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Sensitivity of methicillin-resistant Staphylococcus aureus strains to some antibiotics, antiseptics and disinfectants
S B Al-Masaudi1, M J Day, A D Russell
1Department of Applied Biology, University of Wales Institute of Science and Technology, Cardiff.
Abstract:
The effects of antibiotics, antiseptics and disinfectants against some methicillin-resistant (MRSA) and methicillin-sensitive (MSSA) Staphylococcus aureus strains have been studied. The MRSA and MSSA strains were equally sensitive to phenols, esters of para(4)-hydroxybenzoic acid and chlorhexidine but MRSA strains were slightly more resistant to quaternary ammonium compounds and considerably more so to dibromopropamidine isothionate. Some MRSA strains were also resistant to phenylmercuric nitrate (but not another organomercurial, thiomersal), mercuric chloride and cadmium chloride. All MRSA strains produced beta-lactamase. Strains from the Royal Free Hospital, London were highly resistant to beta-lactam antibiotics, erythromycin, trimethoprim and tetracyclines but were sensitive to other antibiotics. One strain from the University Hospital of Wales, Cardiff was resistant to gentamicin but sensitive to tetracycline and trimethoprim.
Insights
Methicillin-resistant Staphylococcus aureus (MRSA) showed varied resistance to disinfectants and antibiotics compared to MRSA. MRSA strains were more resistant to certain compounds like quaternary ammonium compounds and dibromopropamidine isothionate.
Area of Science:
- Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) is a significant public health concern.
- Understanding the resistance patterns of MRSA to various antimicrobial agents is crucial for effective treatment and infection control.
Purpose of the Study:
- To investigate and compare the susceptibility of MRSA and methicillin-sensitive Staphylococcus aureus (MSSA) strains to a range of antibiotics, antiseptics, and disinfectants.
- To identify specific agents to which MRSA exhibits increased resistance.
Main Methods:
- Phenotypic susceptibility testing of MRSA and MSSA strains against a panel of antiseptics, disinfectants, and antibiotics.
- Assay for beta-lactamase production in MRSA strains.
- Characterization of resistance profiles in geographically distinct MRSA isolates.
Main Results:
- MRSA and MSSA strains demonstrated similar sensitivity to phenols, para(4)-hydroxybenzoic acid esters, and chlorhexidine.
- MRSA strains exhibited increased resistance to quaternary ammonium compounds and dibromopropamidine isothionate compared to MSSA.
- Some MRSA strains displayed resistance to phenylmercuric nitrate, mercuric chloride, and cadmium chloride, but not thiomersal.
- All studied MRSA strains produced beta-lactamase.
- Geographically distinct MRSA isolates showed varied resistance to multiple antibiotics, including beta-lactams, erythromycin, trimethoprim, and tetracyclines.
Conclusions:
- MRSA exhibits differential resistance to certain disinfectants and antiseptics compared to MSSA.
- The presence of beta-lactamase and diverse resistance mechanisms in MRSA contributes to challenges in treatment.
- Variability in antibiotic resistance among MRSA strains necessitates ongoing surveillance and tailored treatment strategies.