Wickremasinghe Hasini, Yu Heidi H, Azad Mohammad A K, Zhao Jinxin, Bergen Phillip J, Velkov Tony, Zhou Qi Tony, Zhu Yan, Li Jian
Infection and Immunity Program, Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia.
Department of Pharmacology and Therapeutics, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, VIC 3053, Australia.
Antibiotics (Basel). 2021 Apr 8;10(4):405. doi: 10.3390/antibiotics10040405.
The emergence of antibiotic resistance has severely impaired the treatment of chronic respiratory infections caused by multidrug-resistant (MDR) . Since the reintroduction of polymyxins as a last-line therapy against MDR Gram-negative bacteria, resistance to its monotherapy and recurrent infections continue to be reported and synergistic antibiotic combinations have been investigated. In this study, comprehensive in vitro microbiological evaluations including synergy panel screening, population analysis profiling, time-kill kinetics, anti-biofilm formation and membrane damage analysis studies were conducted to evaluate the combination of polymyxin B and meropenem against biofilm-producing, polymyxin-resistant MDR . Two phylogenetically unrelated MDR strains, FADDI-PA060 (MIC of polymyxin B [MIC], 64 mg/L; MIC, 64 mg/L) and FADDI-PA107 (MIC, 32 mg/L; MIC, 4 mg/L) were investigated. Genome sequencing identified 57 (FADDI-PA060) and 50 (FADDI-PA107) genes predicted to confer resistance to a variety of antimicrobials, as well as multiple virulence factors in each strain. The presence of resistance genes to a particular antibiotic class generally aligned with MIC results. For both strains, all monotherapies of polymyxin B failed with substantial regrowth and biofilm formation. The combination of polymyxin B (16 mg/L)/meropenem (16 mg/L) was most effective, enhancing initial bacterial killing of FADDI-PA060 by ~3 log CFU/mL, followed by a prolonged inhibition of regrowth for up to 24 h with a significant reduction in biofilm formation (* < 0.05). Membrane integrity studies revealed a substantial increase in membrane depolarization and membrane permeability in the surviving cells. Against FADDI-PA107, planktonic and biofilm bacteria were completely eradicated. In summary, the combination of polymyxin B and meropenem demonstrated synergistic bacterial killing while reinstating the efficacy of two previously ineffective antibiotics against difficult-to-treat polymyxin-resistant MDR .
抗生素耐药性的出现严重损害了对多重耐药（MDR）引起的慢性呼吸道感染的治疗。自从多粘菌素作为针对MDR革兰氏阴性菌的一线治疗药物重新引入以来，对其单一疗法的耐药性和复发性感染仍不断有报道，并且已经对协同抗生素组合进行了研究。在本研究中，进行了全面的体外微生物学评估，包括协同效应筛选、群体分析、时间杀菌动力学、抗生物膜形成和膜损伤分析研究，以评估多粘菌素B和美罗培南联合用药对产生生物膜、对多粘菌素耐药的MDR的效果。研究了两株系统发育无关的MDR菌株，FADDI-PA060（多粘菌素B的最低抑菌浓度[MIC]为64mg/L；美罗培南MIC为64mg/L）和FADDI-PA107（多粘菌素B的MIC为32mg/L；美罗培南MIC为4mg/L）。基因组测序鉴定出57个（FADDI-PA060）和50个（FADDI-PA107）预测赋予对多种抗菌药物耐药性的基因，以及每个菌株中的多种毒力因子。对特定抗生素类别的耐药基因的存在通常与MIC结果一致。对于这两种菌株，多粘菌素B的所有单一疗法均失败，出现大量细菌再生长和生物膜形成。多粘菌素B（16mg/L）/美罗培南（16mg/L）联合用药最为有效，使FADDI-PA060的初始细菌杀灭增加约3 log CFU/mL，随后对细菌再生长的抑制延长至24小时，生物膜形成显著减少（*<0.05）。膜完整性研究显示存活细胞的膜去极化和膜通透性大幅增加。对于FADDI-PA107，浮游菌和生物膜细菌被完全根除。总之，多粘菌素B和美罗培南联合用药显示出协同杀菌作用，同时恢复了两种先前对难以治疗的多粘菌素耐药MDR无效的抗生素的疗效。
