Detection and spread of carbapenem-resistant Citrobacter freundii in a teaching hospital in China

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• 作者：Shudan  ; Chen BS ; PhD(c)^a ;   ; ^b ;   ; ^&lowast ; ; Fupin  ; Hu PhD^b ;   ; ^&lowast ; ; Yang  ; Liu PhD^b ; Demei  ; Zhu BS^b ;   ; ^{zhu_dm@fudan.edu.cn} ; Honghai  ; Wang BS^a ; Yingyuan  ; Zhang BS^b
• 关键词：Antimicrobial susceptibility testing ; carbapenemase ; risk factor ; molecular epidemiology
• 刊名：American Journal of Infection Control
• 出版年：2011
• 出版时间：November 2011
• 年：2011
• 卷：39
• 期：9
• 页码：e55-e60
• 全文大小：195 K

文摘

Background

We examined the detection and spread of carbapenem-resistant Citrobacter freundii in Huashan Hospital, Shanghai, China between 2005 and 2008.

Methods

Twenty-three isolates of carbapenem-resistant C freundii collected in our hospital underwent resistant gene amplification by polymerase chain reaction, followed by minimal inhibitory concentration (MIC) analysis. Molecular epidemiologic analyses included pulsed-field gel electrophoresis and case study.

Results

Analysis of MICs with amikacin, gentamicin, cefotaxime, ceftazidime, cefepime, imipenem, meropenem, ertapenem, cefoxitin, piperacillin-tazobactam, and ciprofloxacin characterized the isolates as highly resistant to antimicrobials. Colistin, tigecycline, minocycline, and doxycycline to all C freundii isolates had lower MICs than the other antimicrobials tested, with MIC₅₀/MIC₉₀ values of 0.5/1, 1/1, 4/8, and 4/4 mg/L, respectively. Molecular typing using pulsed-field gel electrophoresis classified the isolates into 4?groups, of which 15 isolates belonged to a single clone. In total, all of the isolates produced KPC-2-type carbapenemase, of which most were likely to couple with CTX-M-type extended-spectrum ¦Â-lactamases and plasmid-mediated CMY-2-type AmpC enzyme. Subsequent clinical investigations involving the general status of patients, the ward, and antimicrobial and therapeutic outcomes showed that a carbapenem-resistant clone had spread critically in the Department of Neurosurgery. Potential risk factors were identified, including invasive procedures, surgical operations, use of indwelling urine catheters, and number of sickbed changes.

Conclusion

The spread of carbapenem-hydrolyzing C freundii isolates has emerged in regional hospitals in China. Multidrug-resistant mechanisms of strains severely hamper control efforts. Our findings should alert clinicians to issues involved with preventing the spread of carbapenem-resistant C freundii.