Bactericidal activity of antiseptics against methicillin-resistant Staphylococcus aureus

Abstract

Various commonly used antiseptics were tested against three strains of methicillin-resistant Staphylococcus aureus (MRSA) at stock strength and in serial 10-fold dilutions. The stock solutions of 4% chlorhexidine gluconate-alcohol (Hibiclens), 1% p-chloro-m-xylenol (Acute-Kare), and 3% hexachlorophene (Phisohex) produced 2-log reductions of MRSA after a 15-s exposure, but even after 240 s, these solutions failed to kill all the MRSA. Povidone-iodine (Betadine) solution was maximally effective at the 1:100 dilution, killing all the MRSA within 15 s; other dilutions were less effective, though each killed the MRSA within 120 s. Similar results were obtained with three different strains of methicillin-susceptible S. aureus. Thus, of the four most commonly used antiseptics, povidone-iodine, when diluted 1:100, was the most rapidly bactericidal against both MRSA and methicillin-susceptible S. aureus.

Presurgical Hand Antisepsis: Concepts and Current Habits of Veterinary Surgeons

“…The 4% concentration is used in soaps and has bactericidal activity against various Gram-negative 29 and Gram-positive bacteria, 30 but no sporicidal activity. Although uncommon, natural resistance to CHX is described for some bacteria 28 and concerns have been raised about its suitability for prevention of methicillin-resistant Staphylococcus aureus (MRSA) [30][31][32] and transmission of enterococci 33 because acquired resistance to CHX has been shown to be linked with hospital environmental isolates 14 of these bacterial strains. This is of major importance as MRSA infections are increasingly occurring in veterinary medical settings 34 and enterococci are isolated from the hands of veterinary surgical staff.…”

“…These disadvantages are likely the main reasons why the survey revealed limited use of PVPiodine soap among Diplomates. Nevertheless, other studies 31,32 show PVP-iodine to have a good activity against MRSA and other resistant bacteria 52 and therefore PVPiodine should not be totally abandoned as a general antiseptic solution in clinical practice.…”

Oral health promotion interventions on oral reservoirs of staphylococcus aureus: a systematic review

“…Concern has been raised over the possible correlation between antibiotic resistance and reduced susceptibility to antiseptics such as chlorhexidine. Some studies have shown MRSA strains to have reduced MICs compared to methicillin-susceptible S. aureus (MSSA) strains (Brumfitt et al, 1985;Mycock, 1985;Irizarry et al, 1996;Kampf et al, 1998), while others have failed to observe such an association (Haley et al, 1985;Al-Masaudi et al, 1988;Grare et al, 2010). The clinical relevance of such elevated MICs, however, is unclear as they are still greatly exceeded by antiseptic concentrations included in commercial products.…”

Epidemiologic Background of Hand Hygiene and Evaluation of the Most Important Agents for Scrubs and Rubs

“…When used in a liquid soap, chlorhexidine usually has a concentration of 4% and exhibits a bactericidal activity against various gramnegative (130) and gram-positive (249) bacteria. In some comparative studies using suspension tests chlorhexidine (4%) was found to be less effective against MRSA than against methicillin-susceptible S. aureus, which has raised concerns about the suitability of the active agent in the prevention of transmission of MRSA (93,192,249). This concern has been confirmed with enterococci.…”