National Infection Service, Public Health England, London NW95EQ, UK.
British Society for Antimicrobial Chemotherapy, Birmingham B13NJ, UK.
J Antimicrob Chemother. 2017 Oct 1;72(10):2704-2707. doi: 10.1093/jac/dkx207.
Like other streptococci, Streptococcus agalactiae typically has intrinsic low-level aminoglycoside resistance. High-level gentamicin resistance was seen in 2 of 1125 isolates collected in the BSAC Bacteraemia Surveillance Programme between 2001 and 2014. These organisms, both isolated in 2014, were characterized.
Identifications were by latex agglutination, MICs by BSAC agar dilution and sequencing by Illumina methodology.
Gentamicin MICs were >1024 mg/L versus a species mode of 8 mg/L; both isolates also were unusually ciprofloxacin resistant with MICs of 64 mg/L versus a species mode of 1 mg/L. They were distinct by sequence, but both belonged to the ST19 clone, which occurs globally. Both had aac(6')-aph(2″), carried by different transposons, explaining their gentamicin resistance, and had gyrA[81:S-L];parC[79:S-Y], accounting for ciprofloxacin resistance.
These are the first multiresistant S. agalactiae with the bifunctional AAC(6')-APH(2″) enzyme to be reported in the UK for >10 years. Despite belonging to the same clonal complex, the two isolates and their resistance transposons were distinct. Both retained full susceptibility to penicillin, but any penicillin/gentamicin synergy is likely to be lost.
与其他链球菌一样，无乳链球菌通常具有内在的低水平氨基糖苷类药物耐药性。在 2001 年至 2014 年期间，BSAC 菌血症监测计划中收集的 1125 株分离株中，有 2 株出现高水平庆大霉素耐药。这两种分离株均于 2014 年分离得到，其特征如下。
通过乳胶凝集鉴定，BSAC 琼脂稀释法测定 MIC，Illumina 法测序。
庆大霉素 MICs ＞1024mg/L，而种模式为 8mg/L；两种分离株也异常对环丙沙星耐药，MICs 为 64mg/L，而种模式为 1mg/L。它们通过序列不同，但均属于 ST19 克隆，该克隆在全球范围内存在。两者均带有 aac(6')-aph(2″)，由不同的转座子携带，解释了它们的庆大霉素耐药性，并且具有 gyrA[81:S-L];parC[79:S-Y]，导致环丙沙星耐药。
这是 UK 10 多年来首次报道的具有双功能 AAC(6')-APH(2″)酶的多耐药无乳链球菌。尽管属于同一克隆复合体，但两种分离株及其耐药转座子是不同的。两者均保留对青霉素的完全敏感性，但任何青霉素/庆大霉素协同作用都可能丧失。
