Bac 32, a novel bacteriocin widely disseminated among clinical isolates of Enterococcus faecium
Bac 32, a novel bacteriocin widely disseminated among clinical isolates of Enterococcus faecium
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DOI：
10.1128/aac.50.4.1202-1212.2006
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发表时间：
2006-04-01
影响因子：
4.9
通讯作者：
Ike, Y
中科院分区：
文献类型：
--
作者：
Inoue, T;Tomita, H;Ike, Y
对 1994 年至 1999 年间从安娜堡密歇根大学医学院医院获得的总共 636 株耐万古霉素屎肠球菌 (VRE) 分离株进行了细菌素生产测试。 277 株（44%）菌株具有致病性；其中 193 种表现出对抗屎肠球菌、希拉肠球菌和杜兰肠球菌的活性。菌株 VRE200 含有高效接合庆大霉素抗性质粒 pG200 (70 kb) 和细菌素质粒 pTI1 (12.5 kb)。 pTI1 上编码的细菌素被命名为细菌素 32 (Bac 32)。细菌素 32 对屎肠球菌、希拉肠球菌和杜兰斯肠球菌有活性，但对单核细胞增生李斯特氏菌没有活性。 Bac 32 基因座由细菌素基因 (bacA) 和免疫基因 (bacB) 组成。这些基因均未表现出与任何已知细菌素决定簇的显着同源性。推导的 bacA 产物长度为 89 个氨基酸，N 末端有 19 个氨基酸的推定信号肽。 bacB 基因编码推导的 55 个氨基酸的蛋白质，没有信号序列。 193 株对 3 种测试肠球菌菌株具有活性的菌株中，有 189 株 (97.9%) 使用 bacA 特异性引物产生了预期的特异性 PCR 产物，表明 VRE 临床分离株中 Bac 32 产生的发生率很高。使用质粒 pTI1 特异性探针对 189 株 Bac 32 产生菌株的质粒 DNA 进行 Southern 分析，结果表明 137 株（72.5%）菌株含有 pTI1 型质粒。在总共 56 个万古霉素敏感的屎肠球菌临床分离株中的 22 个（39.3%）中也鉴定出了 Bac 32 或 Bac 32 型细菌素活性和决定基因，这表明该细菌素在屎肠球菌菌株中广泛传播。
A total of 636 vancomycin-resistant Enterococcus faecium (VRE) isolates that had been obtained between 1994 and 1999 from the Medical School Hospital of the University of Michigan, Ann Arbor, were tested for bacteriocin production. Two hundred seventy-seven (44%) of the strains were bacteriocinogenic; and 193 of these exhibited activity against Enterococcus faecium, Enterococcus hirae, and Enterococcus durans. Strain VRE200 harbors the highly efficient conjugative gentamicin resistance plasmid pG200 (70 kb) and bacteriocin plasmid pTI1 (12.5 kb). The bacteriocin encoded on pTI1 was designated bacteriocin 32 (Bac 32). Bacteriocin 32 was active against E. faecium, E. hirae, and E. durans but showed no activity against Listeria monocytogenes. The Bac 32 genetic locus consists of a bacteriocin gene (bacA) and an immunity gene (bacB). Neither of these genes showed significant homology to any known bacteriocin determinants. The deduced bacA product is 89 amino acids in length, with a putative signal peptide of 19 amino acids at the N terminus. The bacB gene encodes a deduced 55-amino-acid protein without a signal sequence. One hundred eighty-nine strains (97.9%) of the 193 strains with activity against the 3 test enterococcal strains gave rise to the expected specific PCR product with a primer specific for bacA, indicating that there is a high incidence of Bac 32 production among VRE clinical isolates. Data from Southern analyses of plasmid DNA from 189 of the Bac 32-producing strains with a plasmid pTI1-specific probe suggested that 137 (72.5%) of the strains harbored a pTI1-type plasmid. Bac 32 or Bac 32-type bacteriocin activity and the determinant genes were also identified in 22 (39.3%) of a total of 56 vancomycin-sensitive E. faecium clinical isolates, which suggests that this bacteriocin is widely disseminated among E. faecium strains.