By the WoundSource Editors

All wounds are complex non-sterile environments, often requiring a succession of intersecting phases of wound healing to repair completely. When epithelial tissue is compromised by a wound, contamination by common skin surface microbes may result in infection or the formation of a biofilm that impedes healing. Although systemic antibiotics are necessary for treating clinically infected wounds, the use of antibiotics and antiseptics in non-healing, non-infected wounds is debated.¹

Antimicrobial Stewardship

Health care providers around the world face the growing challenge of rising rates of resistance of bacterial pathogens to antibiotics. This is particularly pronounced in the management of wound infection, where antibiotics play a key role in treating infections. Improving antibiotic use is critical to patient safety and public health,² starting with the elimination of antibiotic use that is inappropriate or unnecessary. Antimicrobial stewardship programs work to optimize treatment for infections and minimize adverse events related to antibiotic use.³

Treatment Methods for Infected Wounds

Treatment methods for infected wounds vary depending on the type, site, and depth of the wound. Traumatic injuries with devitalized tissue and potential contamination are served by approaches different from those used in chronic wounds. Skin and soft tissue infections (SSTIs) encompass a wide spectrum of clinical infections involving microbial infection of the epidermis, dermis, superficial fascia, subcutaneous tissue, and, in some severe cases, muscle. All SSTIs are colonized with bacteria, so antibiotic therapy is inappropriate in the absence of infection symptoms. Treatment of such injuries is aimed at treating infection, promoting wound healing, and preventing a recurrence.

Diagnosis of Infection

An essential first step in treating infected wounds is a comprehensive diagnosis. Wound infections are primarily diagnosed through clinical observations, which are then supported by microbiological findings. An assessment must be made of the complications, risk factors, and severity of injury before performing microbial culture tests.⁴ Risk factors such as animal contact, bite wounds, patient history, diabetes, and recurrent hospital admissions may help identify the pathogens responsible for an infection.⁵ Wound infection is often diagnosed through common signs of inflammation such as erythema, warmth, induration or swelling, pain, and purulent exudate or pus. Certain abnormal inflammatory responses may require an assessment of secondary symptoms to diagnose infection. These include friable granulation, pocketing at the base of the wound, and odor. Only through thorough evaluation is a clinician able to determine the type of care appropriate to an infected wound.

Microbial specimen culture

The more rapidly pathogens can be identified, the more effective an antimicrobial stewardship approach can be in selecting an appropriate, narrowly targeted antibiotic treatment. Treating a superficial wound colonized by commensal bacteria and no inflammation with antibiotics is a common antibiotic prescribing error. This type of treatment has no evidence supporting that it aids wound healing or prevents infections.⁶ To reduce the likelihood of identification of non-pathogenic colonizers, all infected wounds should be cultured by obtaining tissue through either curettage or biopsy to be most accurate. Samples should be collected after wound cleansing and debridement.⁷ If possible, specimens should be collected before antibiotic therapy has begun, to avoid false-negative culture results.

Antimicrobial Treatment

A critical component of diagnosis is determining whether an infection is systemic or localized. Clinically infected wounds may require systemic antibiotic therapy, but for mild and superficial infections, targeted antibiotics and topical antimicrobial agents can support healing. Antimicrobial dressings containing chlorhexidine, honey, iodine, and silver can be used to reduce bioburden and help trigger the healing response.⁸ However, when wound infections have failed to respond sufficiently to antimicrobial agents or standard wound care treatment, a biofilm may be present.⁹ Biofilm is a thick layer of colonized microbes that can form on the surface of a wound, thereby preventing healing and resisting topical treatment. A biofilm-based wound care approach involves a multi-pronged attack on the microorganisms through the mechanical cleaning and debriding of necrotic and infected tissue accompanied by the application of antimicrobial and antibiofilm compounds. Such approaches demand ongoing assessments and revisions in treatment dependent on wound response.¹⁰

Systemic antibiotic therapy is the standard treatment for clinical wound infections, but antimicrobial stewardship can be used to support optimal antibiotic use. Several interventions used in antimicrobial stewardship are antibiotic "time outs," the use of newer antibiotics, switching from intravenous to oral agents, and antibiotic de-escalation. The judicious use of antibiotics that is the hallmark of antimicrobial stewardship can improve clinical outcomes and impede the progress of antimicrobial resistance.

Conclusion

The science of caring for infected wounds is ongoing, with new developments emerging regularly. Because of the constant innovations in the field of wound care, clinicians and health care facilities would be well served to produce guidelines for managing wound infections. Ongoing quantitative review of wound infection diagnosis and antibiotic treatment can provide opportunities in antimicrobial stewardship.

References

1. Bowler PG, Duerden BI, Armstrong DG. Wound microbiology and associated approaches to wound management. Clin Microbiol Rev. 2001;14(2):244-269. doi: 10.1128/CMR.14.2.244-269.2001

2. Centers for Disease Control and Prevention (CDC). Antibiotic Resistance Threats in the United States, 2013. Atlanta, GA: CDC; 2013.

3. Centers for Disease Control and Prevention (CDC). Get smart: know when antibiotics work. http://www.cdc.gov/getsmart/healthcare/. Accessed February 24, 2014.

4. Eron LJ, Lipsky BA, Low DE, et al. Managing skin and soft tissue infections: expert panel recommendations on key decision points. J Antimicrob Chemother. 2003;52(Suppl 1):i3-i17.

5. Dryden MS. Complicated skin and soft tissue infection. J Antimicrob Chemother. 2010;65(Suppl 3):iii35-iii44.

6. Abbas M, Uckay I, Lipsky BA. In diabetic foot infections antibiotics are to treat infection, not to heal wounds. Expert Opin Pharmacother. 2015;16:821-832.

7. Mutluoglu M, Uzun G, Turhan V, Gorenek L, Ay H, Lipsky BA. How reliable are cultures of specimens from superficial swabs compared with those of deep tissue in patients with diabetic foot ulcers? J Diabetes Complications. 2012;26:225-229.

8. WoundSource. Antimicrobial dressings. https://www.woundsource.com/product-category/dressings/antimicrobial-dr…. Accessed November 29, 2019.

9. Costerton W, Veeh R, Shirtliff M, et al. The application of biofilm science to the study and control of chronic bacterial infections. J Clin Invest. 2003;112(10):1466-1477.

10. Wolcott RD, Rumbaugh KP, James G, et al. Biofilm maturity studies indicate sharp debridement opens a time-dependent therapeutic window. J Wound Care. 2010;19(8):320-328.