Test 4 Study Guide Flashcards
sterilization
The complete removal or destruction of all viable microorganisms. Used on inanimate objects.
Ex. Autoclaving, ionizing radiation
disinfection
The destruction or removal of vegetative pathogens but not bacterial endospores. Usually used only on inanimate objects.
Ex. 5% bleach, boiling water
antisepsis
Chemicals applied to body surfaces to destroy or inhibit vegetative pathogens.
Ex. lodophors, antibacterial soap, chlorhexidine
sanitization
any cleansing technique that removes microorganisms from inanimate surfaces to reduce the potential for infection and spoilage
Ex. Dishwashing, laundering clothes
degermation
reduction of microbial load from living tissue by mechanical means
Ex. Surgical handscrub, alcohol wipes
pasteurization
kills non-spore-forming pathogens and lowers overall microbe count; does not kill endospores or many nonpathogenic microbes
sterilizing conditions
Sterilization with Steam Under Pressure
Nonpressurized Steam
Boiling Water: Disinfection
Hot Air and Incineration
Ionizing radiation
thermal death time
shortest length of time required to kill all test microbes at a specified temperature
thermal death point
lowest temperature required to kill all microbes in a sample in 10 minutes
infection
a condition in which pathogenic microbe penetrate host defenses, enter tissues, and multiply
disease
an infection that causes damage or disruption to tissues and organs
resident microbiota
microbes that become established in the body
transient microbiota
microbes that occupy the body for only short periods
endogenous agents
already exist on or in the body (normal flora)
exogenous agents
originate from source outside the body
Conditions for killing different microbes
physical
chemical
mechanical
Mode of operation of aldehydes
Kill by alkylating protein and DNA
Glutaraldehyde
• In 2% solution (Cidex)
• High level
• Used as sterilant for heat sensitive instruments
Formaldehyde
• Formalin – 37% aqueous solution
• Intermediate to high level
• Disinfectant, preservative, toxicity limits use
Mode of operation of detergents
Detergents: Polar molecules, surfactant
• Quaternary ammonia compounds (quats) act as surfactants that alter membrane permeability of some bacteria and fungi
• Very low level
Soaps: alkaline compounds
• Mechanically remove soil and grease containing microbes
• Weak microbicides, destroy only highly sensitive forms (gonorrhea, meningitis, and syphilis)
Mode of operation of alcohols
Alcohols exhibit rapid broad-spectrum antimicrobial activity against vegetative bacteria (including mycobacteria), viruses, and fungi but are not sporicidal. They are, however, known to inhibit sporulation and spore germination, but this effect is reversible.
Mode of operation of other chemicals
s
ionizing radiation
deep penetrating power sufficient energy to cause electrons to leave their orbit
Gamma rays
X rays
Cathode rays
non-ionizing radiation
little penetrating power
Ultraviolet (UV) radiation
Benefits of filtration as a methods of control
Physical removal of microbes by passing a gas or liquid through filter.
Used to sterilize heat sensitive liquids and air in hospital isolation units and industrial clean rooms.
Benefits of heat as a method of control
Heat can kill microbes by altering their membranes and denaturing proteins.
Benefits of radiation as a method of control
Cold sterilization of packaged products such as medical supplies and instruments that cannot be heat sterilized.
Sterilization of foods, including fruits, lettuce and spinach, grains, spices, meats, and packaged meals.
Sterilization of drugs and vaccines.
Rapid and penetrating, prevents infection and spoilage.
Examples of physical methods of control
Incineration Dry oven Steam under pressure Boiling water, pasteurization Ionizing and non-ionizing radiation
Examples of chemical methods of control
Gases
Liquids
Examples of mechanical methods of control
Filtration: air (disinfection) or liquid (sterilization)
Examples of microbial portals of entry and exit
Infectious agents enter the body through various portals, including the mucous membranes, the skin, the respiratory and the gastrointestinal tracts.
Difference between virulence factors and infectious doses and their examples
Infectivity is the ability of the infectious agent to pass from a sick to a susceptible healthy individual and cause disease.
Virulence determines how severe will be the disease in the infected individual.
Ex. toxins, surface coats that inhibit phagocytosis, and surface receptors that bind to host cells, capsules, exoenzymes, endo and exotoxins.
prodromal stage
vague feelings of discomfort; nonspecific complaints
convalescent stage
as person begins to respond to the infection, symptoms decline
incubation period
time from initial contact with the infectious agent to the appearance of first symptoms; agent is multiplying but damage is insufficient to cause symptoms; several hours to several years
period of invasion
multiplies at high levels, becomes well-established; more specific signs and symptoms
Difference between symptom and signs of disease and their examples
Sign –objective evidence of disease as noted by an observer
Symptom – subjective evidence of disease as sensed by the patient
Definition and examples of inflammatory reactions
The inflammatory response (inflammation) occurs when tissues are injured by bacteria, trauma, toxins, heat, or any other cause. The damaged cells release chemicals. These chemicals cause blood vessels to leak fluid into the tissues, causing swelling.
morbidity
number of people afflicted with a certain disease
mortality
the total number of deaths in a population due to a certain disease
incidence
measures the number of new cases over a certain time period, as compared with the general healthy population
prevalence
total number of existing cases with respect to the entire population usually represented by a percentage of the population
endemic
disease that exhibits a relatively steady frequency over a long period of time in a particular geographic locale
sporadic
when occasional cases are reported at irregular intervals
microbistatic agents
slows the growth of microbes
microbicidal agents
kills microbes
Difference between antibiotics and other antimicrobial compounds
Antibiotics specifically target bacteria and are used to treat bacterial infections.
Antimicrobials encompass a broader range of products that act on microbes in general.
antibiotics
Substances produced by the natural metabolic processes of some microorganisms that can inhibit or destroy other microorganisms
narrow-spectrum drugs
effective on a small range of microbes
semisynthetic drugs
Drugs that are chemically modified in the laboratory after being isolated from natural sources
Ex. antibiotic, penicillin, and the chemotherapy.
synthetic drugs
Antimicrobial compounds synthesized entirely in the laboratory through chemical reactions
broad-spectrum drug
greatest range of activity
Know the sources of antibiotic compounds
Known sources of natural compounds with valuable antimicrobial activity include medicinal plants, and marine and terrestrial organisms such as fungi and bacteria.
acute infection
comes on rapidly, severe but short-lived effects
chronic infection
progress and persist over long period of time
local infection
microbes enter the body and remains confined to a specific tissue
focal infection
when infectious agent breaks loose from a local infection and is carried to other tissues
mixed infection
several microbes grow simultaneously at the infection site - polymicrobial
primary infection
initial infection
secondary infection
subsequent infection by a different microbe
fomite and examples
involves a secondary route of exposure such as oral or direct contact for the pathogen to enter the host.
Ex. contaminated vehicles, shovels, clothing, bowls/buckets, brushes, tack, and clippers.
carrier vector
individual who inconspicuously shelters a pathogen and spreads it to others
reservoir
primary habitat of pathogen in the natural world
source
individual or object from which an infection is actually acquired
vertical transmission
Vertical transmission refers to generational transmission of viruses from parents to their offspring.
direct transmission
physical contact or fine aerosol droplets
indirect transmission
passes from infected host to intermediate conveyor and then to another host
vector transmission
utilizes insects to transport the pathogen. Insects such as fleas, ticks, and mosquitos are unharmed by the pathogens they potentially carry but can transmit the bacteria or virus when they bite a host.
oral-fecal transmission
occurs when bacteria or viruses found in the stool of one child (or animal) are swallowed by another child.
mechanical vectors and their examples
not necessary to the life cycle of an infectious agent and merely transports it without being infected.
Ex. House fly
biological vectors
actively participate in a pathogen’s life cycle
infectious disease
Infectious diseases are transmitted from person-to-person through the transfer of a pathogen such as bacteria, viruses, fungi or parasites.
non-infectious disease
A non-infectious disease cannot be transmitted through a pathogen and is caused by a variety of other circumstantial factors.
Important characteristics of antimicrobic drugs
An ideal antimicrobic:
- soluble in body fluids
- selectively toxic
- nonallergenic
- reasonable half life (maintained at a constant therapeutic concentration)
- unlikely to elicit resistance
- has a long shelf life
- reasonably priced
Know the five major areas on microbes that drugs target and examples
Cell wall: penicillin, cephalosporin, bacitracin, vancomycin
Cell membrane: polymyxins, amphotericin B and nystatin
Protein synthesis: aminoglycosides (streptomycin and gentamycin), tetracyclines, erythromycin, chlorampenicol
Metabolic pathways: sulfonamides, trimethoprim, retrovir.
Nucleic acids: chloroquine, quinolones
Mode of action of antiviral drugs and their examples
they can increase the cell’s resistance to a virus (interferons), suppress the virus adsorption in the cell or its diffusion into the cell and its deproteinization process in the cell (amantadine) along with antimetabolites that causes the inhibition of nucleic acids synthesis.
Know the cellular basis for bacterial resistance to antimicrobic compounds
- synthesis of enzymes that alter drug structure
- bacterial chromosomal mutations
- alteration of drug receptors on cell targets
- prevention of drug entry into the cell
Asepsis
Techniques that prevent the entry of microorganisms into sterile tissues
Ex. Cleansing the skin with iodine prior to surgery, using sterile needles
