Persistent enrichment of multidrug resistantKlebsiellain oral and nasal communities during long-term starvation

Abstract

AbstractThe 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 a clinically-significant antibiotic-resistance genes. Among these opportunistic pathogens, theKlebsiellagenus stands out as a notable example, with its members frequently linked to nosocomial infections and multidrug resistance. As with many colonizing opportunistic pathogens, howKlebsiellatransitions from an asymptomatic colonizer to a pathogen remains unclear. Here, we explored a possible explanation by investigating the ability of oral and nasalKlebsiellato outcompete their native microbial community members underin vitrostarvation conditions, which could be analogous to external hospital environments. WhenKlebsiellawas present within a healthy human oral or nasal sample, the bacterial community composition shifted dramatically under starvation conditions and typically became dominated byKlebsiella. Furthermore, introducingK. pneumoniaeexogenously into a native microbial community lackingK. pneumoniae, even at low inoculum, led to repeated dominance under starvation.K.pneumoniaestrains 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 ofKlebsiella, other understudied opportunistic pathogens, such asPeptostreptococcus, dominate under starvation conditions. Our findings establish an environmental circumstance that allows for the outgrowth ofKlebsiellaand other opportunistic pathogens. The ability to outcompete other commensal bacteria and to persist under harsh environmental conditions may contribute to the colonization-to-infection transition of these opportunistic pathogens.