Abdelmalek Nader, Yousief Sally Waheed, Bojer Martin Saxtorph, Alobaidallah Mosaed Saleh A, Olsen John Elmerdahl, Paglietti Bianca
Department of Biomedical Sciences, University of Sassari, 07100 Sassari, Italy.
Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 1870 Frederiksberg C, Denmark.
Antibiotics (Basel). 2025 Jan 21;14(2):112. doi: 10.3390/antibiotics14020112.
: Therapeutic strategies for methicillin-resistant (MRSA) are increasingly limited due to the ability of the pathogen to evade conventional treatments such as vancomycin and daptomycin. This challenge has shifted the focus towards novel strategies, including the resensitization of β-lactams, which are still used as first-line treatments for methicillin-susceptible (MSSA). To achieve this, it is essential to identify the secondary resistome associated with the clinically relevant β-lactam antibiotics. : Transposon-Directed Insertion Site Sequencing (TraDIS) was employed to assess conditional essentiality by analyzing the depletion of mutants from a highly saturated transposon library of MRSA USA300 JE2 exposed to ½ minimal inhibitory concentration (MIC) of oxacillin or cefazolin. : TraDIS analysis led to the identification of 52 shared fitness genes involved in β-lactam resistance that are primarily linked to cell wall metabolism and regulatory systems. Among these, both known resistance factors and novel conditionally essential genes were highlighted. As proof of concept, transposon mutants corresponding to nine genes (, , , , , , , , and ) were grown in the presence of β-lactam antibiotics and their MICs were determined. All mutants showed significantly reduced resistance to β-lactam antibiotics. : This comprehensive genome-wide investigation provides novel insights into the resistance mechanisms of β-lactam antibiotics, and suggests potential therapeutic targets for combination therapies with helper drugs.
耐甲氧西林金黄色葡萄球菌（MRSA）的治疗策略越来越有限，因为该病原体能够逃避诸如万古霉素和达托霉素等传统治疗方法。这一挑战已将重点转向新策略，包括使β-内酰胺类药物重新敏感化，β-内酰胺类药物仍被用作甲氧西林敏感金黄色葡萄球菌（MSSA）的一线治疗药物。为实现这一目标，确定与临床相关β-内酰胺抗生素相关的次级耐药基因组至关重要。采用转座子定向插入位点测序（TraDIS），通过分析来自暴露于1/2最低抑菌浓度（MIC）的苯唑西林或头孢唑林的MRSA USA300 JE2高度饱和转座子文库中的突变体缺失情况，来评估条件必需性。TraDIS分析导致鉴定出52个与β-内酰胺耐药性相关的共享适应性基因，这些基因主要与细胞壁代谢和调节系统有关。其中，既突出了已知的耐药因子，也突出了新的条件必需基因。作为概念验证，对应于9个基因（、、、、、、、和）的转座子突变体在β-内酰胺抗生素存在下生长，并测定其MIC。所有突变体对β-内酰胺抗生素的耐药性均显著降低。这项全面的全基因组研究为β-内酰胺抗生素的耐药机制提供了新见解，并为与辅助药物联合治疗提出了潜在的治疗靶点。
