The Ruth Rappaport Children's Hospital, Rambam Health Care Campus, Haifa, Israel.
Koret School of Veterinary Medicine, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel.
BMC Microbiol. 2020 Sep 17;20(1):288. doi: 10.1186/s12866-020-01970-w.
Tolerance to antibiotics and persistence are associated with antibiotic treatment failures, chronic-relapsing infections, and emerging antibiotic resistance in various bacteria, including Staphylococcus aureus. Mechanisms of persistence are largely unknown, yet have been linked to physiology under low-ATP conditions and the metabolic-inactive state. EttA is an ATP-binding cassette protein, linked in Eschrechia coli to ribosomal hibernation and fitness in stationary growth phase, yet its role in S. aureus physiology is unknown.
Using whole genome sequencing (WGS) of serial clinical isolates, we identified an EttA-negative S. aureus mutant (ettA), and its isogenic wild-type counterpart. We used these two isogenic clones to investigate the role of ettA in S. aureus physiology in starvation and antibiotic stress, and test its role in persistence and antibiotic tolerance. ettA and its WT counterpart were similar in their antibiotic resistance profiles to multiple antibiotics. Population dynamics of ettA and the WT were similar in low-nutrient setting, with similar recovery from stationary growth phase or starvation. Supra-bacteriocidal concentration of cefazolin had the same killing effect on ettA and WT populations, with no difference in persister formation.
Lack of ettA does not affect S. aureus antibiotic resistance, beta-lactam tolerance, resilience to starvation or fitness following starvation. We conclude the role of ettA in S. aureus physiology is limited or redundant with another, unidentified gene. WGS of serial clinical isolates may enable investigation of other single genes involved in S. aureus virulence, and specifically persister cell formation.
抗生素耐药性和持久性与抗生素治疗失败、慢性复发性感染以及包括金黄色葡萄球菌在内的各种细菌中新兴的抗生素耐药性有关。持久性的机制在很大程度上尚不清楚，但与低 ATP 条件下的生理学和代谢非活跃状态有关。EttA 是一种 ATP 结合盒蛋白，在大肠杆菌中与核糖体休眠和固定生长阶段的适应性有关，但它在金黄色葡萄球菌生理学中的作用尚不清楚。
我们使用全基因组测序（WGS）对连续的临床分离株进行分析，鉴定出一株无 EttA 的金黄色葡萄球菌突变株（ettA）及其同源野生型对照。我们使用这两个同源克隆来研究 ettA 在金黄色葡萄球菌生理中的作用，包括在饥饿和抗生素压力下的作用，并测试其在持久性和抗生素耐受性中的作用。ettA 和其 WT 对照在对多种抗生素的耐药性方面相似。在低营养环境中，ettA 和 WT 的种群动态相似，从固定生长阶段或饥饿中恢复的情况也相似。超杀菌浓度的头孢唑啉对 ettA 和 WT 群体具有相同的杀伤作用，没有形成持久性细菌的差异。
缺乏 ettA 不会影响金黄色葡萄球菌的抗生素耐药性、β-内酰胺类药物耐受性、对饥饿的抵抗力或饥饿后的适应性。我们得出结论，ettA 在金黄色葡萄球菌生理学中的作用是有限的或与另一个未被识别的基因冗余。连续临床分离株的 WGS 可能使我们能够研究其他参与金黄色葡萄球菌毒力的单个基因，特别是形成持久性细胞的基因。
