SURGICAL INFECTIONS, surgical site..pptx

Surgical infections are a major historical complication of surgery. Hippocratic teachings described the use of vinegar and alcohol to irrigate wounds before primary and secondary closure.
Advances in the control of infection in surgery;
Aseptic operating theatre techniques have enhanced the use of antiseptics
Antibiotics have reduced postoperative infection rates after elective and emergency surgery.
Delayed primary and secondary closure; This is waiting for the wound to granulate. This remains useful in heavily contaminated wounds.

1. SURGICAL INFECTIONS

2. INTRODUCTION Surgical infections are a major historical complication of surgery. Hippocratic teachings described the use of vinegar and alcohol to irrigate wounds before primary and secondary closure. Advances in the control of infection in surgery; Aseptic operating theatre techniques have enhanced the use of antiseptics Antibiotics have reduced postoperative infection rates after elective and emergency surgery. Delayed primary and secondary closure; This is waiting for the wound to granulate. This remains useful in heavily contaminated wounds.

3. KOCH’S POSTULATES Robert Koch 1843-1910. Postulates in 1882 proving whether a given organism is the cause of a disease; It must be found in every case It should be possible to isolate it from the host and grow it in culture It should reproduce the disease when injected to another healthy host It should be recovered from an experimentally infected host.

4. Definitions Surgical infections is defined as invasion of organisms in tissue following a breakdown of local and systemic host defenses. Surgical site infections are infections of the tissues, organs or spaces exposed by surgeons during performance of invasive procedure. They depend on degree of microbial contamination of the wound during surgery, duration of the procedure, host factors.45 Sepsis is suspected infection with some findings of systemic inflammatory responses(SIRs). Sepsis is mediated by the production of a cascade of proinflammatory mediators in response to exposure to microbial products like lipopolysaccharides from gram negative organisms and peptidoglycans from gram positive organisms. Severe sepsis is characterized as sepsis combined with presence of new onset organ failure. Septic shock is a state of acute circulatory failure identified by the presence of persistent arterial hypotension despite adequate fluid resuscitation.

5. PATHOGENESIS Host defenses; These defenses are integrated and redundant so that various components function as a highly regulated system that is extremely effective in copying with microbial invaders. Entry of microbes into the host is precluded by the presence of a number of barriers that possess either epithelial or mucosal surface. Host barrier cells secrete substances that limit microbial proliferation and prevent invasion. Most extensive physical barrier is the skin which has its own resident micro flora that may block attachment and invasion of noncommensal microbes. Once microbes enter a sterile body compartments additional host defenses act to limit these pathogens. These defenses include proteins such as lactoferrin and transferrin that sequester the critical microbial growth factor thus limiting their growth. Urogenital, biliary, pancreatic ductal and distal respiratory tracts don’t possess resident micro flora in healthy persons.

6. SOURCE OF INFECTION Pathogens resist host defenses by releasing toxins which favor their spread and this is enhanced in anaerobic or necrotic wound tissue. Endogenous organisms are present on or in the patient at the time of surgery. E.g. Superficial surgical site infection following contamination of the wound from a perforated appendix. Exogenous are acquired from a source outside the body. E.g. the operating theatre or on ward.

7. MICROBIOLOGY OF SURGICAL INFECTIONS Streptococci These form chains and are gram positive. The most important is the beta hemolytic spp. Streptococcus pyogenes is the most pathogenic. It has the ability to spread causing cellulitis. Streptococcus pyogenes and faecalis are involved in wound infection following bowel surgery. These ssp are sensitive to penicillin and erythromycin. Cephalosporins are an alternative in patients allergic to penicillin. Staphylococci These form clumps and are gram positive. They are found in the nasopharynx up to 15% of the population. They inhabit the skin. They cause tissue necrosis and suppuration in wounds and around planted prostheses. Methicillin Resistant Staphylococcus Aureus (MRSA) is found in the nose of asymptomatic carriers a potential source of infection after surgery. Its sensitive to flucloxacillin, vancomycin, aminoglycosides and some cephalosporins.

8. Clostridia These gram positive obligate anaerobes that produce resistant spores. Clostridium perfringes causes gas gangrene. Clostridium difficile causes pseudomembranous colitis in which destruction of the normal colonic flora allows an overgrowth of the normal commensal to pathological levels. Severe infection leads to perforation. Aerobic gram negative bacilli These normal inhabitants of the large bowel. E.Coli and Klebisella ssp are lactose fermenting and proteus is nonlactose fermenting. They act in synergy with bacteroides to cause surgical site infections after bowel operations. E.Coli is a major cause of UTIs in relation to urinary catheterization. Pseudomonas ssp tend to colonize burns and tracheostomy wounds. They are sensitive to aminoglycosides and quinolones.

9. CLASSIFICATION OF SURGICAL SITE INFECTIONS Superficial Incisional infection It occurs within 30 days of operation and involves only skin and subcutaneous tissue and one of the following; purulent drainage, organism isolation from the drained fluid ant at least one sign of inflammation. Deep Incisional infection It occurs within 30 days of operation or 1 year if an implant is present and they involve deep soft tissues such as muscle and fascia of the incision and at least one of the following purulent drainage from the deep incision site without organ\space involvement, deep incision that is open, deep dehiscence and deep abscess. Organ space infection It occurs within 30-90 days or a year if an implant is present. Involves anatomic structures within the compartment opened or manipulated during surgery.

10. FACTORS THAT DETERMINE WHETHER A WOUND WILL BECOME INFECTED Host response Virulence and inoculation of the infective agent Vascularity and health of tissue being invaded Presence of dead or foreign tissue Presence of antibiotics during the decisive period. Decisive period; This is an upto 4 hour interval before bacterial growth becomes established enough to cause an infection after a breach in the tissue either by trauma or surgery.

11. RISK FACTORS FOR INCREASED WOUND INFECTION Malnutrition Metabolic diseases Immunosuppression Colonization and translocation in the GIT Poor perfusion Poor surgical technique

12. PRESENTATION OF SURGICAL INFECTIONS Major SSI This is a wound that either discharges significant quantity of pus spontaneously or needs a secondary procedure to drain it. Patients may have systemic signs like tachycardia, pyrexia and elevated WBC count. There is delayed return home. Minor SSI The wound may discharge pus or infected serous fluid but is not associated with excessive discomfort, systemic signs and delay in return home.

13. GRADING SYSTEMS

14. EVALUATION History (host factors, agent factors, environmental factors) Examination Investigations

15. HISTORY Patient particulars-age Co morbidities-DM, immunosuppression, malnutrition etc Personal history-smoking Type of surgery-emergency vs. elective Nature of surgical wound by WHO classification after surgery Patient complaints-pain and d/c at site, fever

16. EXAMINATION Nutritional status (BMI, MUAC, signs of vitamin deficiency) Pallor Temperature Pulse Respiratory rate Local exam-inspect and palpate

17. INVESTIGATIONS Complete hemogram-hb<8gdl-1, leucocyte count, thrombocytopenia RFTs-albumin less than 3mg/dl Culture and sensitivity-confirm microorganisms presence uss and contrast enhanced CT C- xray -for reactive effusion in subphrenic abscess Adjuncts- crp and calcitonin levels

18. PREVENTION OF SURGICAL INFECTIONS Preoperative Preoperative cleaning and antiseptic scrub of surgical site. Skin is colonized by various bacteria mainly staphylococcus aureus . Preoperative skin wash using chlorhexidine decreases bacterial colonization and wound contamination. Surgical site is to be shaved in the operation theatre. Shaving should be done in the theatre itself or within 2 hours of beginning of surgery. However selective shaving is definitely needed in areas like scalp, axilla, groin and perineum. Surgery should be postponed if fingers or hands of the surgeon have open wounds or infected. Obvious infection in patient should be treated Prolonged preoperative admission should be avoided for an elective surgery

19. Care in the operation theatre One should ensure that sterile caps, masks, gowns, sterile gloves are used. Proper skin cleaning is needed on table after anasethesia using antiseptics One should ensure that all drapes are dry throughout the procedure and all instruments are thoroughly sterilized. Gentle tissue handling, absolute hemostasis, holding tissues using instruments, avoiding dead space during closure. One should consider leaving wounds open if it is severely contaminated.

20. Preventive antibiotic therapy It is used whenever high-risk of infection is associated with the procedure and consequences of infection are severe. Antibiotics should be administered as close to the incision time as possible before induction of anesthesia. Selected antibiotic should have activity against likely pathogens. Postoperative antibiotics are for 24 hours Very long procedures should have a redosing strategy during the procedure

21. MANAGEMENT OF SSIs All infected material and pus should be removed from the wound site; debridement Sutures should be removed to allow free drainage of infected material Infected fluid is sent for culture and sensitivity and suitable antibiotics are started Once wound shows signs of healing by healthy granulation tissue, secondary suturing is done

22. PRINCIPLES OF ANTIBIOTIC THERAPY Each hospital has its own formulary that includes an antibiotic policy. First line antibiotics to used for specific conditions based on hospital known resistant species Performing culture and sensitivity to antibiotics so first line drugs may be changed accordingly Therapeutic drug monitoring is necessary to some antibiotics like aminoglycosides Synergistic combination of antibiotics are used in some infections. E.g. aminoglycosides and penicillin for staphylococcal infections Drainage and debridement will improve antibiotic effectiveness due to changes in tissue pH, oxygen tension, production of substances by organisms that inactivate the drugs Special nursing measures and isolation are essential for patients infected with MRSA.

23. INTRAABDOMINAL INFECTIONS Intra-abdominal infections include a broad range of various specific infections. They can cause significant morbidity and mortality and are commonly seen by surgeons classified as uncomplicated (uIAIs) or complicated (cIAIs).

24. UNCOMPLICATED IAIS Infections within the abdomen that are confined to a single organ but do not involve the peritoneal cavity An example of this would be non-perforated appendicitis, where the infection involves the appendix but does not extend into the peritoneal cavity. Management involves source control, most often by surgical excision of the focus of infection or infected organ

25. COMPLICATED IAIS Involve the peritoneum, either through the process of focal peritonitis or generalized peritonitis While it is possible for peritonitis to be non-infectious and related to inflammation, as may occur with pancreatitis, it is usually infectious in nature and treatment involves a combination of source control and antibiotics. cIAIs can be further sub-categorized as primary, secondary, or tertiary peritonitis, depending on the source of the infection

26. PRIMARY PERITONITIS monomicrobial infection that occurs in the setting of underlying ascites, typically from cirrhosis, or from an indwelling peritoneal dialysis catheter. Do not involve a violation of a hollow viscus but instead are due to hematogenous dissemination, or spread through the bloodstream, or through direct introduction of the bacteria, as occurs with a dialysis catheter. Rarely managed by surgeons, though can require removal of the catheter if that is the source

27. SECONDARY PERITONITIS occurs when there is intraperitoneal contamination following hollow viscus perforation and is the most common type of peritonitis. Management requires source control, which may involve surgical resection of the involved organ, repair of a hollow viscus perforation, and/or debridement of necrotic or infected tissue. Depending on the duration of the infection and the host response, this type of infection may result in an intra-abdominal abscess. Source control in this situation may involve percutaneous drainage, often under CT or ultrasound guidance, or through surgical drainage, either laparoscopic or open. In addition, broad spectrum antibiotics, and occasionally, antifungal agents, are given for 3-7 days. Antimicrobial agents should be de-escalated or tailored based on culture results following the source-control procedure

28. TERTIARY PERITONITIS technically represents a progression or persistence of secondary peritonitis, though it is classified as a separate type of peritonitis. It is defined as the recurrence of peritonitis more than 48 hours after surgical source control is thought to be achieved. Associated with mortality rate > 50%, more common in those with critical illness or an immunocompromised state or signals the presence of drug-resistant organisms. Management is like that for secondary peritonitis, though often involves the use of antibiotics of broader spectrum and is more likely to involve the use of antifungal agents.

29. SKIN AND SOFT TISSUE INFECTIONS one of the most common reasons that people seek urgent medical attention. These can be divided into two categories based on the severity of the infection: simple and complex, or more aggressive, skin and soft tissue infections. 

30. SIMPLE SKIN AND SOFT TISSUE INFECTIONS 1. Those that do not require surgery, such as cellulitis, lymphangitis, and erysipelas, Should be treated with antibiotics to cover for gram positive skin flora and elevation if the infection involves a limb. Improvement should be seen within 24 to 72 hours following administration of antibiotics. 2. Abscesses require drainage, which should be done surgically if they have not spontaneously drained. Antibiotics are only needed if there is significant cellulitis or if cellulitis does not resolve after drainage.

31. AGGRESSIVE SKIN AND SOFT TISSUE INFECTIONS Also known as necrotizing soft tissue infections (NSTI) Include necrotizing cellulitis, necrotizing fasciitis, and necrotizing myositis based on the level of tissue involvement. These are rare and pose a diagnostic and treatment challenge. Once diagnosed, they require immediate and often repeated surgical debridement and antibiotics. Mortality with appropriate treatment is 18-24% and without treatment 80-100%. Mortality increases with delays in diagnosis.

32. Infections may be monomicrobial, typically involving Streptococcus or Staphylococcus species, or polymicrobial, which often involve both aerobic and anaerobic bacteria NTSI commonly affect extremities, perineum (Fournier's gangrene), trunk, and mouth and neck (Ludwig's angina).

33. REFRENCES BAILEY AND LOVE’S 28 th EDITION SCHWARTZ’S PRINCIPLES OF SURGERY 10 TH EDITION SRB’S MANUAL OF SURGERY 5 TH EDITIOH