Detection of carbapenemases in Enterobacterales and other Gram-negative bacilli recovered from hospital and municipal wastewater in Mexico City

Wastewater serves as a reservoir for antimicrobial-resistant bacteria. This study revealed the presence of carbapenem-resistant and carbapenemase-producing Gram-negative bacilli (GNB), established clonal relationships among isolates in hospital and municipal wastewater, and identified a high-risk clone in municipal wastewater. A total of 63 isolates of GNB were obtained, with Enterobacterales being the most frequently isolated group (62%). Carbapenemase-producing Lelliottia amnigena , Kluyvera cryocrescens , and Shewanella putrefaciens isolates were documented for the first time in Mexico. The detectableted carbapenemase genes were bla KPC (55%), bla NDM (12%), bla VIM−2 (12%), bla OXA−48 (4%), bla GES (2%), bla NDM−1 (2%), and bla NDM−5 (2%). Clonal relationships were observed among Klebsiella pneumoniae and Enterobacter spp. isolates, and remarkably the high-risk clone Escherichia coli ST361, carrying bla NDM−5 , was identified. This study demonstrates that wastewater harbours carbapenem-resistant and carbapenemase-producing bacteria, posing a public health threat that requires epidemiological surveillance.