Does Hibi Scrub Kill Staphylococcus aureus?
Yes, Hibi scrub (chlorhexidine) effectively kills Staphylococcus aureus, but its efficacy depends critically on formulation—chlorhexidine combined with alcohol is significantly more effective than chlorhexidine alone, particularly against methicillin-resistant strains (MRSA).
Key Evidence on Bactericidal Activity
Chlorhexidine gluconate is a potent, broad-spectrum antiseptic that is effective against nearly all bacteria and yeasts 1. However, the formulation matters substantially for S. aureus eradication:
Alcohol-Based vs Aqueous Formulations
The most compelling evidence comes from in vitro studies specifically examining S. aureus killing:
0.5% chlorhexidine in 80% ethanol completely eliminated all S. aureus strains (both methicillin-resistant and methicillin-sensitive) with no organism growth after exposure 2
In contrast, aqueous formulations showed incomplete killing:
- 10% povidone-iodine reduced colony counts by only 55.2% at 15 seconds, 91.2% at 30 seconds, and 96.7% at 60 seconds
- 0.5% chlorhexidine gluconate (aqueous) reduced counts by only 37.2% at 15 seconds, 77.1% at 30 seconds, and 93.3% at 60 seconds 2
The alcohol-based formulation demonstrated significantly more potent and rapid bactericidal activity 2.
MRSA Considerations
There is an important caveat regarding MRSA susceptibility:
MRSA strains are significantly less susceptible to chlorhexidine than methicillin-sensitive S. aureus (MSSA) 3
Hibiscrub (chlorhexidine-detergent without alcohol) showed reduction factors <5 against MRSA, which is suboptimal 3
Hand disinfectants containing both alcohol and chlorhexidine (like Hibisol) are significantly more effective against MRSA than scrubs based only on chlorhexidine and should be preferred in clinical practice 3
MRSA strains carrying gentamicin and nucleic acid-binding (GNAB) resistance plasmids showed higher chlorhexidine MICs (4-8 μg/ml) compared to strains without these plasmids (0.25-2 μg/ml) 4
Clinical Application
Formulation Selection
For optimal S. aureus killing, use chlorhexidine in alcohol formulations rather than aqueous chlorhexidine alone 1, 2. The guidelines specifically note that chlorhexidine in alcohol provides faster onset and longer duration of action 1.
Concentration Considerations
- Both 0.5% and 2% chlorhexidine in alcohol show comparable efficacy against S. aureus in most clinical scenarios 1
- 0.5% chlorhexidine in 70% alcohol is preferred over 2% solutions due to neurotoxicity concerns without convincing evidence of antimicrobial superiority 1
Clinical Effectiveness
Real-world evidence supports chlorhexidine's effectiveness:
- Preoperative screening and decolonization with chlorhexidine (combined with mupirocin) reduced S. aureus surgical site infections, with decolonization efficacy of 91.6% 5
- Daily scrubbing with chlorhexidine reduced skin colonization by antibiotic-resistant staphylococci to one-tenth of control levels 6
- Chlorhexidine preparation resulted in epidural catheters being six times less likely to be colonized compared to povidone-iodine 1
Critical Pitfalls to Avoid
Do not rely on aqueous chlorhexidine alone for S. aureus decontamination—the alcohol component is essential for rapid and complete killing 2
Allow adequate contact time and drying: The solution must dry completely before proceeding with procedures 1
Be aware of emerging resistance concerns: Increased chlorhexidine usage may select for reduced susceptibility, particularly in MRSA strains with specific resistance plasmids 7, 4
Use only for appropriate indications: Given concerns about resistance development, chlorhexidine should be used only when there is clear patient benefit 7
Avoid sub-lethal concentrations: Exposure to inadequate chlorhexidine concentrations should be avoided to prevent resistance selection 7
FDA-Approved Indications
Chlorhexidine is FDA-approved as a surgical hand scrub to "significantly reduce the number of microorganisms on the hands and forearms" and as a skin wound and general skin cleanser to "help reduce bacteria on the skin" 8.