Sterilization and Disinfection Flashcards
Lecture 4
What are approaches to control infectious disease agents?
1) the body’s own defense mechanisms - the field of immunology
2) chemotherapeutic agents - antibiotics and others
3) public health measures - national, state, local guidelines
4) sterilization and disinfection - control of infectious agents by physical and chemical means
Sterilization
the destruction of all forms of life, including all bacterial spores; complete state/all or nothing
What does - cide / -cidal mean?
to kill, make nonviable
What does -stasis / -static mean?
to prevent multiplication without necessarily killing the agent
Disinfection
a process that eliminates a defined scope of microorganisms, including some spores; used on inanimate objects
Antiseptics
chemical agents applied to the skin to eliminate or reduce the number of bacteria present, spores are unaffected
Sepsis
a toxic condition resulting from the presence of microbes or microbial products (toxins) in the body (NOT related to sterilization or disinfection
Asepsis
a condition free of viable microorganisms
Health-Care Associated Infections (HAIs) or Nosocomial Infections
infections acquired during a hospital stay or from other healthcare providers
Surfactants
compounds that lower the surface tension between two liquids, a gas and a liquid, or between a solid and a liquid
Detergent
a surfactant or mix of surfactants with cleansing properties while in dilue solutions
Soap
a salt/fatty acid used for cleaning and lubricating; soaps are surfactants
What is the primary purpose of soap?
to remove organic matter such as oils and dead skin cells that may harbor microorganisms
Aseptic techniques - Surgical
practices that prevent microorganisms from gaining access to surgical wounds and tissues of patients
How do we practice surgical asepsis?
hand washing with a surgical handrub technique using antiseptic and washed skin being kept wet with antiseptic for 3-5 minutes; cleaning and disinfecting or patient and surroundings before surgery
Aseptic techniques - Medical
practices designed to keep objects, personnel, patients, and the hospital environment free from agents that cause disease
What are examples of medical asepsis practices?
hand-washing, using gloves and gowns, incinerating body discharge, using sharp containers to dispose of syringes and needles
Body substance precautions
a system of isolation in which barrier techniques are used for specific patient interactions vs specific diagnoses; standard of care for all patients; wearing gloves, gowns, face protection, and giving private room for patient as needed
Special precautions
used in situations where patients have high-virulence airborne diseases such as TB
Infection control committee
each hospital establishes their own, includes distinguishing nosocomial infections and identifying the source and methods of transmission of each infection
Universal precautions
biosafety precautions in lab, assume all patients are infected with blood-borne pathogens, place specimens in a well constructed secure container with a lid, never pipette by mouth, always wash hands after completing lab activities
How should healthcare professionals clean a bio-hazard spill?
1) contain the spill (ex. cover with absorbent material)
2) saturate towels with appropriate disinfectant solution (recommended 1:10 dilution of bleach, pour on outer edge of absorbent material and work towards center)
3) wait 10-15 minutes
4) discard everything into appropriate container (including your gloves)
High-level disinfectant
uses a sterilant and kills everything but spores
Intermediate-level disinfectant
uses an agent that kills viruses, fungi, mycobacteria, and vegetative bacteria but not spores
Lowl-level disinfectant
uses an agent that kills vegetative forms of bacteria, some fungi, and lipid viruses
Critical item
introduced into a normally sterile body area, require sterilization (ex. surgical intruments)
Semi-critical items
touch intact mucous membranes; require high-level disinfectant agents (ex. endoscopes)
Non-critical items
touch unbroken skin; require intermediate to low-level disinfection agents (ex. BP cuff, crutches)
What factors influence the degree of killing?
type of bug, number of bigs, surface, contact time, temperature, pH, biofilms, concentration of disinfecting agent, presence of organic material (blood, sputum)
What can interfere with disinfection/killing?
soil can provide protection for microorganisms, a more basic pH is harder to sterilize
What problem can we encounter with bacterial endospores?
they are among the most resistant forms of life, they can survive intense temperatures; the genus Bacillus falls into this category
What problem can we run into with Mycobacteria?
they are rather resistant to aqueous disinfectants because of their waxy cell surface
What problem can we run into with blood-borne viruses?
they are problem agents because we can’t sterilize the bloodstream, meaning transmission is what we can prevent
What issue can we run into with environmental organisms?
they can be found in many different locations and are often resistant to chemical disinfectants (ex. Pseudomonas aeruginosa and Acinetobacter)
What heat methods we can use to achieve sterility and disinfection?
Moist heat, autoclave, dry heat, pasteurization, open flames/incinerators
Moist heat
coagulation of proteins caused by breaking of hydrogen bonds can kill some microorganisms
Autoclave (steam under pressure)
very effective, build 15 lbs of pressure to achieve 12 C for 15 or more minutes
Dry heat
170 C for 2 hours, can be used on powder, oil and glassware
Pasteurization
mild heating we use in food products to retain taste while sufficeintly killing microorganisms
Open flame/incincerators
not very common, but used to be used for tweezers and inoculating loops
What filter methods do we use to sterilize and disinfect?
membrane filters and high-efficiency particulate air filters (HEPA)
Membrane filters
made of multiple materials, used to prepare media that cannot withstand autoclaving and solutions for patient use
High-efficiency particulate air filters (HEPA)
used to filter air in operating suites and rooms of burn patients
What radiation methods do we use to sterilize/disinfect?
Ionizing radiation and ultra-violet light
Ionization radiation (gamma rays)
used for sterilization of plastics
Ultra-violet light
can disinfect air, have very little penetration and can only kill microorganisms suspended in air or on surfaces
What chemical methods do we use to sterilize/disinfect?
Chlorine, aldehydes, phenol, CHG, alcohols, iodine, heavy metals, oxidizing agents, QUATS, gaseous chemo sterilizers (very few achieve sterility, dilute according to manufacturer)
