Hayakawa Kayoko, Miyoshi-Akiyama Tohru, Kirikae Teruo, Nagamatsu Maki, Shimada Kayo, Mezaki Kazuhisa, Sugiki Yuko, Kuroda Emi, Kubota Shiho, Takeshita Nozomi, Kutsuna Satoshi, Tojo Masayoshi, Ohmagari Norio
Disease Control and Prevention Center, National Center for Global Health and Medicine, Tokyo, Japan
Department of Infectious Diseases, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan.
Antimicrob Agents Chemother. 2014 Jun;58(6):3441-50. doi: 10.1128/AAC.02652-13. Epub 2014 Apr 7.
IMP-type metallo-β-lactamase enzymes have been reported in different geographical areas and in various Gram-negative bacteria. However, the risk factors and epidemiology pertaining to IMP-type metallo-β-lactamase-producing Enterobacter cloacae (IMP-producing E. cloacae) have not been systematically evaluated. We conducted a retrospective, matched case-control study of patients from whom IMP-producing E. cloacae isolates were obtained, in addition to performing thorough molecular analyses of the clinically obtained IMP-producing E. cloacae isolates. Unique cases with IMP-producing E. cloacae isolation were included. Patients with IMP-producing E. cloacae were matched to uninfected controls at a ratio of 1 to 3. Fifteen IMP-producing E. cloacae cases were identified, with five of the isolates being obtained from blood, and they were matched to 45 uninfected controls. All (100%) patients from whom IMP-producing E. cloacae isolates were obtained had indwelling devices at the time of isolation, compared with one (2.2%) uninfected control. Independent predictors for isolation of IMP-producing E. cloacae were identified as cephalosporin exposure and invasive procedures within 3 months. Although in-hospital mortality rates were similar between cases and controls (14.3% versus 13.3%), the in-hospital mortality of patients with IMP-producing E. cloacae-caused bacteremia was significantly higher (40%) than the rate in controls. IMP-producing E. cloacae isolates were frequently positive for other resistance determinants. The MICs of meropenem and imipenem were not elevated; 10 (67%) and 12 (80%) of the 15 IMP-producing E. cloacae isolates had a MIC of ≤ 1 μg/ml. A phylogenetic tree showed a close relationship among the IMP-producing E. cloacae samples. Indwelling devices, exposure to cephalosporin, and a history of invasive procedures were associated with isolation of IMP-producing E. cloacae. Screening for carbapenemase production is important in order to apply appropriate clinical management and infection control measures.
IMP型金属β-内酰胺酶已在不同地理区域和多种革兰氏阴性菌中被报道。然而，与产IMP型金属β-内酰胺酶的阴沟肠杆菌（产IMP阴沟肠杆菌）相关的危险因素和流行病学尚未得到系统评估。我们对分离出产IMP阴沟肠杆菌的患者进行了一项回顾性配对病例对照研究，此外还对临床分离的产IMP阴沟肠杆菌进行了全面的分子分析。纳入了产IMP阴沟肠杆菌分离的独特病例。产IMP阴沟肠杆菌患者与未感染对照按1比3的比例进行配对。共识别出15例产IMP阴沟肠杆菌病例，其中5株分离菌来自血液，它们与45例未感染对照进行了配对。所有（100%）分离出产IMP阴沟肠杆菌的患者在分离时均有留置装置，而未感染对照中有1例（2.2%）有留置装置。产IMP阴沟肠杆菌分离的独立预测因素被确定为头孢菌素暴露和3个月内的侵入性操作。尽管病例组和对照组的院内死亡率相似（14.3%对13.3%），但产IMP阴沟肠杆菌所致菌血症患者的院内死亡率（40%）显著高于对照组。产IMP阴沟肠杆菌分离株对其他耐药决定因素通常呈阳性。美罗培南和亚胺培南的最低抑菌浓度未升高；15株产IMP阴沟肠杆菌分离株中有10株（67%）和12株（80%）的最低抑菌浓度≤1μg/ml。系统发育树显示产IMP阴沟肠杆菌样本之间关系密切。留置装置、头孢菌素暴露和侵入性操作史与产IMP阴沟肠杆菌的分离有关。为了采取适当的临床管理和感染控制措施，筛查碳青霉烯酶的产生很重要。
