Seasonal variation of antibiotic resistance of Salmonella spp. and Escherichia coli strains isolated from well water of Moundou city, Chad (Central Africa)

Antibiotic resistance has become a global concern, mainly in developing countries, due to the socio-economic and health issues. This work aims to test the antibiotic susceptibility of germs isolated from well water consumed in the city of Moundou. This study was carried out during the period from May 2019 to July 2020 covering the two seasons of Chad. The results showed that in the rainy season resistance and sensitivity tests presented an increase in resistance to ceftriaxone, 100% for Escherichia coli and 87.5% for Salmonella spp.; ampicillin, 77.7% for Escherichia coli and 75% for Salmonella spp.; amoxicillin + clavulanic acid, 55.5% for Escherichia coli and 50% for Salmonella spp. During the dry season, very high bacterial resistance was noted to ampicillin (100%), amoxicillin + clavulanic acid (66.6%) and amoxicillin +sulbactam (33.3%) for Escherichia coli. This resistance was 88.8% to ceftriaxone, 50% to amoxicillin and ampicillin, 38.8% to amoxicillin + clavulanic acid, and 33.3% to amoxicillin + Sulbactam for Salmonella spp. However, no resistance to gentamicin was noted during both dry and rainy seasons. This study revealed strains of Escherichia coli and Salmonella spp. in the wells water of the city of Moundou and the use of these waters by the populations without prior treatment can lead to health risks. Poor sanitation and hygiene as well as the careless and abusive use of antibiotics in livestock have been felt even in the underground aquatic environment favoring the emergence of resistant strains.