Treatment of Wound Infection
Following the trend to discharge patients earlier, many wound infections may be missed by surgeons unless they undertake a prolonged and carefully audited follow-up with family doctors. Suppurative wound infections take 7—10 days to develop, whereas cellulitis around wounds caused by invasive organisms (such as the beta-haemolytic streptococcus) appears in 3-4 days. Major wound infections with systemic signs or evidence of cebbubitis justify the use of appropriate antibiotics. The choice may be empirical or based on culture and sensitivities of isolates harvested at surgery. Although the identification of organisms in wound infections is necessary for audit and wound surveillance purposes, it is usually 2—3 days before sensitivities are known . It is illogical to withhold antibiotics but if clinical response is poor by the time sensitivities are known then antibiotics can be changed. This is unusual if the empirical choice of antibiotics is sensible — change of antibiotics promotes resistance and risks complications, such as Clostridium difficile enteritis. When the wound is under tension or there is clear evidence of suppuration removal of sutures aids evacuation of pus. There is no evidence that subcuticular continuous skin closure enhances or worsens the effect of suppuration. In severely contaminated wounds, e.g. laparotomy for faecal peritonitis, or incisions made for drainage of an abscess, it is logical to leave the skin layer open. Delayed primary or secondary suture is undertaken when the wound is clean and granulating . Leaving wounds open after dirty operations is not practised as widely in the UK as in the USA or mainland Europe.
When taking pus from infected wounds, specimens should be sent fresh for microbiological culture. Swabs should be placed in transport medium but as barge a volume of pus as possible is likely to yield more accurate results. Communication with microbiologists is essential for the most meaningful results. If bacteraemia is suspected, repeat specimens may be needed to exclude negative results.
Reports on infective material can be based rapidly on an immediate Gram stain. Aerobic and anaerobic culture on conventional media allows sensitivities to be assessed by disc diffusion. The measurements of minimum inhibitory antibiotic concentrations (M1C9O in mg/litre), together with measurements of endotoxin and cytokine bevels, are usually only used in research.
Many dressings are now available for use in wound care. These are listed in Table 7.3. Polymeric films are used as incise drapes and also to cover sutured wounds but are not indicated for use in wound infections. Agents that can be used to help débride open infected wounds, others to absorb excessive exudate or to encourage epitheliabisation and formation of granulation tissue are also listed.
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