What's going on in hospital effluent biofilm?
Résumé
Biofilm is the dominating bacterial lifestyle at the planet scale conferring recalcitrance and persistence properties to their inhabitants. The proximity of cells within biofilm promotes DNA exchanges, and the concomitant presence of antibiotics favors selection of resistant strains. Such criteria fit with hospital effluents, heavily loaded with bacteria and medical drugs. In this study, the “transmission potential” of biofilm present in the outlet pipes of the hospital Gabriel Montpied (France) was investigated Biofilms were formed on glass coupons settled in the flow of the outlet water for 3 weeks. After scraping and disorganization, a plasmid DNA enriched fraction was extracted using an alkaline lysis method. The DNA was then sequenced by Illumina generating more than 107x106 reads. Taxonomy analysis showed mainly the presence of Proteobacteria. The sequences associated with antibiotic resistance mechanisms were mainly efflux pump (EmrE), ABC transporter and beta-lactamase-encoding genes. Plasmid reconstitution was performed using a specific homemade pipeline. Its reliability was confirmed by searching for plasmid markers such as MOB, MPF, OriT and rep sequences. A total of 9490 linear plasmids and 381 circular plasmids (size 1.4 kb to 235 kb) were reconstructed, with 2 of them already in databases. The findings indicate that antibiotics producing bacteria are common in these biofilms and may disseminate the multiple antibiotic resistance traits among bacterial community through genetic exchange mechanisms. This study highlights the major potential role of biofilms in hospital effluents as providers of resistance genes to urban effluents and pose a hazard to environmental and public health.
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