21 Anaerobes 2

Question 1

What is the most common bacteria in colon? How many per gram of feces?

Answer 1

• bacteroides fragilis (anaerobic only!!)

- 10 to the 11 per gram. (also is in oral and female genital tract)

Question 2

Bacteroides fragilis provides what % of colonic mucosal epithelial energy supply? What other function does it have in colon?

Answer 2

70.

produce vitamin K and folate.

Question 3

What 2 particular pathogens (though it competes w/ all) does B. fragilis compete with?

Answer 3

salmonella, shigella

Question 4

B. fragilis morphology?

Answer 4

-pleomorphic

Question 5

B. fragilis toxins?

Answer 5

neuraminidase, hyaluronidase

Question 6

B. fragilis virulence factors other than toxins?

Answer 6

polysaccharide capuse, LPS but LITTLE ENDOTOXIN activity!

Question 7

What is characteristic of B. fragilis infections? (think air supply)

Answer 7

mostly always co-colonize w/ a facultative anaerobe that can use up the O2 for them.

Question 8

Where are B. fragilis infections?

Answer 8

• diverticulosis in intestine

- abdominal cavity after surgery/appendix rupture

Question 9

What happens in B. fragilis bacteremia? (2)

Answer 9

• endocarditis

- skin infection: gangrene, cellulitis, necrotizing fasciitis

Question 10

I grow anaerobically on Bile-esculin agar + gentamicin. What am I?

Answer 10

B. fragilis

Question 11

Drug to treat B. fragilis?

Answer 11

metronidazole [as for many anaerobes]

Question 12

Prevotella morphology?

Answer 12

-pigmented brown/black (from heme) Gram neg rods

Question 13

I cause Periodontitis! What am I?

Answer 13

Prevotella gingivalis (also normal flora of mouth)

Question 14

Prevotella causes infections where? (2)

Answer 14

• head, neck, lower resp. tract ensuing from oral infection

- Rare: pelvic inflammatory disease, tubo-ovarian abscess

Question 15

Porphyromonas used to be considered what species? What is the difference from its parent species?

Answer 15

• Prevotella

- Non-pigmented

Question 16

Where does porphyromonas cause infection?

Answer 16

same as prevotella!

[genitourinary in females, oral/pulmonary]

Question 17

Porphyromonas bivia and disiens cause infection where?

Answer 17

female genitourinary

Question 18

porphyromonas oris and buccae cause infections where?

Answer 18

oral/pulmonary

Question 19

Fusobacterium are found where?

Answer 19

holes. (mouth, GI, genitourinary)

Question 20

What is the most common fusobacterium? What kind of infections does it cause?

Answer 20

• F. nucleatum.

- same as prevotella and porphyromonas!

Question 21

Fusobacterium necrophorum is known for what disease? Describe it?

Answer 21

Lemierre’s syndrome: mass accumulation of septic thrombophlebitis in internal jugular vein following an upper respiratory infection. key signs are fever and lateral neck tenderness! Maybe septic emboli to lung.

Question 22

What are the Gram-positive anaerobic cocci? (non-spore-forming)

Answer 22

peptostreptococcus, anaerococcus

Question 23

What are the Gran-negative anaerobic rods?

Answer 23

bacteroides, prevotella, porphyromonas, fusobacterium

Question 24

What happens to a gram-positive anaerobe (peptostrepto, anaerococcus) when treated with alcohol during the gram stain?

Answer 24

Easily decolorizes! (but not a true gram-negative)

Question 25

T/F peptostreptococcus is normal flora?

Answer 25

T. skin, mucus membranes

Question 26

Where does peptostreptococcus infect?

Answer 26

mixed infections (because anaerobic!) of head, neck, abdomen, lungs, necrotizing pneumonia if aspirated

Question 27

What causes peptostreptococcus bacteremia?

Answer 27

ob/gyn insults or infections, like birth, endometritis, amnionitis

Question 28

What makes peptostreptococcus diagnosis difficult? What’s the solution?

Answer 28

-contamination w/ other anaerobic cocci in samples & it is very slow growing.
Solution: don’t diagnose, just use metronidazole on anaerobes.

Question 29

Where are actinomycetes normal flora?

Answer 29

mucosa

Question 30

actinomycete morphology?

Answer 30

mycelial with sulfur granules!

Question 31

Actinomycete infection types? (2)

Answer 31

-mainly oral, like endodontic & dental-implant associated.
-also granulomatous lesion, abscesses.
[so high risk groups are those w/ poor oral hygiene, or intrauterine devices]

Question 32

T/F actinomyetes spread person to person?

Answer 32

F. Endogenous infection only.

Question 33

Morphology of A. israelii colony?

Answer 33

molar tooth, rough lobate.

Question 34

A. isralii infects where?

Answer 34

cervicofacial, causing lumpy jaw!!

[differentiate from lateral neck tenderness, F. Necrophorum]

Question 35

How do we diagnose A. israelii?

Answer 35

Careful not to contaminate, find sulfur granules and crush to get Gram-pos branching rods

Question 36

Treatment for A. israelii? Prevention?

Answer 36

• drain/debride abscess, use penicillin

- hygiene/prophylactic antibiotic for mouth/GI is penetrated

Question 37

Propionibacterium morphology?

Answer 37

Gram: pleomorphic, and stains unevenly. looks “beaded.”

[recall nocardia looks beaded too but stains acid-fast]

Question 38

Propionibacterium is flora where?

Answer 38

skin, conjunctiva, oral, ear, female GI, colon

[holes, eyes, and skin]

Question 39

High risk group for propionibacterium?

Answer 39

teens, heart devices, catheters

Question 40

What causes acne? How?

Answer 40

• propionibacterium acnes.

- May make inflammatory response. In sebaceous follicles (cleansing doesn’t help)

Question 41

Treatment for propionibacterium?

Answer 41

topical benzoyl peroxide, erythromycin, clindamycin

Question 42

T/F Lactobacillus needs O2?

Answer 42

T, micro-aerophile. Rarely pathogenic.

Question 43

Where is lactobacillus flora?

Answer 43

female GU. (makes vagina acid!)

Question 44

lactobacillus morphology?

Answer 44

long slender rods in Gram stain.