A study of the susceptibility of methicillin resistant coagulase-negative staphylococci isolated from faecal samples of children to commonly used antiseptic agents

Abstract

Background: This study was carried out to provide information on the susceptibility of methicillin resistant coagulase-negative staphylococci (MRCoNS) faecal isolates to some commonly used antiseptic agents.
Materials and Methods: For this purpose, 149 coagulase-negative staphylococci (CoNS) strains recovered from the faecal samples of children in Ile- Ife, a semi-urban settlement in Nigeria were screened against oxacillin by disc diffusion and agar screening methods. They were further screened against five antiseptic agents namely; benzalkonium chloride, cetrimide, chlorhexidine gluconate, gentian violet and acriflavine by the agar dilution method. Oxacillin resistant isolates were confirmed by screening for the mecA gene by the standard PCR method.
Results: Oxacillin resistant isolates were 30.2%. While equal susceptibility was obtained for both MRCoNS and methicillin susceptible CoNS (MSCoNS) against gentian violet, reduced susceptibility to the order of one double dilution was obtained for MRCoNS against the remaining agents although the observed differences were not statistically significant (p > 0.05). Isolates generally showed highest susceptibility to chlorhexidine gluconate (MIC₅₀=4mg/L; MIC₉₀=32mg/L) while they were found to be least susceptible to gentian violet (MIC₅₀=32mg/L; MIC₉₀>32mg/L). S. hominis strains were the most susceptible to chlorhexidine gluconate (MIC₅₀<1mg/L; MIC_mean=2.9mg/L) whereas S. saprophyticus were the least susceptible to this agent (MIC₅₀=16mg/L; MIC_mean=5.8mg/L).
Conclusion: It is concluded that children feces can be an important source of MRCoNS with reduced susceptibility to some commonly used antiseptic agents, a source that appears to receive little attention and thus warrants further investigation.

Key words: surveillance, antimicrobials, drug resistance, efficacy, faeces, antiseptics