Patterns of resistance associated with integrons, the extended-spectrum β-lactamase SHV-5 gene, and a multidrug efflux pump of Klebsiella pneumoniae causing a nosocomial outbreak
Patterns of resistance associated with integrons, the extended-spectrum β-lactamase SHV-5 gene, and a multidrug efflux pump of Klebsiella pneumoniae causing a nosocomial outbreak
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DOI：
10.1128/jcm.41.3.1161-1166.2003
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发表时间：
2003-03-01
影响因子：
9.4
通讯作者：
Verbrugh, H
中科院分区：
文献类型：
--
作者：
Gruteke, P;Goessens, W;Verbrugh, H
多重耐药肺炎克雷伯菌引起医院内爆发。假定爆发分离株的耐药模式在患者之间和患者内部各不相同。为控制疫情，对产超广谱β-内酰胺酶（ESBL）的克雷伯菌进行了筛选。肺炎开始。一些敏感的K.储存肺炎菌株作为遗传菌株分型的对照。脉冲场凝胶电泳分型证明了已确认的暴发患者中菌株的克隆性。通过脉冲场凝胶电泳对对照菌株进行分型，结果显示ESBL筛查程序至少遗漏了一名患者。进一步的基因分型证实了SHV-5 ESBL基因在所有爆发菌株中的存在，但只有一个。结果表明，在所有暴发菌株中均存在携带氨基糖苷类耐药基因aadB和aadA 2的整合子。尽管环丙沙星的MIC存在很大差异，但在所有暴发菌株中均存在密码子83的gyrA突变。环丙沙星和化学无关药物头孢西丁的MIC相关（r = 0.86，P < 0.01），并与暴发菌株亚群中外排泵的过表达相一致。我们的结论是，爆发菌株，仅在一个低水平表达的ESBL基因可能会通过在筛选过程中被忽视，当实验室是不知道的变量ESBL表达。在这一特定的爆发中，筛选环丙沙星MIC>= 0.25 μ g/ml的菌株是检测克雷伯菌最敏感的方法。肺炎爆发菌株。
Multiresistant Klebsiella pneumoniae caused a nosocomial outbreak. Resistance patterns of the presumed outbreak isolates varied among and within patients. In order to control the outbreak, screening for extended-spectrum beta-lactamase (ESBL)-producing K. pneumoniae was commenced. A number of susceptible K. pneumoniae strains were stored to serve as controls in genetic strain typing. Typing by pulsed-field gel electrophoresis proved the clonality of the strains in the recognized outbreak patients. Typing of the control strains by pulsed-field gel electrophoresis showed that at least one patient had been missed by the ESBL screening procedure. Further genetic typing confirmed the presence of the SHV-5 ESBL gene in all but one of the outbreak strains. Variable presence of integrons that carried the aminoglycoside resistance genes aadB and aadA2 was found. A gyrA mutation in codon 83 was present in all outbreak strains tested, despite considerable differences in ciprofloxacin MICs. The MICs of ciprofloxacin and the chemically unrelated drug cefoxitin were correlated (r = 0.86, P < 0.01) and were compatible with the overexpression of an efflux pump in a subset of the outbreak strains. We conclude that outbreak strains that express an ESBL gene only at a low level may pass unnoticed in a screening procedure, when the laboratory is unaware of variable ESBL expression. In this particular outbreak, screening for strains for which ciprofloxacin MICs were >= 0.25 mu g/ml would in retrospect have been the most sensitive method for detection of the K. pneumoniae outbreak strain.