Fosfomycin is a broad-spectrum single-dose therapy approved for treating lower urinary tract infections. Acinetobacter baumannii, one of the five major UTI-causing pathogens, is intrinsically resistant to fosfomycin. Reduced uptake and active efflux are major reasons for this intrinsic resistance. AbaF, a major facilitator superfamily class of transporter in A. baumannii, is responsible for fosfomycin efflux and biofilm formation. This study describes the identification and validation of a novel small-molecule efflux pump inhibitor that potentiates fosfomycin efficacy against A. baumannii. An AbaF inhibitor screening was performed against Escherichia coli KAM32/pUC18_abaF, using the noninhibitory concentration of 24 putative efflux pump inhibitors. The inhibitory activity of IITR08367 [bis(4-methylbenzyl) disufide] against fosfomycin/H⁺ antiport was validated using ethidium bromide efflux, quinacrine-based proton-sensitive fluorescence, and membrane depolarization assays. IITR08367 inhibits fosfomycin/H⁺ antiport activity by perturbing the transmembrane proton gradient. IITR08367 is a nontoxic molecule that potentiates fosfomycin activity against clinical strains of A. baumannii and prevents biofilm formation by inhibiting efflux pump (AbaF). The IITR08367-fosfomycin combination reduced bacterial burden by > 3 log₁₀ in kidney and bladder tissue in the murine UTI model. Overall, fosfomycin, in combination with IITR08367, holds the potential to treat urinary tract infections caused by A. baumannii.

中文翻译：

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小分子 IITR08367 通过抑制外排泵增强磷霉素对鲍曼不动杆菌的抗菌功效

磷霉素是一种广谱单剂量疗法，被批准用于治疗下尿路感染。鲍曼不动杆菌是引起尿路感染的五种主要病原体之一，对磷霉素具有内在耐药性。吸收和主动流出的减少是这种内在阻力的主要原因。 AbaF 是鲍曼不动杆菌中转运蛋白的主要促进超家族，负责磷霉素外流和生物膜形成。本研究描述了一种新型小分子外排泵抑制剂的鉴定和验证，该抑制剂可增强磷霉素对抗鲍曼不动杆菌的功效。使用 24 种假定的外排泵抑制剂的非抑制浓度，针对大肠杆菌KAM32/pUC18_abaF进行了 AbaF 抑制剂筛选。使用溴化乙锭流出、基于奎纳克林的质子敏感荧光和膜去极化测定验证了IITR08367 [双（4-甲基苄基）二硫化物] 对磷霉素/H ⁺反向转运的抑制活性。 IITR08367通过扰乱跨膜质子梯度来抑制 fosfomycin/H ⁺反向转运活性。 IITR08367 是一种无毒分子，可增强磷霉素对抗鲍曼不动杆菌临床菌株的活性，并通过抑制外排泵 (AbaF) 来防止生物膜形成。在小鼠 UTI 模型中，IITR08367-磷霉素组合可将肾脏和膀胱组织中的细菌负荷减少> 3 log _{10 。总体而言，磷霉素与 IITR08367 联合使用，具有治疗}鲍曼不动杆菌引起的尿路感染的潜力。