The relation between positive screening results and MRSA infections in burn patients

Methicillin-resistant Staphylococcus aureus (MRSA) is a key pathogen in burn patients. Several factors put them at increased risk of MRSA infection: partial loss of the skin barrier, the immune-compromising effects of burns, prolonged hospital stays, and invasive procedures. This study aims to find the relation between MRSA screening swab cultures taken within 48 h of admission, weekly surveillance cultures, and MRSA infection secondary to colonization.

The data of all burns patients admitted to the referral centre for burns from 2012 to 2016 were reviewed. MRSA cultures taken at admission and on weekly surveillance screening, including nasal, perianal, and wound swabs, were reviewed. To determine associations between MRSA colonization and infection rates, both MRSA-positive and MRSA-negative swab cultures were included in the analysis. Several risk factors were considered: age, gender, ethnicity, %TBSA, BAUX index, inhalational injury, ICU admission and days, need for ventilator support and days, length of stay (LOS) in hospital, and complications. Univariate and multiple logistic regression analyses were used to predict correlations between positive swab cultures and risk factors.

Data from 396 patients were reviewed. The median age at admission for the burn patients was 46 (IQR: 31-59) years. On admission, 2.5% of patients were MRSA positive, whereas 17.9% were found to be MRSA positive on weekly surveillance screening. At surveillance, 60.6% developed an infection secondary to MRSA colonization. An MRSA infection was not identified for any patient who did not have at least one positive admission or surveillance swab. A statistically significant association was found between any positive swab and MRSA infection (P < 0.001). The median number of complications reported in the MRSA-positive group was 2 (IQR: 1-3) versus 0 (IQR: 0-1) in the MRSA-negative group and the median length of hospital stay in the MRSA-positive group was 34.5 (IQR: 20.25-56.25) days versus 7 (IQR: 3-16) days in the MRSA-negative group (P < 0.001).

Nosocomial MRSA colonization rates are high, and patients incurring infections experience a greater than average LOS in hospital and complications. Over 60% of patients who had a positive swab culture at surveillance developed an infection, whereas, no patient with a negative MRSA swab status developed an infection. Hence, pragmatic prevention strategies have to be implemented.