21 Anaerobes 2 Flashcards
What is the most common bacteria in colon? How many per gram of feces?
- bacteroides fragilis (anaerobic only!!)
- 10 to the 11 per gram. (also is in oral and female genital tract)
Bacteroides fragilis provides what % of colonic mucosal epithelial energy supply? What other function does it have in colon?
70.
produce vitamin K and folate.
What 2 particular pathogens (though it competes w/ all) does B. fragilis compete with?
salmonella, shigella
B. fragilis morphology?
-pleomorphic
B. fragilis toxins?
neuraminidase, hyaluronidase
B. fragilis virulence factors other than toxins?
polysaccharide capuse, LPS but LITTLE ENDOTOXIN activity!
What is characteristic of B. fragilis infections? (think air supply)
mostly always co-colonize w/ a facultative anaerobe that can use up the O2 for them.
Where are B. fragilis infections?
- diverticulosis in intestine
- abdominal cavity after surgery/appendix rupture
What happens in B. fragilis bacteremia? (2)
- endocarditis
- skin infection: gangrene, cellulitis, necrotizing fasciitis
I grow anaerobically on Bile-esculin agar + gentamicin. What am I?
B. fragilis
Drug to treat B. fragilis?
metronidazole [as for many anaerobes]
Prevotella morphology?
-pigmented brown/black (from heme) Gram neg rods
I cause Periodontitis! What am I?
Prevotella gingivalis (also normal flora of mouth)
Prevotella causes infections where? (2)
- head, neck, lower resp. tract ensuing from oral infection
- Rare: pelvic inflammatory disease, tubo-ovarian abscess
Porphyromonas used to be considered what species? What is the difference from its parent species?
- Prevotella
- Non-pigmented
Where does porphyromonas cause infection?
same as prevotella!
[genitourinary in females, oral/pulmonary]
Porphyromonas bivia and disiens cause infection where?
female genitourinary
porphyromonas oris and buccae cause infections where?
oral/pulmonary
Fusobacterium are found where?
holes. (mouth, GI, genitourinary)
What is the most common fusobacterium? What kind of infections does it cause?
- F. nucleatum.
- same as prevotella and porphyromonas!
Fusobacterium necrophorum is known for what disease? Describe it?
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.
What are the Gram-positive anaerobic cocci? (non-spore-forming)
peptostreptococcus, anaerococcus
What are the Gran-negative anaerobic rods?
bacteroides, prevotella, porphyromonas, fusobacterium
What happens to a gram-positive anaerobe (peptostrepto, anaerococcus) when treated with alcohol during the gram stain?
Easily decolorizes! (but not a true gram-negative)
T/F peptostreptococcus is normal flora?
T. skin, mucus membranes
Where does peptostreptococcus infect?
mixed infections (because anaerobic!) of head, neck, abdomen, lungs, necrotizing pneumonia if aspirated
What causes peptostreptococcus bacteremia?
ob/gyn insults or infections, like birth, endometritis, amnionitis
What makes peptostreptococcus diagnosis difficult? What’s the solution?
-contamination w/ other anaerobic cocci in samples & it is very slow growing.
Solution: don’t diagnose, just use metronidazole on anaerobes.
Where are actinomycetes normal flora?
mucosa
actinomycete morphology?
mycelial with sulfur granules!
Actinomycete infection types? (2)
-mainly oral, like endodontic & dental-implant associated.
-also granulomatous lesion, abscesses.
[so high risk groups are those w/ poor oral hygiene, or intrauterine devices]
T/F actinomyetes spread person to person?
F. Endogenous infection only.
Morphology of A. israelii colony?
molar tooth, rough lobate.
A. isralii infects where?
cervicofacial, causing lumpy jaw!!
[differentiate from lateral neck tenderness, F. Necrophorum]
How do we diagnose A. israelii?
Careful not to contaminate, find sulfur granules and crush to get Gram-pos branching rods
Treatment for A. israelii? Prevention?
- drain/debride abscess, use penicillin
- hygiene/prophylactic antibiotic for mouth/GI is penetrated
Propionibacterium morphology?
Gram: pleomorphic, and stains unevenly. looks “beaded.”
[recall nocardia looks beaded too but stains acid-fast]
Propionibacterium is flora where?
skin, conjunctiva, oral, ear, female GI, colon
[holes, eyes, and skin]
High risk group for propionibacterium?
teens, heart devices, catheters
What causes acne? How?
- propionibacterium acnes.
- May make inflammatory response. In sebaceous follicles (cleansing doesn’t help)
Treatment for propionibacterium?
topical benzoyl peroxide, erythromycin, clindamycin
T/F Lactobacillus needs O2?
T, micro-aerophile. Rarely pathogenic.
Where is lactobacillus flora?
female GU. (makes vagina acid!)
lactobacillus morphology?
long slender rods in Gram stain.
