98 terms

Chapter 14 MicroBiology

List the 3 main things that the human body and various mechanisms interact with health and disease
1.a delicate balance exists between our defenses and the pathogenic mechanisms of microbes
2.when our defenses resist these pathogenic capabilities, we maintain health
3.when the pathogens capability overcomes our defenses, disease results
Define Disease
any state away from health
Define infectious disease
-caused by microorganisms
Define infection
invasion and colonization of the body by pathogens
Define pathogens
disease - causing microorganisms
Define Normal Microbiota
-resident microbes (normal flora)
-those microbes normally found in or on the human body, and which under normal conditions do not cause infection or disease
How can normal microbiota cause infection or disease?
1.They are introduce into areas of the body where they are not normally found
2. a weaken or compromised innume system
---They now can cause infection and disease because of one or both of these things
WHat are normal microbiota called when they cause disease or infections?
Opportunistic microbes
Describe Epidemology
-looks for the source of infection (resevoir)
-how it is transmittd
-the specific pathogen that cause it
-how to stop its spread
Describe Pathology
-the scientific study of disease
"pathos"-suffering "logos"-science
--it has 3 sub catagories
What are the 3 sub catagories of Pathology?
Define etiology
the cause of the disease
define pathogenesis
the development(behavior) of a disease in a person or poulation
Define pathosphysiology
the structural and functional changes brought about by the disease and any permament effects
Define Pathogenicity
the ability of a pathogen to cause a disease
Define Virulence
the degree of pathogenicity, how easily they can cause a disease
Why are normal microbiota necessary & benifical?
-they exhibit microbial antagonisms(competitive exclusions)
Define Antagonisms
the ability of the normal microbiota to prevent pathogens from establishing themselves & causing infection and disease
List the examples of howMicrobial antaganism works
1-they out compete for food (nutrients) and space
2-they alter conditions that favor them, but inhibit pathogens
3-E.coli makes antibacterial proteins called BACTERICINS, that inhibit other bacteria
4-affecting conditions such as pH and available oxygen
Define Bactericins
-proteins , produced by E.coli, that inhibit the growth of other bacteria
How can disease result?
when this balance between normal microbiota and pathogenic microbes is upset
Define Symbioss
The relationship between 2 organisms. the normal microbiota and the host
What are the 3 Symbioss relationships
3. parasitism
Define mutualism
-both organisms benefit from the relationship
ex Ecoli-they give us Vit K & B, we give E.coli nutrients to survive
Define Commensalism
-one organism benefits, the other unaffected
(not harmed no benefit)
-most of the normal microbiota are these -commensals
-these bacteria live on secretions and sloughed-off cells
Define Parasitism
-one organism benefits(parasite), the other is harmed (host)
ex:Pathogens, opportunistic pathogens=disease causing
Define transient microbiota
mivroorganisms that may be present for serval days,weeks, or months and then dissappear
Define opportunistic Pathogens
Normal microbiota,
they do cause infection and disease
they are introduces to areas of body not normally found AND/OR
weakened, compromised immune system
What is Kochs Postulates?
a series of experimental steps used to determine the causative agent of infectious disease
-Koch showed that a specific disease is caused by a specific microorganism that can be isolated and cultured on artifical media
List the 4 steps of Koch's Postulates
1.the same pathogen must be present in everycase of the disease
2.the pathogen must be isolated from the diseased host and grow in pure culture
3.The pathogen from the pure culture must cause the disease when it is inoculated into a healthy, susceptible laboratory animal
4.The pathogen must be isolated from the inoculated animal and must be shown to be the original organism
List the 4 exceptions to Koch's Postulates
1.Some pathogens have NEVER been grown on artifical media
2.Some disease conditions(pneumonia,meningitis) have more than one pathogens that cause it
3.Some pathogens can cause more than one disease
Ex: Staph. aureus
Strp. pyogens
mycobactorium tuberculosis
Define Signs
-OBJECTIVE changes in a patient
-these can be seen and measured by a physican
Define Symptoms
-SUBJECTIVE changes a patirnt feels
-(pain,dizzy nausea)= malaise
Define Malaise
a feeling of uneasiness
Define Syndrome
When you put the 2 (signs and symptoms) togehter
-all the the signs and symptoms of a disease
List the 3 terms that diseases are classified by how they behave within a host
1.communicable disease
2.contagious disease
3.Noncommunicable disease
Define communicable disease
-any disease that spreads from one host to another
Define contagious disease
-any disease that is EASILY spread from one person to another
Define Noncommunicable disease
-disease that CANNOT be spread from one person to another
ex. Tetanus
List the 4 classification that is used to describe the frquency of occurance of a disease
Define Sporadic disease
-disease that can only rarely occur, few occassions
Define Endemic disease
-disease that are constantely present in a population
Define Epidemic disease
-many people, in a short time, in a given area come down w/ a specific disease
Define Pandemic disease
-a world-wide epidemic
List the 3 classification used to describe the severity or duration of a disease
Define Acute disease
-a disease that develops rapidly
- very strong symptoms and signs
-only last a short tme
Define chronic disease
-a long term, progressive disease
-the intial symptoms and signs are mild, but get worse overtime
Define Latent disease
-the causative agent is doormant, but after a period of time becomes active to produce the illness
(ex: shingles)
List the 3 classification used to describe the extent of host involvement
1.local infections
2.systemic(generalized) infection
3.focal infection
Describe Local infections
The infection is isolated
-occuring in ONE area of the body
Describe systemic infection
-microorganism or their products are carried (spread) throughout the body by blood and lymph
-4 terms to describe classification of infection
Define Bactermia
-the presence of bacteria in blood
Define Sepsis
-the presence of bacteria in blood, actively multiplying and growing
-a toxic inflammatory condition from a focus infection
Define Toxemia
-the presence of bacterial produced poisons (toxins) in the blood
Define Viremia
-the presence of viral particles in blood
Define Focal infection
-the agents of a local infection are carried in (blood & lymph) to set up other local infections
List the 2 classifaction used to describe the state of the host resistance
1.primary infection
2.secondary infection
Define Primary infection
-usually viral and acute
-and in fighting it off, the body's immune systom is weakend
-it cause the intial illness
Define Secondary infection
-usually bacteria and from opportunistic pathogens that take advantage of a weakened immune system
-happens after the primary infection has weakened the body's defenses
Pattern of disease
-5 periods or sequence of events that usually occur during the infection or disease
-these happen whether the disease is acute or chronic
List the 5 periods of the pattern of disease
1.incubation period
2.prodromal period
3.period of illness
4.period of decline
5.period of convalescence
Describe incubation period
-the interval between the intial infection ant the first appearance of any signs or symptoms
-this period depends on specific microbes involved
-the virulence and the number of infecting microbes
-and depends on the resistance of the host
**here people can spread infection**
Describe prodromal period
-Relatively short period that follows the incubation period
-characterized by early, mild, symptoms of disease (general aches Maliase)
Describe "Period of illness"
-the disease is most severe
-the person exhibits overt signs and symptoms of disease (obvious)
-generally the immune response an other defense mechanisms overcome the pathogens and the period of illness ends
**here the people can serve as reservoirs of disease**
Describe "Period of Decline"
-signs and symptoms subside ( the fever decreases, the feeling of malaise diminshes)
-during this phase, which could take from less than 24 hrs to several days, the patient is vulnerable to secondary infections
Describe "period of convalescence"
-the person regains strength and the body returns to its prediseased state
-Recovery has occured
**here people can still spread infection **
Describe Reserviors of infection
-any person, animal,arthropod, plant,soil or substance in which an infectious agent normally lives and multiples, on which it depends primarily for survival, and where it reproduces itself in a way that allows transmission to a susceptible host
List the 3 criterias to be a Reservior
1. a continual source of the disease-causing organism
2.provides the pathogen with adequate conditions for survival and multiplication
3.provides an apportunity for disease transmission
Describe Human Reserviours
-the principle reservoir of human disease
-many people harbor pathogens and transmit them directly or indirectly to others
-people with signs and symptoms of a disease may transmit the disease
Define Carriers
-Human reservior
-a person who harbors a specific pathogenic organism, has no discernable symptoms or signs of disease, and is potentially capable of spreading the organism to others
**can bepeople with latent disease, or carry a disease during its symptom-free stages (incubation and convalescent periods)
Desribe Animal Reserviors
-both wild and domestic animals are living reserviors of microorganisms tha can cause human diseases
Define Zoonoses
-an infection common in animal populations tha can infect humans
Desribe Nonliving Reserviors
-the 2 major nonliving reserviors of infectious disease are:
SOIL and WATER (if water cntaminated by feces)
-the other is FOOD that is improperly stores or prepared
How are disease transmitted?
-the causative agents of disease can be transmitted from the "Reservior of infection" (source) to a susceptible host by 3 principle routes
List the 3 routes to transmit disease
1. contact transmission
2.vehicle transmission
3.vector transmission
list the 3 types of Contact transmission
1.direct contact
2.indirect contact
3.droplet transmission
Define Direct Contact transmission
-Person to person transmission
-the direct transmission of an agent by physical contact between its source and the susceptible host.
-no imtermediate object is involved
Define Indirect contact transmission
-Fomite are involved
-occurs when the agent of disease is transmitted from its reservior to a host by means of a nonliving object(fomites)
-nonliving object that can spread infection
Define Droplet transmission
-microbes are spread in mucus droplets that travel only short distances (less than 1 meter)
-thses droplets are dischrged into the air by coughing,sneezing,laughing or talking
-these are not regarded as airborne
Describe Vehicle transmission
-the transmission of disease agents by a medium, such as water, food air or blood (and othe bodily fluids)
List the 3 vehicle transmission
Define waterbourne transmission
-pathogens are usually spread by water contaminated with untreated or poorly treated sewage
Define foodbourne transmission
-pathogens are generally transmitted in foods that are: *incompletely cooked
*poorly refrigerated
*prepared under unsanitary conditions
Define airbourne transmission
-the spread of agents of infection br droplet nuclei in DUST that travel MORE THAN 1 METER from the reservior to the host
-the droplets are small enough to remain airbourne for prolonged periods
Describe Vectors
-usually an INSECT or other arthropod, that transmits the causative organisms of disease from infected to noninfected individuals
-especially one in which the organism goes through one or more steps in its life cycle
How do arthropods vectors transmit disease?
By 2 general methods
1. mechanical transmission
2 .biological transmission
Define mechanical transmission
-the passive transport of the insect's feet or other body parts
-if the insect makes contact with a host's food, pathogens can be transferred to the food and later swallowed by the host
Define Biologial transmission
-an Active More complex process
-the arthropod bites and infected person or animal and ingests some of the infected blood
-the pathogens then Reproduce in the vector, and the increase in the number of pathogens increases the possibility that they will be transmitted to another host
-some parasites reproduce in the Vectors gut and migrate to the salivary glands
-some protozoan and helminthic parasites use the vector as a host for a developmental stage in their life cycle
What are Nosocomial infections?
-Hospital-acquired infections
-does not show any evidence of being present or incubating at the time of admission to a hospital
-5-15 % of all hospital patients acquire some type of nosocomial infection
-in U.S. about 2 million people per year contract these infections
-nearly 20,000 die as a result
-8th leading cause of death in U.S.
How do Nosocomial infections happen
1.Microorganisms in the hospital enviroment
2.the compromised (or weakened) status of the host
3.the chain of transmission in the hospital
Decribe the factor "microorganisms in the hospital"
-hospital enviroment is a major reservior for a variety of pathogens
-norma microbiota of the human body are opportunistic and present a particularly strong danger to hosp. patients
-most of these microbes that cause nosocomial infection do not cause disease in healthy people, but are pathogenic only to individual whose defenses have been wekened by illness or therapy
-in addition the oppurtunistic microbes in hospital can become resistant to antimicrobial drugs
Describe the factor "compromised host"
- a host whose resistance to infection is impaired
-a person who acks resistance to infection owing to a deficiency in any of the host defenses
-a host whose resistance to infection is impaired by disease, therapy, or burns
What are the 2 principle conditions that can compromise the host?
1. a broken skin or mucous membranes
2. a suppressed immune system
What provides physical barriers against most pathogens in the human body?
skin and mucous membranes
as long as they remain intact
What can break the first line of defense in humans and make us more susceptible to nosocomial infections
burns,surgical wounds, trauma, injections, invasive diagnostic procedures, ventilators, IV therapy, catheters
What can adversely affect the actions of T and B (white blood) cells and comproise the host?
drugs, radiation therapy, steroid therapy, burns, diabetes, leukemia, kidney disease, stress, malnutrition
Describe the factor " chain of Transmission"
-the principle routes of transmission of nosocomial :
1.direct contact transmission from hospital staff to patient and from patient to patient
2.indirect contact transmission through fomites and the hospital ventilation system (airbounr transmission)
What is the # 1 Control of Nosocomial infections?
-according to the CDC, handwashing is the single most important means of preventing the spread of infection
88handwashing breaks the chain of transmission