Classification of procedures by infection risk
Depending on the probability of developing complications and contact with bacterial flora, all surgeries are divided into four types.
- "Clean" procedures (Type I). These are elective, non-traumatic interventions in which the lumens of the gastrointestinal tract, respiratory tract, or urogenital system are not entered. Examples: hernia repair, mastectomy, joint replacement. The probability of infection is minimal — less than 5%.
- "Clean-contaminated" procedures (Type II). These include elective surgeries on the GI tract, oropharynx, or female reproductive organs in the absence of overt inflammation. Emergency surgeries for closed trauma are also assigned to this group. The risk of complications is about 10%.
- "Contaminated" procedures (Type III). Wounds with signs of non-purulent inflammation. This is typical for opening infected biliary or urinary tracts, opening the lumen of the GI tract, as well as early primary surgical debridement (PSD) of open injuries within the first 24 hours. The probability of infection reaches 20%.
- "Dirty" procedures (Type IV). Interventions on knowingly infected tissues with a purulent process or perforation of hollow gastrointestinal organs. This also includes delayed primary surgical debridement (after 24–48 hours). The risk of suppuration is extremely high — 30–40%.
Risk factors for postoperative infection
The probability of complications depends on the balance between microorganism virulence and the patient's body reactivity. The main factors are divided into three groups:
- Patient factors. The frequency of complications directly correlates with the patient's age. In elderly people, defense mechanisms are reduced, the skin of the anterior abdominal wall is often flabby, and comorbid conditions (diabetes mellitus, anemia) impair healing.
- Disease factors. The presence of latent infections, peritonitis, intestinal obstruction, or malignancies increases the chances of developing a purulent process.
- Intraoperative factors. The highest risk (a 3- to 4-fold increase in infection probability) is posed by excessive surgical trauma, surgery lasting over 3 hours, and the presence of purulent effusion. Violations of asepsis rules, rough tissue handling by the surgeon, and excessive adipose tissue also contribute significantly.
Measures for the prophylaxis of surgical site infection
Even the strictest adherence to sterility in the operating room is often insufficient. Therefore, prophylaxis is comprehensive and divided into two main areas.
Nonspecific prophylaxis begins at the preoperative preparation stage. Its goal is to increase the patient's resistance to trauma. To achieve this, water-electrolyte and protein balances are normalized, blood loss is replenished, and anti-shock therapy is administered. During the surgery itself, the surgeon's operational speed, delicate handling of wound edges, and meticulous hemostasis play a crucial role.
Specific prophylaxis targets the likely causative agent of the infection.
- Systemic antibiotic prophylaxis: Intravenous administration of drugs before, during, and after surgery to maintain their concentration in the blood.
- Local impact: Maintaining the minimum inhibitory concentration of the antibiotic directly in the wound tissues (locus minoris resistentiae). To achieve this, depot drugs are used — antiseptic suture material, collagen sponges, and special adhesive compositions. They slowly release the medication, suppressing bacteria and stimulating regeneration.
Peculiarities of antibiotic prophylaxis by type of surgery
The surgeon determines the need for antibiotics based on the class of surgery and localization:
- Abdominal surgery: For interventions on the stomach with reduced acidity or on the colon, prophylaxis is mandatory (cephalosporins with metronidazole are used). For acute appendicitis, the regimen is similar.
- Biliary tract: The drug must be well excreted in bile (e.g., cefazolin or ciprofloxacin during endoscopic procedures).
- Vascular surgery: The overall risk of suppuration is low, but graft infection (most often by staphylococci in the groin area) threatens limb loss or death. Therefore, a preventive course is necessary.
- Splenectomy: Due to the loss of the spleen, immunoreactivity drops sharply. The risk of severe sepsis persists for more than 20 years, so all such patients are indicated for antibiotics.
Briefly: answers to topical questions
Which microorganisms are the main causative agents of infectious complications in biliary tract surgeries?
The main causative agent of wound infectious complications in biliary tract operations in patients with negative cultures is Staphylococcus aureus (S. aureus).
- Staphylococcus aureus (S. aureus) is the most frequent microbial agent of wound infection in the absence of initial bile infection.
In patients with prior infection, the development of infection is associated with the microflora cultured from bile, however, the specific spectrum of pathogens with a positive culture is not detailed in the materials.
Which antibiotic groups are drugs of choice for specific prophylaxis in vascular surgery?
The drugs of choice for antibiotic prophylaxis in vascular surgery are cephalosporins and fluoroquinolones.
- First- and second-generation cephalosporins are the baseline drugs of choice for preventing infectious complications.
- Third-generation cephalosporins are recommended for use when there is a high risk of infection development.
- Fluoroquinolones are prophylactic agents especially indicated when performing bypass procedures.
Prophylaxis is directed against staphylococci due to the danger of limb loss or death.
Class and exam questions
Are antibiotics always necessary for "clean" surgical operations?
In most cases, antibiotic prophylaxis for type I operations is inappropriate. An exception is made for immunocompromised patients and during the placement of prostheses (artificial joints, vascular shunts), where the consequences of infection are catastrophic.
Why is it difficult to achieve the required antibiotic concentration directly in the wound with systemic administration?
Aseptic inflammation develops in the area of surgical injury, tissue edema occurs, and microcirculation is impaired. This hinders drug delivery from the bloodstream to the focus, which is why surgeons often use local depot carriers.
Which pathogens most frequently cause complications in lower GI tract surgeries?
In interventions on the appendix, colon, and rectum, Escherichia coli (E. coli) is most commonly detected; therefore, the regimen includes drugs active against gram-negative and anaerobic flora (e.g., metronidazole).
What else to study on this topic
- Mechanisms of contact, hematogenous, and lymphogenous spread of endogenous infection
- Principles of application of immobilized depot drugs in surgical materials
- Assessment of risk factors based on the duration and traumatic nature of the intervention
- Delayed septic complications after splenectomy in children and adults
- Differences between antibiotic prophylaxis and therapeutic antibiotic courses
Master the entire topic in the "General Surgery" course
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- Complete study guide on "Prophylaxis of infectious complications in surgery" and 3,335 more pages of the subject
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Other topics in "CHAPTER 8. SURGICAL OPERATION"
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