背景:人口腔和鼻腔可以充当能够引起急性感染的机会病原体的储库。这些微生物无源地定植于人类口腔和鼻腔,有助于通过环境在人群中传播。它们通常具有临床上显著的抗生素抗性基因。在这些机会性病原体中,克雷伯菌属是一个值得注意的例子,其成员经常与医院感染和多药耐药性有关。与许多定殖的机会病原体一样,影响克雷伯氏菌在健康和患病个体中传播的基本传播因素仍不清楚。
结果:这里,我们通过研究口腔和鼻腔克雷伯菌物种在体外饥饿条件下超越其天然微生物群落成员的能力,探索了一种可能的解释。这可能类似于医院外部环境或机械呼吸机的微环境。当健康人体口腔或鼻腔样本中存在肺炎克雷伯菌和产气克雷伯菌时,在饥饿条件下,细菌群落组成发生了急剧变化,通常富含克雷伯菌属。此外,将肺炎克雷伯菌外源引入缺乏肺炎克雷伯菌的本地微生物群落,即使在低接种量下,导致在饥饿下反复富集。与微生物组的其他成员相比,在这些经历饥饿的社区内对肺炎克雷伯菌的精确监测表明快速的初始生长和延长的生存能力。从健康个体口腔和鼻腔分离的肺炎克雷伯菌菌株也表现出对多种抗生素的抗性,并且在遗传上与临床和肠道分离株相似。此外,我们发现在没有克雷伯菌属的情况下,其他研究不足的机会病原体,如肽链球菌,在饥饿条件下相对丰度增加。
结论:我们的研究结果建立了一个环境和微生物群落环境,允许克雷伯氏菌和其他机会性病原体的富集。克雷伯菌的富集可能取决于其迅速超越微生物组其他成员的能力。与其他共生细菌竞争并在恶劣环境条件下持续存在的能力可能是有助于在共生和致病环境中增强传播的重要因素。视频摘要。
BACKGROUND: The human oral and nasal cavities can act as reservoirs for opportunistic pathogens capable of causing acute infection. These microbes asymptomatically colonize the human oral and nasal cavities which facilitates transmission within human populations via the environment, and they routinely possess clinically significant antibiotic resistance genes. Among these opportunistic pathogens, the Klebsiella genus stands out as a notable example, with its members frequently linked to nosocomial infections and multidrug resistance. As with many colonizing opportunistic pathogens, the essential transmission factors influencing the spread of Klebsiella species among both healthy and diseased individuals remain unclear.
RESULTS: Here, we explored a possible explanation by investigating the ability of oral and nasal Klebsiella species to outcompete their native microbial community members under in vitro starvation conditions, which could be analogous to external hospital environments or the microenvironment of mechanical ventilators. When K. pneumoniae and K. aerogenes were present within a healthy human oral or nasal sample, the bacterial community composition shifted dramatically under starvation conditions and typically became enriched in Klebsiella species. Furthermore, introducing K. pneumoniae exogenously into a native microbial community lacking K. pneumoniae, even at low inoculum, led to repeated enrichment under starvation. Precise monitoring of K. pneumoniae within these communities undergoing starvation indicated rapid initial growth and prolonged viability compared to other members of the microbiome. K. pneumoniae strains isolated from healthy individuals\' oral and nasal cavities also exhibited resistance to multiple classes of antibiotics and were genetically similar to clinical and gut isolates. In addition, we found that in the absence of Klebsiella species, other understudied opportunistic pathogens, such as Peptostreptococcus, increased in relative abundance under starvation conditions.
CONCLUSIONS: Our findings establish an environmental and microbiome community circumstance that allows for the enrichment of Klebsiella species and other opportunistic pathogens. Klebsiella\'s enrichment may hinge on its ability to quickly outgrow other members of the microbiome. The ability to outcompete other commensal bacteria and to persist under harsh environmental conditions could be an important factor that contributes to enhanced transmission in both commensal and pathogenic contexts. Video Abstract.