MANAGEMENT OF WOUND INFECTION

MANAGEMENT OFWOUND INFECTIONWound infection has always been a major complication of surgery and trauma.

The infection of wound can be defined as the invasion of organisms through tissues following breakdown of local and systemic host defence leading to cellulitis, lymphangitis , abscess and bacteraemia . Microorganisms are normally prevented from causing infection by intact epithelial surface, most notably the skin, these surfaces are breakdown by trauma or surgery.In addition to these mechanical barrier there are other protective mechanisms and can be divided into chemical low gastric pH humoral antibodies, opsonins and complements cellular phagocytic cells , macrophages and PMNL cellsAll these protective mechanisms may be compromised by surgical intervention or trauma..REDUCE RESISTANCE TO INFECTION HAS SEVERAL CAUSES==OLD AGEIMMUNOSUPPRESSION OBESITYDMMALNUTRITIONPERIPHERAL VASCULAR DISEASEANAEMIAREDIATION EXPOSURERECENT TRAUMALOCAL TISSUE NECROSISORGANISMS RESPONSIBLE FOR WOUND INFECTIONGRAM POSITIVE AEROBIC COCCI===Staphylococcus aureusS. epidermidisS pyogensS pneumoniaeGram negative aerobic bacilliE coliH. influenzaeK. pneumoniaeP. mirabilis . P. aeruginosaGram positive anaerobesCl. PerfringesCl. TetaniCl. SepticumCl. DifficileGram negative anaerobesFusobacterium sppBacteroidsFungusAspergillusCandida albicansCryptococcusHistoplasma capsulatumVIRUSESCytomegalovirusEb virusHIVVariocella virusHepatitis B and C virusMANAGEMENTSuppurative wound infection usually take 7-10 days to develop and even cellulitis around the wound caused by invasive organisms ( beta haemolytic streptococcus) takes 3-4 days to develop.

If an infected wound is under tension or there is any evidence of suppuration , suture or clips need to be removed with curettage if necessary to allow the pus to drain freely.In severely contaminated wounds such as an incision made for drainage of an abscess is logical to leave the skin open.

Delayed primary or secondary suture can be undertaken when wound is clean and granulating.

When taking pus from an infected wound specimen should be send for microbiological examination.PRE OPERATIVE PREPARATIONShort pre operative hospital stay will reduce the the risk of aquiring MRSA OR MRCNS or other HAISEvery medical and nurshing staff should wash their hands after any patient contact.Alcoholic hand gel can be use but it do not destroy the spore of cl difficile which may cause pseudomembrenous colitis..Staff with open infected wound should not enter in OTPre operative skin shaving should be undertaken in OT Immediately before the surgery, as the infection rate after clean wound surgery may be doubled if it is performed the night before the surgery as minor skin injury enhances bacterial colonisation..hair clipping is best with lowest rate of infectionSCRUBBING AND SKIN PREPRATIONAqous antiseptic should be use for hand washing.One application of alcoholic antiseptic is adequate for skin prepration of surgical site. This leads to 95% reduction in bacterial count.Number of staff and movement of staff in and outside of OT should be kept minimum.COMMONLY USED ANTISEPTICSChlorohexidine:-- use for skin preparation.. Effective against gram positive organisms and stable in presence of pus and body fluidsProvidone iodine :--use for skin preparation and surgical scrubbing in dilute solution in open woundsCetrimide :---for hand washing, instrument and surface cleaningAlcohol( 70% ethyl and isopropyl alcohol):---skin prepration Hexachlorophene:----for skin prepration and hand washing.. Action against gram negative organisms.PROPHYLACTIC ANTIBIOTICS FOR WOUND INFECTIONIf antibiotics are given to prevent infection after surgery or instrumentation they should be used when local wound defence are not established..Ideally maximum blood and tissue level should be present at the time at which the first incision is made..In long standing procedures when there is excessive blood loss or when unexpected contamination occurs antibiotic may be repeated at 4 hourly interval during surgery..Choice of antibiotic depends on expected spectrum of organisms likely to be encountered VASCULAR SURGERY=== organisms encountered s. epidermidis s. aureus aerobic gm neg bacilli Drug of choice one dose of amoxycillin + clavulinic acid with or without gentamicin or vancomycin. ORTHOPEDICS SURGERY=== organisms encountered- s.epidermidis s. aureus drugs of choice one dose of amoxycillin + clavulinic acid. OESOPHAGO GASTRIC SURGERIES=== organisms encountered-- enterococci including anaerobic and viridans streptococci Drug of choice---one dose of second generation cephalosporin and metronidazole in severe contamination BILLIARY SURGERIES===== organisms encountered--- E . Coli and streptococcus fecalis drug of choice-- one dose of 2nd gen. cephalosporinsSMALL BOWEL SURGERY==== organisms encountered--- enterobacteriace and bacteroids Drug of choice----one dose of 2nd generation cephalosporin with or without metronidazoleANTIBIOTICS USED IN TREATMENT AND PROPHYLAXIS ==PENICILLIN==Most effective against gm positive pathogens includinng streptococci, clostridia and some staphylococci dont produce beta lactamase .Till effective against actinomyces.All serious infection including gas gangrene require high dose of benzyl penicillin.FLUCLOXACILLIN a beta lactamase resistant penicillin and is therefore used in treating most community acquired staphylococci infection AMPICILLIN AND AMOXYCILLIN Effective against enterobacteriace , enterococcus and group D streptococciMEZLOCILLIN AND AZLOCILLIN Effective against enterobactor and klebsiella Azlocillin effective against pseudomonas having some activity against bacteroids and enterococci combination of both is useful for treatment of mixed infection caused by gram negative organisms in immunocompromised patientsCEPHALOSPORINS Cefuroxime , cefotaxime, ceftazidime are widely used. the first two are effective against intraabdomonal skin and soft tissue infection ceftazidine is effective against gram negative organisms , s aureus and pseudomonas aeruginosa Cephalosporins may be combined with metronidazole or aminoglycosides if anaerobic cover is necessaryAMINOGLYCOSIDES Gentamicin and tobramycin are effective against gram negative enterobacteriace.. Gentamicin is effective against pseudomas. Ototoxic and nephrotoxic VANCOMYCIN Effective against gm positive bacteria and against MRSA. Also effective against cl. Deficille Ototoxic and nephrotoxicIMIDAZOLE Metronidazole is widely used. Active against anaerobes infection caused by anaerobic cocci, strains of bacteroides and clostridia can be treated Useful for prophylaxis of anaerobic infection after abdominal, colorectal and pelvic surgeryCARBAPENAM IMEPENAM, MEROPENAM, ERTAPENAM are stable to beta lactamase Have useful broad spectrum anaerobic as well as gm positive activity and effective for treatment of resistant organisms THANK YOU