Screening Extended-spectrum β-Lactamase Production in Enterobacter cloacae and Serratia marcescens Using Antibiogram-based Methods

Po An Su, Lii Tzu Wu, Kuo-Chen Cheng, Wen Chien Ko, Yin Ching Chuang, Wen Liang Yu

研究成果: 雜誌貢獻文章同行評審

14 引文 斯高帕斯(Scopus)

摘要

Background/Purpose: In Enterobacter cloacae and Serratia marcescens, AmpC β-lactamases can confer resistance to the third-generation cephalosporins and oxacephems, but not to the fourth-generation cephalosporins. Extended-spectrum β-lactamases (ESBL) may confer resistance to all extended-spectrum cephalosporins but not flomoxef. As difficult to detect, the ESBL phenotype of the intrinsically AmpC- producing E. cloacae and S. marcescens is not routinely screened in the clinical microbiology laboratories. The distinct antibiotic resistance phenotype between ESBL- and AmpC-producers may assist to differentiate the type of secreted β-lactamases. Therefore, we attested the validity of an antibiogram-based method to predict the presence of ESBLs in both species. Methods: Polymerase chain reaction-based methods and antibiogram-based methods were compared for their detection of ESBL in 74 E. cloacae and 69 S. marcescens isolates recovered from patients hospitalized at two medical centers in Taiwan. Three major types of antibiogram were defined: type I (3s4s), susceptible to cefotaxime, ceftazidime, and cefepime; type II (3r4s), resistant to cefotaxime or ceftazidime, but susceptible to cefepime; and type III (3r4r), resistant to cefepime plus cefotaxime and/or ceftazidime. Furthermore, subtype-a and subtype-b were defined as being resistant and susceptible to flomoxef, respectively. Results: Overall, ESBL producers were identified in 20 (27.0%) of Enterobacter and 11 (15.9%) of Serratia isolates by polymerase chain reaction-based methods. All type I isolates of both species (n= 49) were non-ESBL producers. In E. cloacae, all subtype IIb (n = 6) and type III (n = 6) isolates produced ESBLs, but only 8 of 17 IIa isolates produced ESBLs. The IIb and III types had the highest positive predictive value (100%) and specificity (100%) for ESBL detection. In S. marcescens, type II isolates rarely produced ESBLs (4/57 isolates), while seven of type III (n = 8) isolates produced ESBLs. Type III antibiogram had the highest positive predictive value (87.5%) and specificity (98.3%) for ESBL detection. Conclusion: The antibiograms of subtype IIb and type III are highly predictive for ESBL detection in E. cloacae, while type III is highly predictive for ESBL detection in S. marcescens. It is imperative to further examine ESBLs, focusing on the E. cloacae isolates with antibiogram subtype IIa.
原文英語
頁(從 - 到)26-34
頁數9
期刊Journal of Microbiology, Immunology and Infection
43
發行號1
DOIs
出版狀態已發佈 - 2月 2010

ASJC Scopus subject areas

  • 微生物學(醫學)
  • 免疫學和過敏
  • 免疫學與微生物學 (全部)
  • 傳染性疾病

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