Negative pressure wound therapy in the management of postoperative infections after musculoskeletal tumour surgery

Adaptive expression of biofilm regulators and adhesion factors of Staphylococcus aureus during acute wound infection under the treatment of negative pressure wound therapy in vivo

Negative pressure wound therapy (NPWT) is gaining acceptance as a physical therapy for a wide variety of infected wounds. To gain insight into the response of bacteria to NPWT in vivo, the adaptive expression of biofilm regulators and adhesion factors of Staphylococcus aureus (S. aureus), the most frequently isolated pathogen in the clinic, during acute wound infection was investigated. A 3 cm full-thickness dermal wound was created on each side of a rabbit back and inoculated with green fluorescent protein-labeled S. aureus. NPWT was initiated at 6 h post inoculation, with the wound on the contralateral side as the untreated self-control. The wounds were subjected to a 28 day observation period. Histological analysis, laser scanning confocal microscopy and scanning electron microscopy revealed a transition of S. aureus to a free-living phenotype in tissues treated with NPWT, compared with microcolonies in untreated wounds. Viable bacteria counts showed a modest reduction in the bioburden of NPWT group on day 8 (P<0.001), with ~1x10⁶ colony-forming units/g tissue. Transcript analysis of biofilm- and colonization-related genes were investigated using reverse transcription-quantitative PCR on postoperative days 1, 2, 4 and 8. The poly-beta-1,6-N-acetyl-D-glucosamine synthase locus and holin-like protein CidA/antiholin-like protein LrgA network were less active in the NPWT group compared with the untreated control group. Accordingly, the expression profile switched to an elevated expression of the adhesive factors UDP-phosphate N-acetylglucosaminyl 1-phosphate transferase (at days 0-4) and fibronectin-binding protein A and iron-regulated surface determinant protein A at >4 days during both stages of colonization. Meanwhile, low expression levels of the effector molecule (RNAIII) of the accessory gene regulator type I (agr) system was detected in NPWT group, suggesting that the bacterial density in NPWT-treated wounds was under the threshold for agr activation, thus not leading to an active and invasive infection. The wounds treated by NPWT healed completely on day 28, compared with an average of an 8.11% defect area in the control group (P<0.001). The results of the current study indicated that S. aureus responds to NPWT by regulating gene expression, manifesting a decrease in biofilm formation and an increase in bacterial colonization in vivo, which potentially benefits the wound repair and healing process.

Negative-Pressure Wound Therapy for Managing Complicated Wounds at Extracorporeal Membrane Oxygenation Sites

OBJECTIVE

To evaluate the effectiveness of negative-pressure wound therapy (NPWT) for management of wound complications at extracorporeal membrane oxygenation (ECMO) removal sites.

METHODS

The authors retrospectively reviewed patients who underwent NPWT at ECMO removal sites followed by the development of wound complications including skin necrosis, lymphorrhea, and femoral vessel exposure. A nonadhesive bacteria-binding mesh was used as a wound contact layer of NPWT application. Patient characteristics and clinical outcomes were evaluated.

RESULTS

Nine patients underwent NPWT for complicated wounds at ECMO sites. The mean age of patients was 49.2 years (range, 14-64 years). All patients exhibited wound complications with lymphorrhea and skin necrosis. Seven of nine patients had wound cultures that were positive for microorganisms, but culture conversion to negative was achieved after NPWT application for a mean period of 21.2 days (range, 12-30 days). Lymphorrhea was successfully managed, and formation of fresh granulation tissue was observed in all patients. Wound healing either by primary closure, skin graft, or secondary healing was achieved without recurrence of wound complications. There were no cases of femoral vessel injury or aneurysm during NPWT application.

CONCLUSIONS

Negative-pressure wound therapy appears to be a safe and effective treatment option in the management of complicated wounds at ECMO sites.

Early application of negative pressure wound therapy to acute wounds contaminated with Staphylococcus aureus: An effective approach to preventing biofilm formation

Negative pressure wound therapy (NPWT) has been demonstrated to be effective at preventing biofilm-associated infections; however, its role in biofilm prevention is unknown. The present study evaluated the effect of NPWT on biofilm prevention when rapidly initiated following wound contamination. Full-thickness dermal wounds (8 mm) were created in rabbit ears and inoculated with green fluorescent protein-labeled Staphylococcus aureus (S. aureus). At 6 h following inoculation, continuous NPWT at -125 mmHg was initiated, with the wounds on the contralateral ear left untreated in order to serve as self-controls. S. aureus rapidly formed mature biofilms in the wound beds post-inoculation, with a persistent bacterial burden of ~10⁵-10⁷ colony-forming units (CFUs)/wound and impaired wound healing. Compared with the untreated group, NPWT resulted in a significant reduction in biofilm matrix, which was verified by scanning electron microscopy and epifluorescence. A reduction in bacterial counts followed (P<0.05) with ~10³ CFUs/wound on postoperative day 13 and improvement in all healing parameters (P<0.05) relative to control wounds. The results of the present investigation suggest that NPWT is an effective strategy to impeding the formation of S. aureus wound biofilms when initiated rapidly following bacterial contamination. The early application of NPWT, aimed at biofilm prevention, may improve wound care.

Lesion mimicking perianal abscess in an immunocompromised patient: Report of a case

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Infectious and bleeding disorders are common in leukemia.

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Intramuscular injections often cause haematomas.

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Sciatic notch connects gluteal to perianal region.

INTRODUCTION

Ischiorrectal tumoral masses mimicking perianal abscess and abscess from uncommon microbiological origins have previously been reported.

PRESENTATION OF CASE

Unusual perianal abscess arising from an hematoma in an elderly woman with myelodysplastic syndrome: the patient presented on the emergency with gluteal pain and fever after intramuscular injection of analgesic drug. Physical examination revealed subcutaneous thickening on gluteus and perianal region, without skin changes. Magnetic resonance reported an heterogeneous mass sized 5 cm × 12 cm × 20 cm from gluteus maximus to ischioanal fat under levator ani muscle, through sciatic notch. Debridement of an staphylococceal infected hematoma through a single left lateral gluteus incision, and primary closure was performed. Proctologic examination was normal, so any perianal incision was done. The site infection progressed, so the patient required new surgery with wet cure. The patient contracted nosocomial pneumonia and died due to sepsis.

DISCUSSION

Hematological diseases can yield infectious and bleeding disorders. Intramuscular injections often cause haematomas that can lead to pyomyositis. Pyomyositis requires early debridement and continue cure.

CONCLUSION

Intramuscular administration of drugs should be avoided in patients with thrombocytopenia. Gluteal region is connected to perianal area through the sciatic notch. Usually perianal abscess in immunocompromised patients arise from proctologic origin, but other causes may be taken into account.