Antibiotic-Resistant Bacteria in Hospital Sewages and Treated Urban Wastewater: A Case Study from Marrakech (Morocco)

This study investigated the evaluation of the emergence of antibiotic resistance in bacteria isolated from untreated hospital wastewaters and their transmission to the receiving Wastewater Treatment Plant (WWTP) of Marrakech city.Water sampling was conducted from January 2015 to June 2015 at fourteen different points (each department of the hospital, main effluent outlet of the hospital, WWTP (inlet, secondary and tertiary treatment)).The study showed that hospital sewages and wastewater collected at the inlet and after secondary treatment by Marrakech WWTP were loaded with pathogenic bacteria such as Escherichia coli, Klebsiella pneumoniae, Salmonella spp, Aeromonas hydrophyla, Pseudomonas aeruginosa, Acinetobacter baumanii, Enterococcus faecalis, Enterococcus faecium and Staphylococcus aureus.In this study we isolated 285 strains: 227 from the sewers of CHU hospital effluents and 58 strains collected at the entrance and after secondary treatment at Marrakech WWTP, they were loaded with potential pathogenic bacteria such as E. coli (n=52), K. pneumoniae (n=29), A. hydrophyla (n=28), P. aeruginosa (n=16), A. baumanii (n=17), E. faecalis (n=23), E. faecium (n=7) and S. aureus (n=8).Most of the isolated strains (63.3%, n=180) were resistant to all the tested antibiotic families: beta-lactams (carbanims n=3; cephalosporins n=6; penicillins n=10; monobactams n=1), fluoroquinolones (n=3) and aminosides (n=4), except for the P. aeruginosa strain which was resistant to beta-lactam antibiotics, especially imipenem and ceftazidime.The majority of these bacterial strains were known to be involved in nosocomial infections.On the other hand, there is an absence of these antibiotic-resistant bacteria after advanced tertiary treatment of these effluents at the Marrakech WWTP.This means that advanced tertiary treatment plays an important role in removing pathogenic strains and preserving the environment.A proper use of antibiotics updated by regular programs to monitor the susceptibility of bacteria to antibiotics remains one of the key tools for reducing the magnitude of the bacterial resistance rising phenomenon.Therefore, the impact of hospital effluents on the diffusion of antibiotic resistance in the environment needs to be carefully considered.