Contribution of storage conditions of antibiotics in pharmacies on efficacy loss of amoxicillin and tetracycline against strains of Escherichia coli and Staphylococcus aureus in the city of Lome


Estelle Judith Abla Gnamey, Banfitebiyi Gambogou, Messanh Kangni Dossou, Kokou Anani, Yaovi Agbekponou Ameyapoh

Background: The resistance of bacteria to antibiotics is now a public health issue. The causes of such resistance are multiple and some are related to non-compliance with recommended doses of antibiotics. The storage conditions of antibiotics can have an impact on their effectiveness. Indeed, at a temperature above 30°C and relative humidity above 60%, pharmaceutical presentations of antibiotics may lose their doses. The goal of our study was to evaluate the existence of a correlation between failures of antibiotic therapy and poor conservation of marketed antibiotics in the city of Lome. Methods: We had prospected five pharmacies in the city of Lome and have collected in each, four pharmaceutical presentations of antibiotics. These antibiotics are amoxicillin, ciprofloxacin, tetracycline, and chloramphenicol. Also, we isolated in two private laboratories in the city of Lome, five hospital strains of these following bacteria: Escherichia coli, E. coli Alkalescens-Dispar, Klebsiella pneumonia, and two strains of Staphylococcus aureus. Reference strains of K. pneumoniae ATCC 13883, E. coli ATCC 25922, S. aureus ATCC 29213, S. aureus ATCC 25923, and Pseudomonas aeruginosa ATCC 27853 were used for analysis control. We carried out a prospective investigation and an analysis of the effectiveness of the antibiotics by the method of diffusion in agar medium. Results: The survey results showed that all pharmacies surveyed had an ambient temperature above what is recommended. In vitro analysis of the efficacy of amoxicillin on hospital strains of E. coli revealed some resistances. Also, the in vitro analysis of the tetracycline on reference strains of S. aureus ATCC 29213 and S. aureus ATCC 25923 was found to be ineffective. Conclusion: The storage conditions of these antibiotics, especially the temperature of their conservation, could be responsible for the loss of their effectiveness. It is possible that, in the city of Lome, some resistances of bacteria to marketed antibiotics are due to inappropriate conservation conditions of these products.