Reducing the impact of methicillin-resistant Staphylococcus aureus infection in an intensive care unit: a nine-year analysis

Abstract number: o275

Pan  A., Raineri  E., Mondello  P., Ferrari  L., Carnevale  G., Acquarolo  A., Lorenzotti  S., Magri  S., Soavi  L., Crema  L.

Objective: 

To evaluate the effectiveness of a control system for nosocomial transmission of methicillin-resistant Staphylococcus aureus (MRSA) in an Intensive Care Unit (ICU) in a hospital with hyperendemic MRSA.

Methods: 

We retrospectively analysed prospectively collected data. This study was performed in a 10 bed general ICU in Italy, with high rates of MRSA transmission and infection rates: 6.0 and 2.8 cases per 100 admissions respectively. Three phases were identified over a 9-year time period. Period 1 (p1), 1996–1997, prior to the introduction of the hospital MRSA control program. Period 2 (p2), 1998–2002, after the introduction of the MRSA control program guidelines. Period 3 (p3), 2003–2004, after the ICU moved into a new ward, when MRSA modified guidelines, including isolation or cohorting, were implemented. All patients admitted to ICU were included in the analysis. MRSA guidelines included active surveillance, contact precautions and topical treatment of carriers. In 2003 modified MRSA guidelines included isolation/cohorting of MRSA positive patients.

Results: 

The rate of MRSA infected patients during p1, p2, and p3 was: 2.8, 1.2, and 0.6 cases per 100 admissions, respectively. A significant reduction of the infection rate was observed comparing p1 both with p2 (P = 0.002; RR: 0.4 CI95%: 0.22–0.73) and p3 (P = 0.0008; RR: 0.22 CI95%: 0.08–0.56). No significant reduction of the infection rate was observed between p2 to p3, (P = 0.2; RR: 0.54 CI95%: 0.21–1.37). A significant reduction of the methicillin resistance rate of Staphylococcus aureus isolates was observed: 51%, 32%, and 16% during p1, p2, and p3 respectively (P < 0.0001 for trend).

Conclusions: 

The "search and destroy" strategy, based upon a combination of active surveillance, contact precautions and topical treatment might be effective in significantly reducing MRSA acquisition rate even in an ICU with high rates of MRSA colonization / infection. Patients' isolation or cohorting did not further improve the results obtained with the "search and destroy" strategy.