Mmg Normal Flora

Front 1

What is normal flora?

Back 1

-microorganisms that are usually found in healthy body tissue

Front 2

What is commensalism?

Back 2

-microbe benefits
-host neither benefits nor is harmed
*Staphylococcus epidermidis

Front 3

What is mutualism?

Back 3

-both microbe and host benefit
*E. coli: vit K synthesis in intestine

Front 4

What is parasitism?

Back 4

-microbe benefits
-host is adversely affected
*Vibrio cholerae

Front 5

What is infection (colonization)?

Back 5

-growth within the host
*does NOT always equal disease!

Front 6

What is disease (morbidity)?

Back 6

-injury to the host

Front 7

How many microorganisms are found in the human body?

Back 7

-about 10^14 microorganisms!

Front 8

Where are most microorganisms found in the human body?

Back 8

-mostly in regions exposed to environment such as skin and mucous membranes

Front 9

What are some reasons that normal flora is important?

Back 9

-physiologically important commensal organisms
-keep harmful microbes out
-remove or out-compete microbes that become harmful

Front 10

Describe the mucous membrane of the mouth, respiratory, gastrointestinal and urogenital tracts.

Back 10

-single layer
-tightly packed epithelial cells that exist in direct contact with external environment
-covered by protective mucus layer
-major sites of infection!

Front 11

How do microbial interactions occur?

Back 11

-binding of ligand (on microbial surface) to receptors on cells (usually sugars or glycoproteins)

Front 12

What are biofilms?

Back 12

-a microbial colony attached to a surface and encased in an adhesive polysaccharide material
-can contain all types of microorganisms
-accounts for 2/3 of bacterial infections in humans

Front 13

How are biofilms good for microbes contained within it?

Back 13

-sheilds against immune system
-limits access to antibiotics

Front 14

What are some common Nosocomial biofilm bacterial species?

Back 14

-S. epidermidis and aureus
-P. aeruginosa
-E. coli
-Actinomyces israelii
-C. albicans

Front 15

Why is the mouth a good microbiological niche?

Back 15

-moist environment with plenty of nutrients and physiological pH
-microbes need to be able to adhere to surfaces due to salivary flow
-each mL of saliva contains >10^6 microbes; mostly bacteria but also fungi

Front 16

Generally, how does colonization of the tooth occur?

Back 16

-sterile at birth, then aerobes, then teeth come in, then anaerobes can occur

Front 17

What is a pellicle?

Back 17

-thin organic film of salivary glycoproteins on tooth surface

Front 18

In detail, what are the colonizers on the tooth?

Back 18

-Streptococci (excpecially S. sanguis and S. mutans)
-in 12-24 hrs later, Fusobacteria
-late colonizers interact with Fusobacteria but not the early colonizers: Actinomyces

Front 19

What is dental plaque known as?

Back 19

-a biofilm!

Front 20

What is the etiological agent in dental caries?
What are its virulence factors?

Back 20

-Streptococcus mutans
-Dextran and pili allow biofilm formation on the tooth

Front 21

What is the susceptibility of dental caries?

Back 21

-consuming high sucrose diets
-S. mutans breaks down sucrose to glucose and fructose (which is food for microbes)

Front 22

How can you prevent dental caries?

Back 22

-proper brushing and flossing of teeth and use of fluoridated toothpaste and water

Front 23

What adverse affect can taking antibiotics cause?

Back 23

-kills normal flora and allows resistant species to flourish
-opportunistic pathogens can also flourish!

Front 24

What are probiotics?

Back 24

-harmless commensal organisms that displace harmful microbes
-Such as: Lactobacilli and Bifidobacteria. *5 x 10^10 bacteria / capsule

Front 25

What are some biochemical or metabolic conributions of intestinal microorganisms?

Back 25

-vitamin synthesis
-gas production
-odor production
-organic acid production
-glycosidase reactions
-steroid metabolism (bile acids)

Front 26

Describe the normal flora of the skin

Back 26

-transient and resident populations
-primarily Gram + bacteria and fungi
-most organisms are associated with the sweat glands

Front 27

What things can affect the type and number of organisms found in teh skin?

Back 27

-age
-weather (humidity)
-personal hygiene

Front 28

What are some microorganisms found in the upper respiratory tract?

Back 28

-Staphylococcus*, Streptococcus*, Moraxella, Haemophilus, Lactobacillus, Veridonella, Fusobacterium, Candida (fungus)*

Front 29

Describe the normal floar found in the lower respiratory system.

Back 29

-usually devoid of resident flora
-cleared by antibodies and ciliary action

Front 30

Describe the normal flora of the urogenital tract.

Back 30

-upper regions are normally sterile
-urethra are colonized with faculatative aerobic Gram - bacteria (E. coli, Proteus mirabilis)
-normal flora of the vagina changes with age/development

Front 31

What are the resident microbiota found in female urogental area?

Back 31

-Lactobacillus*, Streptococcus, Staphylococcus, Bacterioides, Clostridium, Candida, Trichomonas (protozoan)

Front 32

What are the resident microbiota found in male urogential region?

Back 32

-Staphylococcus, Streptococcus, Mycobacterium, Bacteriodes, Fusobacterium, Peptostreptococcus

Front 33

What prevents colonization into the urethra?

Back 33

-the flow of urine

Front 34

Which part of the GI tract is sterile?
What is found in the small intestine?

Back 34

-stomach
-Enterococci and Lactobacilli

Front 35

What is found in the Lg. intestine?

Back 35

-Bacteroides*, Enterobacteria, E. faecalis, Bifidobacterium, Eubacterium, Peptococcus, Peptostreptococcus, Ruminococcus, Clostridia, Lactobacili, Streptococcus, Staphyloccocus