Methicillin-Resistant Staphylococcus aureus in a Trauma Population: Does Decolonization Prevent Infection?

Area of Science:

• Infectious Diseases
• Critical Care Medicine
• Medical Microbiology

Background:

• Methicillin-resistant Staphylococcus aureus (MRSA) poses a significant threat in intensive care units (ICUs).
• Nasal colonization is a primary reservoir for MRSA, increasing infection risk.
• Effective decolonization strategies are crucial for infection prevention in vulnerable patient populations.

Purpose of the Study:

• To evaluate the efficacy of a decolonization regimen (chlorhexidine gluconate baths and mupirocin ointment) in reducing MRSA infections among ICU trauma patients.
• To determine the genetic relatedness between MRSA colonization isolates and subsequent infectious strains.

Main Methods:

• A randomized controlled trial involving ICU trauma patients with positive MRSA nasal swabs.
• Intervention group received daily chlorhexidine gluconate (CHG) baths and mupirocin (MUP) ointment for five days.
• Control group received standard soap and water baths with placebo ointment.
• Post-treatment nasal swabs and surveillance for invasive MRSA infections were performed.
• Polymerase chain reaction (PCR) was used to assess genetic relatedness and resistance genes (mupA, qacA/B, smr).

Main Results:

• The CHG and MUP regimen was ineffective in eradicating MRSA nasal colonization (59.1% positive vs. 90% in control).
• MRSA infections occurred in 31.8% of the CHG group versus 60% in the control group, though not statistically significant (P=0.244).
• All identified invasive MRSA infections were genetically identical to the patients' initial nasal colonization strains.
• No isolates showed resistance to MUP or CHG (mupA, qacA/B), but 35% harbored the smr gene.

Conclusions:

• The combination of CHG baths and MUP ointment is not effective for MRSA nasal decolonization in this patient population.
• Despite lack of eradication, the regimen may potentially reduce the incidence of MRSA infections.
• Endogenous nasal MRSA colonization is the typical source of subsequent invasive MRSA infections in ICU trauma patients.