Disinfectant-resistant mycobacteria

描述(申请人提供)：非结核分枝杆菌属。在环境中无处不在，并在世界各地的卫生保健环境中引起感染和假感染。其中，快速生长的分枝杆菌属(M.abscessus，亚种)。脓肿和亚种。Massiliense)、龟分枝杆菌和偶然分枝杆菌问题尤其严重，因为它们普遍存在于医院的水源中，而且它们引起的感染很难治疗。人们对脓肿分支杆菌亚种的认识不断提高。尤其是作为新出现的病原体的脓肿和肿块。特别令人关切的是，耐戊二醛的RGM与医院内暴发联系在一起的频率越来越高，有时达到巴西最近记录的流行比例。戊二醛(GTA)是全球医院热敏性医疗器械使用最广泛的化学消毒剂。已知的这种消毒剂在其他细菌中的作用模式表明，细胞膜表面暴露成分的变化导致GTA结合和/或穿透减少，可能是RGM产生高水平耐药性的机制之一。由于分枝杆菌外膜在药物敏感性和宿主-病原体相互作用中发挥着重要作用，因此有人担心，临床上广泛使用GTA和相关的乙醛消毒剂正在影响RGM耐药群体的选择，可能会导致交叉耐药和致病。为了支持这些假设，我们最近证明，孔蛋白表达减少是耻垢分枝杆菌和龟分枝杆菌对GTA和另一种醛消毒剂邻苯二甲醛(OPA)产生高水平抗药性的机制之一。部分由于孔蛋白表达的缺陷，研究中的GTA/OPA耐药龟分枝杆菌分离株对包括利福平、环丙沙星、克拉霉素、红霉素、万古霉素、四环素和利奈唑胺在内的多种药物也显示出异常高的耐药性。此外，我们的初步结果表明，与GTA敏感的马氏支原体临床分离株相比，来自巴西的马氏支原体流行分离株对氨基糖苷类抗生素表现出异常的抗药性，并大大增强了对小鼠的致病性。我们已经收集了一系列抗GTA的龟分枝杆菌和脓肿分枝杆菌亚种。Massiliense对世界不同地区的医院感染和假性感染负有责任。事实上，并非所有这些分离株都对OPA表现出交叉耐药性(不同于上述龟分枝杆菌分离株)，这表明分枝杆菌对醛消毒剂的抗性机制肯定不止一种。我们建议使用我们收集的临床分离株，结合基因组、转录、遗传和生化方法来研究RGM对乙醛消毒剂耐药的分子机制，并研究这些菌株所经历的表型变化对其药物敏感性和致病性的潜在影响。这项研究的结果可能会导致实施医疗器械消毒的优化策略，并建议更有效的治疗方法来治愈由消毒剂耐药菌株引起的医院感染。 公共卫生相关性：我们建议阐明医院内快速生长的分枝杆菌病原菌对乙醛消毒剂的抗药性机制，并研究耐药菌株的表型变化对其药物敏感性和致病性的影响。

DESCRIPTION (provided by applicant):Non-tuberculous Mycobacterium spp. are ubiquitous in the environment and cause infections and pseudo-infections in health care settings throughout the world. Among these, the rapidly-growing Mycobacterium (RGM) species, M. abscessus (subsp. abscessus and subsp. massiliense), M. chelonae, and M. fortuitum are particularly problematic due to their ubiquitous presence in hospitals' water sources and the difficulty of treating the infections they cause. There is increasing awareness of M. abscessus subspp. abscessus and massiliense in particular as emerging pathogens. Of particular concern is the increasing frequency with which glutaraldehyde-resistant RGM are being associated with nosocomial outbreaks, sometime reaching epidemic proportions as recently documented in Brazil. Glutaraldehyde (GTA) is the most widely used chemical disinfectant for heat-sensitive medical devices in hospitals worldwide. What is known of the mode of action of this disinfectant in other bacteria suggests that changes in the surface-exposed composition of the cel envelope resulting in decreased binding and/or penetration of GTA may be one of the mechanisms through which RGM develop high levels of resistance. Because of the important role played by the mycobacterial outer membrane in drug susceptibility and host-pathogen interactions, there is thus some concern that the widespread use of GTA and related aldehyde disinfectants in clinical settings is impacting on the selection of resistant populations of RGM with possible consequences on cross-resistance to drugs and pathogenicity. In support of these assumptions, we recently demonstrated that reduced porin expression was one of the mechanisms through which M. smegmatis and M. chelonae develop high levels of resistance to GTA and a further aldehyde disinfectant, ortho-phthalaldehyde (OPA). In part due to defects in porin expression, the GTA/OPA-resistant M. chelonae isolate under study also displayed unusually high levels of resistance to a number of drugs including rifampicin, ciprofloxacin, clarithromycin, erythromycin, vancomycin, tetracycline and linezolid. Further, our preliminary results indicate that, compared to a GTA-susceptible reference M. massiliense clinical isolate, the epidemic M. massiliense isolates from Brazil display unusual resistance to aminoglycosides and much increased pathogenicity in mice. We have assembled a collection of GTA-resistant isolates of M. chelonae and M. abscessus subsp. massiliense responsible for nosocomial infections and pseudo-infections in different regions of the world. The fact that not all of these isolates display cross-resistance to OPA (unlike the M. chelonae isolate described above) indicates that there must exist more than one mechanism of resistance to aldehyde disinfectants in mycobacteria. We propose to use our collection of clinical isolates together with a combination of genomic, transcriptomic, genetic and biochemical approaches to investigate the molecular mechanisms of resistance of RGM to aldehyde-based disinfectants and to study the potential impact the phenotypic changes undergone by these strains might have had on their susceptibility to drugs and pathogenicity. The results of this study could lead to the implementation of optimized strategies for the disinfection of medical devices and suggest more efficient treatments to cure those nosocomial infections caused by disinfectant-resistant isolates. PUBLIC HEALTH RELEVANCE: We propose to elucidate the mechanisms of resistance of nosocomial rapidly-growing mycobacterial pathogens to aldehyde disinfectants and to study the impact of the phenotypic changes undergone by resistant isolates on their susceptibility to drugs and pathogenicity.