KPC-3-, GES-5-, and VIM-1-Producing Enterobacterales Isolated from Urban Ponds

Carbapenems are antibiotics of pivotal importance in human medicine, the efficacy of which is threatened by the increasing prevalence of carbapenem-resistant Enterobacterales (CRE). Urban ponds may be reservoirs of CRE, although this hypothesis has been poorly explored. We assessed the proportion of CRE in urban ponds over a one-year period and retrieved 23 isolates. These were submitted to BOX-PCR, PFGE, 16S rDNA sequencing, antibiotic susceptibility tests, detection of carbapenemase-encoding genes, and conjugation assays. Isolates were affiliated with Klebsiella ( n = 1), Raoultella ( n = 11), Citrobacter ( n = 8), and Enterobacter ( n = 3). Carbapenemase-encoding genes were detected in 21 isolates: bla KPC ( n = 20), bla GES-5 ( n = 6), and bla VIM ( n = 1), with 7 isolates carrying two carbapenemase genes. Clonal isolates were collected from different ponds and in different campaigns. Citrobacter F6, Raoultella N9, and Enterobacter N10 were predicted as pathogens from whole-genome sequence analysis, which also revealed the presence of several resistance genes and mobile genetic elements. We found that bla KPC-3 was located on Tn 4401 b ( Citrobacter F6 and Enterobacter N10) or Tn 4401 d ( Raoultella N9). The former was part of an IncFIA-FII pBK30683-like plasmid. In addition, bla GES-5 was in a class 3 integron, either chromosomal ( Raoultella N9) or plasmidic ( Enterobacter N10). Our findings confirmed the role of urban ponds as reservoirs and dispersal sites for CRE.