Microbial competition in environmental nosocomial reservoirs and diffusion capacity of OXA48-Klebsiella pneumoniae: potential impact on patients and possible control methods.


OXA48-K. pneumoniae


Introduction: We have found clusters of K. pneumoniae with OXA48-carbepenemase cases in some hospital rooms. We decided to investigate whether the bathroom siphons could be a reservoir for OXA48 bacteria by experimental and clinical follow of patients in two clinical Services in a tertiary hospital

Methods: Determination of the âmicrobial competitionâ between strains with OXA48 and VIM carbepenemases,  âdissemination capacityâ of K. pneumoniae with carbepenemase OXA48 or VIM, from hands to standard surfaces and âEpidemiological and microbiological studiesâ of patients and the sink in their rooms, in two Services of our hospital: Traumatology and Oncology.

Results and discussion: Microbial competition studies showed that VIM-bacteria are inhibited by OXA-bacteria. We found a grand possibility of diffusion from contaminated hands, but it was more intense in OXA than VIM bacteria. These observations can explain the concentration of cases of OXA48-K. pneumoniae in some rooms in Traumatology and Oncology. The Risk-ratio was >3 between rooms with OXA48-bacteria-contaminated siphons and the other rooms. This risk was lowered after changing or disinfecting (heat plus chlorinated disinfectant) the contaminated siphons.

In conclusion, bathroom siphons can be a reservoir of OXA48-K. pneumoniae and lead to outbreaks, which can be controlled by change (or heat plus chemical treatment) of the sink-siphons.



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