A6. Asepsis and antisepsis, nosocomial infections

Asepsis and antisepsis

Asepsis refers to a state where there are no microorganisms. Aseptic techniques are those aimed at minimising infection, which is very important in surgery. This includes the use of a sterile room, gloves, gowns, caps, proper hand washing and hygiene beforehand, and the use of sterile instruments.

Antisepsis refers to the procedure or application of antiseptic solution to disinfect an area, most commonly a skin. This is also very important in surgery and involves disinfecting the surgical area before the incision. Commonly used antiseptics in surgery include chlorhexidine, iodine compounds, and alcohols.

Hungarians love the fact that Ignaz Semmelweis introduced the concepts of antisepsis to obstetrics. He introduced the idea of washing hands in chlorinated lime between an autopsy and the examination of patients, which reduced the rate of puerperal fever by 90%. This earned him the nickname of “saviour of mothers”. Of note, Semmelweis was vilified by the medical community at the time for his theory, eventually suffered a nervous breakdown, was admitted to an asylum, beaten by the guards, and died of the injuries only a few days later.

Nosocomial infection

A nosocomial infection, also called healthcare-associated or hospital-acquired infections, refers to an infection which was not present during the time of admission, that the patient has acquired in an institution like a hospital. A nosocomial epidemic is a nosocomial infection that affects two or more patients, and there is a connection between the cases.

Problems with nosocomial infections:

• Many people in small area
• Hospitalized people often have impaired immunity or condition
• Microorganisms in the hospital often have increased resistance to antibiotics
• Microorganisms in the hospital are often more virulent than microorganisms in the community

Although intensive care units (ICUs) account for fewer than 10% of total beds in most hospitals, more than 20% of all nosocomial infections are acquired in ICUs. ICU-acquired infections account for substantial morbidity, mortality, and expense. Most bacterial infections that occur on the ICU have some sort of anti-microbial resistance.

Primary and secondary factors

Primary factors:

• Source of nosocomial infection
  • The patients themselves
    • From commensal bacteria
  • Other patients
  • Staff
  • Visitors
  • Medical equipment
  • Bedsheets
• Route of transmission
  • Direct contact
  • Indirect
    • Airborne
    • Waterborne
    • Foodborne
    • Objects, instruments
      • Clothing
      • Bedsheets
• Susceptible population
  • High number of susceptible people
  • Infants
  • Elderly
  • Immunocompromised
    • Diabetes mellitus
    • Cancer
    • Polytrauma
    • Surgical patients

Secondary factors:

• Crowded rooms
• Insufficient number of cleaning and nursing staff
• Lack of medical staff’s preventive approach

Types

Most common infections:

• Catheter-associated UTI
  • E. coli
• Ventilator-associated pneumonia (VAP) – occurs > 48 hours after initiation of invasive ventilation
  • Gram-negatives (pseudomonas, E. coli)
  • S. aureus
• Catheter-related bloodstream infection (CRBSI)
  • Staphylococci

Pathogens

Most problematic pathogens:

• Vancomycin-resistant enterococci (VRE)
• MRSA
• Pseudomonas aeruginosa
• Multidrug-resistant gram-negative bacteria

Risk factors

• Patients in poor condition
• Invasive interventions and devices
• Older age
• Comorbidities
• Long duration of hospitalization
• Antibiotic use

Prevention

• Risk stratification
• Avoid invasive procedures when possible
• Discontinue indwelling sources of infection when possible
• Reducing person-to-person transmission
  • Disinfection of hands
    • Before, during and after patient contact
    • Disinfection = reduce the number of microorganisms, killing most harmful microorganisms
    • Sterilization = kill all microorganisms
  • Personal hygiene
  • Protective equipment
• Preventing transmission from the environment
  • Asepsis, antisepsis, isolation of patients
  • Ensure sterility during procedures
  • Sterilization of equipment
  • Limit overuse of antibiotics
• Education and training of medical staff