S. Ya. Kosyakov, G. Z. Piskunov. This lecture examines the main indications for prescribing antibiotics in the perioperative period to prevent infectious complications. Specific recommendations are provided for selecting a class of antibiotic and specific antibiotics depending on the degree of bacterial contamination. Infectious complications are one of the main causes of failure in ENT surgery. Preventing postoperative infections is currently a matter of exceptional importance. Creating a predictably sterile wound is impossible, especially in ENT surgery. In 1964, a standard classification system was developed, dividing surgical interventions into four main groups based on the degree of microbial contamination: clean, clean-contaminated, contaminated, and dirty. According to this classification, as applied to otolaryngology, "clean" interventions are those performed in the absence of trauma or infection and not accompanied by entry into the respiratory tract and gastrointestinal tract. Consequently, the main sources of wound contamination during "clean" surgical procedures are air or exogenous factors. Infections occur in less than 5% of clean surgical procedures; examples of these in otolaryngology include stapedoplasty and cosmetic ENT surgery. Clean-contaminated surgical procedures are defined as those that involve entry into the respiratory tract but without significant contamination with its contents. The infection rate in clean-contaminated surgical procedures is less than 10%. Examples include operations on the nasal septum and turbinates. Contaminated surgical procedures include those that involve acute (but not purulent) inflammation, as well as procedures with a serious violation of sterility (surgery of the middle ear, pharynx, nose, and paranasal sinuses). This type of intervention is accompanied by postoperative infections in approximately 20%. Dirty surgical procedures include operations in the presence of an acute purulent infection. Infectious complications occur in at least 30% of "dirty" surgical procedures. Broadly speaking, perioperative prophylaxis may include general preventive measures such as antisepsis, the use of special cleaning, washing, and sterilization methods, and appropriate surgical techniques. Narrowly speaking, perioperative infection prophylaxis refers to the perioperative administration of anti-infective drugs to patients without signs of an existing infection to prevent postoperative infectious complications. The need for perioperative prophylaxis is dictated by the following: 1) postoperative infectious complications are the leading cause of morbidity and mortality among surgical patients; 2) postoperative infections can prolong hospital stay, increase the cost of patient treatment, and increase the workload of hospital staff. Consequently, perioperative prophylaxis is generally more reliable and cost-effective than treating infections that develop in patients who have not received prophylaxis or who have received it inadequately. Antibiotic prophylaxis is generally not required for clean surgical procedures, necessary for clean-contaminated procedures (surgery of the upper respiratory tract), and mandatory for contaminated procedures (surgery of the upper respiratory tract, pharynx, and ear). Thus, perioperative prophylaxis is considered an important part of any operation in which the postoperative infection rate exceeds 5% (this includes all contaminated and contaminated procedures, and some clean-contaminated procedures), as well as any operation in which the development of a postoperative infection can lead to catastrophic consequences (tympanoplasty, surgery for congenital defects, cochlear implantation, cosmetic surgery of the ENT organs). In addition, perioperative prophylaxis should be administered to any patient who, due to one or more risk factors, is at increased risk for postoperative infections (age, diabetes mellitus) or is at risk of death from a potential infection (e.g., with exposure of the dura mater, sigmoid sinus, or with the development of mediastinitis). Factors contributing to infection may be: A. External - humidity and heat, poor hygiene. B. Concomitant diseases: diabetes mellitus, malnutrition, vitamin deficiency, coagulation disorders. C. Previous treatment - radiation therapy, cytostatics, immunosuppressants, corticosteroids. D. Wound type - burns and shock, multiple injuries. D. Patient's condition - advanced age, decreased defense mechanisms. E. Inadequate treatment - lack of timely wound care, lack of wound immobilization, insufficient hemostasis, lack of antibiotic prophylaxis. Perioperative prophylaxis can protect surgical patients from a wide range of infectious complications, including abscesses, septicemia, foreign body infections (e.g., suture material and surgical implants), vascular infections, urinary tract infections, and respiratory tract infections. Antibiotic prophylaxis should take into account the following factors: surgical tactics, surgical technique, preoperative and postoperative treatment (e.g., hair shaving and skin preparation affect the incidence of infection), and the type of antibiotic. It is important to remember that the term "prophylaxis" can only be applied to surgical interventions undertaken in the absence of an established infection. If an infection is diagnosed before or during surgery, the term "treatment" should be used instead of "prophylaxis." It is important to clearly understand that antibiotics do not replace aseptic technique, are not antipyretics, or a tranquilizer for the physician. Antibiotics do not replace hand washing, surgical knowledge, or experience. The incidence of postoperative infection is influenced by the following characteristics of surgical technique: duration of surgery, one- or two-stage procedure, surgical approach, surgical technique, and the environment or technical equipment. To prevent postoperative infections, the following standards of surgical technique must be observed: minimal surgical trauma (gentle tissue handling, use of atraumatic suture material), infection prevention (disinfection, irrigation), prevention of suture tension, and prevention of tissue ischemia and dehydration. The incidence of infectious complications in an inexperienced surgeon can be 4 times higher than in an experienced one. Antimicrobials will not prevent trauma due to extensive tissue excision or excessive coagulation. It is a mistake to believe that short prophylactic courses of antibiotics can eliminate the consequences of serious surgical errors. Antimicrobials selected for a specific procedure should be active against the microorganisms that are most likely to be encountered; they do not necessarily eliminate all potential pathogens. The purpose of antibiotic administration is to reduce the number of microorganisms below the critical level required for infection development. In this regard, bactericidal antibiotics are preferable to bacteriostatic ones. The half-life and distribution in tissues and body fluids are important factors when choosing antibiotics for prophylaxis. Table 1. Half-lives of cephalosporins frequently used for perioperative prophylaxis. Cefamandole 0.5 hours Cefoxitin 0.7-1.0 hours Cefotaxime 1.0 hours Cefuroxime 1.3 hours Cefazolin 1.4 hours Ceftazidime 1.7 hours Cefoperazone 2.0 hours Cefonicid 4.5 hours Ceftriaxone 8.0 hours Ideally, drugs selected for perioperative prophylaxis should be characterized by a low frequency of side effects and allergic reactions. Therefore, antibiotics such as aminoglycosides, which can cause kidney damage, and penicillins, which can lead to severe allergic reactions, are less desirable in this regard than cephalosporins, which have a lower toxicity rate. Even if the anti-infective drug selected for perioperative prophylaxis is active against potential pathogens in vitro and has the desired pharmacokinetic properties, it is crucial that it demonstrates clinical efficacy in well-controlled clinical trials. When selecting a dose, the patient's body weight (volume of distribution) must be taken into account. Parenteral administration is preferable because it ensures patient compliance, full dose delivery, and eliminates the risk of aspiration. Many Russian hospitals continue to administer postoperative antibiotic prophylaxis (e.g., 5-7 days). Clinical studies have shown that prescribing antibiotics after surgery does not significantly reduce the incidence of postoperative infections. Pre- and intraoperative antibiotic prophylaxis with a single intravenous dose is most effective. Since the primary site of most postoperative infections is tissue, not serum, the ability of antibiotics to penetrate tissue (penetration index) is an important factor in selecting appropriate agents for surgical prophylaxis. The penetration index values ??of various beta-lactam antibiotics vary widely, ranging from approximately 14% for cefonicide to 92% for ceftriaxone (Table 2). Table 2. Tissue Penetration Index of Selected Beta-Lactam Antibiotics. Cefonicid (2 g) 14% Cefotetan (2 g) 33% Ceftazidime (2 g) 56% Cefotaxime (2 g) 70.6% Piperacillin (2 g) 73.5% Ceftriaxone (1 g) 92% Prolonging antibiotic prophylaxis for more than one day increases the risk of bacterial resistance to the drug, and during reoperations, antibiotic prophylaxis must be repeated. A single use of a short-acting antibiotic immediately before surgery provides adequate tissue drug levels to prevent wound infection for only 1-2 hours and does not provide the necessary coverage for the prevention of respiratory tract infections. The action of the antibiotic at an effective concentration for perioperative prophylaxis should extend throughout the entire perioperative "risk period". It covers the period from the beginning of the surgical procedure to its completion, as well as the postoperative period, during which the patient may be at increased risk of infectious complications directly related to the surgical procedure, the presence of catheters, tubes, and other postoperative factors. Postoperative prophylaxis that adequately covers the entire risk period will reduce not only the risk of wound infections but may also reduce the risk of other types of postoperative infections, such as respiratory and urinary tract infections. Perioperative prophylaxis should be administered 15-90 minutes before the scheduled time of surgery, depending on the drug's half-life and tissue penetration, to allow adequate drug concentrations to build up at the surgical site. When using a short-acting antibiotic, it is usually administered 15-45 minutes before surgery. If a drug with a long half-life, such as ceftriaxone, is used, it can be administered anytime between 15 minutes and 2 hours before surgery. Because the risk period can last much longer than the surgery itself, the effectiveness of antimicrobial prophylaxis may be reduced if its duration is too short. For example, a single administration of an antimicrobial with a short half-life immediately before surgery may ensure adequate tissue concentrations to prevent wound infection for 1-2 hours, but it will not always prevent the perioperative risk of infections, such as those of the respiratory tract. Therefore, in patients undergoing prolonged surgical procedures, antimicrobials with short half-lives should be repeated at intervals equal to twice their half-lives. Thus, despite the wide variety of antibiotics currently available to physicians, when choosing a drug for the prophylaxis of postoperative infections, it is advisable to favor third-generation cephalosporins, as they offer a sufficiently broad spectrum of activity and high efficacy. Within this group, ceftriaxone clearly has the advantage. Firstly, it has a broad spectrum of activity against common pathogens, including most gram-positive and gram-negative bacteria, as well as some anaerobes, and can therefore prevent postoperative infections in a wide range of surgical procedures. Secondly, it is highly resistant to inactivation by beta-lactamases, making prophylaxis failure unlikely. Thirdly, ceftriaxone has the longest half-life of all cephalosporins, so a single dose can protect patients from infection even during the longest surgical procedures. Finally, ceftriaxone is highly effective in clinical practice in preventing postoperative infections. The drug can be administered in a convenient and cost-effective single-dose regimen. These advantages currently make ceftriaxone the drug of choice for surgical prophylaxis. Antibiotics from other groups, such as fluoroquinolones and carbapenems, according to current thinking, should be used not for infection prevention but only for their treatment, leaving these drugs in reserve. Their unnecessary use can contribute to the development of resistant microorganisms, thereby depriving physicians of the ability to combat existing infections.