Survival of clinical and environmental carbapenem-resistant Klebsiella pneumoniae ST147 in surface water.

Carbapenem-resistant Klebsiella pneumoniae represents a healthcare threat, already disseminated in the environment. This study aimed to compare the behaviour of a clinical and an environmental K. pneumoniae strain (multilocus sequence type ST147) harbouring the gene bla in water. The abundance of the genes phoE (specific for K. pneumoniae) and bla was monitored by quantitative PCR in urban runoff water and sterile ultra-pure water microcosms, aiming to assess survival, bla persistence, and the effect of the native water microbiota. In sterile ultra-pure water, the abundance of cultivable K. pneumoniae and bla gene did not change over the incubation period (8 days). In contrast, in urban runoff, the K. pneumoniae and the genes phoE and bla genes decreased by up to 3 log-units. These results suggest that K. pneumoniae were outcompeted by the native microbiota of the urban runoff water and that the decay of bla gene was due to host death, rather than to gene loss. The study highlights that although native microbiota is essential to hamper the persistence of non-native bacteria, carbapenemase producing K. pneumoniae can survive in urban runoff water for at least one week.