PDF(Pubmed)
Abstract：
We evaluated the role of Staphylococcus aureus AbcA transporter in bacterial persistence and survival following exposure to the bactericidal agents nafcillin and oxacillin at both the population and single-cell levels. We show that AbcA overexpression resulted in resistance to nafcillin but not oxacillin. Using distinct fluorescent reporters of cell viability and AbcA expression, we found that over 6-14 hours of persistence formation, the proportion of AbcA reporter-expressing cells assessed by confocal microscopy increased sixfold as cell viability reporters decreased. Similarly, single-cell analysis in a high-throughput microfluidic system found a strong correspondence between antibiotic exposure and AbcA reporter expression. Persister cells grown in the absence of antibiotics showed neither an increase in nafcillin MIC nor in abcA transcript levels, indicating that survival was not associated with stable mutational resistance or abcA overexpression. Furthermore, persister cell levels on exposure to 1×MIC and 25×MIC of nafcillin decreased in an abcA knockout mutant. Survivors of nafcillin and oxacillin treatment overexpressed transporter AbcA, contributing to an enrichment of the number of persisters during treatment with pump-substrate nafcillin but not with pump-non-substrate oxacillin, indicating that efflux pump expression can contribute selectively to the survival of a persister population.
摘要：
我们评估了金黄色葡萄球菌AbcA转运体在人群和单细胞水平上暴露于杀菌剂纳夫西林和苯唑西林后在细菌持久性和存活中的作用。我们表明AbcA过表达导致对纳夫西林的耐药性，而不是苯唑西林。使用细胞活力和AbcA表达的不同荧光报道分子，我们发现持续形成6-14小时,通过共聚焦显微镜评估的AbcA报道分子表达细胞的比例随着细胞活力报道分子的减少而增加了六倍。同样，高通量微流体系统中的单细胞分析发现，抗生素暴露与AbcA报道分子表达之间存在很强的对应关系。在没有抗生素的情况下生长的支持细胞既没有显示nafcillinMIC的增加，也没有显示abcA转录水平的增加，表明生存与稳定的突变抗性或abcA过表达无关。此外，在abcA敲除突变体中暴露于1×MIC和25×MIC的纳夫西林时，保留细胞水平降低。纳夫西林和苯唑西林治疗过表达转运蛋白AbcA的幸存者，在用泵基质纳夫西林治疗期间，而不是用泵非基质苯唑西林治疗期间，这表明外排泵的表达可以选择性地促进持久群体的存活。
