SURGICAL INFECTIONS & ANTIBIOTICS M K ALAM MS, FRCS Prof. & Consultant Surgeon College of Medicine & KSMC

Intended learning objectives At the end of this presentation students will be able to:   Explain the pathogenesis of infection   Recognize clinical features of infection.   Name common pathogens involved in surgical infections   Recognize surgical site infections and describe its causes and prevention.   Describe common aerobic and anaerobic infections seen in surgical practice.   Discuss the principles of therapeutic and prophylactic use of antibiotics.

Definition & importance of surgical infections. Definition & importance of surgical infections. Pathogenesis of infections. Pathogenesis of infections. Common clinical features. Common clinical features. Surgical microbiology. Surgical microbiology. Common surgical infections. Common surgical infections. Antibiotics use in surgery. Antibiotics use in surgery.

Definition Infection: Infection: Invasion of the body by pathogenic microorganisms and reaction of the host to organisms and their toxins Invasion of the body by pathogenic microorganisms and reaction of the host to organisms and their toxins Surgical infection: Surgical infection: 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 Infections A major challenge A major challenge Accounts for 1/3 of surgical patients Accounts for 1/3 of surgical patients Increased morbidity Increased morbidity Increased mortality Increased mortality Increased cost to healthcare Increased cost to healthcare

Pathogenesis of infections Pathogenesis of infections

Interaction between microbes & host related factors Microorganism related factors: Microorganism related factors: Adequate dose. Adequate dose. Virulence (pathogenicity) of microorganisms. Virulence (pathogenicity) of microorganisms. Host related factors: Host related factors: Suitable environment. Suitable environment. Susceptible host. Susceptible host.

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

Host related factors  Skin / mucous membrane breach surgery/ trauma surgery/ trauma  Suitable environment hematoma, seroma, closed space hematoma, seroma, closed space  Compromised immunity cellular (phagocytes ), antibodies cellular (phagocytes ), antibodies

Clinical features of infections Clinical features of infections

Local- pain, heat, redness, swelling, Local- pain, heat, redness, swelling, loss of function. loss of function. (apparent in superficial infections) (apparent in superficial infections) Systemic- fever, tachycardia, chills Systemic- fever, tachycardia, chills

Principles of surgical treatment Principles of surgical treatment Debridement- necrotic, injured tissue Debridement- necrotic, injured tissue Drainage- abscess, infected fluid Drainage- abscess, infected fluid Excision- infection source (appendectomy) Excision- infection source (appendectomy) Supportive measures: Supportive measures: antibiotics antibiotics immobilization immobilization limb elevation limb elevation

Surgical Microbiology Surgical Microbiology

Gram positive bacteria STAPHYLOCOCCI Inhabitants of skin, Inhabitants of skin, Infection characterized by suppuration Infection characterized by suppuration Sensitive to Sensitive to penicillinase-resistant β-lactam antibiotics MRSA – resistant to MRSA – resistant to penicillinase-resistant β-lactam antibiotics Treated by Vancomycin Staph. aureus- SSI, nosocomial,superficial infections Staph. aureus- SSI, nosocomial,superficial infections Staph. epidermidis- opportunistic ( wound, endocarditis ) Staph. epidermidis- opportunistic ( wound, endocarditis )

Gram positive bacteria STREPTOCOCCI Aerobe/anaerobe Aerobe/anaerobe Flora of the mouth and pharynx, bowel Flora of the mouth and pharynx, bowel Streptococcus pyogenes –( β hemolytic) 90% of infections - lymphangitis, cellulitis, rheumatic fever Streptococcus pyogenes –( β hemolytic) 90% of infections - lymphangitis, cellulitis, rheumatic fever Strep. viridens- endocarditis, urinary infection Strep. viridens- endocarditis, urinary infection Enterococci- urinary infection, intra-abddominal infections Enterococci- urinary infection, intra-abddominal infections

Gram negative rods Most - family Enterobacteriaceae. Escherichia, Proteus, and Klebsiella All are facultative anaerobic bacteria Common in mixed surgical infections Susceptible a variety of antibiotics, e.g second-generation cephalosporins

Gram negative rods Other Enterobacteriaceae in surgical infections- Enterobacter, Morganella, Providencia, and Serratia. Exhibit greater antimicrobial resistance. Antibiotic- third-generation cephalosporin, expanded-spectrum penicillins, monobactam, carbapenem, quinolone, or aminoglycoside.

Gram negative rods Pseudomonas and Acinetobacter species Obligate aerobic common: hospital-associated pneumonia, peritoneal cavity or severe soft tissue infections. ceftazidime, cefepime, aztreonam, imipenem/cilastatin, meropenem, ciprofloxacin, an acylureidopenicillin, or an aminoglycoside

Anaerobes Bacteroides fragilis Inhabitants of GIT, & the mouth. Gram negative bacillus Distal bowel related infection Antibiotics-metronidazole, clindamycin, imipenem, meropenem, ertapenem, the combinations ticarcillin/clavulanate, ampicillin/sulbactam, & piperacillin/tazobactam

CLOSTRIDIA Anaerobes CLOSTRIDIA Gram positive, rod shaped Gram positive, rod shaped 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

SPECIFIC SURGICAL INFECTIONS SPECIFIC SURGICAL INFECTIONS

SPECIFIC SURGICAL INFECTIONS Surgical Site Infections Surgical Site Infections Soft Tissue Infections Soft Tissue Infections Body Cavity Infections Body Cavity Infections Prosthetic Device related Infections Prosthetic Device related Infections Miscellaneous Miscellaneous

Surgical site infections (SSI) 38% of all surgical infections 38% of all surgical infections Infection within 30 days of operation Infection within 30 days of operation Infection within 1 year if prosthetic device used Infection within 1 year if prosthetic device used

Surgical site infection (SSI) Classification: Classification: Superficial SSI: skin & subcutaneous plane (47%) Superficial SSI: skin & subcutaneous plane (47%) Deep SSI: subfascial and muscle plane (23%) Deep SSI: subfascial and 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, B fragilis E coli, Entercoccus, B fragilis

Surgical site infection (SSI) Risk factors Risk factors age age malnutrition malnutrition obesity obesity immuno-compromised immuno-compromised poor surgical technique poor surgical technique prolonged surgery prolonged surgery preoperative shaving preoperative shaving type of surgery type of surgery

Surgical site infection (SSI) Diagnosis: Diagnosis: Sup.SSI- erythema, oedema, discharge and pain Sup.SSI- 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 -shaving vs clipping Hair removal -shaving vs clipping Intra-operative: Antiseptic technique Intra-operative: Antiseptic technique Good surgical technique Good surgical technique Normothermia Normothermia Post-operative: Wound dressing in hours Post-operative: Wound dressing in hours Early drain removal Early drain removal Blood sugar control Blood sugar control

Soft tissue infections Erysipelas Soft tissue 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 Organism-Strep pyogenes Organism-Strep pyogenes Penicillin, Erythromycin Penicillin, Erythromycin

Soft tissue infections 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 )

Soft tissue infections Abscess Localized pus collection Superficial - trunk, head and neck - S. aureus, (Streptococci) Axillae- gram-negative bacteria Perineum- mixed aerobic and anaerobic gram-negative flora Abscess may be mistaken for cellulitis when located deep Treatment: drainage, antibiotics *

Soft tissue infections Furuncle- infection of hair follicle / sweat glands Furuncle- infection of hair follicle / sweat glands Carbuncle- extension of furuncle into subcutaneous tissue Carbuncle- extension of furuncle into subcutaneous tissue common in diabetics common in diabetics common sites- back, back of neck common sites- back, back of neck Treatment: drainage, antibiotics, Treatment: drainage, antibiotics, control diabetes control diabetes

NECROTIZING SOFT TISSUE INFECTIONS ( NECROTIZING FASCIITIS) Necrosis of superficial fascia, overlying skin Necrosis of superficial fascia, overlying skin Risk group- elderly, diabetics, immunosuppressed Risk group- elderly, diabetics, immunosuppressed Polymicrobial : Streptococci, Staphylococci, Polymicrobial : Streptococci, Staphylococci, Gram-negative Bacilli, and the anaerobes. Gram-negative Bacilli, and the anaerobes. Sites- Limbs Sites- Limbs Perineum (Fournier’s), Perineum (Fournier’s), Abdominal wall (Meleny’s), Abdominal wall (Meleny’s), Trunk- elderly, diabetics, immunosupressed Trunk- elderly, diabetics, immunosupressed

NECROTIZING SOFT TISSUE INFECTIONS ( NECROTIZING FASCIITIS) Starts as cellulitis, edema, systemic toxicity, shock Starts as cellulitis, edema, systemic toxicity, shock 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 (broad spectrum) Treatment: IV fluid, IV antibiotics (broad spectrum) (ampicillin, cephalsporins,clindamycin l metronidazole, aminoglycosides ) (ampicillin, cephalsporins,clindamycin l metronidazole, aminoglycosides ) Repeated debridement, dressings, skin grafting Repeated debridement, dressings, skin grafting

Clostridial myonecrosis (GAS GANGRENE) Cl. Perfringens, Cl. Septicum, Cl. Novyi (exotoxins) Cl. Perfringens, Cl. Septicum, Cl. Novyi (exotoxins) Large wounds of muscle ( contaminated by soil, foreign body ), drug users Large wounds of muscle ( contaminated by soil, foreign body ), drug users Myonecrosis, crepitus, seropurulent discharge, foul smell, swollen, Myonecrosis, crepitus, 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 Penicillin, clindamycin, metronidazole Penicillin, clindamycin, metronidazole Debridement, drainage, amputation, hyperbaric oxygen Debridement, drainage, amputation, hyperbaric oxygen

TETANUS Cl. Tetani, (neurotoxin) Cl. Tetani, (neurotoxin) Penetrating wound ( rusty nail, thorn ) Penetrating wound ( rusty nail, thorn ) Trismus- first symptom, stiffness in neck & back Trismus- first symptom, stiffness in neck & back 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 Prophlaxis- wound debridement, penicillin, T toxoid Prophlaxis- wound debridement, penicillin, T toxoid Previously immunized - booster >10 years Previously immunized - booster >10 years

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

Body Cavity Infections Primary peritonitis: Primary peritonitis: Spontaneous Spontaneous Children, Ascitic Children, Ascitic Haematogenous/ lymphatic route Haematogenous/ lymphatic route Antibiotic Antibiotic Secondary peritonitis: Secondary peritonitis: Inflammation, rupture of viscera Inflammation, rupture of viscera Polymicrobial Polymicrobial Investigations: blood, radiological Investigations: blood, radiological Treatment of original cause Treatment of original cause

Prosthetic Device Related Infections Artificial valves and joints Artificial valves and joints Peritoneal and haemodialysis catheters Peritoneal and haemodialysis catheters Vascular grafts Vascular grafts Staphylococcus aureus Staphylococcus aureus Antibiotics, washing of prosthesis or removal Antibiotics, washing of prosthesis or removal

Hospital Acquired Infections Occurring within: 48 h of hospital admission/ 3 days of discharge /30 days following an operation Occurring within: 48 h of hospital admission/ 3 days of discharge /30 days following an operation 10% of patients admitted to hospitals 10% of patients admitted to hospitals Spent 2.5-times longer in hospital – UK Spent 2.5-times longer in hospital – UK Highest prevalence in ICU Highest prevalence in ICU Enterococcus, Pseudomonas, E coli, Staph. aureus. Enterococcus, Pseudomonas, E coli, Staph. aureus. Sites: Urinary, surg. Wounds, resp., skin, blood, GIT Sites: Urinary, surg. Wounds, resp., skin, blood, GIT

ANTIBIOTICS ANTIBIOTICS

ROLE OF ANTIBIOTICS Chemotherapeutic agents that act on organisms 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

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

THERAPEUTIC USE OF ANTIBIOTICS 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 )

Prophylactic use of antibiotics Administration of antimicrobial(s) prior to surgical procedures to reduce the number of microbes that enter the tissue or body cavity. Administration of antimicrobial(s) prior to surgical procedures to reduce the number of microbes that enter the tissue or body cavity. Antibiotics are selected according to microbes likely to be present at the surgical site. Antibiotics are selected according to microbes likely to be present at the surgical site.

SURGICAL WOUND CLASSIFICATION SURGICAL WOUND CLASSIFICATION Clean wound (Class I)- thyroid surgery, breast biopsy ( 5% ) Clean wound (Class I)- thyroid surgery, breast biopsy ( 5% ) Class ID when graft, mesh used Class ID when graft, mesh used Clean-contaminated (Class II)- minimal contamination e.g., biliary, urinary, GI tract surgery ( 11% ) Clean-contaminated (Class II)- minimal contamination e.g., biliary, urinary, GI tract surgery ( 11% ) Contaminated (Class III)- gross contamination e.g., during bowel surgery- (17%) Contaminated (Class III)- gross contamination e.g., during bowel surgery- (17%) Dirty (Class IV)- surgery through established infection e.g., peritonitis ( >27% ) Dirty (Class IV)- surgery through established infection e.g., peritonitis ( >27% )

ANTIBIOTIC PROPHYLAXIS Prophylaxis in class ID, II, III, IV Prophylaxis in class ID, II, III, IV Antibiotic is given just before patient sent for surgery Antibiotic is given just before patient sent for surgery Duration of antibiotic is controversial ( one dose- 24 hour regimen ) Duration of antibiotic is controversial ( one dose- 24 hour regimen )