Sterilization, Disinfection, and Antiseptics Flashcards
Sterilization
Disinfection
Killing all forms of microbial life, including spores
Sterilization
Killing pathogenic microbes but not necessarily all microbes, prions, and spores
Disinfection
Removal of pathogenic microbes on inanimate objects to make them safe to handle or dispose
Decontamination
Factors affecting successful treatment
Organic load (e.g., blood, body fluids), type and number of organisms, germicide concentration, exposure time, object surface, temperature, pH, humidity, biofilm presence, and compatibility of germicides
Sterilization methods for critical items like surgical instruments, cardiac/urinary catheters, and ultrasound probes
Ethylene oxide, hydrogen peroxide gas plasma, cold sterilization chemicals
Sterilization methods for semi-critical items like respiratory therapy equipment, endoscopes, and laryngoscope blades
Cold sterilization chemicals
Disinfection methods for non-critical items like bedpans, blood pressure cuffs, and environmental surfaces (e.g., bed rails, floors)
Low or intermediate level disinfectant
Sterilization method using steam under pressure at 121°C, 15 psi for 15-30 minutes; used for broth and media sterilization
Moist heat: Autoclave
Autoclave steam under pressure for medical waste and used media sterilization
132°C, 15 psi, 30-60 min
Method that uses 100°C, 30 min, 3 consecutive days: 1st day kills vegetative cells, 2nd day kills spores, 3rd day eliminates remaining cells
Moist heat: Tyndallization/Fractional sterilization
Method for sterilizing Lowenstein Jensen medium at 70-80°C, 2 hours, 3 consecutive days
Inspissation
Method for sterilizing glassware, cotton swabs, oils, petrolatum, and powders at 160-170°C for 1.5-3 hours
Dry heat: Oven sterilization
Method for sterilizing research animals and medical waste at 870-980°C with clean airflow
Incineration
Method for sterilizing heat-sensitive materials (e.g., antibiotics, vaccines, carbohydrates) with pore sizes of 0.45-0.80 µm for liquids, 0.22 µm for parenteral solutions, and 0.1 µm for small viruses
Membrane filtration
Method for air filtration in isolation rooms, operating rooms, and biological safety cabinets with 0.3 µm filtration capacity
HEPA filter
Method for sterilizing disposables using high-energy gamma rays, suitable for syringes, blood tubes, catheters, and gloves
Ionizing/Gamma radiation
Most common gas sterilant for heat-sensitive material, but with lengthy cycle times and health hazards
Ethylene oxide (ETO)
Oxidizing agent used in sterilizing HEPA filters in BSCs, metals, and medical instruments like scissors with no toxic by-products
Vapor-phase hydrogen peroxide
Method that generates plasma by exciting hydrogen peroxide gas in an enclosed chamber under deep vacuum using radiofrequency or microwave energy
Hydrogen peroxide gas plasma (H2O2)
Kills vegetative bacteria but not spores
Boiling at 100°C for 15 minutes
Batch method pasteurization for food pathogens, preserving nutritional value and flavor
63°C for 30 minutes
Flash pasteurization method for food pathogens with minimal nutrient damage
72°C for 15 seconds
Bailey’s pasteurization method to kill food pathogens
70°C for 30 minutes
Test for properly pasteurized milk to confirm absence of pathogens
Negative ALP/Phosphatase test
Non-penetrating radiation for disinfecting surfaces in BSC and contaminated rooms
Ultraviolet (UV) rays (long wavelength, low energy); requires direct surface exposure
Bioindicator for Autoclave
Geobacillus (Bacillus) stearothermophilus
Bioindicator for Dry heat/Oven
Bacillus subtilis, Bacillus atrophaeus
Bioindicator for Radiation
Bacillus pumilus
Bioindicator for Gas sterilant (Ethylene oxide)
Bacillus subtilis, Bacillus atrophaeus
Bioindicator clarification
Bacillus subtilis var. niger and Bacillus subtilis var. globigii are former names of Bacillus atrophaeus
Common autoclave used
Gravity displacement autoclave
Autoclave performance indicators
- Autoclave tape (white → black diagonal lines), 2. Autoclave strip (white → black), 3. Biological indicator (change of color after incubation)
Kills bacteria, mycobacteria, viruses, and fungi but not spores
“Alcohol (60-90% v/v); 60-62% waterless alcohol-based products can substitute for handwashing”
Common household disinfectant; kills bacteria, mycobacteria, viruses, fungi, and spores
“Sodium hypochlorite (NaOCl) 5.25-6.15%; Recommended 1:10 dilution for blood spills”
Used for disinfecting drinking water and daily disinfection tasks
“Sodium hypochlorite stable for 1 month when stored in dark; 1 week if exposed to light”
Disadvantage: can cause ocular, oropharyngeal, and esopharyngeal irritation
“Sodium hypochlorite”
Disinfects BSC hoods; carcinogen; MTB survives despite treatment
“Formaldehyde 37% solution or gas form”
Sporicidal for medical equipment in 3-10 hours; does not corrode lenses, metals, or rubber (e.g., bronchoscope)
“Glutaraldehyde”
Disadvantage: can cause ocular and nasal irritation
“Glutaraldehyde”
More stable than glutaraldehyde, requires no activation, no exposure monitoring, and is not a mucous membrane irritant
Ortho-Phthalaldehyde (OPA)
Effective even in the presence of organic material; used for surface sterilization of surgical instruments; kills bacteria, fungi, and spores
“Peracetic acid plus hydrogen peroxide”
Cold sterilization for medical equipment; kills bacteria, fungi, and spores
“Glutaraldehyde, Orthophthalaldehyde (OPA), Peracetic acid plus hydrogen peroxide”
Kills bacteria, mycobacteria, viruses, fungi, and spores; used in household cleaning materials
“3% Hydrogen Peroxide (H2O2)”
Used in lab testing for catalase and superoxol tests; higher concentrations available
“30% Hydrogen Peroxide (H2O2)”
Used on bench tops, surfaces, floors, furniture, and walls; inactivated by organic compounds; non-tuberculocidal, non-sporicidal
“Quaternary ammonium compounds (Quats), Example: Zephiran (Benzalkonium chloride)”
Derived from carbolic acid; kills bacteria, mycobacteria, viruses, and fungi; not sporicidal
Phenolics (e.g., Ortho-phenylphenol, Ortho-benzyl-para-chlorophenol)
Used for blood culture and surgery; contact time for iodophor must be >30 seconds; iodine must be removed to avoid irritation; not sporicidal
“Iodine (Tincture of iodine, Iodine + Alcohol)”
Contains iodine and neutral polymer; used as a skin disinfectant; not sporicidal
Iodophor (Povidone-Iodine, Poloxamer-Iodine)
Used to kill bacteria, mycobacteria, viruses, and fungi; not sporicidal
Alcohol (Ethyl alcohol)
Stable, biodegradable, and active in the presence of organic materials; kills bacteria, mycobacteria, viruses, fungi; not sporicidal
Phenolics (Ortho-phenylphenol, Ortho-benzyl-para-chlorophenol)
Has high antimicrobial activity (better than iodine), low toxicity; more effective on gram(+) bacteria; less effective on fungi and mycobacteria; not effective on naked viruses
Chlorhexidine gluconate (CHG)
Effective for outbreaks of gram(+) infections; primarily effective against gram(+), not effective on gram(-), fungi, viruses, or mycobacteria
Hexachlorophene
Halogen-substituted phenolic compound; primarily effective against gram(+); not affected by organic compounds; less effective on gram(-), fungi, viruses, and mycobacteria
Chloroxylenol
Added to household products for bacterial contamination prevention; effective against gram(+), gram(-), and viruses; fair effectiveness on mycobacteria; less effective on fungi
Triclosan
Economical alternative to expensive antiseptics; used for cleaning chronic wounds, handwashing, and disinfection of equipment and surfaces; requires onsite preparation
Superoxidized water (Hypochlorous acid + Chlorine)
Prevents ophthalmia neonatorum caused by N. gonorrhoeae; substitutes: erythromycin ointment or eye drops, or povidone-iodine; no longer manufactured in the US
1% silver nitrate;
Used as skin antiseptic before; no longer in use
Heavy metals (Mercurial chloride)
Most Resistant arrangement for sterilization
Prions > Endospore > Mycobacteria > Naked/Nonlipid viruses > Fungi > Bacteria > Enveloped/Lipid viruses
Most Sensitive arrangement for sterilization
Enveloped/Lipid viruses > Bacteria > Fungi > Naked/Nonlipid viruses > Mycobacteria > Endospore > Prions
Method of Killing Prions: Autoclave (Prevacuum sterilizer)
134°C for 18 minutes
Method of Killing Prions: Autoclave (Gravity displacement sterilizer)
132°C for 1 hour
Method of Killing Prions: 1 N NaOH Immersion and Autoclave (Prevacuum sterilizer)
Immersion for 1 hour, then autoclave at 134°C for 1 hour
Method of Killing Prions: Autoclave (Gravity displacement sterilizer)
121°C for 30 minutes
