Literature Update - September, 2004
Compiled by Dr Deb Friedman, VICNISS ID Physician
Community Acquired MRSA
The increase in methicillin-resistant strains of Staphylococcus aureus in the community has
been a source of concern in many countries including Australia. A recent American Study (Charlebois ED et al, Clin Infect Dis
2004; 39:47-54) has looked at the predictors for community-acquired MRSA.
They found that the majority (58%) of infections were caused by strains traceable to the hospital or to long-term care
facilities. Injecting drug users were less likely to have a strain traceable to a hospital.
This type of data once again shows that previous contact with hospitals or long-term care facilities is a risk factor
for acquisition of resistant organisms, even for those who reside in the community.
Prevention of Meningococcal Infection in Household Contacts
In both the community and health care settings, a diagnosis of meningococcal infection in a patient causes panic among
possible contacts. Guidelines recommend prophylaxis in the community for individuals who are either household contacts,
or have had the equivalent amount of contact as would people in a household.
A new paper has reviewed the evidence for the effectiveness of prophylaxis in preventing secondary cases of meningococcal
disease among household contacts (Purcell B et al. BMJ 2004;328:1339-42). From the 5 studies included in their evaluation,
they found that prophylaxis reduced the risk of secondary infection within a 30-day period by 89%.
They also found that about 3% of appropriately treated patients with meningococcal infection remain colonised with
N.meningitidis after hospital discharge. This is not unexpected given that penicillin does
not eradicate carriage. Now this of course raises questions about whether or not these patients should also receive prophylaxis.
Transmission of Common Cold Viruses
Rhinoviruses are the most common cause of the colds, however it has been unclear whether or not they are transmitted via
aerosol spread. In a recent study, (Myatt et al, Am J Respir Crit Care Med 2004;169:1187-90) air filters in office buildings
were tested to detect both rhinoviruses and enteroviruses via PCR. They found these viruses in 32% of filters, and also
detected virus in the nasal mucous of 17 employees who complained of symptoms of a cold at that time. The virus from one
mucous sample and a building air sample collected in the same week were identical!
The buildings chosen for this study were built in the 1960s, and likely had reduced ventilation. Nonetheless, this
study does illustrate the airborne transmission of respiratory viruses, and this may be a difficult problem to tackle.
Antibiotic Resistant Bacteria are Expensive
In a recent study, the costs of treating patients with either methicillin-susceptible Staphylococcus
aureus (MSSA) or methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia were
compared (McHugh CG et al. Infect Control Hosp Epidemiol 2004;25:425-30). They found that the difference in the cost of
bacteraemia was related to the severity of illness of the patients. Among patients with lower severity of illness, the
average costs were $2462 ($US) for MSSA and $2715 for MRSA. However, among patients with a high severity of illness average
costs were $4442 for MSSA and $9744 for MRSA (P<0.001).
In the same issue of this journal another paper (Puzniak LA et al, Infect Control Hosp Epidemiol 2004; 25:418-24)
performed a cost-benefit analysis on the use of gowns for controlling the transmission of vancomycin-resistant enterococci
(VRE). They found that the use of gloves and gowns (when compared to a time period when only gloves were used) prevented
58 cases of VRE colonisation and 6 cases of VRE bacteraemia.
The net benefit of the gown policy was as much as $419,346 per year, and the authors estimated that gown use would
have been cost-effective if it prevented just 7 cases of VRE colonisation.
These studies add to the body of evidence that shows that effective infection control programs that reduce both
colonisation or infection with resistant organisms will benefit hospitals in many respects, including financially.