Chapter 1 Flashcards
(92 cards)
What is pathogenicity?
The ability to cause disease by overcoming the defenses of the host
What is a pathogen
A microorganism causes infection/disease
What is the virulence?
The degree or extent of pathogenicity
What is an infection?
The invasion or colonization of the body by pathogenic microorganisms
When does a disease occurs?
When the infection results in any chance in the normal state of the body to the abnormal
Name an example for an infection without a disease
AIDS
Identify inflammation
The localized tissues response to an injury or infection, often characterized by redness, swelling,pain, warmth, and pus
What does the ability of microorganisms to infect or cause disease depends on?
1 Interactions with the host defence mechanisms
2 the virulence factor
3 quantity/ number of invading microbes
Name the factors that determine the distribution and composition of normal microbes
Nutrients
Physical and chemical: temperature, pH, Oxygen, Co2, sunlight
Mechanical factors: chewing of the teeth and tongue, flow of saliva, flushing action of urine, mucus and cilia I’m the respiratory system
Defenses of the host,age, diet, health, disability, hygiene, stress
What is the relationship between normal and pathogenic microorganisms?
Microbial antagonism or competitive exclusion
What does microbial antagonism involves?
COMPETITION FOR:
nutrients
Producing harmful substances to the invading microbes (E.coli—-bacteriocin)
Affecting conditions such as PH
Give an example on bacteria that produce harmful substances to the invading microbes
E.coli:
It produces bacteriocins protein that inhibits the growth of salmonella and shigella
Give an example for a microorganism that grows after the PH or other conditions have been effected
After pH change Candida albicans (fungi) causes vaginitis
After normal bacteria elimination Clostridium difficile (gram positive anaerobic) causes fatal colitis
What are the the relationships between normal microbes and the host are? (Symbiosis) with examples
Commensalism: one benefits other doesn’t
Example staphylococcus epidermis (gram positive)
Mutualism: both benefits
Example E.coli ( gram -) synthesis vitamin K and B
Parasitism: one benefits while the other gets badly effected
Example: many disease causing bacteria
Identify opportunistic pathogens
They are pathogens that doesn’t cause a disease on normal states but do so on different environmental conditions
Give examples for opportunistic pathogens conditions with examples
Gaining access to other body sites such as the skin and mucous membranes
Example E.coli ( gram negative)
The host immunity is weakened by an infection
Example: Pneumocystis pneumonia (fungal) onlu happens after AIDS
Cooperation among microorganisms
Example in the mouth pathogens that causes periodontal disease and gingivitis have receptors for the oral streptococci
What are the exception to Koch’s postulates with examples
1 some have unique culture requirements
Example: Treponema pallidum that causes syphilis
- Signs and symptoms can be only exhibited in humans
- Some diseases have poorly defined etiologies
Example: nephritis have several pathogens with the same signs and symptoms
4 some pathogens causes several diseases for example: mycobacterium tuberculosis causes diseases in the lungs, skin and bones
Streptococcus pyogenes can cause sore throat, scarlet fever and skin infections
What are the sources of microbes?
Another host or nonliving disease reservoir
What are the requirements for a successful pathogen
1 Surviving the passage
2 attach or penetrate the hosts tissues
3 withstand the host’s defenses
4 induce damage or malfunction to the tissues
What does symptoms mean
Changes in the body functions, such as pain ( can’t be observed or seen by an observer)
What does signs mean
Changes in the body that can be seen and measured such as swelling and fever
What does syndrome means
A group of symptoms or sings are evaluated together
What is a communicable disease
A disease that spreads from one host to another, directly or indirectly
Incidence vs prevalence
Incidence: probability of developing a disease, counting ONLY NEW cases, requires a follow up from individuals, doesn’t depend on the duration of the illness, preferred when studying the cause
Prevalence: probability of already having a disease, counts BOTH new and old, does not require a follow up, depends on the duration of the disease, preferred when estimating the population based burden of chronic disease