Bacterial reduction and shift with NPWT after surgical debridements: a retrospective cohort study.

Background: Surgical debridement, negative-pressure wound therapy (NPWT) and antibiotics are used for the treatment of open wounds. However, it remains unclear whether this treatment regimen is successful in the reduction and shift of the bacterial load.

Methods: After debridement in the operating room, NPWT, and antibiotic treatment, primary and secondary consecutive microbiological samples of 115 patients with 120 open wounds with bacterial or yeast growth in ≥1 swab or tissue microbiological sample(s) were compared for bacterial growth, Gram staining and oxygen use at a level one trauma center in 2011.

Results: Secondary samples had significantly less bacterial growth (32 vs. 89%, p < .001, OR 17), Gram-positive bacteria (56 vs. 78%, p = .013), facultative anaerobic bacteria (64 vs. 85%, p = .011) and Staphylococcus aureus (10 vs. 46%, p = .002). They also tended to include relatively more Coagulase-negative Staphylococci (CoNS) (44 vs. 18%) and Pseudomonas species (spp.) (31 vs. 7%). Most (98%) wounds were successfully closed within 11 days, while wound revision was needed in 4%.

Conclusions: The treatment regimen of combined use of repetitive debridement, irrigation and NPWT in an operating room with antibiotics significantly reduced the bacterial load and led to a shift away from Gram-positive bacteria, facultative anaerobic bacteria, and S. aureus, as well as questionably toward CoNS and Pseudomonas spp. in this patient cohort. High rates of wound closure were achieved in a relatively short time with low revision rates. Whether each modality played a role for these findings remains unknown.