Asepsis and Antisepsis in Surgical Practice

Overview and Core Principles

• Conceptual Definitions:     * Asepsis: A set of practices designed to prevent contamination by ensuring that microorganisms do not enter the operative field or wound.     * Antisepsis: The process of killing or inhibiting the growth of microorganisms already present on living tissues (skin or wounds).
• Goal of Asepsis and Antisepsis: The primary objective is to avoid Surgical Site Infection (SSI).
• Clinical Significance: Prevention is paramount because surgical infection is considered one of the most serious complications in the field of surgery.
• The Critical Window: The first $2\,\text{hours}$ of surgery represent the critical period for preventing infection.

Historical Milestones in Asepsis and Antisepsis

• Ignaz Semmelweis ($1847$):     * Introduced hand washing with chlorinated lime.     * Successfully reduced mortality rates from $14.5\%$ to $1.2\%$.     * Exam Association: Semmelweis is primarily associated with Asepsis.
• Joseph Lister ($1865$):     * Introduced the use of carbolic acid (phenol) for disinfecting wounds and instruments.     * Exam Association: Lister is primarily associated with Antisepsis.
• Louis Pasteur: Demonstrated that microorganisms are the causative agents of infection.
• Robert Koch: Developed Koch’s postulates, providing a framework to identify the specific causative agents of disease.

Surgical Site Infections (SSI): Sources and Routes

• Primary Sources of Pathogens:     1. Patient: Derived from endogenous flora (the patient's own microorganisms).     2. Personnel: Microbes carried on the hands or clothing of the surgical team.     3. Environment: Pathogens present in the Operating Room (OR) air or on various surfaces.
• Routes of Contamination:     1. Direct Inoculation: Occurs via the surgeon’s hands, surgical instruments, the patient’s own skin flora, or through drains and catheters.     2. Airborne: Contamination via skin flakes, clothing particles, or through OR airflow patterns.     3. Hematogenous: Infection spreading to the surgical site from distant infection sites via the bloodstream.
• Epidemiology and Impact:     * SSI is the most common nosocomial (hospital-acquired) infection in surgical patients.     * Incidence Rates:         * General Surgery: $1\text{--}3\%$.         * Colon Surgery: Approximately $10\%$.     * Healthcare Burden: SSIs increase the duration of hospital stays by an average of $5\text{--}15\,\text{days}$.

Contamination Types and Risk Factors

• Patient-Related Risk Factors:     * Advanced age.     * Obesity and malnutrition.     * Smoking habit.     * Diabetes (specifically poor glycemic control).     * Immunosuppression.     * Prolonged preoperative hospital stays.
• Surgical Risk Factors:     * Long duration of operation.     * Hypothermia during surgery.     * Poor surgical technique (e.g., inadequate hemostasis).     * Break in sterility during the procedure.
• Classification of Skin Flora:     * Resident Flora: Microorganisms found in deep layers of the skin; they are difficult to remove entirely.     * Transient Flora: Microorganisms found superficially on the skin; they are easily removed through proper hygiene.     * High-Yield Fact: Hand hygiene is primarily effective at removing transient flora.

Prevention Strategies for Surgical Site Infection (SSI)

• Preoperative (Before Surgery):     * Adherence to strict hand hygiene.     * Thorough skin preparation of the patient.     * Administration of antibiotic prophylaxis when indicated.     * Rigorous control of blood sugar levels.     * Minimizing the length of the preoperative hospital stay.
• Intraoperative (During Surgery):     * Employing good surgical technique, with a focus on meticulous hemostasis.     * Maintaining the patient’s body temperature (preventing hypothermia).     * Ensuring adequate tissue oxygenation.     * Frequent glove changes as necessary.
• Postoperative (After Surgery):     * Practicing sterile wound care.     * Maintaining hand hygiene during dressing changes.     * Recognizing the critical window for infection development is within the first $2\,\text{hours}$.

Comparison: Asepsis vs. Antisepsis

Sterilization and Disinfection Methodologies

• Sterilization: Defined as the complete destruction or removal of all forms of life, including bacterial spores.     * Autoclave (Steam under pressure): The gold standard and most important method.         * Settings: $134^{\circ}\text{C}$ for $3\,\text{min}$ OR $121^{\circ}\text{C}$ for $15\,\text{min}$.         * Requirement: Steam must have direct contact with all surfaces; a vacuum is required to remove air.     * Ethylene Oxide: Used for heat-sensitive items.     * Dry Heat: Utilizes high temperatures without moisture.     * Gas Plasma (H_2O_2): Hydrogen peroxide plasma for sterilization.
• Disinfection: Defined as the reduction or destruction of pathogenic microorganisms, though it does not necessarily eliminate spores.     * Common Disinfectants:         * Alcohol ($70\%$ Isopropyl).         * Chlorhexidine.         * Povidone-iodine (Betadine).         * Hydrogen peroxide.

Patient Preparation Protocols

• Pre-Surgical Hygiene: The patient should take a bath or shower as close to the time of surgery as possible.
• Hair Removal Timing and Infection Risk:     * Immediately before surgery: results in a $1\%$ infection rate.     * $12\,\text{hours}$ before surgery: results in a $5\%$ infection rate.     * Preferred Method: Clippers are preferred over razors to avoid skin micro-trauma.
• Skin Preparation Agents:     * Alcohol: Fast-acting but has a short duration of action.     * Chlorhexidine: Provides long-lasting residual activity.     * Iodine/Povidone-iodine: Offers a broad spectrum of activity.

Hand Hygiene and Surgical Scrubbing Procedures

• Hospital Hand Hygiene:     * Duration: $30\,\text{sec}$.     * Purpose: Removes transient flora.
• Surgical Scrubbing:     * Duration: $5\,\text{min}$.     * Purpose: Removes transient flora and significantly reduces resident flora.
• WHO ―5 Moments for Hand Hygiene‖:     1. Before touching a patient.     2. Before a clean/aseptic procedure.     3. After body fluid exposure risk.     4. After touching a patient.     5. After touching patient surroundings.
• Surgical Scrub Phases:     1. Mechanical Phase ($2\,\text{min}$): Involves washing, rinsing, and drying with a sterile towel.     2. Chemical Phase: Involves applying disinfectant/alcohol rub for $5 \times 1\,\text{minute}$ rubbing cycles.

Operating Room (OR) Attire and Sterile Zones

• Required Attire:     * Surgical scrub suit.     * Surgical cap/hood (must fully cover hair).     * Mask (must cover mouth and nose completely; change if wet).     * Sterile gown.     * Sterile gloves.     * Shoe covers.     * Protective eyewear (if needed).
• Sterile Zones on a Gowned Person:     * Sterile: Front of the gown from the chest to the level of the waist; sleeves from the cuff to $10\,\text{cm}$ above the elbow.     * Non-Sterile: The back of the gown, the axillary region (armpits), and anything below the waistline.

Operating Room Design and Personnel Roles

• Environmental Design: Controlled airflow, designated sterile zones, and minimal foot traffic/movement.
• Personnel Responsibilities:     * Surgeon: Leads the team, makes clinical decisions, executes the operation, and maintains asepsis.     * Scrub Nurse: Maintains the sterile field, manages sterile instruments, assists the surgeon, and performs counts of instruments and sponges.     * Circulating Nurse: Provides non-sterile support, manages patient transfer, logistics, and documentation; does not enter the sterile field.

Patient Positioning on the Operating Table

• Positioning Importance: Ensures proper surgical exposure, prevents complications (pressure sores/nerve damage), and maintains physiological stability.

Postoperative Wound Management

• Dressing Functions:     * Absorb fluid and exudate.     * Protect the wound from environmental contamination.     * Maintain hemostasis (pressure).
• Dressing Change Rules: Hand hygiene must be performed during dressing changes; drapes should not be moved once placed.

Questions and Discussion (Self-Assessment)

• Q: What is the definition of nosocomial infection?     * A: A hospital-acquired infection that was not present or incubating at the time of admission and develops during the course of medical care or hospitalization.
• Q: How can wound infections be classified?     * By Contamination Class: Clean, Clean-contaminated, Contaminated, Dirty/infected.     * By Depth: Superficial, Deep, Organ/space infection.     * By Source: Endogenous (from the patient) or Exogenous (from the environment/personnel).
• Q: What are the rules of movement in the OR after scrubbing?     * Always keep hands above the waist and in front of the body.     * Never touch non-sterile objects.     * Sterile persons must pass each other sterile-to-sterile.     * Face the sterile field at all times.     * Minimize unnecessary movement and talking.
• Q: How should surgical gowns be donned and removed?     * Donning: Touch only the inner surface initially; keep hands inside sleeves until gloved; have an assistant tie the back.     * Removal: Remove gloves first (or together safely); touch only the contaminated inner surface; roll the gown inside-out to contain microbes.
• Q: What is the purpose of operative field isolation?     * To maintain a sterile field, prevent contamination, and expose only the necessary surgical area. Drapes should not be repositioned once placed; if movement is necessary, it must be in a sterile-to-sterile direction.