SURGICAL INFECTIONS & ANTIBIOTICS

OBJECTIVES Definitions. Definitions. Pathogenesis. Pathogenesis. Clinical features. Clinical features. Surgical microbiology. Surgical microbiology. Common infections. Common infections. Antibiotics use. Antibiotics use.

SURGICAL INFECTIONS Infections that require surgical intervention as a treatment or develop as a result of surgical procedure. Infections that require surgical intervention as a treatment or develop as a result of surgical procedure.

Surgical Infection A major challenge A major challenge Accounts for 1/3 of surgical patients Accounts for 1/3 of surgical patients Increased cost to healthcare Increased cost to healthcare

PHYSIOLOGY Micro-organisms are normally prevented from causing infection in tissues by intact epithelial surfaces. These are broken down in trauma and by surgery. Micro-organisms are normally prevented from causing infection in tissues by intact epithelial surfaces. These are broken down in trauma and by surgery.

there are other protective mechanisms, which can be divided into: chemical: low gastric pH; humoral: antibodies, complement and opsonins; cellular: phagocytic cells, macrophages, polymorphonuclear cells and killer lymphocytes. there are other protective mechanisms, which can be divided into: chemical: low gastric pH; humoral: antibodies, complement and opsonins; cellular: phagocytic cells, macrophages, polymorphonuclear cells and killer lymphocytes.

causes of reduced host resistance to infection ■ Metabolic: malnutrition (including obesity), diabetes, uraemia, jaundice ■ Disseminated disease: cancer and acquired immunodeficiency syndrome (AIDS) ■ Iatrogenic: radiotherapy, chemotherapy, steroids

Delayed healing relating to infection in a patient on highdose steroid.

Pathogenicity of bacteria Exotoxins: specific, soluble proteins, remote cytotoxic effect Cl.Tetani, Strep. pyogenes Cl.Tetani, Strep. pyogenes Endotoxins: part of gram-negative bacterial wall, lipopolysaccharides e.g., E coli Resist phagocytosis: Protective capsule Klebsiela and Strep. pneumoniae Klebsiela and Strep. pneumoniae

Preventation of surgical infections **Pt in best general condition (host defense). **minimize introduction of pathogenesis during surgery. **good surgical technique. **peri-operative care (support defence).

Clinical features Clinical features Local Local pain, heat, redness, swelling, pain, heat, redness, swelling, loss of function. loss of function. (apparent in superficial infections) (apparent in superficial infections) Systemic Systemic tachycardia, pyrexia and a raised white count tachycardia, pyrexia and a raised white count [systemic inflammatory response syndrome (SIRS)]

Investigation *** Leukocytosis. ***Exudate (gram stain, culture) ***Blood culture. ***Special Inv. (radiology, biobsy)

Principles of surgical treatment Principles of surgical treatment Debridement necrotic, injured tissue Debridement necrotic, injured tissue Drainage abscess, infected fluid Drainage abscess, infected fluid Removal infection source, foreign body Removal infection source, foreign body Supportive measures: Supportive measures: immobilization immobilization elevation elevation antibiotics antibiotics

Common infections

STREPTOCOCCI Gram positive, aerobe/anaerobe Gram positive, aerobe/anaerobe Flora of the mouth and pharynx, ( bowel ) Flora of the mouth and pharynx, ( bowel ) Streptococcus pyogenes –( β hemolytic) 90% of infections e.g.,lymphangitis, cellulitis, rheumatic fever Streptococcus pyogenes –( β hemolytic) 90% of infections e.g.,lymphangitis, cellulitis, rheumatic fever Strep. viridens- endocarditis, urinary infection Strep. viridens- endocarditis, urinary infection Strep. fecalis – urinary infection, pyogenic infection Strep. fecalis – urinary infection, pyogenic infection Strep. pneumonae – pneumonia, meningitis Strep. pneumonae – pneumonia, meningitis

STREPTOCOCCAL INFECTIONS Erysipelas Superficial spreading cellulitis & lymphangitis Superficial spreading cellulitis & lymphangitis Area of redness, sharply defined irregular border Area of redness, sharply defined irregular border Follows minor skin injuries Follows minor skin injuries Strep pyogenes Strep pyogenes Common site: around nose extending to both cheeks Common site: around nose extending to both cheeks Treatment: Penicillin, Erythromycin Treatment: Penicillin, Erythromycin

SREPTOCOCCAL INFECTION Cellulitis Inflammation of skin & subcutaneous tissue Inflammation of skin & subcutaneous tissue Non-suppurative Non-suppurative Strep. Pyogenes Strep. Pyogenes Common sites- limbs Common sites- limbs Affected area is red, hot & indurated Affected area is red, hot & indurated Treatment : Rest, elevation of affected limb Treatment : Rest, elevation of affected limb Penicillin, Erythromycin Penicillin, Erythromycin Fluocloxacillin ( staph. suspected ) Fluocloxacillin ( staph. suspected )

Streptococcal cellulitis of the leg

NECROTIZING FASCIITIS Necrosis of superficial fascia, overlying skin Necrosis of superficial fascia, overlying skin Polymicrobial : Streptococci (90%), Polymicrobial : Streptococci (90%), anaerobic Grampositive Cocci, aerobic Gram-negative Bacilli, and the Bacteroides spp. anaerobic Grampositive Cocci, aerobic Gram-negative Bacilli, and the Bacteroides spp. Sites- abd.wall (Meleny’s), Sites- abd.wall (Meleny’s), perineum (Fournier’s), perineum (Fournier’s), limbs, limbs, Usually follows abdominal surgery or trauma Usually follows abdominal surgery or trauma

NECROTIZING FASCIITIS Diabetics more susceptible Diabetics more susceptible Starts as cellulitis, edema, systemic toxicity Starts as cellulitis, edema, systemic toxicity Appears less extensive than actual necrosis Appears less extensive than actual necrosis Investigation: Aspiration, Gram’s stain, CT, MRI Investigation: Aspiration, Gram’s stain, CT, MRI Treatment: IV fluid, IV antibiotics Treatment: IV fluid, IV antibiotics (ampicillin, clindamycin l metronidazole, aminoglycosides ) (ampicillin, clindamycin l metronidazole, aminoglycosides ) Debridement, repeated dressings, skin grafting Debridement, repeated dressings, skin grafting

STAPHYLOCOCCI Inhabitants of skin, Gram positive Inhabitants of skin, Gram positive Infection characterized by suppuration Infection characterized by suppuration Staph.aureus- Staph.aureus- SSI, nosocomial,superficial infections SSI, nosocomial,superficial infections Staph. epidermidis- Staph. epidermidis- opportunistic ( wound, endocarditis ) opportunistic ( wound, endocarditis )

STAPHYLCOCCAL INFECTIONS STAPHYLCOCCAL INFECTIONS Abscess- localized pus collection Treatment- drainage, antibiotics Abscess- localized pus collection Treatment- drainage, antibiotics Furuncle- infection of hair follicle / sweat glands Furuncle- infection of hair follicle / sweat glands Carbuncle- extension of furuncle into subcut. tissue Carbuncle- extension of furuncle into subcut. tissue common in diabetics common in diabetics common sites- back, back of neck common sites- back, back of neck Treatment: drainage, antibiotics, control diabetes Treatment: drainage, antibiotics, control diabetes

Surgical site infection (SSI) 38% of all surgical infections 38% of all surgical infections Infection within 30 days of operation Infection within 30 days of operation Classification: Classification: Superficial: Superficial SSI–infection in subcutaneous plane (47%) Deep: Subfascial SSI- muscle plane (23%) Superficial: Superficial SSI–infection in subcutaneous plane (47%) Deep: Subfascial SSI- muscle plane (23%) Organ/ space SSI- intra-abdominal, other spaces (30%) Organ/ space SSI- intra-abdominal, other spaces (30%) Staph. aureus most common organism Staph. aureus most common organism E coli, Entercoccus,other Entetobacteriaceae- deep infections E coli, Entercoccus,other Entetobacteriaceae- deep infections B fragilis – intrabd. abscess B fragilis – intrabd. abscess

Surgical site infection (SSI) Risk factors: age, malnutrition, obesity, immunocompromised, poor surg. tech, prolonged surgery, preop. shaving and type of surgery. Risk factors: age, malnutrition, obesity, immunocompromised, poor surg. tech, prolonged surgery, preop. shaving and type of surgery. Diagnosis: Diagnosis: Superficial infection erythema, oedema, discharge and pain Superficial infection erythema, oedema, discharge and pain Deep infections- no local signs, fever, pain, hypotension. need investigations. Deep infections- no local signs, fever, pain, hypotension. need investigations. Treatment: surgical / radiological intervention. Treatment: surgical / radiological intervention.

Prevention of SSI Pre-op: Treat pre-existing infection Pre-op: Treat pre-existing infection Improve general nutrition Improve general nutrition Shorter hospital stay Shorter hospital stay Pre-op. shower Pre-op. shower Hair removal timing? Hair removal timing? Intraoperative: Antiseptic technique Intraoperative: Antiseptic technique good Surgical technique good Surgical technique Post-operative: Hand hygiene Post-operative: Hand hygiene

GRAM NEGATIVE ORGANISMS ( Enterobactericiae ) Escherichia coli 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 Pseudomonas aerobes, occurs on skin surface aerobes, occurs on skin surface opportunistic pathogen opportunistic pathogen may cause serious & lethal infection may cause serious & lethal infection colonize ventilators, iv catheters, urinary catheters colonize ventilators, iv catheters, urinary catheters Wound infection, burn, septicemia Wound infection, burn, septicemia Treatment: aminoglycosides, piperacillin, ceftazidime Treatment: aminoglycosides, piperacillin, ceftazidime

CLOSTRIDIA Gram positive, anaerobe Gram positive, anaerobe Rod shaped microorganisms Rod shaped microorganisms Live in bowel & soil Live in bowel & soil Produce exotoxin for pathogenicity Produce exotoxin for pathogenicity Important members: Important members: Cl. Perfringens, Cl. Septicum ( gas gangrene ) Cl. Perfringens, Cl. Septicum ( gas gangrene ) Cl. Tetani ( tetanus ) Cl. Tetani ( tetanus ) Cl. Difficile ( pseudomembranous colitis ) Cl. Difficile ( pseudomembranous colitis )

GAS GANGRENE Cl. Perfringens, Cl. Septicum Cl. Perfringens, Cl. Septicum Exotoxins: lecithinase, collagenase, hyaluridase Exotoxins: lecithinase, collagenase, hyaluridase Large wounds of muscle ( contaminated by soil, foreign body ) Large wounds of muscle ( contaminated by soil, foreign body ) Rapid myonecrosis, crepitus in subcutaneous tissue Rapid myonecrosis, crepitus in subcutaneous tissue Seropurulent discharge, foul smell, swollen Seropurulent discharge, foul smell, swollen Toxemia, tachycardia, ill looking Toxemia, tachycardia, ill looking X-ray: gas in muscle and under skin X-ray: gas in muscle and under skin ttt :Penicillin, clindamycin, metronidazole ttt :Penicillin, clindamycin, metronidazole Wound exposure, debridement, drainage, amputation Wound exposure, debridement, drainage, amputation Hyperbaric oxygen Hyperbaric oxygen

TETANUS Cl. Tetani, produce neurotoxin Cl. Tetani, produce neurotoxin Penetrating wound ( rusty nail, thorn ) Penetrating wound ( rusty nail, thorn ) Usually wound healed when symptoms appear Usually wound healed when symptoms appear Incubation period: 7-10 days Incubation period: 7-10 days Trismus- first symptom, stiffness in neck & back Trismus- first symptom, stiffness in neck & back Anxious look with mouth drawn up ( risus sardonicus) Anxious look with mouth drawn up ( risus sardonicus) Respiration & swallowing progressively difficult Respiration & swallowing progressively difficult Reflex convulsions along with tonic spasm Reflex convulsions along with tonic spasm Death by exhaustion, aspiration or asphyxiation Death by exhaustion, aspiration or asphyxiation

TETANUS Treatment: Treatment: wound debridement, penicillin wound debridement, penicillin Muscle relaxants, ventilatory support Muscle relaxants, ventilatory support Nutritional support Nutritional support Prophylaxis: Prophylaxis: wound care, antibiotics wound care, antibiotics Human TIG in high risk ( un-immunized ) Human TIG in high risk ( un-immunized ) Commence active immunization ( T toxoid) Previously immunized - booster >10 years needs a booster dose Commence active immunization ( T toxoid) Previously immunized - booster >10 years needs a booster dose booster <10 years- no treatment in low risk wounds booster <10 years- no treatment in low risk wounds

PSEUDOMEMBRANOUS COLITIS Cl. Difficile Cl. Difficile Overtakes normal flora in patients on antibiotics Overtakes normal flora in patients on antibiotics Watery diarrhea, abdominal pain, fever Watery diarrhea, abdominal pain, fever Sigmoidoscopy: membrane of exudates (pseudomembranes) Sigmoidoscopy: membrane of exudates (pseudomembranes) Stool- culture and toxin assay Stool- culture and toxin assay Treatment : Treatment : stop offending antibiotic stop offending antibiotic oral vancomycin/ metronidazole oral vancomycin/ metronidazole rehydration, isolate patient rehydration, isolate patient

ANTIBIOTICS Chemotherapeutic agents that act on organisms Chemotherapeutic agents that act on organisms Bacteriocidal: Penicillin, Cephalosporin, Vancomycin Bacteriocidal: Penicillin, Cephalosporin, Vancomycin Aminoglycosides Aminoglycosides Bacteriostatic: Erythromycin, Clindamycin, Tetracycline Bacteriostatic: Erythromycin, Clindamycin, Tetracycline

ANTIBIOTICS Penicillins- Penicillin G, Piperacillin Penicillins- Penicillin G, Piperacillin Penicillins with β-lactamase inhibitors- Tazocin Penicillins with β-lactamase inhibitors- Tazocin Cephalosporins (I, II, III)- Cephalexin, Cefuroxime, Ceftriaxone Cephalosporins (I, II, III)- Cephalexin, Cefuroxime, Ceftriaxone Carbapenems- Imipenem, Meropenem Carbapenems- Imipenem, Meropenem Aminoglycosides- Gentamycin, Amikacin Aminoglycosides- Gentamycin, Amikacin Fluoroquinolones- Ciprofloxacin Fluoroquinolones- Ciprofloxacin Glycopeptides- Vancomycin Glycopeptides- Vancomycin Macrolides- Erythromycin, Clarithromycin Macrolides- Erythromycin, Clarithromycin Tetracyclines- Minocycline, Doxycycline Tetracyclines- Minocycline, Doxycycline

ROLE OF ANTIBIOTICS Therapeutic: To treat existing infection Therapeutic: To treat existing infection Prophylactic: To reduce the risk of wound infection Prophylactic: To reduce the risk of wound infection

ANTIBIOTIC THERAPY Pseudomembranous colitis- oral vancomycin/ metronidazole Pseudomembranous colitis- oral vancomycin/ metronidazole Biliary-tract infection- cephalosporin or gentamycin Biliary-tract infection- cephalosporin or gentamycin Peritonitis- cephalosporin/ gentamycin + metronidazole/ clindamycin Peritonitis- cephalosporin/ gentamycin + metronidazole/ clindamycin Septicemia- aminoglycoside + ceftazidime, Tazocin or imipenem, ( may add metronidazole ) Septicemia- aminoglycoside + ceftazidime, Tazocin or imipenem, ( may add metronidazole ) Septicemia due to vascular catheter- Flucloxacillin/ vancomycin or Cefuroxime Septicemia due to vascular catheter- Flucloxacillin/ vancomycin or Cefuroxime Cellulitis- penicillin, erythromycin ( flucloxacillin if Staphylococcus infection. Suspected ) Cellulitis- penicillin, erythromycin ( flucloxacillin if Staphylococcus infection. Suspected )

ANTIBIOTIC PROPHYLAXIS BASED ON SURGICAL WOUND CLASSIFICATION Clean wound Clean wound Clean-contaminated Clean-contaminated Contaminated Contaminated Dirty Dirty

Clean wound: class I e.g surg. Of thyroid gland,breast,hernia no need to prophylaxis except for: **immunocomprized pt e.g. diabetecs **if surgery include inserting foreign materials e.g. artificial valve. **high risk pt like those with infective endocarditis. The risk of pos-operative wound infection is 2%

Clean–contaminated wound: class II e.g. biliary,urinary surg. The risk of infection is 5-10%

Contaminated wound: class III e.g. bowel surgery The risk of infection is up to 20%

Dirty wound : class IV e.g. peritonitis The use of antibiotic is considered to be of therapeutic nature (no prophylaxis) The risk of infection is up to 60%

Type of surgery Infection rate (%) Rate before prophylaxis Clean 1–2 1-2% Clean-contaminated < 10 up to 30% Contaminated 15–20 Variable but up to 60% Dirty < 40 Up to 60% or more