ABC of wound healing:Infections

Despite optimal treatment some wounds are slow to heal. The challenge clinically and microbiologically is to identify those wounds in which healing is impaired as a result of infection or heavy bacterial burden and in which systemic or topical antimicrobial treatment will be of benefit. Staphylococci and streptococci are the most commonly encountered pathogenic organisms in community acquired superficial wounds. More unusual organisms may be found in bite wounds, and these reflect the source of the bite. Pathogenic organisms causing surgical wound infections vary according to the anatomical site of surgery. Antibiotic resistant organisms, such as methicillin resistant Staphylococcus aureus (MRSA), are more commonly encountered, reflecting the hospital flora. It is inappropriate to swab all wounds: swabs should be taken only from overtly infected wounds and from wounds that are deteriorating, increasing in size, or failing to make satisfactory progress despite an optimal environment for wound healing. Indicators of wound infection include redness, swelling, purulent exudate, smell, pain, and systemic illness in the absence of other foci. Subtle signs of local wound infection include unhealthy “foamy” granulation tissue, contact bleeding, tissue breakdown, and epithelial bridging. Superficial wound swabs-The ease of obtaining and processing superficial wound swabs, combined with their relatively low cost and non-invasive nature, make them in most instances the most appropriate method for wound sampling. Organisms cultured from a superficial swab may, however, simply reflect the colonising bacterial flora and are not always representative of the pathogenic organisms invading deeper tissue. This is particularly relevant to deep surgical and deep penetrating wounds in which infection from internal sources may occur. Tissue and pus-Tissue or pus, or both, should be collected whenever possible, as growth from these samples is more representative of pathogenic flora. These are amenable to quantitative microbiological analysis and other techniques used to improve the diagnostic …