Microbiological profiling and the demonstration of in vitro anti-bacterial traits of the major oral herbal medicines used in Dhaka Metropolis

Present study attempted to assess the level of microbiological contamination in oral herbal medicines, frequently used for medications, through conventional cultural and biochemical tests along with the antibiogram of the isolates. Moreover, the anti-bacterial potential of the herbal medicines was also aimed to be checked by the agar well diffusion method and minimum inhibitory concentration (MIC) assay. Out of 10 categories of liquid oral herbal medicine samples (n = 50) studied, all were found to be contaminated with bacteria (10(3)-10(5) cfu/mL), specifically with Staphylococcus spp. in 8 samples; while 2 samples harbored Klebsiella spp. Fungal presence was observed only in one sample. Study of antibiogram revealed Klebsiella spp. to be strongly resistant against penicillin G and erythromycin, whereas S. aureus possessed 80% sensitivity. The in vitro anti-bacterial activity was observed in 7 samples. Of them, one sample was found to exhibit the activity against almost all the test bacteria and another was found effective against 5 out of 8 test bacteria. Five samples showed the activity within a minor range while 3 samples were devoid of such trait. Samples 2 and 4 were found to stall the bacterial growth below 10 mg/mL of concentration in MIC test. Overall, the prevalence of specific pathogens was not so significant in the samples studied as well as only one drug-resistant isolate was identified. Besides, the anti-bacterial trait of 5 samples indicated that most of herbal medicines might be considered effective for medication. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/2193-1801-3-739) contains supplementary material, which is available to authorized users.