Rosvoll Torill C S, Lindstad Belinda L, Lunde Tracy M, Hegstad Kristin, Aasnaes Bettina, Hammerum Anette M, Lester Camilla H, Simonsen Gunnar S, Sundsfjord Arnfinn, Pedersen Torunn
Research Group for Host-Microbe Interactions, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway.
FEMS Immunol Med Microbiol. 2012 Nov;66(2):166-76. doi: 10.1111/j.1574-695X.2012.00997.x. Epub 2012 Jun 27.
Gentamicin is important in synergistic bactericidal therapy with cell wall agents for severe enterococcal infections. During 2003-2008, a 10-fold increase in the prevalence of high-level gentamicin resistance (HLGR), to above 50%, in blood culture isolates of Enterococcus faecium, was reported by the Norwegian Surveillance System for Antimicrobial Resistance. A representative national collection of invasive E. faecium isolates (n = 99) from 2008 was examined by a multilevel approach. Genotyping revealed a polyclonal population dominated by major hospital-associated lineages (mainly ST203, ST17, ST18, ST202 and ST192). The presence of aac(6')-Ie-aph(2″)-Ia, encoding the bi-functional aminoglycoside-modifying enzyme, was found in 98% of HLGR isolates (56/57). Furthermore, a significantly higher prevalence of potential virulence genes, toxin-antitoxin loci as well as pRE25 and pRUM type replicons was demonstrated in isolates belonging to major hospital-associated lineages compared to other sequence types. Megaplasmids of pLG1 replicon type (200-330 kb) were present in 90% of the isolates. Co-hybridization analyses revealed genetic linkage of aac(6')-Ie-aph(2″)-Ia to this replicon type. Transfer of HLGR-encoding plasmids was restricted to E. faecium. In conclusion, the increased prevalence of HLGR in invasive E. faecium in Norway is associated with hospital-adapted genetic lineages carrying aac(6')-Ie-aph(2″)-Ia-encoding transferable megaplasmids of the pLG1 replicon type.
庆大霉素在与细胞壁药物联合进行协同杀菌治疗严重肠球菌感染中具有重要作用。2003年至2008年期间，挪威抗菌药物耐药性监测系统报告称，粪肠球菌血培养分离株中高水平庆大霉素耐药（HLGR）的患病率增加了10倍，超过了50%。采用多级方法对2008年来自挪威的99株具有代表性的侵袭性粪肠球菌分离株进行了检测。基因分型显示，该菌为多克隆群体，主要由与医院相关的主要菌系（主要是ST203、ST17、ST18、ST202和ST192）主导。在98%的HLGR分离株（56/57）中发现了编码双功能氨基糖苷修饰酶的aac(6')-Ie-aph(2″)-Ia。此外，与其他序列类型相比，在属于主要医院相关菌系的分离株中，潜在毒力基因、毒素-抗毒素位点以及pRE25和pRUM型复制子的患病率显著更高。90%的分离株中存在pLG1复制子类型的大质粒（200 - 330 kb）。共杂交分析显示aac(6')-Ie-aph(2″)-Ia与该复制子类型存在遗传连锁。编码HLGR的质粒转移仅限于粪肠球菌。总之，挪威侵袭性粪肠球菌中HLGR患病率的增加与携带pLG1复制子类型的aac(6')-Ie-aph(2″)-Ia编码可转移大质粒的医院适应性遗传菌系有关。
