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.