Genotypic and phenotypic analysis of antimicrobial resistance in the denitrifying isolate Pseudomonas veronii
Résumé
We investigated the antibiotic resistance in a non-pathogenic, denitrifying bacteria Pseudomonas veronii. This isolate, from a river sediment, is capable of complete denitrification from NO3- to N2. P. veronii was tested towards a range of antibiotics via the classical disc method as well as a cultivation method allowing to determine dose-effect curves. In parallel antibiotic resistance genes in the genome of the denitrifier were identified via annotation through MaGe from the MicroScope platform. The genotypic antibiotic resistance of the denitrifier P. veronii showed the presence of several genes encoding efflux pumps (e.g. AcrAB-TolC). P. veronii was resistant towards macrolides (erythromycin and tylosin), tetracycline the quinolone flumequine, chloramphenicol, the B lactam amoxicillin and the aminocoumarin novobiocin. On the other hand, P. veronii was sensitive towards the sulfonamide sulfamethoxazole and the quinolones ciprofloxacin and ofloxacin. A tolerance, i.e. a delayed impact, was observed for the beta-lactam ampicillin and fosfomycin. Resistance towards the large lipophilic antibiotics (novobiocin, erythromycin and tylosin) is most likely related to the exclusionary properties of the cell envelope. The presence of efflux pump genes most likely explains resistance towards the other antibiotics tested, but needs to be confirmed. Our results show that the non-pathogenic denitrifier P. veronii exhibits resistance towards several antibiotics, however sensitivity and tolerance towards others. The latter most likely affects the functioning of this species in the environment and it’s denitrifying activity which will be investigated in the future.
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