Department of Internal Medicine, Taipei Medical University Hospital, Taipei, Taiwan.
J Microbiol Immunol Infect. 2011 Oct;44(5):364-8. doi: 10.1016/j.jmii.2010.08.012. Epub 2011 Jan 20.
Urinary tract infections (UTIs) caused by extended-spectrum β-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae have become clinical problems because of limited therapeutic options. The role of fosfomycin in the era of growing bacteria resistance has been widely discussed recently. In this study, we aimed to know the local antimicrobial susceptibilities, fosfomycin susceptibility in particular, of urinary ESBL-producing E coli and K pneumoniae isolates in Taiwan.
We collected 200 urine isolates, including 134 ESBL-producing E coli (ESBL-EC) and 66 ESBL-producing K pneumoniae (ESBL-KP) isolates from July 2008 to December 2009 in a university-affiliated teaching hospital in Taiwan. We used disk diffusion method to determine susceptibility to fosfomycin. Fosfomycin may have lower susceptibility when using disk diffusion method compared with agar dilution method. Broth microdilution test was also used to determine minimal inhibitory concentrations (MICs) and susceptibilities to other antimicrobial agents.
Imipenem was active against ESBL-EC and ESBL-KP. Fosfomycin had good susceptibility to ESBL-EC (95.5%), including in hospital-acquired isolates, but lower antimicrobial activity against ESBL-KP (57.6%). Trimethoprim-sulfamethoxazole had the highest resistance rate to ESBL-EC and ESBL-KP. Comparing with non-hospital-acquired isolates, hospital-acquired ESBL-KP was associated with significantly lower susceptibility of gentamicin (13.3% vs. 66.7%), trimethoprim-sulfamethoxazole (8.9% vs. 38.1%), ciprofloxacin (26.7% vs. 61.9%), and amikacin (46.1% vs. 81.0%) (p<0.05). The resistance of some strains to ciprofloxacin was significantly associated with lower susceptibilities of gentamicin (32.6% in ESBL-EC), nitrofurantoin (2.4% in ESBL-KP) and trimethoprim-sulfamethoxazole (9.8% in ESBL-KP) (p<0.05) but not accompanied with decreasing susceptibility of fosfomycin.
Fosfomycin had the excellent activity against ESBL-EC but not ESBL-KP in this study. Based on the study findings, we suggest that fosfomycin can be a therapeutic option for UTIs with ESBL-EC. Nitrofuranoin was actively against ESBL-EC. Nitrofurantoin may be an alternative option for uncomplicated UTIs with ESBL-EC in Taiwan.
产超广谱β-内酰胺酶（ESBL）的大肠埃希菌和肺炎克雷伯菌引起的尿路感染（UTIs）由于治疗选择有限，已成为临床问题。在细菌耐药性日益严重的时代，磷霉素的作用已被广泛讨论。在这项研究中，我们旨在了解台湾产 ESBL 的大肠埃希菌和肺炎克雷伯菌尿分离株的当地抗菌药物敏感性，特别是磷霉素的敏感性。
我们收集了 200 株尿液分离株，包括 2008 年 7 月至 2009 年 12 月在台湾一所教学医院分离的 134 株产 ESBL 的大肠埃希菌（ESBL-EC）和 66 株产 ESBL 的肺炎克雷伯菌（ESBL-KP）。我们使用纸片扩散法测定磷霉素的敏感性。与琼脂稀释法相比，纸片扩散法可能对磷霉素的敏感性较低。肉汤微量稀释法也用于测定最小抑菌浓度（MIC）和其他抗菌药物的敏感性。
亚胺培南对 ESBL-EC 和 ESBL-KP 均有活性。磷霉素对 ESBL-EC（95.5%）具有良好的敏感性，包括医院获得性分离株，但对 ESBL-KP 的抗菌活性较低（57.6%）。复方磺胺甲噁唑对 ESBL-EC 和 ESBL-KP 的耐药率最高。与非医院获得性分离株相比，医院获得性 ESBL-KP 与庆大霉素（13.3%对 66.7%）、复方磺胺甲噁唑（8.9%对 38.1%）、环丙沙星（26.7%对 61.9%）和阿米卡星（46.1%对 81.0%）的敏感性显著降低（p<0.05）。一些菌株对环丙沙星的耐药性与庆大霉素（ESBL-EC 中 32.6%）、呋喃妥因（ESBL-KP 中 2.4%）和复方磺胺甲噁唑（ESBL-KP 中 9.8%）的敏感性降低显著相关（p<0.05），但与磷霉素的敏感性降低无关。
在本研究中，磷霉素对 ESBL-EC 具有极好的活性，但对 ESBL-KP 则不然。基于研究结果，我们建议磷霉素可作为治疗产 ESBL-EC 的尿路感染的一种选择。呋喃妥因对 ESBL-EC 有活性。在台湾，对于产 ESBL 的大肠埃希菌引起的单纯性尿路感染，呋喃妥因可能是一种替代选择。
