Does Negative Pressure Wound Therapy Impact the Outcome of NSTI patients Infected with Anaerobic Bacteria?

Author(s):
Hussain Afzal; Erin Andrade; Ricardo Fonseca; Melissa Canas; Leonardo Diaz; Alejandro De Filippis; Jennifer Leonard; Kelly Marie Bochicchio; Grant Bochicchio

Background:

Negative pressure wound therapy (NPWT) has improved the management of necrotizing soft tissue infection (NSTI) wounds. There continues to be debate among clinicians regarding efficacy of NPWT for removal of bacteria as compared to traditional wet to dry dressings. Recent studies have shown NPWT leading to oxygen deprivation effects in the underlying wound tissue but there remains a lack of clinical studies evaluating the impact of decreased oxygen on soft tissue infections with anaerobic bacteria.

Hypothesis:

We hypothesized that patients with NSTI infected only by anaerobic bacteria and treated with NPWT will have worse outcomes as compared to patients infected with other types of bacteria.

Methods:

Our prospectively maintained Acute and Critical Care Surgery database spanning 2008-2022 was queried for patients with the diagnosis of necrotizing fasciitis, Fournier’s gangrene, or gas gangrene with a positive wound culture taken during initial debridement and who received NPWT treatment. Co-morbidities, operative management, and clinical outcome were collected. Patients were stratified based on wounds infected with anaerobic vs various groups of bacteria i.e. polymicrobial, aerobic, etc. Data were analyzed using ANOVA, chi-squared, and multiple regression.

Results:

A total of 112 patients with NSTI treated with NPWT were included. We identified 16 (14.3%) patients with anaerobic (only) NSTI. The remaining patients 96 (85.7%) had a combination of either aerobic, facultative, or polymicrobial NSTI. The initial size of wounds in both groups was not significantly different. Anaerobic NSTI patients treated with NPWT had a higher number of debridement [3 (1-9) vs 2(1-4); p=0.012] and 30-day readmission rate [50% vs 10%; p=<0.01] as compared to patients that received NPWT for non-anaerobic only NSTIs. When analyzed by logistic regression, NSTIs infected by anaerobic bacteria treated with NPWT had 11 times greater 30 day readmission rate [OR=10.94, 95% CI: 2.94-40.61, p=<0.001].

Conclusions:

NSTI patients with anaerobic bacteria (only) required a greater number of debridement and were 11 times more likely to be readmitted within 30 days when compared to NSTI patients infected with other types of bacteria. Further prospective studies aimed at identifying additional risk factors and treatment options for patients diagnosed with an anaerobic only NSTI are recommended.