Surgical Infections: Guo Xueli ( )

Surgical Infections Guo Xueli ( 郭学利 ) Dept. General Surgery, First Affiliated Hospital

Surgical infections and choice of antibiotics Many operations were developed ---after anesthesia during the 2nd half of the 19th century Advances were few --- the high rate of infections the high mortality that followed infections

The antiseptic principle---Lister The concepts of asepsis and antisepsis ---Louis Pasteur el al revolutionized the practice of surgery Application of antiseptic practices ---infection rate for elective operations to drop from 90% to 10% Around the turn of the century--the practice of wearing gloves during operations

These basic principles of controlling infections--Changing surgical therapy Despite these gains #the many procedures performed ---numerous postoperative surgical site infections #infections--- increased morbidity and mortality #the cost of the care of postoperative wound infections---enormous

Antibiotic therapy---the serious surgical infections would be eliminated Unfortunately #postoperative wound and hospital-acquired infections---continued #prevention and control of surgical infections---more difficult

New serious infections related to a complex combination of factors #more complicated and longer operations #accompanying chronic or debilitating diseases #new surgical procedures ---implants of foreign materials ---organ transplants requiring the use of immunosuppressive agent ---use of diagnostic and treatment modalities that caused bacterial exposures or the suppression of normal host resistance

YOU, a modern surgeon, cannot escape the responsibility to deal with infections! To realize the knowledges #microbiology, immunology, pharmacology #how the body defends itself against infections #therapeutic principle to control of infections

Causes of wound infection #Bacterial factors #Local wound factors #Patient factors

All clean operative wound ---small numbers of bacteria Only a small number---infections #Microbial numbers and virulence #Host defense

Bacterial factors The development of infection #Prerequisite---the deposition and growth of bacteria #the kind and number #the toxins produced by the organism #the organism’s ability to resist phagocytosis and intracellular destruction

Surface components---contribute to their pathogenicity by inhibiting phagocytosis Gram-negative bacteria---endotoxin or lipopolysaccharide that are toxic Clostridia and streptococci---exotoxins that permit bacteria to establish invasive infections

Most wounds ---one or more types of organisms can be culture Clean wounds---skin bacteria, staphlococcus epidermidis or diphtheroid Traumatic wounds---staphlococcus aureus and streptococcus pyogens Devitalized tissues and foreign materials ---far fewer organisms cause infection in wounds than normal tissues

Overt infection is unusual unless cardinal surgical principles have been violated or exceptionally large numbers of organisms have been introduced into the wound ---the normal defense mechanism are great importance in preventing infections

Local wound factors Inhibition of local defense mechanisms for clearing bacteria---the most important cause of wound infection anything---that interferes with the ability of phagocytic cell to contact directly and kill bacteria---infection

The use of foreign bodies---sutures and drains Lack of accurate approximation of tissues Strangulation of tissue with suture that are tight The presence of any dead tissue, hematomas, or seromas If you have good surgical technique, you can minimize the most of these factors!

Patient factors Wound infections are more common in the very young and the very old ---immature or senescent resistance mechanisms #anything that reduces blood flow to the surgical incision---vascular occlusive states, hypovolemic shock, or with use of vasopressors or vasoconstrictor #local decrease in tissue oxygen tension

#condition that reduce vascular reactivity as in uremia, old age, or the use of high doses of corticosteroids and other drugs cause an increased susceptibility to infection #cancer and trauma---complement activation which influence both T-cell and phagocytic cell function

Prevention of wound infection Preventing infectious complications is far more practical than treating them #strict adherence to the principles of wound care #application of knowledge concerning the pathogenesis of wound infections ---can preventing the vast majority of infectious complications Most important ---constant vigilance of the operating team, including the surgeon

Avoidance of bacterial contamination Environmental Factors Engineering and architectural advances ---limit airborne contamination the two greatest sources of significant microbial contamination ---exogenous contract from break in technique by operative team ---exogenous contract from the patient’s skin and various bacteria containing tracts

#The use of ultraviolet light #Laminar flow ventilation systems #Important---limiting traffic in and out providing positive pressure limiting activity and talking #Increasing numbers of people ---increase opportunity for breaks in sterile technique and dispersion of airborne bacteria #Air handling, sterilization techniques must be strictly monitored

Preoperative Preparation of the Patient #Take a preoperative shower the night before operation using an antibacterial soap #All cutaneous infections should be controlled or cleared Presence of a distant-site infection at the time of an elective clean operation doubles the postoperative infections rate

Hair Removal Shaving hair increases the infection rate about 100% compared with removing the hair by clippers at the time of the procedure or not removing it at all # Extensive removal of hair---no #Any that is done should be performed by electric clippers with disposable heads in the operating room at the time of the procedure

Skin Preparation The skin---an important source of organisms contaminating surgical wounds Two methods ---to scrub the entire operative area of the patient for 5 to7 minutes with a germicidal detergent solution, then paint the region with an antimicrobial solution of either tincture of iodine, povidone-iodine, or chlorhexidine ---to use an antimicrobial incise drape

The operating room team and discipline the operating room team---one of the most important sources of organisms in clean cases ---wear clean scrub suits, caps, masks ---the hands and forearms should be cleansed and scrubbed thoroughly with an antimicrobial soap for 3-5 minutes ---careful gowning and gloving techniques, special attention should be paid to avoiding contamination when the patient is draped Another frequent source of contamination---the use of sterile light handles, which become contaminated by the headgear of the operating team

#the gloves punctured or torn should be changed immediately The safest gloving practice---to wear two pairs of gloves #the gowns worn---an important source of contamination The contact areas (i.e., sleeves and front of the gown) should be impervious to bacteria and fluids whether the gowns are disposable or reused

Endogenous contamination Another very important but not always heeded source of contamination--- Endogenous contamination at the time of transection of the gastrointestinal, respiration, or genitourinary tract Bacterial contamination occurs to varying degrees any time a hollow viscus is transected

#The operative area should be carefully isolated from the remainder of the operative field before a hollow viscus is entered #A completely different set of instruments should be used for that portion of the operation until the hollow viscus is closed #All instruments, towels, and sponges that may have come into contact with the contaminated area must be removed from the operative field #The gowns and gloves of the operative team should be changed

The importance of surgical technique Gentle care of the tissues to minimize local damage--one of the most important ways to prevent infection ---all devitalized tissues and foreign bodies should be removed from traumatic wounds The wound not be closed---complete debridement is not possible ---try to avoid the introduction of new foreign bodies (prostheses, grafts, and suture materials)

The presence of hematomas, seromas, or dead spaces factors bacterial localization and growth and prevents the delivery of phagocytic cells to such foci The best way to prevents the fluid collection and infection ---to provide a system of closed suction drainage

Systemic factors Host resistance is abnormal in a variety of systemic conditions and diseases, including leukemia, diabetes mellitus, uremia, prematurity, burn or traumatic injury, advanced malignancy, old age, obesity, malnutrition , and several diseases of inherited immunodeficiency. ---extraordinary precautions should be taken, including correction or control of the underlying defect whenever possible

Malnutrition---significantly impair host defense mechanisms Hypermetabolism, this type of insidious malnutrition is probably the most important cause of acquired immunologic deficiencies ---to correct any underlying malnutrition before surgical therapy Alimentation by the oral route is preferable

Social considerations #Infection rates---determined at 30days postoperatively rather than at discharge because more than one half of the infections occur after discharge #Each infection that is noted should be ---discussed in the surgical complications meeting ---categorized as apparently avoidable or apparently unavoidable The goal of surveillance and quality assurance should be to have no avoidable infections

Immunotherapy Active and passive immunotherapy to prevent surgical infection has merit in only a few specific instance *outstanding success in preventing tetanus * in preventing rabies * the use of pooled human gammaglobulin --agammaglobulinemia or a dysgammaglobulinemia

Reducing the bacterial load by prophylactic chemotherapy The administration of therapeutic doses of antimicrobial agents can prevent infection in wound contaminated by bacteria highly sensitive to the agents To use prophylactic antibiotic therapy---must be based on the weight of evidence for possible benefit against the weight of evidence for possible adverse effects

#indiscriminate or blind use of antibiotics---lead to emergence of antibiotic-resistant strains of organisms or serious hypersensitivity reaction #prolonged use of prophylactic antibiotics--mask the signs of established infections, making diagnosis more difficult # prophylactic antibiotic therapy ---no substitute for careful surgical technique ---be used effectively only adjuvants to adequate surgery

# prophylactic antibiotic therapy ---in these situations which involve a brief period of contamination by organisms that can predicted with reasonable accuracy Prophylactic antibiotic therapy in the following circumstances: 1.High-risk gastroduodenal procedures 2.High-risk biliary procedures 3.Resection and anastomosis of colon or small intestine

4.Cadiac procedures through a median sternotomy 5.Vascular surgery of the lower extremities or abdominal aorta 6.Amputation of an extremity with impaired blood supply, particularly in the presence of a current or recent ischemic ulcer 7.Vaginal or abdominal hysterectomy 8.Primary cesarean section 9.Operations entering the oral pharyngeal cavity in continuity with neck dissections 10.Craniotomy

14.Injuries prone to clostridial infection because of extensive devitalization of muscle, heavy contamination, and/or impairment of blood supply 15.Presence of pre-existing valvular heart damage, to prevent the development of bacterial endocarditis

11.The implantation of any permanent prosthetic material 12.Any wound with known gross bacterial contamination 13.Accidental wounds with heavy contamination and tissue damage.

#prophylactic antibiotic therapy is clearly more effective when begun preoperatively and continued the intraoperative period #the use of topical antibiotics often effectively diminishes the incidence of infection in contaminated wounds # prophylactic antibiotic therapy is generally ineffective in clinical situations in which continuing contamination is likely to occur