Normal Microbial Flora

Question 1

What are the Important Contributions of Microbiota?

Answer 1

1a. PROTECTIVE
- decrease pathogen colonization

1b. BUT, can cause disease (esp in immunocompromised)

2a. NUTRITIONAL
- provide B and K vitamins

2b. BUT overgrowth can lead to fat malabsorption and vitamin deficiency

Question 2

What are the common aerobic MOUTH flora?

Answer 2

V. Streptococci

Neisseria

Diptheroids

S. Epidermidis

(Strep, Staph, and diplococci)

Question 3

What’s the predominant mouth organism?

Answer 3

V. Streptococci

106 per ml saliva

Positive cocci chains

Question 4

What does oral Strep thrive on?

Answer 4

Sugar, obvs,

Sucrose -> plaque

Lactic acid byproduct causes cavities

Question 5

What’s the second most common mouth organism?

Answer 5

Non pathogenic Neisseria

NOT meningitidis (which can colonize throat but is a pathogen)

Question 6

How can you tell it’s Neisseria?

Answer 6

Gram negative diplococci

Question 7

What’s a common cause of blood culture contaminant?

Answer 7

Diptheroids/Corynebacterium

Colonize skin

Also mouth

Gram positive

Question 8

Most common contaminant of blood cultures in presence of foreign body?

Answer 8

Staph Epidermidis

Gram positive grapes

coagulate negative

Question 9

Why shouldn’t you bite people?

Answer 9

Eikenella Corrodens

Gram negative rod normally found in mouth

BUT

Can cause skin and soft tissue infections

Question 10

What are the normal anaerobes in the mouth?

Answer 10

Fusobacterium -rod

Prevotella -rod

Peptostrep +cocci

Actinomyces

Question 11

oral flora diseases and treatments

Answer 11

Periodontal infections

Aspiration pneumonia

Most sensitive to penicillin

Question 12

What’s most common cause of subacute bacterial endocarditis?

Answer 12

V. Strep

Question 13

What’s normally found in the stomach?

Answer 13

NOTHING

Ha, too much acid

Bacteria can proliferate in Gastric Achlorhydria or gastric obstruction

Question 14

Who usually colonizes upper small intestine?

Answer 14

Generally no one in fasting individual

1. Fast movement through
2. Unconjugated bile = killer

Question 15

Ok the, what about the terminal ileum?

Answer 15

Usually less than 106 per ml

Resembles stool biota

Coliforms and anaerobes (B. Fragilis)

Question 16

The juicy stuff: What does the colon and feces look like?

Answer 16

Bacterial proliferation (1000 per gram of wet feces)

Stasis and better pH

Predominantly ANAEROBES

Question 17

Most common organism in colon and feces?

Answer 17

BACTEROIDES (Fragilis)

Gram- anaerobic rods

Question 18

*What’s the important metabolic activity of bacteroides?

Answer 18

Generate:
ammonia,
acid,
gas

Ammonia formed by splitting urea and proteins

Question 19

How would you treat abdominal infections?

Answer 19

DON”T USE PENICILLIN

Fragilis is resistant

Clindamycin
Cefoxitin
Metronidazole

+

Aminoglycoside

Question 20

What are the lesser known colonizers of bowel?

Answer 20

Bifidobacterium

• not pathogenic
• sensitive to Penicilin
• common in breast fed infants

Lactobacillus

Clostridium

Coliforms (enteric gram negative rods)
-e. Coli

Question 21

How do bacteria and bile interact?

Answer 21

Bacteria turn conjugated bile acids -> free bile acids

Conjugated bile acids necessary for fat absorption

-> Overgrowth in small intestine leads to malabsorption

Question 22

Bacteria and ammonia?

Answer 22

Bacterial degradation in colon

-> inc blood ammonia levels

Liver tries to bring back down

Question 23

What happens to Carbs in the gut?

Answer 23

Those not absorbed are fermented by intestinal flora

-> pH drop

Good for local flora, Keeps out pathogens

Question 24

Which bacteria are usually found on the skin?

Answer 24

Staph Epidermidis

Staph Aureus

Diptheroids

Anaerobes

Question 25

What’s the most common skin organism?

Answer 25

S. Epidermidis

Generally non pathogenic
-EXCEPT with foreign bodies