Risk factors for the acquisition of imipenem-resistant Acinetobacter baumannii in a burn unit: An appraisal of the effect of colonization pressure

Abstract

Imipenem-resistant Acinetobacter baumannii (IRAB) is a major threat for critically ill patients, including those admitted to burn units. Recent studies have suggested that colonization pressure (the proportion of patients or patient-days harbouring the pathogen of interest) is an important driver of the risk for acquisition of multidrug-resistant organisms. With that in mind, we conducted a cohort study, enrolling 208 patients admitted to a burn unit from November 2008 through December 2009. The outcome of interest was the acquisition of IRAB. In addition to the usual risk factors, we assessed the impact of colonization pressure. The number of wound excisions (odds ratio (OR) 12.06, 95% confidence interval (CI) 2.82-51.64) and the number of antimicrobials used (OR 22.82, 95% CI 5.15-101.19) were significant risk factors for the outcome of interest. On the other hand, colonization pressure (measured for whole time of exposure or up to the last 14, 7, or 3 days) was not associated with the risk for IRAB acquisition.

Modifiable risk factors for multidrug‐resistant Gram‐negative infection in critically ill burn patients: a systematic review and meta‐analysis

“…There exists a growing body of research on modifiable risk factors for MDR Gram‐negative infection and colonization following burn injury . To date, consensus on the hierarchy of modifiable risk factors has not yet been reached.…”

Risk factors for multidrug‐resistant Gram‐negative infection in burn patients

“…While prior research has noted the presence of full thickness burn as a risk factor for MDR Gram‐negative organism acquisition, to our knowledge none have identified superficial partial thickness burn size. Prior studies which looked at superficial partial thickness burn dichotomized presence versus absence and did not consider size . It is likely that we identified superficial partial thickness burn as a risk factor because we compared burn severity percentages as continuous variables.…”

“…Our finding may also reflect a unique pattern of burn injury among our cases where superficial partial thickness burn size was a closer reflection of the TBSA burned. Larger TBSA burned has been shown on bivariate and multivariate analyses to be a risk factor for MDR Gram‐negative organisms in this population, an unsurprising finding considering that patients with a larger TBSA burn are often sicker, suffer greater losses to the protective functions of the skin barrier and are more likely to have intravenous access sites that overlie areas of damaged epithelia …”

“…on bivariate analysis of 29 cases demonstrated that prior carbapenem exposure was a risk factor for the acquisition of MDR A . baumannii . Tekin et al .…”

“…To our knowledge, no studies have assessed escharotomy as a risk factor, although prior work has implicated the total number of operations as a predictor of longer hospital stay . Escharotomy often reflects the severity of underlying injury and may be associated with other risk factors including more operations, longer ICU stay, increased intravascular and indwelling catheter use, more intensive antibiotic therapy and overall greater health worker interaction …”