Lecture 5 - Normal Flora

Question 1

What is a microbiome?

Answer 1

total community of microorgs in an enviro or body loc

Question 2

What is normal flora?

Answer 2

microorgs present in or on a healthy animal
constant change in #’s and species within body
relationship btw normal flora and host is symbiosis

Question 3

What is symbiosis?

Answer 3

An association of two or more diff species/organisms
refers to 1) bacteria/virus/yeast and 2) anima/plant in microbiology
relationship can be pos or neutral

Question 4

How do you describe a symbiosis on or in the host?

Answer 4

ectosymbionts - on host
endosymbionts - in host

Question 5

What is mutualism?

Answer 5

Both orgs benefit from relationship

A -> B -> A

Question 6

What is commensalism?

Answer 6

Only one org benefits from relationship. The other is neither helped nor harmed
commensal is the org that is helped

A -> +B (Commensal)

Question 7

What is competition symbiosis?

Answer 7

occurs when 2+ orgs share space
compete for available resources
2 outcomes
1: one will out compete the other(A,A,A,B,A)
2: both will exist at lower lvls(A,A,B,B)

Question 8

What is the 4 roles of normal flora?

Answer 8

1. aid w/ food product digestion (ruminant to digest insoluble fiber)
2. Provides essential nutrients (GI flora synth vita’s, AA’s)
3. Stims immune response (maintains low-lvl of ongoing immune activity for fast response to infection)
4. Protect against infect by more virulent microbes

Question 9

How does the normal flora help protect against infection by more virulent microbes?

Answer 9

• trhu comp. for space, nutrients
  -bact alter pH to inhib growth of other microbes
  -bact prod their own anti-microbial factors (bacteriocins) that prevent colonization
• maintains low lvls of immune stim
• bind to + block pathogenic bact from binding to receptors on cell surface

Question 10

What are two ways to control normal flora?

Answer 10

1. competition - each popu. exists in low #’s than if only one popul. was present
2. Immune system - balance btw normal flora + immune system (immune system to maintain normal flora lvls)

Question 11

In regards to normal flora, when does disease occur? (3)

Answer 11

1. too much normal flora
2. too little normal flora
3. normal flora moves to new loc not normally found in

Question 12

What happens if there is an overgrowth of normal flora?

Answer 12

• common cause is decreased func of immune systems bc can’t maintain normal flora lvls
• when normal flora causes disease, now called opportunistic pathogen
  when infection caused by normal flora is called a oppertunistic infection

Question 13

What happens with a loss of normal flora?

Answer 13

• can be dec in all overall numbers of bact or dec. # of species
• = lack of compete., lack of bacteriocins, pathogenic bact have space to attach
  -allows for pathogenic species to colonize or allows inc. in #’s of one species normally present in low numbers
  -anims grown in labs w/o normal flora very high risk of infect/Dz

Question 14

What normal flora is found in the nose?

Answer 14

staphylococcus aureus + Staphylococcus epidermidis

inside nostrils

Question 15

What normal flora is found in the oro-nasopharynx

Answer 15

combo of aerobic + anaerobic bact
Common : Staphylococcus, streptococcus, haemophilus
mostly non-pathogenic bact unless they gain access to tissues that are normally sterile (sinues, middle ear, brain)

Question 16

What normal flora is found in the trachea

Answer 16

“transiently colonized” by bact from oronaspharynx
microbes continually removed by mucociliary elevator

Question 17

What is the mucociliary elevator

Answer 17

-mucus traps microbs + particles
- cilia loc on mucosal epithelial cells sweep mucus up into oral cavity to be spit our or swallowed
- main mechanism to keep microbes out of lower airways
-damage (virus infect, smoke inhale) will inc. infection risk

Question 18

What is the normal flower of the lower resp tract?

Answer 18

NONE! Generally sterile
May transiently colonize w/ bact from upper respt tract butbact cannot establish
- microbes removed by mucociliary elevator
- phagocytosis by alveolar macrophages
- lysozyme in mucus

Question 19

What are the risk factors for microbial colonization of the lower respt tract?

Answer 19

1. acute/chronic aspiration - inhale infection material into lung via stomach/esophagus + inc risk of megaesophagus, chronic vomit
2. Damage to mucus-generat cells + vilia of upper R tract - traumatic/chem injury, primary viral infect causes damage to cells, inflam (asthma)

Question 20

What is the normal flora of the skin?

Answer 20

• Few bc hostile enviro (dry, oils, sloughing of skin cells)
• NoF tends to be transient
  -Common Flora (most to least com)
  Staphlococcus intermedius
  Staphylococcus aureus
  Fungi (malasezzia) in moist areas like groin, armpits
  less often: Corynebacterium, streptococcus

Question 21

What happens with normal flora and abnormal skin?

Answer 21

• if skin is warm/moist = inc bact + yeast - can cause pathology
  -breach of intact skin allows bact to adhere to underlying subcutis and proliferate
  -if bact popul. is disrupted, yeast popul may go into “overgrowth” and cause disease

Question 22

What is the lay term for bacterial pyoderma?

Answer 22

A hot spot, red inflammed flesh

Question 23

What is the normal flora of hair, fur and wool?

Answer 23

• contam by anything in enviro
• always considered a contaminant
  -diff flora w/ external hair versus hair follicle (bact, mites)
• can support its own biofilm under certain enviro conditions

Question 24

What is the normal flora of the eye/ear

Answer 24

EYE: Sm #’s of bact present on conductive. Includes staphylococcus + streptococ. #’s held in check by lysozyme in tears

Ext Ear: sim bact + yeast on skin, common is staphylococ, also streptococ, Pseudomonas, enterbacteriacae

Question 25

What is the normal flora of the mouth?

Answer 25

2 popul’s - aerobic (associated w/ teeth) facultative anaerobes, anaerobes (periodontium)
- bact plaque = mats of microbes (biofile) solidly attached to teeth.
inc. colonization if enamal wear/scratches, malocclusion, diet high in fermentable carbs
if plaque extensive, will extend subgingivally where change from aerobic to anaerobic populs’

Question 26

what is the normal flora of the stomach - monogastric?

Answer 26

limited # of normal flora
most common lactobacillus, enterococc, helicobacter felis

Question 27

Describe rumen flora

Answer 27

-distinct + complex
-allows anim to digest + extract nutr.s from cellulose
-microbes also digested by anim for macronutrints
-ability to derive nutr.s from cellulose and NoF enable ruminants to survive under very harsh nutr.s/ enviro conditions
10^12 microbes/ml rumen fluid

Question 28

What are rumen normal flora composed of? What is typically found there?

Answer 28

composed of bact, protozoa, funci, archaea, virus
gram neg bact predominat
common E. coli, Lactobacilli, Streptococ bovis, Bacteroids
-Fibrolytic microbes brake down cellulose
-mostly strict (some facul.) anaerobes
- anaerobic bact ferment sugars to alcohols + acids that absorb thru rumen wall
lactobacilli prod building blods for milk sugar prod

Question 29

What are archaea?

Answer 29

archaea are evolutionarily “old” prokaryotic organisms
make-up ~3% of microbial mass
convert H gas and Co2 to methane
methane belched out during rumination

Question 30

What are viruses?

Answer 30

bacteriophage are viruses that infect + kill bact
causes cells to lyse
contents are then used as nutr.s by anim

Question 31

Explain colonization of viruses in ruminants?

Answer 31

colonization of rumen is slow
microbes transmitted btw animals via nursing or transfer of cud
primary factor determining bact profile is diet
diet change must be slow (proper microbes reg to digest new diet takes 2-3 wks to estab)

Question 32

What is the normal flora for sm intestine?

Answer 32

bact, fungi, protozoa
vry few microbes in duodenum
microbes #’s inc. moving distally towards cecum
mixed anaerobes (strict anaerobes > facul. anaerobes) (enterococ, E. coli, Enterobacteriaceae, clostridum
som pathogenic bact present in VERY sm #’s in healthy anims (salmonella, campylobacter)

Question 33

What is the func of the sm intestinal flora?

Answer 33

1. vita synth (Vita K prod + Vita B9, B12)
2. contribute to digestion, (fiber)
3. enhance segmental contractions
4. inhib colonization by patho bact (via compet. prod of bacterocins)
5. stim immune tissues in sm int
6. take part in drug metab pathways

Question 34

what is the normal flora of the lg intestine?

Answer 34

• lgst microbial popul. in body
• 10^11 bact/gram feces
  -mostly anaerob bact (strict + facul)
• dom species is e.coli in feel, k0 catl
  also fecal streptococ, enterococ, klebsiella, bacteroides, clostridium, lactobacillus
  -strains of e.coli that are pathogenic to humans found in 30% of dog feces sampled in 1 study

Question 35

When does colonization start with normal flora in lg intestine?

Answer 35

colonization starts at birth w/ ingestion of birth canal secretion + feces
also acquired thru nursing
profile of flora changes w/diet
will also change w/ GI inflam
rapidly affected by oral antib’s
lack of balance btw normal flora and immune system can contribute to irritable bowel disorder

Question 36

What are coliforms?

Answer 36

-rodshaped, gram neg, motile
-nonsporeforming bact
-can ferment lactose
-normallyfound in feces
-also found in water, soil, vegetation
- fecal coliforms include: Escherichia, enterobacter, klebsiella

Question 37

What is SIBO? Sm int bact overgrowth

Answer 37

• when normal flora of sm int starts to resemble the colon
  -occurs when there is dec. peristalsis and/or damage to the cecum -> allows normal lg int flora to migrat to sm int
  Colon bact: creat gas -> gas distension, interfere with digestion/absorption, compete for nutrients
  results in inflam, diarrhea, colic