Comparison of surface swab and quantitative biopsy cultures dependent on isolated microorganisms from burn wounds

Infections are one of the most important and potentially serious complications of burn wounds. Quantitative biopsy cultures are useful for showing that a burn wound infection is not present, but these cultures are not useful for showing that an infection is present. Swab cultures are used to diagnosis surface colonization and may not accurately reflect the organism(s) causing the wound infection.

To perform a comparison of surface swab and biopsy cultures for isolated microorganisms from burn wounds, 160 biopsy/surface swab pairs were collected from 160 patients.

Seventy-seven patients (48.1%) showed positive micro-organism cultures from the burn wounds; 19.3 percent had both positive surface cultures and significant bacterial counts from the biopsy cultures, whereas 28.8 percent of the patients had only positive surface cultures. There was moderate agreement (41%) between the results of surface swab and quantitative biopsy cultures used to diagnose burn wound infections. Pseudomonas aeruginosa (45.5%) was the most predominantly isolated bacteria from the wounds, and there was good concordance between the results of the surface swab and quantitative biopsy culture samples (78%). Coagulase-negative Staphylococci (CNS) and Escherichia coli strains were only isolated from the surface swab samples because they are colonizing bacteria. The univariate analysis revealed that there were significant associations between the results of the positive biopsy cultures and the total surface body area, open flame burns, prolonged hospitalization and female gender (p<0.05).

Surface swab and quantitative biopsy cultures have a high rate of concordance in predicting P. aeruginosa invasion and the colonization of E. coli and CNS strains in burn wounds.