Occurrence of blaNDM−5 and blaNDM−29 variants and genetic diversity among Enterobacterales in hospitalized patients in northeastern Brazil

This study investigated the genetic diversity and occurrence of bla NDM variants associated with carbapenem resistance in Enterobacterales obtained from colonization (rectal swabs) and infection sites in patients hospitalized in a public hospital in northeastern Brazil. A total of 58 multidrug-resistant clinical isolates were analyzed using ERIC-PCR to assess clonal relatedness, and PCR followed by amplicon sequencing to detect resistance genes ( bla NDM , bla KPC , bla GES , bla VIM , and bla IMP ). Klebsiella pneumoniae was the most frequently identified species ( n = 28, 48.27%), followed by Serratia marcescens and Proteus mirabilis , among others. All seven P. mirabilis isolates were classified as XDR, as were six K. pneumoniae and three S. marcescens isolates. Amikacin ( n = 46, 79.31% susceptible) and colistin ( n = 37, 97.37% susceptible) exhibited the highest susceptibility rates among all antimicrobials tested against the majority of isolates. ERIC-PCR revealed multiclonal dissemination and high genetic variability among the isolates. The bla KPC gene was the most prevalent ( n = 32, 55.17%), followed by bla NDM ( n = 26, 44.83%). Among the bla NDM allelic variants, bla NDM−1 ( n = 12, 46.15%) was the most common, followed by bla NDM−5 ( n = 7, 26.92%) and bla NDM−29 ( n = 1, 3.85%). This study reports the first detection in Brazil of bla NDM−5 in Klebsiella aerogenes , Citrobacter freundii , and Escherichia coli , in addition to reporting the first identification of bla NDM−29 in K. pneumoniae . Additionally, this study gives the first report in the Americas of bla NDM in Klebsiella ozaenae . These findings highlight the substantial potential for mutation and interspecies dissemination of bla NDM variants within the Enterobacterales order.