Assessment of microbiological status of some herbal medicines sold in Calabar, Nigeria

Abstract

Aim: The upsurge of cases of adverse reactions, complications and herbal drug- induced infections in developing countries, due to the use of herbal remedies , have generated deep public health concern about the microbiological status and safety of the products. The aim of this study was to assess the level of microbial contamination of herbal medicines commonly sold in Calabar, Nigeria. Methodology and results: A total of 28 herbal medicines comprising 16 liquid and 12 solid dosage forms were evaluated for microbial contaminants. The isolation of microbial contaminants was carried out using standard plate techniques, while specific microbial genera were enumerated on appropriate selective media. The microorganisms were identified using standard identification protocols with the aid of identification and taxonomic manuals. The results showed that 71.43% of the samples yielded high counts of viable microorganisms, which exceeded the tolerable limit stated in United State Pharmacopoeia. The total viable microbial count of all the solid dosage forms ranged from 2.05 x 10 4 to 5.6 x 10 4 CFU/g. Of the 28 samples studied, 18 samples (64.29%) contained heterotrophic bacteria and molds, respectively, while coliforms and yeast were present in 15(53.57%) and 12(42.86%) of the samples. The microorganisms recovered and their percentage occurrence in the solid and liquid dosage forms were Pseudomonas aeruginosa (11.54, 18.31%); Bacillus subtilis (17.31, 11.27%); Klebsiella sp. (5.77, 9.86%); Staphylococcus aureus (15.38, 14.08%); Escherichia coli (3.85,12.60%);Salmonella sp.(3.85,9.86%); Enterobacter sp. (5.77, 7.04%); Aspergillus flavus (5.77,2.82%) Aspergillus niger (11.54, 4.23%); Fusarium sp. (5.77,2.82%) and Candida tropicalis (3.85, 1.41%). Conclusion, significance and impact of study: Microbial contaminants may cause spoilage of the herbal drugs and hence pose serious health risk to consumers. Therefore, adequate quality control measures and good manufacturing practice must be employed by herbal drugs producers, while relevant regulatory agencies should closely monitor the production processes, to ensure that microbiologically safe herbal drugs are marketed.