Literature Update - February, 2007
Compiled by Dr Emma McBryde, VICNISS ID Physician
How many infection control staff do we need in hospitals?
Given the changing nature of the healthcare system with more day of admission surgery,
reduced stays and higher throughput, it is no longer useful to determine the need for infection control practitioners
based on hospital bed numbers. P.J. van den Broek et al. (Journal of Hospital Infections 65(2) 108-111) report
a consensus meeting in which medical microbiologists debated how much time was needed for the delivery of infection control
activities in a model hospital using the number of admissions as the denominator. They determined that
one FTE ICP per 5000 admissions and one medical microbiologist or epidemiologist per 25 000 admissions was adequate.
Still much to learn about
Clostridium difficile.
This pathogen has long been recognised as the agent of antibiotic associated diarrhoea.
Initially, it was believed that cases arose from patient’s endogenous flora, however it is now
increasingly recognised that in the setting of hospital outbreaks, the same strains of
C. difficile are transmitted from patient to patient (Samore MH
et al.Am J Med 1996 Jan;100(1):32-40). Other relatively recent realisations
are that C.difficile is emerging in the community (Dial S. et al. JAMA.
2005 Dec 21;294(23):2989-95) and that a highly toxigenic strain (producing about 15 to 20 times
the amount of toxin as usual strains) is emerging which can cause disease in healthy individuals.
More is being discovered and it is the “feature pathogen” in the February 2007 [vol 28 (2)] edition of
Infection Control and Hospital Epidemiology.
A 30 month retrospective cohort study on a ICU population in the US by Lawrence et al. found that
risk factors for C.difficile included antibiotic exposure, mechanical ventilation,
enteral feeding, VRE colonisation and C.difficile colonisation pressure
(univariate analysis). Only C.difficile colonisation pressure and VRE colonisation
remained significant in the multivariate analysis. This is further evidence to support the transmission of
C.difficile in the healthcare setting. The important features of
this study is that the evidence for transmission was not in an outbreak setting and that the risk was quantified
(odds ratio for acquisition of C.difficile was 3.77 for those with 30 case days of exposure).
A 5 year review of all C.difficile cases in a large French teaching hospital
by Barbut et al. found that 19% was community acquired. Ten percent of isolates
were identical tp another isolate from the same hospital within 2 months and were thus presumed to be transmitted within
the hospital. Eleven percent of strains were positive for binary toxin and these strains were associated with more-severe
diarrhoea and a higher case-fatality rate.
Rapid PCR testing accompanied by isolation
appears to reduce transmission of MRSA
A planned interrupted time-series study by Cunningham et al. (Journal of Hospital Infection 65(1): 24-28)
found that a rapid diagnostic test used to identify MRSA colonisation (same day PCR in phase 2
compared with three day culture in phase 1) implemented in a critical care unit led to
a reduction in transmission of MRSA from 13.89/1000 patient days to 4.9/1000 patient days.
The cause of the reduced transmission is hard to tease out as patients were both put into standard precautions
and decolonised using mupiricin intranasally and triclosan topically.
These results are interesting because an earlier study by Cepeda et al (Lancet. 2005 Jan 22-28;365(9456):295-304)
found that isolating patients in a critical care unit did not reduce MRSA transmission. This study
did not however have rapid identification or routine decolonisation.
WHO releases Guidelines on Hand Hygiene in Health Care
New hand hygiene guidelines released by WHO the advanced draft of which can be accessed at the website
www.who.int/patientsafety/challenge/clean.care/en/
as part of the “clean care is safer care” campaign. It is a useful up to the minute guide with clear
account of the evidence base for recommendations.