Reliability of superficial swab culture results compared with deep wound culture results in Fournier's gangrene: A retrospective study

Abstract

Objectives

To compare isolates from deep wound and superficial swab cultures to evaluate the detectability of pathogens by each culture in Fournier's gangrene; and evaluate the association between microorganisms isolated from deep wounds and those isolated from blood or urine.

Methods

Patients with Fournier's gangrene who underwent debridement between October 2006 and January 2023 were retrospectively reviewed. In addition to comparing the isolates from deep wound cultures at initial debridement with those from superficial swab, blood, and urine cultures, the relationship between the traits of the organisms from deep wounds and patient disease severity and prognosis was examined.

Results

Among 25 patients, deep wound and superficial swab cultures were obtained from 25 to 18 patients, respectively. The frequency of anaerobic isolates was significantly lower in the superficial cultures than in the deep wound cultures (31/76 versus 13/56, p = 0.034). Bacteria not isolated from deep wounds were isolated from superficial cultures in 55.6 % of the patients; the concordance rate between deep and superficial cultures was 27.8 % (5/18). The positive rates of blood and urine cultures were 20.8 % and 35.7 %, respectively; all isolates from the urine and blood cultures reflected the results of the deep wound culture. No significant association was observed between the severity or mortality and the type of causative bacteria.

Conclusions

Superficial swab cultures cannot be substituted for deep wound cultures in Fournier's gangrene. Although the positivity rates for blood and urine cultures were not high, they were helpful in determining antibiotic de-escalation.