Effectiveness of preemptive barrier precautions in controlling nosocomial colonization and infection by methicillin-resistant Staphylococcus aureus in a burn unit

Abstract

We report the effectiveness of preemptive enhanced barrier precautions in containing a methicillin-resistant Staphylococcus aureus (MRSA) outbreak in a university hospital burn unit and further controlling endemic nosocomial MRSA infection in the unit during the succeeding 27 months. During a 6-month period, 12 patients in a 7-bed burn unit were found to be colonized (7) or infected (5) by MRSA. An epidemiologic study was undertaken. Seven of the 10 strains of MRSA from patients that were available for DNA typing were clonally identical. Early in the outbreak, a health care worker was found to be a concordant nasal carrier and was successfully decolonized with nasal mupirocin. However, despite stringent compliance with isolation of MRSA-positive patients (targeted precautions), new cases of MRSA colonization or infection continued to occur. The outbreak was rapidly terminated after implementing preemptive barrier precautions with all patients in the unit: a new, clean gown and gloves for any physical contact with the patient or their environment. Although 25% of all nosocomial S aureus isolates in our hospital are resistant to methicillin, the incidence of endemic MRSA colonization and infection in the burn unit has remained very low since implementing barrier precautions unit wide (baseline rate, 2.2 [95% CI: 1.0-4.2] cases per 1000 patient-days; outbreak rate, 7.2 [95% CI: 4.4-11.0] cases per 1000 patient-days; post-outbreak termination endemic rate, 1.1 (95% CI: 0.4-2.3) cases per 1000 patient-days). The rate ratio comparing the outbreak and the baseline period was 3.20 (95% CI: 1.40-7.95, P = .002); the rate ratio comparing the post-outbreak period with the baseline period was 0.48 (95% CI: 0.14-1.53, P = .10), and it has not been necessary to screen personnel for MRSA carriage to prevent nosocomial MRSA infections in this highly vulnerable population. Preemptive barrier precautions were highly effective in controlling the outbreak and, most notably, have also been highly effective in maintaining a very low incidence of nosocomial MRSA infection endemically in the succeeding 27 months of follow-up. Use of clean gloves, with or without a gown, bears consideration for all high-risk hospitalized patients to prevent cross transmission of all multiresistant nosocomial pathogens.