The Endophytic Strain Klebsiella michiganensis Kd70 Lacks Pathogenic Island-Like Regions in Its Genome and Is Incapable of Infecting the Urinary Tract in Mice

CLAPS, MP; DANTUR, KI ; JURE, A; TÓRTORA, ML; VOJNOV, A; PORCELL, N; CASTAGNARO, AP; CHALFOUN, N; SILVA, C; BIANCO, MI; WELIN, B

Frontiers in Microbiology

Frontiers in Microbiology

Año: 2018 vol. 9

1664-302X

Klebsiella spp. have been isolated from many different environmental habitats but havemainly been associated with nosocomial acquired diseases in humans. Although thereare many recently published sequenced genomes of members of this genus, thereare very few studies on whole genome comparisons between clinical and non-clinicalisolates, and it is therefore still an open question if a strain found in nature is capableof infecting humans/animals. Klebsiella michiganensis Kd70 was isolated from theintestine of larvae of Diatraea saccharalis but genome analysis revealed multiple genesassociated with colonization and growth promotion in plants suggesting an endophyticlifestyle. Kd70 cells labeled with gfp confirmed capability of root colonization and soilapplication of Kd70 promoted growth in greenhouse grown sugarcane. Further genomicanalysis showed that the Kd70 genome harbored fewer mammalian virulence factorsand no pathogen island-like regions when compared to clinical isolates of this species,suggesting attenuated animal/human pathogenicity. This postulation was corroboratedby in vivo experiments in which it was demonstrated that Kd70 was unable to infect themouse urinary tract. This is to the best of our knowledge the first experimental exampleof a member of a pathogenic Klebsiella spp. unable to infect a mammalian organism.A proteomic comparison deduced from the genomic sequence between Kd70 andseveral other K. michiganensis strains showed a high similarity with isolates frommany different environments including clinical strains, and demonstrated the existenceof conserved genetic lineages within this species harboring members from differentecological niches and geographical locations. Furthermore, most genetic differenceswere found to be associated with genomic islands of clinical isolates, suggestingthat evolutionary adaptation of animal pathogenicity to a large extent has dependedon horizontal gene transfer. In conclusion our results demonstrate the importance ofconducting thorough in vivo pathogenicity studies before presupposing animal/humanvirulence of non-clinical bacterial isolates.