Emerging of blaNDM-5 in Providencia rettgeri and Morganella morganii from Brazilian Clinical Isolates.

The genus Providencia and Morganella are part of the World Health Organization (WHO) critical priority pathogens when carbapenem-resistant. This study characterized the molecular epidemiology of carbapenemase genes in 13 clinical isolates of carbapenem-resistant Providencia spp. and Morganella morganii from a Brazilian tertiary hospital. Following species confirmation by MALDI-TOF MS, one of the isolates was reclassified as M. morganii. PCR and amplicon sequencing screened for blaKPC, blaNDM, blaVIM, blaIMP, blaGES, and blaOXA-23, -24, -48-LIKE, -51, -58, -143. The blaNDM (11/13, 84.6%) and blaKPC (4/13, 30.8%) were the only carbapenemase genes detected. All isolates tested negative for blaVIM, blaIMP, blaGES, and OXA-type genes. blaNDM-5 was identified in one P. rettgeri and one M. morganii (first reports in Brazil). blaKPC-2/blaNDM-1co-occurrence was documented in two P. stuartii isolates. Clinical analysis of blaNDM-5carriers revealed severe outcomes: one patient self-discharged without targeted therapy, and another died following amputation, extensive antimicrobial exposure, and COVID-19 co-infection. The accumulation of co-expressed resistance mechanisms highlights Providencia spp. and M. morganii as emerging therapeutic challenges.