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67 Cards in this Set

  • Front
  • Back

Type of symbiosis


both members benefit from their interactions

ex bacteria in colon. beneficial but not required

Type of symbiosis


one member of relationship benefits without harming or benefiting other

ex- staph on skin

Type of symbiosis


benefits from host while harms it


any parasite that causes a disease

Normal microbiota

microbes that colonize surfaces of body without normally causing disease

aka- normal flora, & indigenous microbiota

Normal microbiota 2 types

-Resident microbiota

-Transient microbiota

Resident microbiota

What and Where

remain part of normal microbiota of a person throughtout life.

-organisms found on skin, mucous membrane of digestive tract, distal of urethra, vagina. most are commensal feed on dead cells cellular waste

Transient microbiota

remain in body for few hours, days or months before disappearing. found same as resident microbiota

opportunistic pathogens

takes advantage of suppressed immune system or disrupted ecosystem

Conditions that provide opportunities for pathogens

- immune suppression

- changes in normal microbiota (competition & antagosism dec or eliminated)

- intro of normal flora into unusual site (ex thrush)

Reservoirs of infections

3 types

-sites where pathogens are maintained as a source of infection

-Animal reservoirs

-Human carriers

-Nonliving reservoirs

Animal Reservoirs

Zoonoses (how can you get them)

-diseases that are naturally spread from their usual animal host to humans

-Direct contact with animal or waste

-Eating animals

-Blood sucking arthropods

(humans are dead end host to zoonotic pathogens)

Human Carriers

-infected person who is asymptomatic but can infect others

-some will eventually get illness while other never get sick

-healthy carriers may have defensive systems that protect them from illness

Nonliving reservoirs

-soil, water and food can be reservoirs of infection

-presence of microorganisms often due to contamination by feces or urine


the mere presence of microbes in or on the body ex food, drink air, wounds, intercourse


results when the organism overcomes body's external defenses, multiplies and becomes established in body

Four major pathways of entry

Skin- it has a thick layer or dead, dry cells that most pathogens cant get it but can enter through natural openings, abrasions

Mucous Membrane- major portal, tightly packed cells moist, living cells. (lining or respiratory, gastrointestinal, urinary,reproductive)

Placenta- nutrients from mother, typically forms an effective barrier to most pathogens

Parenteral Route- not a portal entry, can be avoided. pathogen must b deposited directly into tissure beneath skin or mucous memb, break in skin.


degree to which it can cause a disease


process by which microorganisms attach themselves to cells

Attachment proteins

Viruses- attachment proteins

bacteria- ligands are called adhesins

-both have surface lipoproteins or glycoproteins called ligands, bind host cell receptors


bacterial or viruses inability to make ligands (attachment proteins)


bacterial pathogens attach to each other forming a sticky web adheres to a surface within host


is invasion of the host by a pathogen

disease (morbidity)

alters normal functions of the body


the cause of disease


subjective characteristics of a disease that can be felt only by patient


objective manifestations of disease that can be observed or measured (temp, spots, rashes etc)


group of symptoms and signs that characterize a disease or abnormal condition

Asymptomatic (subclinical)

infections lack symptoms but may still have a sign of infection

Koch's postulates

1.suspected germ must be present in every case of disease

2.germ must be isolated n grown in pure culture

3. cultured germ must cause disease when it is inoculated into a healthy susceptible experimental host

4. same germ must be reisolated from diseased experimental factors


degree to which is can cause a disease

Virulence factors

-Adhesion factors

-biofilms form

-extracellular enzyme


-antiphagocytic factors

extracellular enzymes

-Hyaluronidase and collagenase degrade specific molecules to invade deeper tirrues

- coagulase- causes blood proteins to clot where they hide

-kinases- digest blood clots


cheicals either harm tissues or trigger host immune responses that cause damage


cytotoxin-kills host cell or affect function

neurotoxin- interfere with nerve cell function

enterotoxin- affect cell lining the gastrointertinal tract


gramnegative bacteria release endotoxin (lipid A) induces effects as fever, inflammation, diarrhea, shock, blood coagulation

Antiphagocytic factors

Bacterial capsules- many capsules composed chemicals normally found in body, result dont stimulate host immune response

antiphagocytic chemicals- some prevent fusion of lysosome and phagocytic vesicles. leukocidins directly destroy phagocytic white blood cells

stages of infection diseases (5)

1) Incubation period- time between infection and occurence of the first symptoms or signs of disease

2) Prodromal period- mild symptoms (muscle ache)

3) Illness- most severe signs and symptoms

4) Decline- body gradually returns to normal decline in signs and symptoms

5) convalescence- patient recovers from illness no signs and symptoms

modes of infectious diseases transmission

contact transmission

vehicle transmission

vector transmission

contact transmission

Direct- person to person, touching, huging,

indirect- spread from one host to another by fomites(toys, needles, money)

droplets- sneezzing coughing, less then one meter

vehicle transmission

Air- sneezing coughing but farther than one meter

water- water getting contaminated

food- food uncooked, poorly refrigerated

bodily fluids- blood, urine, saliva

vector transmission

biological- biting from flease, mosquitos ect

mechanical- fly has pathogen on its body or legs

acute disease

disease develops rapidly but lasts relatively short time

chronic disease

develops slowly and are continual or recurrent

subacute disease

disease with time course and symptoms btwn acute and chronic

asymptomatic disease

disease without symptoms

latent disease

disease that appears a long time after infection

communicable disease

disease transmitted from one host to another

contagious disease

communicable diease that is easily spread

noncommunicable disease

disease arising from outside hosts or disease from opportunistic pathogen

local infection

infection confines in a small region of body

systemic infection

widespread infection in many systems of body often travel in blood or lymph

focal infection

infection that serves as a source of pathogens for infection at other sites in the body

primary and secondary infection

primary- initial infection

secondary- infection that follow primary often opportunistic


# of a new cases of a disease in a given area during given period of time


# of total cases of a disease in a given area during given period of time

endemic disease

certain amount that happens normal


dont see it their often but randomly it will


larger # of cases in a period of time in a region


global large # of cases in a period of time

descriptive epidemiology

involves the careful tabulation of data concerning a disease

record location n time collect patient info

analytical epidemiology

seeks to determine probable cause, mode of transmission, methods of prevention. occurs when outbreak happens

experimental epidemiology

involves testing a hypothesis

father of epidemiology

john snow


pathogens acquired from healthcare environment


pathogen arises from normal microbiota due to factors within healthcare (medical treatment)


direct results of modern medical procedures. catheters, surgery etc