Study on the epidemiology and characteristics of AmpC β-lactamase in Klebsiella pneumoniae isolated from bacteriemia in a medical center in Northern Taiwan

• Main Authors: Wen-Chien Hsu, 許文謙
• Other Authors: Hsueh-Hsia Wu
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/7s9q43

碩士 === 臺北醫學大學 === 醫學檢驗暨生物技術學系所 === 102 === Klebsiella pneumoniae belongs to the family Enterobacteriaceae, a Gram-negative bacilli, with a capsule, can cause pneumonia, bacteraemia, meningitis, liver abscess, urinary tract infections and endogenous bacterial endophthalmitis. Arising broad spectrum β-lactamase producing strains with multi-drug resistance makes clinical treatment more difficult. ESBL (extended spectrum β-lactamase) and AmpC β-lactamase are both the members of β-lactamase. Clinical And Laboratory Standards Institute (CLSI) guideline suggests that screening and confirming ESBL strains for epidemiology only, but AmpC β-lactamase strains don’t. In this study, we evaluate whether AmpC β-lactamase is as significant as ESBL in epidemiology. Totally, 133 Klebsiella pneumoniae isolates were collected from bacteraemia patients at a medical center in Northern Taiwan from 2011 to 2012.These strains were detected and analysed AmpC β-lactamases by using AmpC Disc test (phenotype) and multiplex PCR (genotype). After screening, the results showed that there are 15 AmpC β-lactamase strains and only 7 confirmed to be ESBL strains. The sensitivity of AmpC Disc test for AmpC β-lactamase strains screening is 86.7%, and specificity is 98.3%. Then we assess using ceftazidime resistance (CLSI M100-S24) to screen AmpC β-lactamase strains. The results demonstrate better performance in 92.9% sensitivity and 97.1% specificity. Furthermore, the result of Double Disk Synergy test to confirm ESBL strains would be interfered when the strains have both ESBL and AmpC β-lactamase. In conclusion, this study demonstrates that AmpC β-lactamase plays an important role in epidemiological survey.