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Flashcards in Normal Flora vs. Pathogens Deck (12):

Natural microbial habitats

Natural microbial habitats




animals and animal products




Indogenous Microbiota

Transient Flora



Flora: AKA Microbiota. microorganisms present in a special location

Indogenous Microbiota: AKA Resident Flora. microbial flora typically occupying a certain niche.

Transient Flora: microbial flora temporarily occupying a niche.

Niche: place of an organism within its community. 

Opportunistic: microbes that are normally harmless, but become invasive when given an opportunity (weakened immune defense)


Roles of resident flora

Roles of Resident Flora

1. Common source of infection

  • oportunistic infections (ex. ecoli=UTI)

2. Immune stimulation

  • ex. ABO blood type

3. Keeping out invaders

  • produce substance inhibiting new invaders (ex. antibiotic)

4. Role in nutrition and metabolism

  • ex. E.coli synthesizes vitamin K


Acquiring Infectious Agents

Acquiring Infectious Agents

1. Entry: by ingestion, inhalation, or direct penetration

2. Colonization: occupation of new habitat

3. Invasion: entry/spread throughtout cells and tissue

4. Multiplication: microorganism reproduction during infection



transmission of diseases: vocab

Transmission of diseases: vocab

Vector: carrier of disease that transfers agent from host to host

Carrier: symptomless individual who passes pathogen to others

Nosocomial Infections: infections aquired in a hospital setting


Koch's postulates

Koch's postulates

= criteria to identify causative agent of a particular disease. 

1. microorganism must be present in ALL cases of disease

2. pathogen can be isolated from host and GROWN in pure culture.

3. pathogen from pure culture cause same disease when INOCULATED into another animal. 

4. pathogen must be REISOLATED from new host and shown to be the same as isolate from primary host. 



1. all these sick things have IT

2. take it out of sick thing and grow IT

3. put IT into heathy thing and IT makes thing sick

4. take IT out of new sick thing and make sure IT is the same as IT was in the first sick things. 




Host- Microbe Relationships

Host- Microbe Relationships

Symbiosis: relationship between two dissimilar organisms

Mutualism: both benefit (+/+)

Commensalism: one benifits (+/0)

Parasitism: one benifits and other suffers (+/-)


Steril Sites


Steril Sites should not have any flora!

  • Brain
  • Blood/tissue/organ systems
  • sinuses and inner ear
  • lower respitory tract
  • internal urinary tract- kidney, ureters, bladder, posterior urethra
  • uterus, cervix, fallopian tubes


List Resident Flora



List Resident Flora

  • Skin
    • microbes colonize epidermis
  • Oral Cavity
    • colonize cheeks and gums
  • Upper Respiratory Tract
    • strep and staph
  • Eye + Outer Ear
  • Intestinal Tract
    • E.coli, Lactobacillus etc. 
  • Genitourinary Tract
    • vaginal flora
    • microbes near urethral orifice (opportunistic UTI)


Infection vs. Disease

Infection vs. Disease

Infection: colonization and/or invasion and multiplication of pathogenic microorganisms in a host WITH OR WITHOUT MANIFESTATION OF DISEASE.


Disease: ABNORMAL condition of body function or structure that is harmful to the host. 


Factors controlling growth of microorganisms

Factors controlling growth of microorganisms

  • Nutrient Availability
  • Environmental Parameters
  • Competition
  • Host Immune System


Define: epidemic, endemic, pandemic

epidemic: disease that occurs suddenly, in numbers greater than normal expectancy. 

endemic: disease present in a pop or geographic area at all times.

pandemic: widespread epidemic, throughout region, country, continent, or globe.