Department of Clinical Laboratory, Shanghai Municipal Hospital of Traditional Chinese Medicine, Shanghai University of Traditional Chinese Medicine, 274 Zhijiang Middle Rd, Shanghai, 200071, People's Republic of China.
Department of Clinical Laboratory, Shanghai General Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China.
BMC Microbiol. 2024 Jun 14;24(1):212. doi: 10.1186/s12866-024-03364-8.
Long-term treatment with trimethoprim-sulfamethoxazole (SXT) can lead to the formation of small-colony variants (SCVs) of Staphylococcus aureus. However, the mechanism behind SCVs formation remains poorly understood. In this study, we explored the phenotype and omics-based characterization of S. aureus SCVs induced by SXT and shed light on the potential causes of SCV formation.
Stable SCVs were obtained by continuously treating S. aureus isolates using 12/238 µg/ml of SXT, characterized by growth kinetics, antibiotic susceptibility testing, and auxotrophism test. Subsequently, a pair of representative strains (SCV and its parental strain) were selected for genomic, transcriptomic and metabolomic analysis.
Three stable S. aureus SCVs were successfully screened and proven to be homologous to their corresponding parental strains. Phenotypic tests showed that all SCVs were non-classical mechanisms associated with impaired utilization of menadione, heme and thymine, and exhibited slower growth and higher antibiotic minimum inhibitory concentrations (MICs), compared to their corresponding parental strains. Genomic data revealed 15 missense mutations in 13 genes in the representative SCV, which were involved in adhesion, intramolecular phosphate transfer on ribose, transport pathways, and phage-encoded proteins. The combination analysis of transcriptome and metabolome identified 35 overlapping pathways possible associated with the phenotype switching of S. aureus. These pathways mainly included changes in metabolism, such as purine metabolism, pyruvate metabolism, amino acid metabolism, and ABC transporters, which could play a crucial role in promoting SCVs development by affecting nucleic acid synthesis and energy metabolism in bacteria.
This study provides profound insights into the causes of S. aureus SCV formation induced by SXT. The findings may offer valuable clues for developing new strategies to combat S. aureus SCV infections.
长期使用甲氧苄啶-磺胺甲恶唑（SXT）治疗可导致金黄色葡萄球菌形成小菌落变种（SCV）。然而，SCV 形成的机制仍知之甚少。在这项研究中，我们通过连续使用 12/238μg/ml 的 SXT 处理金黄色葡萄球菌分离株来探索 SXT 诱导的金黄色葡萄球菌 SCV 的表型和基于组学的特征，并阐明了 SCV 形成的潜在原因。
通过使用 12/238μg/ml 的 SXT 连续处理金黄色葡萄球菌分离株获得稳定的 SCV，通过生长动力学、抗生素药敏试验和营养缺陷型试验进行特征描述。随后，选择一对具有代表性的菌株（SCV 和其亲本菌株）进行基因组、转录组和代谢组分析。
成功筛选并证实了 3 株稳定的金黄色葡萄球菌 SCV 与其相应的亲本菌株同源。表型试验表明，与相应的亲本菌株相比，所有 SCV 均表现出非经典机制，与对甲萘醌、血红素和胸腺嘧啶的利用受损有关，并且生长缓慢，抗生素最小抑菌浓度（MIC）较高。基因组数据显示，代表 SCV 中的 13 个基因中有 15 个错义突变，这些基因涉及到粘附、核糖上的分子内磷酸转移、运输途径和噬菌体编码蛋白。转录组和代谢组的联合分析确定了 35 个可能与金黄色葡萄球菌表型转换相关的重叠途径。这些途径主要包括代谢变化，如嘌呤代谢、丙酮酸代谢、氨基酸代谢和 ABC 转运体，它们可能通过影响细菌的核酸合成和能量代谢，在促进 SCV 发育中发挥关键作用。
本研究深入了解了 SXT 诱导金黄色葡萄球菌 SCV 形成的原因。这些发现可能为开发新策略以对抗金黄色葡萄球菌 SCV 感染提供有价值的线索。
