WEEK 5

Objectives
  • Identify safety practices based on Biosafety level classification.
  • Enumerate the physical and chemical methods of microbial control.
  • Explain how the rate of microbial death is determined.
  • Identify and explain the different factors that influence the effectiveness of antimicrobial treatments.
  • Differentiate surgical asepsis from medical asepsis.
  • Describe nosocomial and healthcare-associated infections and their prevention.
  • Understand common protocols for infection control.
Importance of Microbial Control

To prevent the spread of human disease, it's essential to control the growth and abundance of microbes in or on items frequently used by humans. Proper microbial control measures are crucial in healthcare settings to protect both patients and staff from infections.

Biological Safety Levels

Biosafety Levels (BSL)

Each BSL requires a different level of biocontainment to prevent contamination and the spread of infectious agents to laboratory personnel and the community. Understanding these classifications helps establish appropriate safety protocols based on the risk associated with the microbes being handled.

Biological Safety Levels (BSL)
  • BSL-1: Low-risk microbes such as non-infectious bacteria and viruses. Minimal precautions needed, suitable for undergraduate labs.
  • BSL-2: Moderate-risk microbes typically indigenous to the community with limited transmission potential. Access restrictions and personal protective equipment (PPE) like gloves and face shields are required.
  • BSL-3: High-risk microbes that can cause serious illness or lethal infections via inhalation. Access is restricted, and workers must undergo medical surveillance and potential vaccination. Facilities must be equipped with specialized safety features such as HEPA filters.
  • BSL-4: Extremely dangerous microbes that pose a high risk of transmission and for which no vaccines are available. Maximum safety measures, including full hazmat suits and sophisticated laboratory design, are mandatory to prevent any escape of the agents.
Methods of Microbial Growth Control
  • Physical Methods: These include heat (moist and dry), radiation, and filtration. Effective against various microorganisms depending on the method used and exposure conditions.
  • Chemical Methods: Involves disinfectants, antiseptics, and sterilants to eliminate or reduce microbial populations on surfaces and tissues. Different chemicals target different microbial structures and functions, such as cell walls or metabolic pathways.
Effective Disinfection

Factors include:

  • Contact time: Longer contact with disinfectant can enhance effectiveness.
  • Concentration of disinfectant: Higher concentrations often lead to better kill rates but must be balanced with safety considerations.
  • Clean surface: A clean surface allows for more effective microbial kill as organic matter can shield microbes from disinfectants.
  • Correct application methods: Proper techniques ensure the contact time and coverage are adequate to maximize effectiveness.
Infection Control Guidelines
  • Medical Asepsis: Clean technique focused on reducing the presence and transmission of pathogens. Regular cleaning and disinfection of equipment and surfaces are critical components.
  • Surgical Asepsis: Sterile technique designed to keep areas free from all microorganisms, particularly during surgical procedures. This includes sterilization of instruments, maintaining sterile fields, and using sterile drapes.
Transmission-Based Precautions

Enhanced precautions for patients with known or suspected highly transmissible pathogens, categorized into:

  • Airborne precautions: Used for diseases transmitted through the air; requires special ventilation systems.
  • Droplet precautions: Required for diseases spread by respiratory droplets; involves the use of masks.
  • Contact precautions: Implemented to prevent transmission through direct or indirect contact with the patient or their environment.