Madison Casey L, Steinert Anja S J, Luedeke Corrin E, Hajjafar Neeka, Srivastava Prakhar, Berti Andrew D, Bayer Arnold S, Kebriaei Razieh
P3 Research Laboratory, Division of Pharmaceutics and Pharmacology, College of Pharmacy, The Ohio State University, Columbus, Ohio, USA.
Department of Pharmacy Practice, College of Pharmacy, Wayne State University, Detroit, Michigan, USA.
Microbiol Spectr. 2024 Oct 29;12(12):e0067924. doi: 10.1128/spectrum.00679-24.
Daptomycin (DAP) is a cyclic lipopeptide antibiotic that targets the cell membrane and is commonly used for the treatment of multidrug-resistant infections, especially methicillin-resistant strains (MRSA). Emergence of DAP resistance during DAP therapy is increasingly reported; however, the mechanisms by which resistance occurs are diverse. Using phages in combination with antibiotics is of high interest to circumvent antibiotic resistance, due to their minimal side effects, accessibility, and synergistic effects with antibiotics. Here, we have investigated the relationship between DAP resistance and sensitivity to phage Sb-1 in a cohort of 14 clinical MRSA strains. This cohort consists of four isogenic pairs (a clinical DAP-susceptible parent and its isogenic DAP-resistant variant isolated during DAP treatment), and three DAP-susceptible/DAP-resistant strain pairs are created by traditional serial passaging in the presence of increasing DAP concentrations. Efficiency of plating (EOP) and bacteriophage plaque sizes were recorded, and synergy between the antibacterial agents was tested using the phage-antibiotic combination (PAC) checkerboard method. Plaque sizes and EOP significantly increased ( = 0.019 and = 0.008, respectively) as strains developed resistance to DAP. The PAC checkerboards conveyed less antagonistic patterns in DAP-resistant mutant strains compared with their DAP-susceptible counterparts. Antagonism was displayed in 71.4% (5/7) of the DAP-susceptible strains, while it was only present in 14.3% (1/7) of the DAP-resistant mutants. Transmission electron microscopy images showed significantly thicker cell walls in DAP-susceptible strains exposed to DAP monotherapy compared with either growth control or DAP-phage ( = 0.0002 and 0.0007, respectively). These data indicate increased sensitivity to phage Sb-1 concurrent with the emergence of DAP resistance.
Multidrug-resistant is a threat to the health care system, especially cross-resistance between daptomycin (DAP) and glycopeptides through various mutations such as (which is involved in the modification of membrane phospholipids in some bacteria) and yycG (part of a two-component regulatory system in bacteria that is important for regulating cell wall biosynthesis and other cellular processes) has been reported previously. Our current study shows adjunctive treatment with phage in DAP-resistant strains will lead to synergistic activity and larger phage plaque sizes, translating to elevated lytic performance. The addition of bacteriophage to standard-of-care antibiotic therapies for multidrug-resistant infections has the potential to hinder, and possibly revert, resistance to antibiotics. Applying this strategy can potentially lead to the preservation of the current antibiotics. Verification of this salutary outcome in relevant and models of endovascular infections is required to validate translatability.
达托霉素（DAP）是一种靶向细胞膜的环脂肽抗生素，常用于治疗多重耐药感染，尤其是耐甲氧西林菌株（MRSA）。越来越多的报道称在DAP治疗期间出现了DAP耐药性；然而，耐药发生的机制多种多样。由于噬菌体副作用极小、易于获取且与抗生素具有协同作用，因此将噬菌体与抗生素联合使用对于规避抗生素耐药性具有很高的研究价值。在此，我们研究了14株临床MRSA菌株中DAP耐药性与对噬菌体Sb-1敏感性之间的关系。该队列包括四对同基因菌株（一株临床DAP敏感亲本菌株及其在DAP治疗期间分离出的同基因DAP耐药变体），另外通过在不断增加的DAP浓度存在下进行传统连续传代培养创建了三对DAP敏感/耐药菌株。记录平板接种效率（EOP）和噬菌体噬菌斑大小，并使用噬菌体 - 抗生素联合（PAC）棋盘法测试抗菌剂之间的协同作用。随着菌株对DAP产生耐药性，噬菌斑大小和EOP显著增加（分别为P = 0.019和P = 0.008）。与DAP敏感菌株相比，PAC棋盘法在DAP耐药突变菌株中显示出较少的拮抗模式。71.4%（5/7）的DAP敏感菌株表现出拮抗作用，而在DAP耐药突变菌株中仅14.3%（1/7）存在拮抗作用。透射电子显微镜图像显示，与生长对照或DAP - 噬菌体处理组相比，接受DAP单一疗法的DAP敏感菌株的细胞壁明显更厚（分别为P = 0.0002和P = 0.0007）。这些数据表明，随着DAP耐药性的出现，对噬菌体Sb-1的敏感性增加。
多重耐药性对医疗保健系统构成威胁，尤其是达托霉素（DAP）与糖肽类药物之间通过各种突变产生的交叉耐药性，例如之前已报道的mprF（参与某些细菌中膜磷脂的修饰）和yycG（细菌中双组分调节系统的一部分，对调节细胞壁生物合成和其他细胞过程很重要）。我们目前的研究表明，对DAP耐药菌株进行噬菌体辅助治疗将导致协同活性和更大的噬菌体噬菌斑大小，从而转化为更高的裂解性能。将噬菌体添加到针对多重耐药感染的标准护理抗生素疗法中有可能阻碍并可能逆转对抗生素的耐药性。应用这种策略有可能保存当前的抗生素。需要在相关的体内和体外血管内感染模型中验证这种有益结果，以证实其可转化性。
