臺灣北部某醫學中心菌血症克雷白氏肺炎桿菌 (Klebsiella pneumoniae)菌株之AmpC β-lactamase其流行病學以及抗藥特性之研究

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

許文謙(Wen-Chien Hsu)

指導教授 ： 吳雪霞

共同指導教授 ： 崔可忠(Ko-Chung Tsui)

臺北醫學大學/醫學科技學院/醫學檢驗暨生物技術學系所/碩士(2014年)

https://doi.org/10.6831/TMU.2014.00078

摘要

克雷白氏肺炎桿菌 (Klebsiella pneumoniae) 屬於腸桿菌科中的克雷白氏菌屬，為革蘭氏陰性桿菌，具夾膜 (capsule)，可引起菌血症、肺炎、腦膜炎、肝膿瘍、泌尿系統感染、內源性細菌性眼內炎等疾病。臨床上治療的困難是常碰到產生broad spectrum β-lactamase的多重抗藥性菌株。β-lactamase有許多種，目前臨床實驗室多常規篩檢ESBL (Extended spectrum β-lactamase) 菌株，而甚少對AmpC β-lactamase進行常規篩檢。本論文將針對AmpC β-lactamase的抗藥特性以及其在流行病學上的重要性進行研究與探討。

本研究針對北部某醫學中心自2011年至2012年收集之菌血症 (Bacteremia) 克雷白氏肺炎桿菌 (Klebsiella pneumoniae) 菌株共133株，以AmpC Disc test及multiplex PCR兩種方法分別針對AmpC β-lactamase菌株的表現型 (phenotype) 及基因型 (genotype) 進行篩選檢測。研究結果得知，在133株菌株裡有15株帶有AmpC β-lactamase的菌株，卻只有7 株ESBL菌株。經效能分析後，以AmpC Disc test方法來篩選AmpC β-lactamase菌株，其敏感性為86.7%，特異性為98.3%。我們同時以菌株對ceftazidime具抗藥性與否 (CLSI M100-S24標準) 來篩選AmpC β-lactamase菌株，其敏感性為92.9%，特異性為97.1%。此外實驗結果也觀察到當菌株為同時具有AmpC β-lactamase及ESBL的dual type時，若以CLSI標準建議的雙紙錠協同試驗 (Double Disk Synergy test) 來進行ESBL菌株的確認時，會因為受到AmpC β-lactamase的干擾而導致偽陰性 (false negative) 的結果。總而言之，本研究證實AmpC β-lactamase菌株在流行病學上佔有重要的地位，由於ESBL與AmpC β-lactamase其治療特性不同，若能常規篩檢AmpC β-lactamase 對臨床醫師在治療上將會有很大的助益。

關鍵字

克雷白氏肺炎桿菌 ； 乙內醯胺分解酶

並列摘要

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.

並列關鍵字

Klebsiella pneumoniae ； β-lactamase

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