Department of Pediatrics, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
Curr Opin Crit Care. 2010 Feb;16(1):8-12. doi: 10.1097/MCC.0b013e3283354710.
To consider the relevance to severe human lung infections of recently discovered virulence mechanisms of Staphylococcus aureus and Francisella tularensis.
S. aureus has long been considered an opportunistic pathogen. However, due to the emergence of community-acquired methicillin-resistant S. aureus (CA-MRSA) strains that can readily infect and kill normal hosts, S. aureus must now be considered a potentially virulent pathogen. The evolution of S. aureus from an organism associated with asymptomatic nasopharyngeal colonization to one associated with community-acquired lethal infections may reflect horizontal acquisition of bacterial genes that enable efficient spread, aggressive host invasion, and effective immune evasion. Alleviating the burden of staphylococcal disease will require better understanding of host susceptibility and of staphylococcal virulence and antibiotic resistance. In contrast to the rapidly evolving staphylococcal virulence strategy, recent genomic analysis of F. tularensis has revealed a small set of bacterial genes associated with the marked virulence of its North American subspecies. This suggests that a relatively stable strategy of immune evasion underlies this pathogen's ability to establish serious life-threatening lung infections from a very small inoculum.
Understanding bacterial pathogenesis will require additional research into both host susceptibility factors and bacterial virulence mechanisms, including horizontal gene transfer. Refinements in the molecular detection of bacteria in the clinical setting, as well as whole genome analysis of both pathogens and patients, are expected to aid in the understanding of bacterial-induced lung injury.
考虑金黄色葡萄球菌和土拉弗朗西斯菌最近发现的毒力机制与严重人类肺部感染的相关性。
金黄色葡萄球菌长期以来一直被认为是一种机会致病菌。然而，由于社区获得性耐甲氧西林金黄色葡萄球菌（CA-MRSA）菌株的出现，这些菌株能够轻易感染和杀死正常宿主，金黄色葡萄球菌现在必须被视为一种潜在的致病病原体。金黄色葡萄球菌从与无症状鼻咽定植相关的生物体演变为与社区获得性致死性感染相关的生物体，这可能反映了细菌基因的水平获得，这些基因使细菌能够更有效地传播、更积极地侵袭宿主并有效地逃避免疫。减轻金黄色葡萄球菌病的负担将需要更好地了解宿主易感性以及金黄色葡萄球菌的毒力和抗生素耐药性。与快速演变的金黄色葡萄球菌毒力策略形成鲜明对比的是，最近对土拉弗朗西斯菌的基因组分析揭示了一小部分与北美亚种明显毒力相关的细菌基因。这表明，一种相对稳定的免疫逃避策略是该病原体能够从非常小的接种量建立严重危及生命的肺部感染的基础。
了解细菌发病机制将需要进一步研究宿主易感性因素和细菌毒力机制，包括水平基因转移。临床环境中细菌的分子检测以及病原体和患者的全基因组分析的改进，有望有助于理解细菌引起的肺部损伤。
