Understanding Nosocomial Infections: Types, Factors, and Prevention
Transitory and Resident Flora
Transitory flora: Microorganisms that colonize the upper layers of the skin, acquired by direct contact. They are the most frequent microorganisms in nosocomial infections and are easily removed with handwashing.
Resident flora: Microorganisms that reside in the deeper layers of the skin. They are more difficult to remove with handwashing and are less related to nosocomial infections.
Surgical Wound Classification
- Clean: Wounds not originating from the airway, gastrointestinal tract, or infected tissues. The risk of contamination is exogenous.
- Clean-contaminated: Wounds resulting from interventions in cavities connected to the outside.
- Contaminated: Open wounds less than 4 hours old.
- Dirty or infected: Traumatic wounds more than 8 hours old.
Factors Influencing Infection Risk
Exogenous Factors (Preventable)
- Room scheduling software system
- Deficient or contaminated aeration
- Inadequate sterilization of surgical material
- Contaminated antiseptics
- Inappropriate patient preparation
- Poor surgical technique
Endogenous Factors (Patient-Related)
- Age
- Underlying diseases
- Prolonged hospitalization
- Preoperative treatment
- Pathogens introduced during surgery
Universal and Specific Precautions
Universal precautions: Precautions that should be used during any contact with blood or body fluids.
Standard precautions: Must be applied to patients with coughs, and when handling blood, body fluids, secretions, non-intact skin, and mucous membranes.
Specific precautions: Applied to infected patients and are divided into categories based on the mode of transmission: airborne, droplet, contact, or for immunocompromised patients.
Isolation Measures
Isolation measures are barriers for each transmission mode, preventing the spread of infection to other people.
Specific Rules for Each Isolation Type
Airborne
- Mask
- Room with negative ventilation
- Educate the infected person
- Seal waste in a plastic bag before disposal
- Minimize exits from the room
- Examples: Measles, chickenpox, herpes zoster, SARS
Droplet
- Mask
- Minimize exits from the room
- Examples: Pharyngitis, influenza, meningitis, Neisseria, mumps, whooping cough, diphtheria
Contact
- Transmission by direct or indirect contact with mucous membranes and skin
- Gloves
- Gowns
- Clean room
- Restricted exits from the room
- Examples: Multiresistant bacterial infections, Staphylococcus aureus, head lice, scabies, cutaneous diphtheria, Clostridium difficile, hepatitis, conjunctivitis, decubitus ulcers, furuncles
Methicillin-Resistant Staphylococcus Aureus (MRSA)
MRSA are bacteria resistant to most antibiotics, are very difficult to eliminate, and often cause very serious consequences.
Frequent Types of Nosocomial Infections
- Urinary: 25%
- Respiratory: 25%
- Surgical wound: 15%
- Sterile sites: 3%
- Other: 32%
Prevention Measures
- Source of infection: Specific isolation, application of universal precautions
- Transmission mechanism: Handwashing, hygiene protocols
- Host: Isolation, chemoprophylaxis, vaccination
Epidemiologic Chain
Causative agent (bacteria, fungi, parasites) → Source of infection (endogenous, exogenous: caregiver) → Transmission mechanism (direct, important in hospitals, or indirect: contaminated objects) → Host (healthcare and non-healthcare personnel)
Operating Room Attire
Cap, mask, socks, surgical handwashing, sterile gown.
The Uniform
The uniform serves as identification and protection, indicating who is healthcare personnel.