Koh Tse Hsien, Sng Li-Hwei, Wang Grace Chee Yeng, Hsu Li-Yang, Zhao Yi
Department of Pathology, Singapore General Hospital, Outram Road, Singapore 169608, Singapore.
J Antimicrob Chemother. 2007 Apr;59(4):627-32. doi: 10.1093/jac/dkl544. Epub 2007 Feb 6.
To compare the incidence of carbapenemase genes in Acinetobacter baumannii between two time periods.
We studied 114 isolates of imipenem-resistant A. baumannii collected over two 5 month periods (in 1996 and 2001). Isolates showing carbapenemase activity by plate bioassay were screened for carbapenemase genes using PCR. Chromosomal DNA from strains carrying carbapenemase genes was subjected to PFGE after digestion with ApaI.
The incidence of imipenem-resistant A. baumannii in our hospital rose from 1.1 per 1000 admissions in 1996 to 2.3 per 1000 admissions in 2001. However, the number of carbapenemase-producing A. baumannii rose only slightly in 2001 (0.8 per 1000 admissions) compared to 1996 (0.5 per 1000 admissions). Of 44 isolates with carbapenemase activity, 4 isolates carried bla(IMP-4), 5 carried bla(OXA-58), and 40 carried bla(OXA-23). In addition, most isolates carried a bla(OXA-51)-type beta-lactamase gene. All strains with bla(IMP-4), also carried bla(OXA-58) and bla(PSE-1), but not bla(OXA-51)-type beta-lactamase genes. PCR analysis repeated on seven recent isolates of susceptible A. baumannii showed only the presence of bla(OXA-51)-type beta-lactamase genes. A total of five novel bla(OXA-51)-type beta-lactamase genes (bla(OXA-88),-91,-93,-94, and -95) and one new bla(OXA-58)-type beta-lactamase gene (bla(OXA-96)) were found.
The incidence of carbapenemase genes did not vary significantly between the two study periods. There is a wide diversity of OXA genes in A. baumannii in Singapore. The most common carbapenemase gene found in our study was bla(OXA-23).
比较两个时间段鲍曼不动杆菌中碳青霉烯酶基因的发生率。
我们研究了在两个5个月期间（1996年和2001年）收集的114株耐亚胺培南鲍曼不动杆菌分离株。通过平板生物测定显示具有碳青霉烯酶活性的分离株使用PCR筛选碳青霉烯酶基因。用ApaI消化后，对携带碳青霉烯酶基因的菌株的染色体DNA进行脉冲场凝胶电泳（PFGE）。
我院耐亚胺培南鲍曼不动杆菌的发生率从1996年的每1000例住院患者1.1例上升至2001年的每1000例住院患者2.3例。然而，与1996年（每1000例住院患者0.5例）相比，2001年产碳青霉烯酶鲍曼不动杆菌的数量仅略有上升（每1000例住院患者0.8例）。在44株具有碳青霉烯酶活性的分离株中，4株携带bla(IMP-4)，5株携带bla(OXA-58)，40株携带bla(OXA-23)。此外，大多数分离株携带bla(OXA-51)型β-内酰胺酶基因。所有携带bla(IMP-4)的菌株也携带bla(OXA-58)和bla(PSE-1)，但不携带bla(OXA-51)型β-内酰胺酶基因。对最近7株敏感鲍曼不动杆菌分离株重复进行PCR分析，结果显示仅存在bla(OXA-51)型β-内酰胺酶基因。共发现5个新的bla(OXA-51)型β-内酰胺酶基因（bla(OXA-88)、-91、-93、-94和-95）和1个新的bla(OXA-58)型β-内酰胺酶基因（bla(OXA-96)）。
两个研究时间段之间碳青霉烯酶基因的发生率没有显著差异。新加坡鲍曼不动杆菌中OXA基因存在广泛多样性。我们研究中发现的最常见碳青霉烯酶基因是bla(OXA-23)。
