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单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,Surgical Infection,Teng Changsheng,Dept. of general surgery,Beijing Friendship Hospital,Affiliated to Capital University of Medical Sciences,GENERAL CONSIDERATIONS,Surgical infections can be defined as infections that require operative treatment,or result from operative treatment.,Infections that require operative treatment,1. necrotizing soft tissue infection,2. body cavity infection,3. confined tissue, organ, and joint infection,4. prosthetic device-associated infections,Classification of Surgery Infection,一 according to pathogenic bacterial:1. Nonspecific infection,staphylococcus aureus ， Streptococcus Escherichia coli， Bacillus proteus，pseudomon.,2. Specific infection,二 according to pathogenic process1.Acute infection2.Chronic infection3.Subacute infection,Infections that result from operative treatment include:,1. wound infection,2. postoperative abscess,3. postoperative peritonitis,4. postoperative body cavity infections,5. hospital-acquired infection(,result from the transmission of pathogens from a source in the hospital environment to a previously uninfected patient,) such as pneumonias, urinary tract infection.,Determinants of Infection,The development of surgical infection depends on several factors:,1. Microbial pathogenicity,2. Host defenses,3. The local environment,4. Surgical technique,Microbial Pathogenicity,1.Thick capsules,2. Resist digestion by lysosomal enzymes.3.Elaborate toxins: endotoxins ,neurotoxins,Local Environmental Factors,Local environmental factors inhibit systemic host defenses from being fully effective:,Devitalization of tissue,Foreign bodies,Diagnosis,Diagnosis of surgical infection should be accorded to clinical examination and laboratory examination.,Clinical Examination,1.Systemic symptoms:,Fever and Chills,Elevated pulse rate,2.Endemic signs and symptoms:,Redness Swelling Heat Pain,Loss of function.,3. shock , dysfunction of organs,4.Special manifestation,Laboratory Examination,1. Blood routine examination,Leukocytosis :white cell count 10000 /ml,immature granulocytes85 % .,2. Exudate Examination,Exudate should be examined by macro and micro method,Physical nature:color,odor,consistency,3.,Blood culture,It is the single most definitive method of determining etiology in infectious disease . The laboratory should be requested to do aerobic and,anaerobic cultures and antibiotic-sensitivity tests.,When should we take a blood culture ?,Principle of Therapy,The aim of principle of therapy is to inhibit bacterial proliferation and promote body tissue recurrence. The patients own host defenses and antibiotic therapy are adequate to overcome most infections,(1) Endemic treatment,Immobilization of infective area and have a rest,Medicines,Physical therapy,Operation,Operative treatment include,:,incising and draining an abscess,opening an infected wound,removing an infected foreign body,repairing or diverting a bowel leak,draining an intra-abdominal abscess,Systemic treatment,It apply for severe infection especially systemic infection. Methods include: support treatment, antibiotics and operation.,TYPES OF SURGICAL INFECTIONS,Soft Tissue Infections:,Infection of the soft tissues, skin, subcutaneous fat, fascia, and muscle, usually can be treated by antibiotics unless an abscess is present or tissue necrosis is present.,Cellulitis,Cellulitis is a spreading infection of the skin and subcutaneous tissues.,It is characterized by local pain and tenderness, edema, and erythema. Usually the border between infected and uninvolved skin is indistinct,Cellulitis and lymphangitis can be treated by antibiotics alone. Local care includes immobilization and elevation to reduce pain and swelling. Failure to achieve prompt clinical response should suggest that suppuration has occurred and that surgical drainage is required.,Erysipelas,Erysipelas is an acute spreading cellulitis and lymphangitis, usually caused by hemolytic,strepotococcus,which gain entrance through a break in the skin.,Characteristics: abrupt onset, chills, fever, and prostration. The skin is red, swollen, and tender, and there is a distinct line,Abscess and Furuncle,An abscess is localized collection of pus surrounded by an area of inflamed tissue in which hypermia and infiltration of leukocytesis marked.,A furuncle is an abscess in a sweat gland or hair follicle. The inflammatory reaction is intense, leading to tissue necrosis and the formation of a central core. This is surrounded by a peripheral zone of cellulitis.,Carbuncle,A carbuncle is a multilocular suppurative extension of a furuncle into the subcutaneous tissue.,The nape of the neck, dorsum of trunk, hands and digits, and hirsute portions of the chest and abdomen are apt to be involved. Individual compartments in a carbuncle are maintained through persistence of fascial attachments to the skin. As these numerous component locules rupture separately, individual fistulas appear.,Necrotizing Soft Tissue Infections,Soft tissue infection that result in tissue necrosis are less common than other forms of soft tissue infections but are more serious because of their propensity for extensive destruction of tissues and high mortality rate.,Names such as necrotizing fasciitis, streptococcal gangrene, bacterial synergistic gangrene, clostridial myonecrosis, and Fourniers gangrene are commonly used.,Differentiate these infections are based on predisposing conditions, presence of pain, toxicity, fever, presence of crepitus, appearance of the skin and subcutaneous tissues, and whether or not bullae are present.,Necrotizing fasciitis is rarely limited to fascia and myonecrosis is rarely limited to muscle.,Pathogenic bacterial,Most necrotizing soft tissue infection are caused by mixed aerobic and anaerobic gram-negative and gram-positive bacteria.,Clostridium,species are the most common, cause the most dramatic infections with rapid progression, early toxicity, and high mortality rate.,Manifestation and Diagnosis,skin necrosis or bullae crepitus,Early mental confusion, toxicity, and failure to respond to nonoperative therapy,Treatment,Surgical treatment requires debridement of all necrotic tissue. All necrotic tissue must be removed. Amputation may be required for myonecrosis of the extremities. The wound must be inspected daily until the surgeon can be sure there is no further necrosis.,Initially, broad-spectrum antibiotics should be administered.,Hyperbaric Oxygen Treatment,The use of hyperbaric oxygen to treat necrotizing soft tissue infections is controversial.,Hyperbaric oxygen inhibits production of alpha toxin by clostridium.,Tetanus,Tetanus is caused by,C. tetani,a large gram-positive sporeforming bacillus. It is acquired by implantation of the organisms into tissues by means of breaks in the mucosal or skin barriers.,Action of C. tetani,C. tetani,elaborates :,tetanospasmin,tetanolysin.,Tetanospasmin acts on the anterior horn cells of the spinal cord and on the brainstem. It blocks inhibitor synapses at these sites, leading to muscle spasms and hyperreflexia.,Tetanolysin is cardiotoxic and causes hemolysis,Manifestation of Tetanus,Symptoms: restlessness, headache, muscle spasms with vague discomfort in the neck, lumbar region, and jaws,swallowing difficult, stiff neck,Progressively,Orthotonos, opisthotonos, and emprosthotonos ,Generalized toxic convulsions. These convulsions may involve the laryngeal and respiratory muscles and result in fatal acute asphyxia.,Other symptom:Throughout these spasms, which can be extremely painful and even cause fractures, the patient remains mentally alert. The pulse is elevated and there is profuse perspiration. Fever may or may not be present.,Diagnosis,Diagnosis of tetanus is based on the clinical picture associated with no prior history of immunization.The differential diagnosis can be difficult in early tetanus. Even with adequate treatment.,Treatment,Patients require exquisite nursing care and should be monitored. Initially therapy consist of administration of tetanus immune globulin(TIG), 500 to 10,000 units, as soon as the diagnosis is made. Currently most are treated in an intensive care unit on a respirator with paralytic drugs given to prevent muscle spasms.,Mild cases can be treated with sedation, but most physicians administer muscle relaxants. Adequate doses of analgesics are required because of,the pain associated with muscle spasms. Detailed attention must be given to care a paralyzed individual who is on a respirator. Adequate nutrition must be provided. Laxatives are generally indicated so that gastro-intestinal elimination can be facilitated. A urinary catheter should be provided. The patient will require eye protection to prevent desiccation.,The wound must be treated to remove as much of the,C. tetani,and nonviolable tissue as possible. Debridement of all necrotic tissue should be done. Penicillin G should be administered to treat any,bacteria that remain behind, but antibiotics are no substitute for good wound care.,Prevention.,Active immunization with tetanus toxoid (TD) is a safe and effective way of preventing tetanus. Unfortunately many children in the United States are not adequately vaccinated; immunization is also inadequate in many developing countries. One month after the diagnosis of tetanus is made, the patient should be begun on tetanus toxoid immunization. The dose of tetanus toxin mediated during an infection is so small that immunization does not occur.,Bacteremia,Bacteremia is defined as bacteria in the circulating blood with no indication of toxemia or other clinical manifestations. Bacteremia is usually transient and may last only a few moments,In toxemia, toxins are circulating in the blood, though the microorganism producing the toxin need not be. Toxemia is usually associated with infection by toxin-producing bacteria(e.g.,the clostridia of gas gangrene and the diphtheria bacillus), but this is not always so. For example, botulinum toxin or staphylococcal enterotoxin may have been ingested directly to cause a profound toxemia without true infection.,Septicemia,Septicemia is a diffuse infection which infectious bacteria and their toxins are present in the bloodstream. Septicemia may arise directly from the introduction of infecting otganisms into the circulation but, as a rule, is secondary to a focus of infection within the body. The major routes by which bacteria reach the blood are (1) by direct,extension and entrance into an open vessel.,(2) by release of infected emboli following thrombosis of a blood vessel in an area of inflammation, (3) by discharge of infected lymph into the bloodstream following lymphangitis. Many specific diseases, e.g., typhoid fever and,brucellosis, include a septicemic phase. In the absence of systemic disease, beta-hemolytic streptococci are most frequently responsible.,Septicemia caused by alpha-hemolytic streptococci is usually a consequence of subacute bacteria endocarditis.,The majority of bacteria that produce suppurative lesions may give rise to secondary septicemia. Pyemia is septicemia in which pyogenic,microorganisms, most notably,staphylococcus aureus,and their toxins are carried in the bloodstream and sequentially initiate multiple focal,abscess in many parts of the body. Before the advent of chemotherapy, staphylococcic pyemia was almost always fatal; the mortality is still high.,ANTIMICROBIAL THERAPY,The use of antimicrobials in treating surgery infections does not differ fundamentally from antimicrobial usage in general medicine. The same basic considerations apply in treating all infections. One difference, however, is that antimicrobial therapy is only an adjunct in treating surgical infection; operative treatment is the main method of therapy. The goal of antomicrobial therapy is to prevent or treat infection by reducing or eliminating pathogenic organisms until the hosts own defenses can get rid of the last pathogens.,The basic consideration in antimicrobial therapy are efficacy, toxicity,and cost. Effectiveness is the most important consideration in choosing antimicrobial therapy. Effective antimicrobial agents must be active against the pathogens the infection and must be able to reach the site of infection in adequate concentrations.,All antibiotics have potential toxicity. Toxic effects may be idiosyn-craticsuch as allergy or the rare instance of bone marrow aplasia caused by chloramphenicol or result in damage to tissue and organs as renal or ototoxicity seen with the aminoglycosides or amphotericin B. Antimicrobial agents also exert selective pressures on the microbial ecology of the hospital that lead to resistant microbes, a problem that can occur especially in intensive care unit settings.,Cost is the final consideration in the selection of antimicrobial agents. Determining antimicrobial costs includes, nursing time, intravenous fluid,and lines, and monitoring costs must also be added to drug costs. The increased hospital time that occurs when an inexpensive but also less,effective agent is used should also be included in costs. Obviously an inexpensive agent that is not effective or that causes more toxicity ultimately becomes a more expensive antimicrobial.,Distribution of Antimicrobial Agents,Successful treatment of localized infections with systemic antimicrobial agents requires that an adequate concentration of drug be delivered to,the site of infection. Ideally the tissue concentration of antibiotics should exceed the minimum inhibitory concentration. Tissue penetration depends in part on protein binding of antibiotics. Only the unbound form,of antibiotics will pass through the capillary wall or act to inhibit bacterial growth.,Therapeutic outcome, on the other hand, appears,uncorrelated with protein affinity, presumably because protein binding is easily reversible. Lipid solubility of antibiotics is also an important,factor in tissue penetration. it determines the ability of antibiotics to pass through membranes by nonionic diffusion or into wounds, bone,cerebrospinal fluid, the eye, endolymph of the ear, vegetation of bacterial endocarditis, and abscesses.,Blood.,Rapidity of excretion and protein binding are two main determinants of blood concentration of antimicrobial agents. Protein binding affects the rapidity of excretion. Antibiotics that are highly protein bound are not excreted as rapidly as those with a low binding affinity and thus have longer half-lives. Therefore, highly protein bound antibiotics generally do not have to be given as frequently as those with low protein binding. Efficacy of penicillins, cephalosporins, and other antibiotics that affect bacterial cell wall synthesis depends on the time during which serum levels are above the minimum inhibitory concentra- tions rather than a peak serum concentration.,Efficacy of aminoglycosides, on the other hand, is related to achieving peak serum concentrations that are four to eight times the minimum inhibitory concentration. Monitoring of serum aminoglycoside concentration is usually necessary to ensure that these concentration have been achieved; patients more commonly have subtherapeutic levels rather than toxic levels. On the other hand, some antimicro- bial agents such as nitrofurantoin and norfloxacin are rapidly in the urine that they never achieve blood levels sufficient to achieve effective antibacterial concentrations. They do, however, reach high urinary concentrations and are effective agents fortreating urinary tract infections.,urine.,Most commonly used antibiotics (sulfonamides, penicillins, cephalosporins, aminoglycosides, tetracyclines, quinolones, azoles) are excreted principally in the urine and achieve high urinary,concentrationsup to 50to 200 times their serum concentration.Notable exceptions are erythromycin and chloramphenicol. Since concentrating ability is severely compromised in patients with renal disease, infections of the urinary tract are more difficult to,treat in these patients.,The pH of urine can be changed to facilitate,antibiotic activity. For instance aminoglycosides are more active in an alkaline medium, whereas other urinary antibacterial agents are more,active in an acidic environment. Fortunately, the antimicrobials most commonly used to treat urinary tract infections have antimicrobial,activity across a broad pH range.,Bile.,Besides urine, only bile regularly has concentra- tions of antibiotics higher than found in serum. The biliary concentrations of many of the penicillins especially nafcillin, piperacillin mezlocillin, and azlocillin; cephalosporins especially cefazolin, cefadroxil; tetracyclines; and clindamycin frequently are several times their serum contractions. Nafcillin and rifampin achieve biliary concentrations 20 to 100times that of serum. Aminoglycoside antibioticsenter bile less well, especially in the presence of liver disease. Their biliary concentrations are usually lower than serum levels.,Interstitial Fluid and Tissue.,High , prolonged serum concentration and low protein binding favor diffusion of antibiotics from serum into extra vascular tissue. Absolute tissue levels may not accurately reflect the therapeutic of the antibiotic, however, because the agent may be tightly bound to tissue and thus be unavailable for binding to bacteria.,Abscesses.,There are few date of clinical relevance concerning the distribution of antibiotics into abscesses. The generalization that no antibiotics penetrate abscesses is not true. While the penicillins, ephalosporins, and some other antibiotics penetrate mature abscesses poorly, others such as metronidazole, chloramphenicol, and clindamycin an achieve inhibitory concentrations in abscesses.,A separate problem is whether, after penetration, antibiotic retain its antimicrobial efficacy under the conditions that exist in an abscess. The acidic pH, low redox potential, and the large numbers of microbial and tissue products that can bind antibiotics all serve to reduce antimicrobial efficacy. Multiple types of bacteria within an abscess make it more likely that one type will inactivate an agent effective against it or another bacteria.,The lack of efficacy of penicillins and,cephalosporins in treating most abscess may be due to high concentrations of betal lactamasesthat accumulate there.Metronidazole and clindamycin can both enter abscesses and retain antibacterial activity in such environments. but these antibiotics are not effective against the aerobic gram-negative bacteria that are usually present together with the anaerobic bacteria against which they are effective, so the abscess usually persists.,An additional reason that antibiotics alone are seldom effective in treating abscesses is that antibiotics are most effective against actively metabolizing, rapidly dividing bacteria. Conditions in,abscesses are usually unfavorable for such active metabolic activity, so the antibiotics is not able to enter and be active against the bacteria. For all these reasons antibiotics alone should not be relied on to treat most abscesses. Despite occasional reports of success with such treatment, drainage remains the mainstay of abscess treatment.,Use of Antibiotics in Surgery,Prophylactic antibiotics.,Antibiotics are frequently administered prophylactically to patients undergoing operation to prevent wound infection where the likelihood of infection is high (when the tissue,have been exposed to bacteria such as occurs during colon surgery) or where the consequences of infection are great even though the risk of infection is low .Ant
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