The Antibiotic Resisting Profile of Salmonella spp Isolated from the Sewage of the Campus of the University of Cocody, Abidjan, Côte d’Ivoire

Background: Recent studies have shown that wastewater is contaminated by salmonella sp., pathogenic antibiotics-resisting bacteria. Using wastewater in periurban agriculture in Abidjan is likely to be the source of food-borne diseases such as salmonellosis. However, what we know about these resistant salmonella spp. in wastewater is limited in the country.

Aims: This study aims to establish the susceptibility profile of Salmonella spp., isolated from wastewater to antibiotics and to antimetabolite commonly used by medical practitioners.

Study Design: Spatio-temporal variation was taken into account.

Place and Duration of Study: The study took place from August 2008 to January 2009 at the main campus of the University of Cocody in Abidjan.

Methodology: Sampling was done on a weekly basis. Wastewater samples were collected at four different sewers in the campus area. Salmonella sp was isolated by a standard method of laboratory. The resistance of these isolated species to antibiotics was determined according to the disk diffusion method of Kirby-Baeur. The serotypes of salmonella were identified with the Kauffman-White table.

Results: Five serotypes of eleven strains, which consist of 4 Hato, 3 Farmsen, 2 Derby, 1 Essen and 1 Ovonmouth, were isolated and tested in order to determine their resistance to antibiotics.   Amongst the various classes of antibiotics, high resistance was found to sulfonamid (100%), followed by cefotaxime (46.67%) and tetracycline (9.1%).  Ampicillin, amoxicillin and clavulanic acid, gentamicin, kanamycin, amikacin, ciprofloxacine,  nalidixic acid and chloramphenicol had a high potentiality: their efficacity in the elimination of the Salmonella sp was proved at a level of 100%. Although the majority of strains tested (85.94%) were eliminated by the antibiotics, the serotypes Derby, Hato and Farmsen   showed resistance.

Conclusion: The Wastewater in the area of the main campus of the University of Cocody contains the antibiotic-resisting strains of salmonella sp. In spite of the fact that the efficacity of some antibiotics in the elimination of Salmonella sp. is proved, the resistance of these strains to third generation of cephalosporin and sulfamid is worrisome. Further studies should be carried out to determine the effects of this antibiotic-resisting salmonella species on humain health. This study revealed, the presence of various Salmonella serotypes in wastewater Salmonella Derby, S. Essen, S. Farmsen, S. Hato and S. ovonmouth. It also showed out the degree of resistance of these strains to commonly used antibiotic drugs. It also revealed that the strains are resistant to 3rd generation cephalosporins (β-lactam antibiotics (cefotaxime)), cyclin including tetracycline and antimetabolites (sulfonamide). Even though, 11.58% of Salmonella strains resisted to antibiotics, Salmonella serovars remain totally sensitive to  phenicoles, aminoglycosides, quinolones and other β-lactam particularly the penicillins Group A. These phenotypic characters of Salmonella allow to understand the challenges related to the treatment of salmonellosis and also to understand the necessity on a rational use of antibiotics.

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