NDM-producing Enterobacteriaceae responsible for environmental contamination of internal medicine wards in a Portuguese Hospital

Objective: The hospital environment plays a role in the cross-transmission of multidrug-resistant bacteria. The aim of this study was to identify potential carbapenemase-producing Enterobacteriaceae (CPE) reservoirs that might be responsible for a NDM-1 outbreak at a hospital in Portugal. Methods: An environmental investigation was instituted in a Portuguese hospital, after the occurrence of NDM-1-producing Providencia stuartii in five patients characterized by whole-genome sequencing. CPE screening was performed in critical infection sites of internal medicine wards and intensive care units where the patients stayed during hospitalization, by using MacConkey agar supplemented with ertapenem. Air samples were also obtained for the same locations. Antimicrobial susceptibility was determined by the disk diffusion method according to EUCAST guidelines. PCR and sequencing were applied to detect and identify carbapenemase-encoding genes. PCR-based replicon typing was used to characterize the plasmids. The genetic relationship between CPE was evaluated by PFGE. Results: Sixty-three Gram-negative isolates (Acinetobacter baumannii, Burkholderia cepacia, Klebsiella pneumoniae, Providentia stuartii and Pseudomonas spp.) were obtained from the 91 surface samples collected. A total of 17 NDM-1-producers were found: 9 K. pneumoniae and 8 P. stuartii in flush handles, bathroom door handles, dinamap monitors and/or hygiene cars from internal medicine wards. No CPE were obtained from air samples. The five NDM-1-producing P. stuartii clinical strains obtained during the outbreak were all genetically indistinguishable from those collected in the hospital environment. Regarding NDM-1-producing K. pneumoniae, no clinical cases were described. However, PFGE analysis identified two clusters, one of them indistinguishable, consisting of 7 NDM-1-K. pneumoniae producers and 7 K. pneumoniae non-CPE. PCR-based replicon typing revealed the presence of the same plasmid type among NDM-1-producers, suggesting horizontal transfer within the hospital surfaces. Conclusion: These results showed the importance of the hospital environment as a potential reservoir and source of CPE. This study also emphasizes the need of early environmental screening to interrupt the transmission of CPE.

Keywords

NDM-1 P. stuartii Environmental contamination Antibiotic resistance Resistência aos Antimicrobianos Ar e Saúde Ocupacional

URI

http://hdl.handle.net/10400.18/4179

Citation

Manageiro, V., Ferreira, E., Romão, R., Rodrigues, J., Pereira, P., Cano, M., Rodrigues, P., Palos, C., Caniça, M. 2016. NDM-producing Enterobacteriaceae responsible for environmental contamination of internal medicine wards in a Portuguese Hospital. RICAI 2016: 36e Réunion interdisciplinaire de chimiothérapie anti-infectieuse, Paris, France. P036.