-23 conferred a four-fold higher ceftazidime MIC (>1024 mg/L), which in the presence of avibactam was reduced (>7-fold) to 8 mg/L, which is just within the limit of the susceptibility breakpoint.
Ceftazidime-avibactam resistance in a KPC-23- producing K. pneumoniae clinical isolate was due to increased ceftazidime hydrolysis and was likely enhanced by OmpK35 porin deficiency.
在 ceftazidime-avibactam 引入临床实践之前，我们对在希腊首次检测到的产 KPC 头孢他啶-阿维巴坦耐药肺炎克雷伯菌临床分离株进行了特征描述。
在 2014 年至 2016 年进行的全国性监测研究中，从塞萨洛尼基的一名住院患者中分离出肺炎克雷伯菌 KP-90。对该分离株进行了针对一组药物的药敏试验。对分离株进行全基因组测序（Ion Torrent TM 平台），以鉴定与头孢他啶-阿维巴坦耐药相关的获得性耐药基因和突变。
肺炎克雷伯菌分离株属于多位点序列型 ST258，仅携带 bla 作为唯一的碳青霉烯酶基因。该分离株对头孢他啶-阿维巴坦的最小抑菌浓度（MIC）为 16 mg/L，对亚胺培南、美罗培南（MICs，512 mg/L）和头孢他啶（MIC，>1024 mg/L）高度耐药。bla 位于 Tn4401a 转座子上，位于 pKPQIL 型质粒上。检测到非功能外膜蛋白 OmpK35 和先前与 ST258 肺炎克雷伯菌分离株相关的 OmpK36 变体。用大肠杆菌 TOP10 进行的转化研究表明，KPC-23 提供的碳青霉烯 MIC 与 KPC-2 和 KPC-3 相似。然而，KPC-23 导致头孢他啶 MIC 升高四倍（>1024 mg/L），在阿维巴坦存在的情况下，MIC 降低（>7 倍）至 8 mg/L，这刚好在药敏折点范围内。
产 KPC-23 肺炎克雷伯菌临床分离株对头孢他啶-阿维巴坦的耐药性是由于头孢他啶水解增加所致，可能是由于 OmpK35 孔蛋白缺乏而增强。
