How long do pathogens persist on surfaces?
- Systematic review
- Results
- Comment
So
what's the answer? Given the major interest in hospital acquired
infections, one might expect large amounts of useful information presented in a
straightforward way, in order that we can organise services to minimise risk to
professionals and patients. A systematic review [1] implies that our knowledge
is limited.
Systematic
review
The
review set out to find articles in PubMed relating to survival of pathogens on
surfaces using a broad strategy, and following up on any useful citations in
studies that had been found, supplemented by checking textbooks on infection
control and microbiology. Any report was included, and the range of duration
abstracted.
Results
Many
reports were found, and there are 126 references, a useful source for others
wanting more detailed information. For most pathogens there were only a few
citations. The larger the number of citations, the wider the range of
persistence.
For
bacteria, for example, the range for E coli (11 references) was 1.5 hours to 16
months, and for S aureus, including MRSA (six references), between seven days
and seven months. For clinically relevant fungi, the range was up to four
months, and for viruses days to months.
Comment
Not
the answer to everything, but possibly the only answers that are available. It
seemed to be the case that, as one might expect, low temperatures and higher
humidity increased persistence. It seems that, whatever the actual answer,
persistence of nosocomial pathogens on surfaces is sufficiently long to become
a continuous source of transmission in the absence of effective preventive
surface disinfection. Keep cleaning effectively is the message that is being
heavily reinforced here.
Of
course, it is all more complex than this when it comes to hospital acquired
infections and the damage they do to individuals and hospitals. The arguments
appear to have been simplified to handwashing, and while that is important,
along with cleaning surfaces, an effective response will come from a number of
different actions combining to reduce the problem. Reading this paper is a
start because it helps show one element of this huge problem.
Reference:
- A Kramer et al. How long do nosocomial pathogens persist on inanimate surfaces? A systematic review. BMC Infectious Diseases 2006 6:130 (www.biomedcentral.com/1471-2334/6/130).
