Prophylaxis of Wound Infection
Prophylactic antibiotics. If antibiotics are given empirically they must exert their action when local wound defences are at their beast (the decisive period). Ideally, maximal blood and tissue levels should be achieved at incision before contamination occurs. Intravenous administration at induction of anaesthesia is optimal. In long or prosthetic operations, or unexpected contamination, antibiotics may be repeated 8 and 16 hours later. The empiric choice of an antibiotic depends on the expected spectrum of organisms likely to be encountered, the cost and local policies, which are based on experience of local resistance trends. The use of the newer, wide-spectrum antibiotics for prophylaxis should be avoided. Table 7.4 gives some examples of prophylaxis which can be used in elective surgical operations.
Lower limb amputation should be covered against C. per fringens using 1.2 g of benzyl penicillin intravenously at induction or anaesthesia and 6-hourly thereafter for 48 hours.
Patients with known vabvubar disease of the heart (or with any implanted vascular or orthopaedic prosthesis) ought to have prophylaxis during dental, urobogical or open viscus surgery. Single doses of wide-spectrum penicillin, e.g. amoxyciblin, orally or intravenously administered, are sufficient for dental surgery. In urobogical instrumentation a second generation of cephabosporin, such as cefuroxime, is sufficient but, in open viscus surgery, addition of metronidazole should be considered.
Preoperative preparation. Short preoperative hospital
stay bowers the risk of acquisition of methicibbin-resistant S. aureus(MRSA) and multiply resistant, coagulase-negative staphylococci (MRCNS). The value of personal hygiene is obvious (both patient and surgeon). Open, infected skin lesions should preclude admission to the operating theatres.
The value of antiseptic bathing (usually chborhexidine) is popular in Europe but there is no hard evidence for its efficacy in reducing wound infections. Preoperative shaving should be avoided except for aesthetic reasons or to prevent adherence of dressings. Shaving should be undertaken immediately before surgery but poses a higher infection rate (over 5 per cent) when performed the night before because minor skin injury enhances superficial bacterial colonisation. Cream depilation is messy but clipping is best, with beast infection (reportedly under 2 per cent in clean wounds).
Scrubbing of operators’ hands with aqueous antiseptics should be confined to nails for the first operation of the day (repeated extensive scrubbing releases more organisms), with washing to the elbows, repeated alone for subsequent operations. Skin preparation of the operative site is adequate with one application of an alcoholic antiseptic (over 95 per cent reduction in flora and fauna). Antiseptics in common use are listed in Table 7.5.
Theatre technique and disciplines also contribute. Only careful surveillance can ensure the quality of theatre ventilation, instrument steribisation and aseptic technique. Operator skill in gentle manipulation and dissection of tissues is much more difficult to measure but avoidance of dead space, excessive use of diathermy and haematomas surely contribute. There is no evidence that drains, incise drapes or wound guards help to reduce wound infection.
Similar wound surveillance is needed in postoperative care. Secondary (exogenous) nosocomial infections are related to poor hospital wound care. Outbreaks of MRSA are rare but serious. This organism also acts as a marker of adequacy of postoperative wound care but can be very difficult and expensive to eradicate.
Careful audit should bead to changes in practice and follow-up should ensure that ioops are closed. It is critical that surgeons manage their own audit — league tables kept by nonmedicab or related personnel must be accurate but are to be deprecated. Scoring systems are useful in audit but, in general, have only been used in wound infection research.
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