persistence of microbes

How long do nosocomial pathogens persist on inanimate surfaces?

A systematic review

Reviewed by Dr. Sayan Chakraborty

MD (JR-2), Dept. of Tropical MedicineCalcutta School of Tropical Medicine

Author: Axel Kramer

BMC Infectious Diseases BMC series open, inclusive and trusted 2006 6:130

DOI: 10.1186/147123346130© Kramer et al; licensee BioMed Central Ltd.

2006Received: 26 April 2006

Accepted: 16 August 2006Published: 16 August 2006

BACKGROUND• Global infection control community: ongoing

controversy about the appropriate t/t of inanimate surfaces in hospitals

• Non-antimicrobial detergents/ antimicrobial agents ??

• Parameters to be noted: Type of ward Expected frequency of hand contact with a

surfacePersistence of nosocomial pathogens on surfaces

METHODS• Search strategy:Reviewed in MedLine on the internet

homepage of the National Library of MedicineStandard textbooks on infection control,

bacteriology and virology• Selecting studies: Reports with experimental

evidence• Interpretation of studies: Pathogens were

grouped according to importance and persistence

RESULTS• Persistence of bacteria

RESULTS- Bacteria

RESULTS - Bacteria• Gram negative persist longer than gram positive• Humid conditions improved persistence• Only Staphylococcus aureus persist longer at low

humidity• Low temperatures, e.g., 4°C or 6°C, also improved

persistence• Test material -no consistent result. However, longer

persistence noted on plastic & steel• Longer persistence with higher inocula, in the

presence of protein, serum, sputum or without dust

RESULTS- FungiThe presence of serum or albumin, low temp & high humidity lead to longer persistence

RESULTS - Virus

RESULTS - Virus

RESULTS - VIRUS• Viruses of Respiratory tract: a few days• Viruses of GI tract: 2 months• Blood borne viruses eg HBV or HIV > 1 week• High humidity: Entero- & Rhinovirus• Low humidity: HSV & HAV• Low temp: Astro-, Adeno-, Polio, HSV & HAV• Type of material inconsistent• Non-porous substance- Influenza; Fomica & gloves-

RSV; Telephone receiver- FCV• Longer persistence in fecal suspension & higher

inoculum

DISCUSSION• Factors influencing higher persistence:Low temperatureHigh humidityHigher inoculumType of surface & suspension medium –

inconsistent

• Cryptosporidium species survive on dry surfaces for only 2 hours

HAND HYGIENE• Transmission to hands: Escherichia coli (100%) Salmonella spp. (100%) Staphylococcus aureus (100%) Candida albicans (90%) Rhino virus (61%) HAV (22% – 33%) Rota virus (16%).• Contaminated hands can transfer viruses to 5 more surfaces or

14 other subjects.• Recontaminating of surface, as in HAV.• Compliance rates of healthcare workers in hand hygiene

around 50%

Common modes of transmission from inanimate surfaces to susceptible patients

DISCUSSION …. contd• During outbreaks, role of environmental

contamination stronger for Clostridium difficile, MRSA and VRE than for Pseudomonas aeruginosa or Acinetobacter baumannii

• Routine treatment of floors with surface disinfectants - no significant impact

• Disinfection of surfaces in the immediate environment of patients reduce nosocomial infection

CONCLUSION

• Most nosocomial pathogens persist on inanimate surfaces for weeks or even months

• Disinfection of surfaces in specific patient care areas

• PROPER HAND HYGIENE

THANK YOU