Disinfectant-resistant mycobacteria

描述（由申请人提供）：非结核分枝杆菌在环境中无处不在，在世界各地的卫生保健机构中引起感染和假感染。其中，快速生长的分枝杆菌（RGM）种，M.脓肿(亚sp.；脓肿和小脓肿由于它们在医院的水源中无处不在，以及治疗它们引起的感染的困难，马氏杆菌、切隆支原体和偶发支原体尤其成问题。人们对脓疡分枝杆菌亚种的认识越来越高。特别是作为新兴病原体的脓肿和马尾蚴。特别令人关切的是，戊二醛耐药RGM越来越频繁地与医院暴发有关，有时达到流行病的程度，正如最近在巴西记录的那样。戊二醛（GTA）是世界范围内医院热敏性医疗器械使用最广泛的化学消毒剂。这种消毒剂在其他细菌中的作用方式的已知情况表明，细胞包膜表面暴露成分的变化导致GTA结合和/或渗透减少，这可能是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，因此人们担心GTA和相关醛类消毒剂在临床环境中的广泛使用正在影响RGM耐药群体的选择，并可能对药物的交叉耐药和致病性产生影响。为了支持这些假设，我们最近证明，减少的孔蛋白表达是耻毛分枝杆菌和螯合分枝杆菌对GTA和另一种醛类消毒剂邻苯二醛（OPA）产生高水平抗性的机制之一。部分由于孔蛋白表达缺陷，对GTA/ opa耐药的chelonae分离物对包括利福平、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表现出异常高的耐药水平。此外，我们的初步结果表明，与gta敏感的参考马尾蚴临床分离株相比，来自巴西的流行马尾蚴分离株对氨基糖苷类具有不同寻常的抗性，并且在小鼠中的致病性大大增加。我们收集了具有gta耐药菌株的chelonae和脓肿分枝杆菌亚种。马尾蚴在世界不同地区造成医院感染和假感染。并非所有这些分离株都表现出对OPA的交叉耐药（不像上文所述的chelonae分离株），这一事实表明分枝杆菌对乙醛消毒剂的耐药机制一定不止一种。我们拟利用收集到的临床分离株，结合基因组学、转录组学、遗传学和生物化学方法，研究RGM对醛类消毒剂耐药的分子机制，并研究这些菌株的表型变化可能对其药物敏感性和致病性的潜在影响。本研究结果可为优化医疗器械消毒策略的实施提供指导，并为治疗耐药菌株引起的医院感染提供更有效的治疗方法。

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.