Évaluation de la contamination bactériologique des eaux usées des stations d’épuration du Grand Agadir : Isolement, caractérisation moléculaire et antibiorésistance des espèces du genre Vibrio

In countries such as Morocco, characterized by scarce rainfall, lack of freshwater resources and high groundwater salinity where agriculture reuse of municipal wastewater is becoming a compulsory choice for water resources management. This study evaluated the efficiency of the three wastewater treatment plants (WTPs) for the removal of physico-chemical and microbiological contaminants. Resistance to antibiotics, pulsed field gel electrophoresis and MALDI-TOF mass spectrometry were used to characterize Vibrio isolates. Mean values were used to determine treatment performances of the 3 WTPs, electric conductivity didn’t showed any difference between raw and treated wastewater and the mean values varying from 2900 μS/cm to 3300, the pH varying from 6,66 to 8,6, and the temperature varying between 16°C and 26. 4°C. Removal efficiencies of fecal coliforms, enterococci and spores of sulphite reducing anaerobic bacteria were betwenn 3 and 4 log unit for the 3WTPs. 4 species of Vibrio were identified, among the 58 Vibrio sp. Isolated, 53,44% were identified as V. Cholerae, 29,31% as V. Alginolyticus, 17,78% as V. Fluvialis and 1,74% as V. Metschnikovii. Of the total 58 Vibrio isolates, 53,44% were susceptible to all antibiotics. Of the resistant (46,56%) Vibrio strains, 39,83% were resistant against one to three antibiotics. PFGE with NotI digestion produced patterns with higher level of heterogeneity, and about 31% of Vibrio isolates were untypeable. MALDI-TOF-MS-based fingerprinting of Vibrio isolates has potential as a rapid for identification and finest differences between strains can readily be evaluated by the dendrogram based on percentage identity of MALDI-TOF mass spectra of Vibrio isolates, but requires further development for database of BioTyper.