MICROPENIS PART 2 Flashcards
Sterilization
is the removal or destruction of all microorganisms and viruses on or in a product.
Sterile Item
is free of all viable microbes, including endospores but is not necessarily free of prions.
Disinfection
is the elimination of most or all pathogens on or in a material using chemicals called
disinfectants on inanimate objects (virucides, fungicides, and bactericides) or antiseptics on living
tissue.
Decontamination
reduces the number of pathogens to a safe level.
Sanitization
substantially reduces the microbial population to minimize the spread of disease.
Preservation
is the process of delaying spoilage of perishable products, including refrigeration and pasteurization, a brief heat treatment usually applied to food items that reduce the number of spoilage organisms and destroy pathogens without changing the characteristics of the product.
the type and number of microbes to be controlled
some infectious agents are highly
resistant, including bacterial endospores, protozoan cysts and oocysts, Mycobacterium and Pseudomonas species, and non-enveloped viruses. The time it takes to kill a microbial
population depends in part on the number of cells present. It takes more time to kill a large
population than to kill a small population, because only a fraction of organisms die during a
given time interval.
environmental conditions
dirt, grease and body fluids can affect antimicrobial procedures. Bacteria in biofilms are often resistant. Temperature and pH impact effectiveness of
procedures.
risks for infection
medical instruments are categorized as critical, semi-critical or non-critical according to their risks of transmitting infectious agents.
Moist heat
denatures proteins. Relatively fast, reliable, safe, and inexpensive.
Boiling
Boiling for 5 minutes destroys most microorganisms and viruses but not
endospores.
Pasteurization
Significantly decreases the numbers of heat-sensitive microorganisms, including spoilage microbes and pathogens (except endospore
formers).
Autoclaving
destroys all infectious agents including endospores.
Dry heat
destroys cell components and denatures proteins.
Incineration
burns cell components to ashes
Dry heat ovens
less efficient and requires longer time
Filtration
o filters retain microbes while allowing the suspending fluid or air to pass through
small holes.
o Membrane filters are used for fluids. High-efficiency particulate air (HEPA) filters are
used for air.
Irradiation
o Ionizing radiation: Destroys DNA and damages membranes. Includes gamma rays and
X rays.
o Ultraviolet radiation: Damages DNA but penetrates poorly.
o Microwaves: Kill by heat rather than radiation.
High pressure
Denatures proteins and alters cell permeability.
Sterilant
destroy all microbes including endospores and viruses.
High-level disinfectants
destroy all viruses and vegetative microorganisms, but they do not reliably kill endospores.
Intermediate-level disinfectants
destroy all vegetative bacteria (including mycobacteria),
as well as fungi, and most viruses.
Low-level disinfectants
destroy fungi, vegetative bacteria except mycobacteria, and enveloped viruses but not endospores or non-enveloped viruses.
Factors to consider when choosing a germicide include
- Toxicity
- Activity in the presence of organic matter
- Compatibility with the material being treated
- Cost and availability
- Residue
- Storage and stability
- Environmental risk.
Fungi
-include molds, single-celled yeasts, and mushrooms.
-zygomycetes, ascomycetes, basidiomycetes, and chytridiomycetes.
-cell wall contains chitin
-contain ergosterol
-fungal filaments called hyphae
-a tangled mass of hyphae (mycelium)
Dimorphic Fungi
can grow either as single cells (yeast) or as mycelia
Protozoa
- a diverse group of single-celled, non-photosynthetic organisms.
- are free-living and are found
in marine and freshwater as well as terrestrial environments
-decomposers - vegetative trophozoite can develop into a resting cyst.
- some reproduce by multiple fissions or schizogony.
Algae
-most algae are aquatic; they may be
microscopic or macroscopic, unicellular or multicellular
-unicellular algae make up a significant part
of the phytoplankton
-Their cell walls are made of cellulose and other commercially important
materials such as agar and alginic acid
-contain chlorophyll a
Helminths
-are worms. Some are parasitic and can invade human tissues, causing disease or robbing
the body of nutrients.
-asexual stages occurring in one or more intermediate hosts and the sexual
or adult stage occurring in the definitive host.
-A human being may be a dead-end host in which the organism cannot complete its life cycle.
Nematodes (roundworms)
has a cylindrical, tapered body with a digestive tract that extends from the mouth to the anus.
Nematodes (roundworms)
has a cylindrical, tapered body with a digestive tract that extends from the mouth to the anus.
cestodes (tapeworms)
worms with segmented bodies and hooks to
attach to the wall of the intestine.
Arthropods
-animals that include the insects (such as flies, mosquitoes, lice, and fleas) and the
arachnids (such as ticks and mites).
-main role in disease is to serve as vectors that can
transmit microorganisms and viruses to humans.
Viruses
-They are composed of nucleic acid (either DNA or RNA) surrounded by a protein coat called the capsid.
-icosahedral, helical, or complex.
-enveloped, nonenveloped
Caspid
-nucleic acid (either DNA or RNA) surrounded by a protein coat
Nucleocaspid
The capsid together with the nucleic acid it encloses is called the
Lytic or virulent phages
the T4 phage exit the host at the end of the cycle by lysing the host, resulting in a productive infection.
Five steps of infection
attachment, genome entry, synthesis of phage proteins and genome,
assembly (maturation), and release.
Temperate phages
such as lambda have the option of either directing a productive infection or
initiating a lysogenic infection
Lysogen
an infected cell
Repressor
maintains prophages
Lysogenic conversion
occurs if a prophage carries genes that change the phenotype of the host cell
Generalized transduction
results from a packaging error during phage assembly.
Specialized transduction
results from an excision mistake made by a temperate phage during its transition from a lysogenic to a lytic cycle.
Plaque assays
are routinely used to determine the
concentration of phage particles in samples such as sewage, seawater, and soil.
Acute
infections
characterized by the sudden onset of symptoms of a relatively short duration e.g.
influenza.
persistent infections
can continue with or without symptoms for years, or even for the life span of the host.
Oncogene
is a proto-oncogene that has been changed in such a way that it promotes uncontrolled growth.
Oncogene
is a proto-oncogene that has been changed in such a way that it promotes uncontrolled growth.
oncogenic viruses
Viruses that lead to cancer
formation
Viroids
consist solely of a small single-stranded RNA molecule that forms a closed ring. They are
about one-tenth the size of the smallest infectious viral RNA genome known
Prion
- composed only of protein
-They have no nucleic acid.
