Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India.
Department of Anaesthesiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India.
J Med Microbiol. 2021 Mar;70(3). doi: 10.1099/jmm.0.001345. Epub 2021 Mar 19.
Carbapenem resistance in () is an emerging global threat. The adaptation strategies of for this emergence as a nosocomial pathogen has been less studied. This prospective study analysed a sustained outbreak of carbapenem resistant (CRAB) in the intensive care unit (ICU) with reference to antimicrobial resistance and virulence in the colonizing and pathogenic isolates under carbapenem stress. The CRAB isolates from initial and sustained outbreak were found harbouring multiple carbapenemase genes. These genes included , and . From NICU environment three phenotypically carbapenem susceptible isolates were found carrying , genes. Prior imipenem therapy was one of the risk factors (=0.0016). The outbreak was polyclonal. Under imipenem stress, outbreak isolates showed no loss of carbapenemase genes against stress free conditions (23.7±1.33 days). Biofilm formation increased with imipenem concentration, with outbreak isolates producing highest biomass. While the pathogens showed a slow growth rate on imipenem exposure, the colonisers grew rapidly ( <0.0001). Sustained outbreak of CRAB was identified in the ICU (July 2015 to December 2017). Risk factors for acquisition of CRAB was studied. isolates were also collected from the environments of ICU and neonatal ICU (NICU) and blood cultures of septic neonates. Isolates were characterized based on antimicrobial susceptibility, genetic profile, integrons carriage and clonality. Biofilm formation and growth kinetics were studied under varying carbapenem stress. Intense carbapenem exposure in the ICU facilitates persistence of CRAB by several adaptations causing sustained outbreaks.
耐碳青霉烯肠杆菌属在（）中是一种新兴的全球威胁。作为医院获得性病原体，该细菌对此类威胁的适应策略研究较少。本前瞻性研究分析了 ICU 中持续爆发的耐碳青霉烯肠杆菌属（CRAB），并参考了定植和致病分离株在碳青霉烯类药物压力下的抗生素耐药性和毒力。初始和持续爆发的 CRAB 分离株均携带多种碳青霉烯酶基因。这些基因包括、和。从 NICU 环境中分离到 3 株表型上对碳青霉烯类敏感的分离株，携带、基因。先前使用亚胺培南治疗是一个危险因素（=0.0016）。此次爆发是多克隆的。在亚胺培南压力下，爆发分离株在无压力条件下未丢失碳青霉烯酶基因（23.7±1.33 天）。生物膜形成随着亚胺培南浓度的增加而增加，爆发分离株产生的生物量最高。虽然病原体在亚胺培南暴露下的生长速度较慢，但定植菌生长迅速（<0.0001）。2015 年 7 月至 2017 年 12 月期间 ICU 中持续发生 CRAB 爆发。研究了获得 CRAB 的危险因素。还从 ICU 和新生儿 ICU（NICU）的环境中以及败血症新生儿的血培养中收集了肠杆菌属分离株。根据抗生素敏感性、遗传谱、整合子携带和克隆性对分离株进行了特征描述。在不同的碳青霉烯类药物压力下研究了生物膜形成和生长动力学。在 ICU 中进行强烈的碳青霉烯类药物暴露会通过多种适应性导致 CRAB 的持续存在，从而促进其持续爆发。
