LO 2 Flashcards
Define: Normal Flora
Microorganisms growing in or on the body all the time without causing injury to the host
- They permanently reside on our bodies and do not produce disease under normal circumstances
Define: Pathogenic
Capable of causing disease
What is the composition of normal flora?
Fairly constant for a given site; but varies depending on the site ( ex. the flora in the mouth is different then normal flora of the intestine or skin)
Which area of the body has the greatest amount of normal flora?
The large intestine has the greatest normal flora population
Define: Escherichia coli (E.coli) and where is it located?
E. coli is a rod-shaped bacterium (Bacilli- gram negative) found in the feces
Normal intestinal flora plays an important role in what?
Food digestion and evacuation of feces
What type of bacteria(normal flora) is found in mucous membrane of the upper respiratory tract? And what is their role?
Streptococci of the viridans group. They occupy attachment sites on host cells and prevent pathogenic bacteria from invading the respiratory tissue
What type of normal flora bacteria is found on the skin?
Staphylococci. (Live on a cool, dry, salty surface) Main normal flora on the skin. It is gram positive & blue
What are the two factors that affect Normal Flora? How?
1) Excess moisture on the skin = increase in staphylococci on skin
2) Antibiotic use = alters normal flora as the sensitive bacteria are killed allowing more resistant strains to predominate
Define: Contamination
Microorganisms present on the body (on a site where they are not expected) but they are not growing or causing damage to the host
- ex. saliva on skin
Define: Colonization
Microorganisms present and growing in or on the body but without causing any damage to the host
Define: Disease
Microbes multiplying in the host and causing damage to the host (it is evident and measurable)
Define: Infection
Often used to mean the same as disease (Microbes multiplying in the host and causing damage to the host) but also used to indicate growth of microbes in the host before disease symptoms become evident.
- Has been invaded with a pathogenic organism but there are no signs of lasting host damage
HIV/ AIDS infection or disease?
A person may be infected with HIV but show no signs of injury for some time. Once the symptoms of AIDS becomes evident, the host is described as having the disease AIDS
The lining of the urinary bladder is normally sterile. Bacteria will occasionally grow on the bladder mucosa without causing any disease or harm to the host. The term covering this relationship is ________
Colonization
The bacteria causing tuberculosis multiply inside white blood cells of the body for several weeks without causing any injury to the host. The person is described as being ____ with tubercle bacilli. Several weeks later symptoms of tuberculosis become evident and the person is said to now have the ______
The bacteria causing tuberculosis multiply inside white blood cells of the body for several weeks without causing any injury to the host. The person is described as being infected with tubercle bacilli. Several weeks later symptoms of tuberculosis become evident and the person is said to now have the disease
Throat cultures of most individuals with no evidence of sore throats will show viridans _____. These streptococci are ______.
Throat cultures of most individuals with no evidence of sore throats will show viridans streptococci. These streptococci are normal flora.
Staphylococcus aureus growing in a surgical incision causing swelling and inflammation would be described as ______
Staphylococcus aureus growing in a surgical incision causing swelling and inflammation would be described as infection.
Fecal bacteria on the hands of a person visiting the bathroom and failing to wash their hands after this visit would be called ______ as long as the bacteria were not growing and injuring the host
Fecal bacteria on the hands of a person visiting the bathroom and failing to wash their hands after this visit would be called contamination as long as the bacteria were not growing and injuring the host
Define: Pathogen
A disease-causing organism
Define: Virulence
The degree of pathogenicity
What are the factors of virulence? (4)
1) Enzymes that dissolve hyaluronic acid (tissue cement), collagen and fibrin clots, allowing bacteria to spread faster in the tissue
2) Substances that destroy RBC, releasing iron necessary for bacterial growth
3) Substances that destroy WBC, weakening the body defence
4) Capsules, or slimy coatings, which prevent attachment of phagocytic (eating) white blood cells
Define: Non-pathogen
An organism unable to cause disease
* Most common type of bacteria
Define: Low grade pathogen or opportunistic pathogens
They are non-pathogenic under most condition but may cause disease when the host’s defenses are lowered by predisposition conditions
- Only causing disease when the host defenses are lowered
- Only become bad when they have the opportunity to
Define: Exotoxins
- A bacterial product excreted from the cells and causing damage to specific host tissues
- Gram positive (blue)
- Exotoxins are carried away from the infection site by blood or along nerve cells
- Attack a specific target tissue
Define: Endotoxins
- A bacterial product that is part of the cell wall causing nonspecific damage to a variety of host tissues
- Gram negative (pink); located in the cell wall
- Released only when the bacterial cells are disrupted
- Can result in fever, aches, drop in blood pressure, circulatory collapse when accompanying bacterial infections
What is the difference between gram positive and gram negative?
Gram positive = blue
Gram negative = pink
Tetanus toxin
Exotoxins
Also called “lockjaw”
- Results in locked jaw
- Affects the central nervous system and interferes with transmission of impulses from the brain to muscles
Pyrogens
Endotoxins
- Cause fever, and life-threatening kidney damage
- Associated with hamburger disease,
What are the 3 elements required for transmission of infection?
1) Reservoir (source of infectious microbes)
2) Means of Transmission for the microbes
3) Susceptible host
What is the Chain Infection?
For an infection to occur, the elements of transmission must all occur. If the process is stopped, infection can be prevented
- We want to stop the chain at the transmission stage
What are the 3 types of reservoirs?
Human, animal, nonliving
Define: Human reservoirs
Principal reservoir of human infectious disease is the human body itself
- people with the disease & carriers
Define: Carriers
A person carrying potentially pathogenic microbes without any signs of disease or infection
Define: Chronic Carrier
A person who is a carrier for more than 6 months
What is a classic example of a carrier?
Typhoid Carrier
- Had typhoid and recovered but some of the typhoid bacteria remain in the body (often the gallbladder)
- Typhoid is transmitted by the ingestion of food contaminated with feces
Which diseases are transmitted by carriers?
Streptococcal sore throat, AIDS, Hepatitis B, and diphtheria
Define: Convalescent carrier
Once the person has recovered from the disease but may still be carrying infectious organisms
- A person carrying an infectious microbe for up to 6 months after the acute stage of the disease
Define: Zoonoses
Diseases that are primarily found in animals but may be transmitted to humans
Ex. Salmonella (eating improperly cooked poultry), rabies, and the plague