外科感染与抗生素（英文ppt）surgicalinfectios

SURGICAL INFECTIONS & ANTIBIOTICS M K ALAM MS, FRCS Prof. & Consultant Surgeon College of Medicine & RCH OBJECTIVES n Definitions. n Pathogenesis . n Clinical features . n Surgical microbiology. n Common infections. n Antibiotics use. INFECTION Invasion of the body by pathogenic microorganisms and reaction of the host to organisms and their toxins SURGICAL INFECTIONS Infections that require surgical intervention as a treatment or develop as a result of surgical procedure. Surgical Infection n A major challenge n Accounts for 1/3 of surgical patients n Morbidity n Mortality n Increased cost to healthcare Factors contributing to infections n Microorganism related factors: -Adequate dose -Virulence of microorganisms n Host related factors: -Suitable environment ( closed space ) -Susceptible host Pathogenicity of bacteria Exotoxins: specific, soluble proteins, remote cytotoxic effect Cl.Tetani, Strep. pyogenes Endotoxins: part of gram-negative bacterial wall, lipopolysaccharides e.g., E coli Resist phagocytosis: Protective capsule Klebsiela and Strep. pneumoniae Host Resistance Intact skin / mucous membrane. (surgery/ trauma- causes breach) Immunity: Cellular (phagocytes ) Antibodies Clinical features n Local- pain, heat, redness, swelling, loss of function. (apparent in superficial infections) n Systemic- fever, tachycardia, chills Principles of surgical treatment n Debridement- necrotic, injured tissue n Drainage- abscess, infected fluid n Removal- infection source, foreign body n Supportive measures: immobilization elevation antibiotics STREPTOCOCCI n Gram positive, aerobe/anaerobe n Flora of the mouth and pharynx, ( bowel ) n Streptococcus pyogenes ( hemolytic) 90% of infections e.g.,lymphangitis, cellulitis, rheumatic fever n Strep. viridens- endocarditis, urinary infection n Strep. fecalis urinary infection, pyogenic infection n Strep. pneumonae pneumonia, meningitis STAPHYLOCOCCI n Inhabitants of skin, Gram positive n Infection characterized by suppuration n Staph.aureus- SSI, nosocomial ,superficial infections n Staph. epidermidis- opportunistic ( wound, endocarditis ) CLOSTRIDIA n Gram positive, anaerobe n Rod shaped microorganisms n Live in bowel & soil n Produce exotoxin for pathogenicity n Important members: Cl. Perfringens, Cl. Septicum ( gas gangrene ) Cl. Tetani ( tetanus ) Cl. Difficile ( pseudomembranous colitis ) GRAM NEGATIVE ORGANISMS ( Enterobactericiae ) Escherichia coli Facultative anaerobe, Intestinal flora Produce exotoxin & endotoxin Endotoxin produce Gram-negative shock Wound infection, abdominal abscess, UTI, meningitis, endocarditis Treatment- ampicillin, cephalosporin, aminoglycoside GRAM NEGATIVE ORGANISMS Pseudomonas n aerobes, occurs on skin surface n opportunistic pathogen n may cause serious & lethal infection n colonize ventilators, iv catheters, urinary catheters n Wound infection, burn, septicemia n Treatment: aminoglycosides, piperacillin, ceftazidime GRAM NEGATVE ANAEROBES Bacteroides fragilis n Normal flora in oral cavity, colon n Intra-abdominal & gynecologic infections ( 90% ) n Foul smelling pus, gas in surrounding tissue, necrosis n Spiking fever, jaundice, Leukocytosis n No growth on standard culture n Needs anaerobe culture media n Treatment: Surgical drainage Antibiotics- clindamycin, metronidazole TYPES OF SURGICAL INFECTION n A. Surgical Site Infection n B. Soft Tissue Infection n C. Body Cavity Infection n D. Prosthetic Device related Infection n E. Miscellaneous Surgical site infection (SSI) n 38% of all surgical infections n Infection within 30 days of operation n Classification: Superficial: Superficial SSIinfection in subcutaneous plane (47%) Deep: Subfascial SSI- muscle plane (23%) Organ/ space SSI- intra-abdominal, other spaces (30%) n Staph. aureus- most common organism n E coli, Entercoccus ,other Entetobacteriaceae- deep infections B fragilis intrabd. abscess Surgical site infection (SSI) n Risk factors: age, malnutrition, obesity, immunocompromised, poor surg. tech, prolonged surgery, preop. shaving and type of surgery. n Diagnosis: Sup.SSI- erythema, oedema, discharge and pain Deep infections- no local signs, fever, pain, hypotension. need investigations. n Treatment: surgical / radiological intervention. Prevention of SSI n Pre-op: Treat pre-existing infection Improve general nutrition Shorter hospital stay Pre-op. shower Hair removal timing? n Intraoperative: Antiseptic technique Surgical technique n Post-operative: Hand hygiene STREPTOCOCCAL INFECTIONS Erysipelas n Superficial spreading cellulitis & lymphangitis n Area of redness, sharply defined irregular border n Follows minor skin injuries n Strep pyogenes n Common site: around nose extending to both cheeks n Penicillin, Erythromycin SREPTOCOCCAL INFECTION Cellulitis n Inflammation of skin & subcutaneous tissue n Non-suppurative n Strep. Pyogenes n Common sites- limbs n Affected area is red, hot & indurated n Treatment : Rest, elevation of affected limb Penicillin, Erythromycin Fluocloxacillin ( staph. suspected ) NECROTIZING FASCIITIS n Necrosis of superficial fascia, overlying skin n Polymicrobial : Streptococci (90%), anaerobic Grampositive Cocci, aerobic Gram-negative Bacilli, and the Bacteroides spp. n Sites- abd.wall (Melenys), perineum (Fourniers), limbs, n Usually follows abdominal surgery or trauma NECROTIZING FASCIITIS n Diabetics more susceptible n Starts as cellulitis, edema, systemic toxicity n Appears less extensive than actual necrosis n Investigation: Aspiration, Grams stain, CT, MRI n Treatment: IV fluid, IV antibiotics (ampicillin, clindamycin l metronidazole, aminoglycosides ) Debridement , repeated dressings, skin grafting STAPHYLCOCCAL INFECTIONS n Abscess- localized pus collection Treatment- drainage, antibiotics n Furuncle- infection of hair follicle / sweat glands n Carbuncle- extension of furuncle into subcut. tissue common in diabetics common sites- back, back of neck Treatment: drainage, antibiotics, control diabetes GAS GANGRENE n Cl. Perfringens, Cl. Septicum n Exotoxins: lecithinase, collagenase, hyaluridase n Large wounds of muscle ( contaminated by soil, foreign body ) n Rapid myonecrosis, crepitus in subcutaneous tissue n Seropurulent discharge, foul smell, swollen n Toxemia, tachycardia, ill looking n X-ray: gas in muscle and under skin n Penicillin, clindamycin, metronidazole n Wound exposure, debridement , drainage, amputation n Hyperbaric oxygen TETANUS n Cl. Tetani, produce neurotoxin n Penetrating wound ( rusty nail, thorn ) n Usually wound healed when symptoms appear n Incubation period: 7-10 days n Trismus- first symptom, stiffness in neck & back n Anxious look with mouth drawn up ( risus sardonicus) n Respiration & swallowing progressively difficult n Reflex convulsions along with tonic spasm n Death by exhaustion, aspiration or asphyxiation TETANUS n Treatment: wound debridement, penicillin Muscle relaxants, ventilatory support Nutritional support n Prophylaxis: wound care, antibiotics Human TIG in high risk ( un-immunized ) Commence active immunization ( T toxoid) Previously immunized- booster 10 years needs a booster dose booster 10 years- no treatment in low risk wounds PSEUDOMEMBRANOUS COLITIS n Cl. Difficile n Overtakes normal flora in patients on antibiotics n Watery diarrhea, abdominal pain, fever n Sigmoidoscopy: membrane of exudates (pseudomembranes) n Stool- culture and toxin assay n Treatment : stop offending antibiotic oral vancomycin/ metronidazole rehydration, isolate patient Body Cavity Infection n Primary peritonitis: Spontaneous Children, Ascitic Haematogenous/ lymphatic route Antibiotic n Secondary peritonitis: Inflam./ rupture of viscera Polymicrobial Investigations: blood, radiological Treatment of original cause Prosthetic Device Related Infection n Artificial valves and joints n Peritoneal and haemodialysis catheters n Vascular grafts n Staphylococcus aureus n Antibiotics, washing of prosthesis or removal Hospital Acquired Infection n Occurring within 48 h of hospital admission, three days of discharge or 30 days following an operation n 10% of patients admitted to hospitals n Spent 2.5-times longer in hospital - UK n Highest prevalence in ICU- n Enterococcus, Pseudomonas spp.,E coli, Staph. aureus. n Sites: Urinary, surg. Wounds, resp., skin, blood, GIT ANTIBIOTICS Chemotherapeutic agents that act on organisms n Bacteriocidal: Penicillin, Cephalosporin, Vancomycin Aminoglycosides n Bacteriostatic: Erythromycin, Clindamycin, Tetracycline ANTIBIOTICS n Penicillins- Penicillin G, Piperacillin n Penicillins with -lactamase inhibitors- Tazocin n Cephalosporins (I, II, III)- Cephalexin, Cefuroxime, Ceftriaxone n Carbapenems- Imipenem, Meropenem n Aminoglycosides- Gentamycin, Amikacin n Fluoroquinolones- Ciprofloxacin n Glycopeptides- Vancomycin n Macrolides- Erythromycin, Clarithromycin n Tetracyclines- Minocycline, Doxycycline ROLE OF ANTIBIOTICS n Therapeutic: To treat existing infection n Prophylactic: To reduce the risk of wound infection ANTIBIOTIC THERAPY n Pseudomembranous c