A Study of the Antimicrobial Effectiveness of Diluted Antiseptics in Nigeria

Aim: The antimicrobial effectiveness of diluted antiseptics and the health risks that may be associated with any surviving pathogens were investigated.

Study Design: Experimental Study.

Place and Duration of Study: Faculty of Pharmacy, Obafemi Awolowo University, Ile-Ife, Nigeria, between March 2013 to December 2014.

Methodology: Six of the commonly used antiseptics selected for the study contain phenolics as main active agents while the seventh contains chlorhexidine gluconate and cetrimide. Dilutions of the antiseptics in Mueller Hinton Agar were done with water from the tap and with sterile distilled water inoculated with 108cfu/ml multidrug resistant Escherichia coli and Staphylococcus aureus clinical isolates. The identity, antibiotic resistance characteristics and production of Extended Spectrum β-lactamase (ESβL) by microbes that grew on antiseptics-agar plates at dilutions higher than manufacturers stated in-use concentrations were determined using morphological and biochemical characteristics as well as disc-diffusion methods.

Results: The tap water samples were found to contain heterotrophic bacteria, coliforms and staphylococci as contaminants. Four of the antiseptic product samples could not inhibit growth at dilutions higher than the in-use concentration while the effects of dilutions on the remaining were inconclusive since the concentrations after dilution could not be determined in all cases from the instruction given by the manufacturer. Nineteen (70.4%) of the 27 surviving organisms on the diluted antiseptics were Klebsiella pneumonia strains. Other isolates were 3 Streptococcus spp; 2 Pseudomonas aeruginosa; 2 S. aureus and 1 S. epidermidis strain. All the isolates were multidrug resistant and four of the K. pneumonia isolates produced ESβL. There was no growth in the antiseptics diluted with sterile distilled water.

Conclusion: It is concluded that instructions for dilutions of antiseptics should consider the effects of dilutions on the antimicrobial activities of the antiseptics in order to prevent failure of antisepsis which might have been happening all along with these commonly used antiseptics.