Evaluation of some commercial antimicrobial ointments on selected bacterial and fungal strains of clinical importance

Abstract

Background: Antimicrobial ointments are topical products used for the treatment of common skin infections. Potency superiority between certain ointments and creams used in the treatment of skin infections has been a controversial subject among clinicians.
Objective: This study was carried out to investigate the activities of some antimicrobial ointments on selected bacteria and fungi of clinical importance that caused skin infections.
Methods: Three brands of antibacterial; gentamicin, chloramphenicol, bactroban and two brands of antifungal ointments; nystatin and Whitefield’s were evaluated by agar - cup diffusion method for their antimicrobial activity. Minimum inhibitory concentration,
minimum bactericidal concentration and minimum fungicidal concentration of the ointments were determined. Kinetic study of bactroban on all the clinical isolates was evaluated to determine their efficacy within a specific time lag.
Results: All the isolates of Pseudomonas aeruginosa were susceptible to bactroban while 4 of the 5 isolates of Streptococcus pyogenes were resistant. Three of the five isolates of Staphylococcus aureus were susceptible to bactroban. Gentamicin had no activity on Pseudomonas aeruginosa while 4 of the 5 isolates of Streptococcus pyogenes were susceptible to gentamicin. Three of the 5 isolates of Staphylococcus aureus were susceptible to gentamicin and varied resistance were recorded for chloramphenicol and antifungal agents. The MIC’’s values recorded for the antimicrobial ointments examined varied with respect to concentrations and composition.  Bactroban and gentamicin gave the MIC’s 20µg/mL - 2000µg/mL and 50µg/mL - 400µg/mL while the MIC’s range 160µg/
mL - 400µg/mL, 100µg/mL -160µg/mL and 180µg/mL -200µg/mL were also recoded for chloramphenicol, nystatin and Whitefield’s against the isolates concerned respectively. The MBC’s and MFC’s values recorded against the isolates doubled the values obtained
from the MIC’s. Kinetic studies showed various population reduction to zero at varied contact time for clinical isolates of bacterial and fungi exposed to bactroban.
Conclusion: These findings elicited potency differences among the ointments tested on the selected clinical microbial isolates  examined, this could be useful in the selection of antimicrobial ointments for the management of skin infections caused by the
microorganisms tested and their closely related strains.

Keywords: Antimicrobial ointments, Skin infection, Microbial agents.