中文摘要：已经证实引起慢性感染的铜绿假单胞菌可快速获得抗菌素耐药性（AMR）。因此，噬菌体作为一种有前景的抗菌剂受到了广泛的关注；但噬菌体的抗性会发生变异。铜绿假单胞菌通过MutL的进化选择丢失了大量的染色体片段。由于hmgA编码高龙胆酸代谢酶，galU的缺失导致缺乏O-抗原多糖从而使噬菌体缺乏受体，二者座位邻近，因此galU和hmgA缺失突变体表现出噬菌体抗性和棕色表型。本研究评估了铜绿假单胞菌兽医分离物Pa12中控制噬菌体耐药性的机制；分离了galU和hmgA缺失的噬菌体抗性Pa12棕色突变体（BRMT）。BRMT的全基因组测序结果显示，Pa12亲本染色体上galU上游148- 27kbp和下游261- 110kbp区域大片段缺失。此外，Pa12 BRMT（暂定为噬菌体诱导的galU缺乏（BigD）区域）中所有这些流动性缺失序列都含有多药外排系统基因（mexXY）。最小抑菌浓度（MIC）分析表明，与Pa12亲本相比，BRMT改变了对抗生素的敏感性，但提高对左氧氟沙星的敏感性。奥比沙星和恩诺沙星也能有效抑制Pa12 BRMT的生长，表明介导喹诺酮类药物外排并位于BigD区的MexXY可能与氟喹诺酮类药物敏感性的恢复有关。可见，BigD区域的AMR相关基因可以在噬菌体和药物敏感性之间产生平衡效应，从而有助于在噬菌体治疗中控制和预防噬菌体耐药变异的潜在策略。
外文摘要：Pseudomonas aeruginosa, which causes chronic infections, has demonstrated rapid acquisition of antimicrobial resistance (AMR). Therefore, bacteriophages have received significant attention as promising antimicrobial agents; however, previous trials have reported the occurrence of phage-resistant variants. P. aeruginosa has lost large chromosomal fragments via evolutionary selection by MutL. Mutants lacking galU and hmgA, located in close proximity, exhibit phage resistance and brown color phenotype since hmgA encodes a homogentisic acid metabolic enzyme and deletion of galU results in a lack of O-antigen polysaccharide and absence of the phage receptor. In the present study, we evaluated this mechanism for controlling phage resistance in P. aeruginosa veterinary isolate Pa12. Phage-resistant Pa12 brown mutants (brmts) with galU and hmgA deletions were iso-lated. Whole-genome sequencing of the brmts revealed that regions 148-27 kbp upstream and 261-110 kbp downstream of galU were largely deleted from the Pa12 parental chromosome. Furthermore, all of these fluc-tuating deleted sequences in Pa12 brmts, tentatively designated bacteriophage-induced galU deficiency (BigD) regions, harbor multi-drug efflux system genes (mexXY). Minimum inhibitory concentration (MIC) assays demonstrated that brmts altered sensitivity to antibiotics and exhibited increased levofloxacin sensitivity compared with the Pa12 parent. Orbifloxacin and enrofloxacin also effectively suppressed growth of the Pa12 brmts, suggesting that MexXY, which mediates quinolone efflux and is located in the BigD region, might be associated with restoration of fluoroquinolone sensitivity. Our findings indicate that AMR-related genes in the BigD region could produce trade-off effects between phages and drug sensitivity and thereby contribute to a potential strategy to control and prevent phage-resistant variants in phage therapy.
外文关键词：Bacteriophage；galU；Pseudomonas aeruginosa；Phage resistance；Phage therapy；Trade-off；Fitness cost
作者：Nakamura, K；Fujiki, J；Nakamura, T；Furusawa, T；Gondaira, S；Usui, M；Higuchi, H；Tamura, Y；Iwano, H
作者单位：Rakuno Gakuen Univ
期刊名称：VIRUS RESEARCH
期刊影响因子：0.0
出版年份：2021
出版刊次：
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