March 25, 2008
More on MRSA
The waters got muddied in the last month on what to do to prevent some hospital-associated infections (HAIís). Our January 2008 Whatís New in the Patient Safety World column on ďTwo Timely Articles on MRSA InterventionsĒ noted that a universal screening program at Evanston Northwestern had been successful in reducing both MRSA transmission and MRSA blood stream infections. Now two new studies on universal screening seem to come to contradictory conclusions about the value of universal screening for MRSA.
A Swiss study published in JAMA (Harbarth et al. 2008) found that universal screening for MRSA in surgical patients resulted in no reduction in surgical MRSA infections even though it did identify many previously unknown MRSA carriers.
But a US study published in the Annals of Internal Medicine concluded that universal MRSA screening on admission resulted in a 70% reduction in MRSA infections. This study was actually an extension of the previously published Evanston Northwestern work. It was a study done in 3 hospitals and consisted of a preliminary phase in which MRSA screening was done just in ICUís, then a second phase in which MRSA screening was performed on all patients at admission. They found no statistically significant improvement when screening was performed on just ICU patients but the 70% reduction in MRSA infections found after implementation of the universal screening was statistically significant.
So why the different results and conclusions? Both studies utilized rapid turnaround molecular testing techniques for MRSA and did not rely on culture results for screening. The average time from admission screening to test reporting was 22.5 hours in the Swiss study and slightly less (0.67 days) in the US study. The Swiss study only included patients admitted for surgery, whereas the US study included all admitted patients. A relatively low background MRSA infection rate in the Swiss study may have made demonstration of statistically significant improvement after the intervention more difficult.
Note that both studies actually used multiple interventions. Both used conventional contact isolation, with private rooms or cohorting of MRSA patients, mandatory gown/gloves/mask for all visits, and dedicated equipment (eg. stethoscopes) in the rooms. In addition to the rapid screening, both used topical treatments for decolonization of carriers to varying degrees. One also suspects that adherence to infection control techniques such as hand hygiene were probably more closely adhered to in the setting of a formal study than they are in a typical hospital setting.
Though both studies should be lauded for their practical designs, they reflect the great difficulty in developing an effective strategy for dealing with MRSA and related issues in the absence of true randomized controlled trials. So the jury is still out on what is the most effective way to deal with prevention of MRSA infections.
One consideration not noted in either study is that of unintended consequences of contact isolation. Kirkland and Weinstein (Kirkland 1999) found that healthcare workers who treated patients in contact isolation entered their rooms less frequently and had significantly less direct contact with them. Saint et al. (2003) found that attending physicians in two teaching hospitals were about half as likely to examine patients in contact isolation. Another study (Stelfox et al. 2003) showed that isolated patients are twice as the likely as control patients to suffer an adverse event during hospitalization. The difference was primarily due to preventable adverse events and included event such as falls, decubiti, and fluid/electrolyte disorders. In fact, the latter events were 8† times more likely in isolated patients. They also had a cohort of congestive heart failure patients in isolation and these patients were much less likely to have certain interventions and evidence-based care than a control group of congestive heart failure patients. And we have all seen that patients in contact isolation often do not get services such as active rehabilitation that they might get were they not in isolation.
These potential unintended consequences of contact isolation need to be closely monitored and every attempt should be made to ensure they do not happen. It would be a tragedy to allow an asymptomatic carrier of MRSA to get a decubitus because he/she was seen less frequently while in isolation.
Harbarth S, Fankhauser C, Schrenzel J, Christenson J, Gervaz
P, Bandiera-Clerc C, Renzi G, Vernaz N, Sax H, Pittet D. Universal Screening
for Methicillin-Resistant Staphylococcus aureus at Hospital Admission and
Nosocomial Infection in Surgical Patients. JAMA. 2008;299(10):1149-1157
Robicsek A, Beaumont JL, Paule SM, Hacek DM, Thomson RB, Kaul KL, King P, Peterson LR. Universal Surveillance for Methicillin-Resistant Staphylococcus aureus in 3 Affiliated Hospitals. Ann Intern Med 2008; 148: 409-418 http://www.annals.org/cgi/content/abstract/148/6/409#FN
Kirkland KB, Weinstein JM. Adverse effects of contact isolation. The Lancet 1999; 354: 1177-1178 http://www.thelancet.com/journals/lancet/article/PIIS0140673699041963/abstract
Saint S, Higgins LA, Nallamothu BK, Chenoweth C. Do physicians examine patients in contact isolation less frequently? A brief report. Am J Infect Control 2003; 31: 354-356 http://www.ajicjournal.org/article/S0196-6553(02)48250-8/abstract
Stelfox HT, Bates DW, Redelmeier DA. Safety of Patients Isolated for Infection Control. JAMA. 2003;290:1899-1905