Microbial quality of soft drinks sold in Abuja, Nigeria

Abstract

This study assessed the microbial quality of sixteen brands of soft drink marketed in Abuja, Nigeria. Antimicrobial resistance testing was also carried out on the isolates from these soft drinks. Six bottles each of sixteen brands of soft drinks purchased from five different locations were assessed in duplicate. Isolates were identified using growth on nutrient agar and broth, Gram’s reaction, colony morphology, biochemical tests results and criteria for disregarding negative cultures. Resistance of isolates from soft drinks was determined using the antibiotic sensitivity test (zones of inhibition). Twenty six bacterial isolates belonging 5 genera were identified from the soft drink samples. 27.4% of assessed samples contained yeast cells and 17.9% contained mould. 35% of samples were sterile. There were considerable differences in the microbial quality of batches assessed. Among the six antibiotics tested for resistance on the isolated bacterial strains, four different resistance patterns were observed and several strains showed high Minimum Inhibitory Concentration (MIC) for Penicillin and a low MIC for Ampicillin + Cloxacillin. This study shows that soft drinks marketed in Nigeria poses some yet undefined risk. Visual inspection of packages, quality assessment of soft drinks plants/vessels and packaging materials, as well as resistance testing should be critically considered.

Keywords: Soft drinks, bacteria, yeast, resistance, antibiotics, Nigeria