Chapter 9 - Controlling Microbial Growth in the Environment Flashcards
Antisepsis
reduction in the number of microorganisms and viruses
Aseptic
refers to an environment or procedure free of pathogenic contaminants
Sanitization
removal of pathogens from objects to meet public health standards
Sterilization
destruction of all microorganisms and viruses in or on an object
Antimicrobial agents
alters cell walls and membranes, damages proteins and nucleic acids
Most resistant microbes
prions, followed by mycobacteria
High level germicides
kill all pathogens, including endospores
Intermediate level germicides
kill fungal spores, protozoan cysts, viruses, pathogenic bacteria
Low level germicides
kill vegetative bacteria, fungi protozoa, some viruses
Methods for evaluating disinfectants and antiseptics
phenol coefficient, use-dilution test, Kelsey-Sykes capacity test, in-use test
Heat-related methods for controlling microbes
moist heat and dry heat
Moist heat
boiling, autoclaving, pasteurization, ultrahigh-temperature sterilization
Autoclaving
121C, 15psi, for 15 min
refrigeration
halts growth of most pathogens
desiccation
drying inhibits growth because of removal of water
osmotic pressure
high concentration of salt or sugar in foods to inhibit growth
Ionizing radiation
shorter wavelengths
nonionizing radiation
longer wavelengths, UV light
Toughest bacterium
Deinococcus radiodurans
Biosafety Level 1
do not cause disease in healthy humans
Biosafety Level 2
moderately hazardous agents; gloves, mask, coat, sterilize, door closed
Biosafety Level 3
safety cabinets; pathogenic, potentially fatal, double doors, treatment is available, transmitted through air
Biosafety Level 4
pathogenic, no treatment, airborne
phenols
intermediate to low level disinfectant
