Fawley W N, Freeman J, Smith C, Harmanus C, van den Berg R J, Kuijper E J, Wilcox M H
Department of Microbiology, Leeds Teaching Hospitals NHS Trust and University of Leeds, Leeds, United Kingdom.
J Clin Microbiol. 2008 Mar;46(3):954-60. doi: 10.1128/JCM.01764-07. Epub 2008 Jan 23.
We compared multilocus variable-number tandem-repeat analysis (MLVA) and macrorestriction endonuclease analysis using pulsed-field gel electrophoresis (PFGE) to determine their utility to identify clusters of Clostridium difficile infection (CDI) among 91 isolates of PCR ribotype 027 (NAP1, for North American pulsed-field type 1) from nine hospitals (and 10 general practitioners associated with one institution) in England. We also examined whether mortality in CDI cases was associated with specific MLVA subtypes. PFGE discriminated between ribotype 027 strains at >98% similarity, identifying five pulsovars (I to V) of 1 to 53 isolates. MLVA was markedly more discriminatory, identifying 23 types of 1 to 15 isolates (>71% similarity). PFGE pulsovars I and IV contained 14 and 8 MLVA types, respectively. Twenty-one of twenty-three (91%) of MLVA types were specific to individual PFGE pulsovars. Four CDI clusters were identified in institution A by conventional epidemiological analysis. MLVA typing identified two enlarged and two additional clusters. Thirty of forty-four (68%) patients in institution A with CDI caused by ribotype 027 strains were assigned to seven distinct clusters by a combination of MLVA typing and epidemiological records. Of 33 patients, comprising 14 different MLVA types, nine (27%) died by day 30 (early deaths). Eight of nine (89%) were associated with PFGE type IV C. difficile ribotype 027. Five of nine early deaths were associated with MLVA type 16, which was the dominant type in this cohort (10/33 cases); 4 other distinct MLVA types accounted for the other early deaths. MLVA was far superior to PFGE for analyzing clusters of CDI both within and between institutions. Further study is needed to examine whether subtypes of C. difficile ribotype 027 affect outcome.
我们比较了多位点可变数目串联重复序列分析（MLVA）和使用脉冲场凝胶电泳（PFGE）的宏观限制性内切酶分析，以确定它们在鉴定来自英格兰九家医院（以及与一家机构相关的10名全科医生）的91株PCR核糖体分型027（北美脉冲场类型1的NAP1）艰难梭菌感染（CDI）聚集群方面的效用。我们还研究了CDI病例的死亡率是否与特定的MLVA亚型相关。PFGE在相似度>98%时区分核糖体分型027菌株，鉴定出1至53株分离株的五个脉冲场型（I至V）。MLVA的鉴别力明显更强，鉴定出1至15株分离株的23种类型（相似度>71%）。PFGE脉冲场型I和IV分别包含14种和8种MLVA类型。23种MLVA类型中的21种（91%）特定于单个PFGE脉冲场型。通过传统流行病学分析在机构A中鉴定出四个CDI聚集群。MLVA分型鉴定出两个扩大的聚集群和另外两个聚集群。机构A中44例由核糖体分型027菌株引起的CDI患者中的30例（68%）通过MLVA分型和流行病学记录的组合被分配到七个不同的聚集群。在33例患者中，包括14种不同的MLVA类型，9例（27%）在第30天前死亡（早期死亡）。9例中的8例（89%）与PFGE IV型艰难梭菌核糖体分型027相关。9例早期死亡中的5例与MLVA 16型相关，MLVA 16型是该队列中的主要类型（10/33例）；其他4种不同的MLVA类型导致了其他早期死亡。在分析机构内部和机构之间的CDI聚集群方面，MLVA远优于PFGE。需要进一步研究以检查艰难梭菌核糖体分型027的亚型是否影响结局。
