Prophylaxis
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.