Genomic analysis reveals the presence of emerging pathogenicKlebsiellalineages aboard the International Space Station
Authors: Miliotis Georgios , Singh Nitin Kumar , McDonagh Francesca , O’Connor Louise , Tuohy Alma , Morris Dearbháile , Venkateswaran Kasthuri 
Published: May 2023

AbstractKlebsiellaspecies, includingKlebsiella pneumoniae, Klebsiella aerogenes, andKlebsiella quasipneumoniae, are opportunistic pathogens that are known to cause infections in humans. HypervirulentKlebsiella pneumoniae(hvKP) is a subgroup ofK. pneumoniaethat has gained attention due to its global dissemination and its ability to cause invasive infections in community settings amongst immunocompetent individuals as well as its increasing levels of antibiotic resistance. Our study reports the first complete genotypic analysis including mobile genetic elements (MGEs) ofKlebsiellaisolates from the International Space Station (ISS). The genomes ofK. pneumoniae, K. aerogenes, andK. quasipneumoniaeprovided valuable insights into their antimicrobial resistance, virulence, thermotolerance, disinfectant resistance, and MGEs. All isolates belonged to emerging lineages with pathogenic potential, withK. quasipneumoniaeST138 presenting spatial and temporal persistence aboard the ISS, possibly due to its genotypic profile encoding for numerous resistance genes to disinfectants and heavy metals. We also report on the isolation of a yersiniabactin encodingK. pneumoniae, belonging to the emerging high-risk ST101 clone, aboard the ISS. Potential dissemination of hvKp strains on ISS could pose a putative risk to the immunocompromised crew. The presence of MGEs containing virulent loci could facilitate horizontal gene transfer to other benign microorganisms on the ISS, potentially increasing their virulence. In addition, genetic divergence from their respective lineages for someKlebsiellagenomes was predicted and hypothesized to be due to the unique spaceflight environmental pressures. These findings highlight the importance of monitoring problematic microbial communities in space to understand their surviving abilities and potential impact on human health.ImportanceThe International Space Station (ISS) is a unique hermetically sealed environment that poses environmental pressures not encountered on Earth, including microgravity and radiation While the adaptability of bacteria during spaceflight is not fully understood, recent research has suggested that it may be species and even clone specific. Given the spaceflight-induced suppression of the human immune system, it is essential to understand the genomics of potential human pathogens in spaceflight. Such understanding could provide valuable insights into species and lineages of medical astromicrobiological importance. Here, we used hybrid assembly approaches and comparative genomics to provide the first comprehensive genomic characterisation of 10Klebsiellaisolates retrieved from the ISS. Our findings revealed thatK. quasipneumoniaeST138 exhibits spatial and temporal persistence aboard the ISS, with evidence of genomic divergence from the ST138 lineage on Earth. Additionally, we characterized plasmids fromKlebsiellaspecies of ISS origin, which encoded disinfectant and thermoresistance genes suggesting that these might aid adaptability. Furthermore, we identified an MGE containing a hypervirulence-associated locus belonging to aKlebsiella pneumoniaeisolate of the “high risk” ST101 clone. Our work provides valuable insights into the adaptability and persistence ofKlebsiellaspecies during spaceflight, highlighting the importance of understanding the behaviour of potential pathogenic bacteria in space.