Klebsiella pneumoniae is an important opportunistic pathogen with significant potential for virulence and multidrug resistance. Treatment failure often occurs because the pathogen may couple virulence and drug resistance with the stringent response. This study assessed the role of the spoT gene in environmental and nutritional stress tolerance, exopolysaccharide capsule production and biofilm formation. spoT mutants were constructed using the lambda red recombinase technique, and mutant and wild-type (WT) strains were exposed to limiting concentrations of carbon (glucose), phosphate and aminoacid, and environmental stresses of ethanol, salt and heat. Cell viability, capsule production and cell length were assessed as well as the ability to grow biofilm under antibiotic pressure using gentamicin and ceftazidime. spoT mutants were more susceptible to stresses versus WT; the reverse was true for survival during biofilm susceptibility assay (p < 0.05), especially when carbon and phosphate were present. spoT mutants were elongated and lacked a capsule versus WT and non-starved strains. The inability to produce capsule in mutants before and after starvation was likely a general effect of spoT mutation. These data suggest that the spoT-mediated stringent response is important for K. pneumoniae in conditions of nutrient limitation, environmental stress and antimicrobial pressure.

中文翻译：

---

spoT介导的严格反应影响肺炎克雷伯菌的环境和营养胁迫耐受性，生物膜形成和抗菌素耐药性。

肺炎克雷伯菌是一种重要的机会病原体，具有强大的毒力和多药耐药性潜力。通常会发生治疗失败，因为病原体可能会将毒力和耐药性与严格的反应结合在一起。这项研究评估了spoT基因在环境和营养胁迫耐受性，胞外多糖胶囊生产和生物膜形成中的作用。使用Lambda Red重组酶技术构建spoT突变体，并将突变体和野生型（WT）菌株暴露于碳（葡萄糖），磷酸盐和氨基酸的限量浓度以及乙醇，盐和热的环境胁迫。使用庆大霉素和头孢他啶评估细胞活力，胶囊产量和细胞长度，以及在抗生素压力下生长生物膜的能力。与WT相比，spoT突变体更容易受到压力的影响。对于生物膜药敏试验中的存活率则相反（p <0.05），特别是当存在碳和磷酸盐时。spoT突变体被拉长，并且与野生型和非饥饿型菌株相比缺乏胶囊。饥饿之前和之后无法在突变体中产生荚膜可能是spoT突变的普遍影响。这些数据表明，spoT介导的严格反应在营养限制，环境压力和抗菌压力条件下对肺炎克雷伯菌很重要。饥饿之前和之后无法在突变体中产生荚膜可能是spoT突变的普遍影响。这些数据表明，spoT介导的严格反应在营养限制，环境压力和抗菌压力条件下对肺炎克雷伯菌很重要。饥饿之前和之后无法在突变体中产生荚膜可能是spoT突变的普遍影响。这些数据表明，spoT介导的严格反应在营养限制，环境压力和抗菌压力条件下对肺炎克雷伯菌很重要。