The global phylogenetic landscape and nosocomial spread of the multidrug-resistant opportunist Stenotrophomonas maltophilia

Recent studies portend a rising global spread and adaptation of human- or healthcare-associated pathogens. Here, we analysed an international collection of the emerging, multidrug-resistant, opportunistic pathogenStenotrophomonas maltophiliafrom 22 countries to infer population structure and clonality at a global level. We show that theS. maltophiliacomplex is divided into 23 monophyletic lineages, most of which harboured strains of all degrees of human virulence. Lineage Sm6 comprised the highest rate of human-associated strains, linked to key virulence and resistance genes. Transmission analysis identified potential outbreak events of genetically closely related strains isolated within days or weeks in the same hospitals.One Sentence SummaryTheS. maltophiliacomplex comprises genetically diverse, globally distributed lineages with evidence for intra-hospital transmission.