Persistence of microbes
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Transcript of 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