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.