Two Stage Study of Wound Microorganisms Affecting Burns and Plastic Surgery Inpatients

Abstract

This study was designed to identify wound microorganisms and the reasons for differing prevalence between the wards, burns unit and intensive care unit (ICU) in a regional centre for burns and plastic surgery. Antibiotic sensitivities of the 10 most prevalent microorganisms cultured from inpatient wound swabs were also investigated. Inpatient wound swab data were collected retrospectively using notes and departmental database information between January and June 2007. Data were analyzed using chi-squared tests and P-values. Eight hundred five positive wound swabs from 204 swab positive inpatients were analyzed. Stage 1 of this study demonstrated 917 positive swab episodes and 30 varieties of organism. The five most prevalent organisms cultured were Staphylococcus (23.9%), Acinetobacter (21.2%), Methicillin Resistant Staphylococcus aureus (MRSA) (20.8%), Pseudomonas (9.7%) and Enterococcus (5.2%). Stage 2 revealed that Acinetobacter baumanni (ABAU) was significantly more prevalent in military over civilian inpatients (P < .001) and that military inpatients had a significantly greater proportion of ABAU over civilian inpatients within the first 24 hours after admission (P < .001). ABAU episodes were significantly higher on the ICU over the burns unit and on the wards (P < .001). MRSA was significantly more prevalent in military inpatients (P < .001); however, no significant difference was observed within the first 24 hours after admission (P = .440). MRSA was more prevalent on the ICU over the burns unit (P = .023). Pseudomonas aeruginosa (PAER) was significantly more prevalent in military inpatients over civilian inpatients (P < .001), and on the ICU over the burns unit and wards (P = .018). Stage 1 generated a comprehensive, up to date cross section of bacterial flora, with corresponding percentage antibiotic sensitivities, in a regional burns and plastic surgery centre. This will give clinicians a snapshot of organisms affecting inpatient wounds in advance of culture and sensitivity results. Stage 2 demonstrated that ABAU, MRSA, and PAER were significantly more prevalent in the ICU setting. Furthermore, military inpatient wounds grew more ABAU, MRSA, and PAER than civilians, probably due to the longer inpatient stay, dirty nature of wounds, site and complex mechanism of injury. Finally, this study suggests that ABAU was brought into the unit by military patients.