Microbiological Quality of Selected Local and Imported Non-Sterile Pharmaceutical Products in Dar es Salaam, Tanzania

Background: Pathogenic and non-pathogenic microbial contaminants can cause physical-chemical alterations of pharmaceuticals and medicine-related infections. This study aimed to examine the microbiological quality of selected local and imported non-sterile pharmaceutical products in the Dar es Salaam market and the antibiogram of the isolated microorganisms. Methods: Samples were collected between April and June 2021 and analysed for microbial content as per the harmonised methods of the European Pharmacopoeia (EP). Antibiotic susceptibility of the microbial isolates was studied using Kirby-Bauer disc diffusion method. Results: Fifty percent (50%) of the samples failed both bacterial and fungal enumeration tests. In this study, local products recorded lower microbial counts than imported products. Major bacterial contaminants isolated were P. aeruginosa (45.5%), S. epidermidis, (45.5%) and K. pneumoniae, while major fungal contaminants were A. flavus (58.3%), followed by A. fumigatus (25%) and Penicillium spp (16.7%). The isolated bacterial contaminants recorded high resistance levels to commonly used antibiotics. Conclusion: The tested products were contaminated with microorganisms at different levels, most of them exceeding the maximum acceptable colony counts. Syrups or suspensions were more contaminated than tablets and capsules. The isolated bacterial contami-nants were highly resistant to commonly used antibiotics. Recommendations: We recommend that pharmaceutical manufacturers abide by good manufacturing, distribution and storage practices to limit contamination and cross-contamination of products. Responsible drug regulatory authorities should heighten the frequency of inspection of manufacturing facilities and regularly conduct post-marketing surveillance (PMS) of registered products to assess continued conformity to GMP guidelines. Future studies should involve samples collected directly from manufacturing sites.

Automated summary

This study examined the microbiological quality of selected local and imported non-sterile pharmaceutical products in the Dar es Salaam market and the antibiotic susceptibility of the isolated microorganisms. The results showed that 50% of the samples failed both bacterial and fungal enumeration tests. Local products had lower microbial counts than imported products. The major bacterial contaminants were P. aeruginosa, S. epidermidis, and K. pneumoniae, while the major fungal contaminants were A. flavus, A. fumigatus, and Penicillium spp. The isolated bacterial contaminants showed high resistance levels to commonly used antibiotics.