Antimicrobial activity of medicated soaps commonly used by Dar es Salaam residents in Tanzania

An in vitro evaluation of the anti-microbial activity of medicated soaps was conducted using ditch-plate and hand washing techniques. Strains of reference microbes namely Candida albicans (ATCC90028), Staphylococcus aureus (ATCC25923), Pseudomonas aureginosa (ATCC27853) and Escherichia coli (ATCC25922) were tested at three different soaps′ concentrations (1.0, 4.0 and 8.0 mg/ml). A total of 16 medicated soaps were assayed for their antimicrobial efficacy. Of these, 13 were medicated and 3 non-medicated soaps, which served as control. Ciprofloxacin and ketaconazole were employed as positive controls. Label disclosure for the soaps′ ingredients and other relevant information were absorbed. The most common antimicrobial active ingredients were triclosan, trichloroxylenol and trichlorocarbanilide. ANOVA for means of zones of inhibition revealed variability of antimicrobial activity among the medicated soaps. Positive correlation (r=0.318; P<0.01) between zones of inhibition and soaps′ concentrations was evidenced. Hand washing frequencies positively correlated with microbial counts. Roberts soap exhibited the largest zone of inhibition (34 mm) on S. aureus. Candida albicans was the least susceptible microbe. Regency and Dalan exhibited the least zone of inhibition on the tested bacteria. Protex, Roberts, Family and Protector were equally effective (P<0.01) against S. aureus. In conclusion, majority of the assayed medicated soaps have satisfactory antibacterial activity; though lack antifungal effect with exception of Linda liquid soap. The hand washing technique has proved to be inappropriate for evaluation of soaps′ antimicrobial efficacy due to presence of the skin microflora.