MicrobiologyTier 2Medical Sciences concept

Alcohol-based hand hygiene efficacy by organism (spore-forming vs non-spore-forming)

Core concept

Alcohol-based hand rub (ABHR) kills by denaturing microbial protein/lipid membranes - effective against enveloped viruses, most vegetative bacteria, fungi
Ineffective against bacterial spores (C. difficile) - no lipid envelope to disrupt
Reduced efficacy against non-enveloped ("naked") viruses - norovirus, rotavirus - much more resistant to alcohol

Key detail

Organism	ABHR effective?
Enveloped viruses (HIV, HBV, HSV, coronaviruses)	Yes
Vegetative bacteria (MRSA, VRE)	Yes
Fungi (Candida)	Yes
Non-enveloped viruses (norovirus, rotavirus)	Reduced
Bacterial spores (C. difficile, B. anthracis)	No

C. difficile and norovirus outbreaks -> soap and water (mechanical removal), not ABHR alone

Clinical relevance

Outbreak setting on a ward with C. difficile or norovirus -> mandate soap-and-water hand washing in addition to/instead of ABHR
WHO's 5 Moments for Hand Hygiene assumes ABHR as default; the spore-forming/non-enveloped exceptions are the exam trap

Correlations

C. difficile infection and pseudomembranous colitis
Norovirus gastroenteritis outbreaks
Standard vs transmission-based (contact) precautions

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