GN anaerobes

where are GN anaerobes found?

• resp: prevotella, porphyro, fuso

• GI: bacteroides

• GU: fuso, prevotella, bacteroides

anaerobic infections

• endogenous: trauma or accidental contact with other sites

  • surgery, punctures, aspiration of oral secretions to lungs

• exogenous is bite wounds

• local or spreads

  • abscess, bacteremia, peritonitis, pneumonia

bacteroides

• most commonly isolated anaerobic GNR

• abscess formation = hallmark

• polymicrobic infections in abd, pelvis, perirectal skin, solid organs

bacteroides virulence factors

• capsule

• pili/fimbriae

• enzymes to spread/digest tissue and survive prolonged oxygen exposure

b. frag group

• b. fragilis, distasonis, ovatus, thetaiotamicron, vulgatus

• bile resistant: black on BBE

• infections: intra abd, perirectal, decubitus ulcers, bacteremia

• R to penicillin (beta lactamase producer)

• enterotoxigenic = diarrhea

b. ureolyticus group

• bile sensitive

• S to kanamycin

• campylobacter spp

• bilophila wadsworthia (resistant, fish eyes)

• sutterella (resistant)

• all nitrate pos

b. frag presumptive ID

• anaBAP/LKV: large, convex with chartreuse fluoro

• GNR

• BBE: large, convex, gray black

• R to K and V

• indole not performed

esculin hydrolysis bacteroides frag group

b. uniformis neg (others pos)

indole - bacteroides frag group

• pos: b. ovatus, thetaiotamicron, uniformis

• neg: others

cat 15% - bacteroides frag group

• pos: b. fragilis, distasonis, ovatus, thetaiotamicron

• V: uniformis

• neg: others

presumptive ID of b. ureolyticus

• anaBAP: translucent, pitting

  • no LKV: S to kana

• neg 15% catalase, indole

• tiny GNR/ccb

• no BBE

bilophila wadsworthia presumptive ID

• anaBAP: tiny translucent

  • no LKV: S to K and V

• strong cat pos 15%

• BBE: fish eye colonies (black centers)

• neg indole

esculin hydrolysis b. ureolyticus group

b. wadsworthia pos, others neg

oxidase bacteroides ureolyticus group

c. ureolyticus pos, others neg

cat 15% - b. ureolyticus group

pos: b. wadworthia

V: c. ureolyticus

neg: others

urease - b. ureolyticus group

pos: c. ureolyticus

V: b. wadsworthia

neg: others

prevotella spp

• normal oral, GU tract

• all clinically relevant species are bile sensitive

pigmented prevotella species

• p. denticola, intermedia, loescheii, melanginogenica

• oral, dental, bite infections

• head, neck, LRT infections

nonpigmented prevotella species

• p. bivia, disiens

• female genital tract infections and soft tissue infections

prevotella presumptive ID

• anaBAP, LKV: small translucent/opaque colonies

  • brown black pigment

  • fluoro brick red

• tiny GN ccb

• no growth BBE

• indole:

  • intermedia pos, others neg

colistin - prevotella

p. bivia R, others V

lipase - prevotella

p. intermedia, loescheii pos; others neg

porphyromonas spp

• common oral flora

• p. endodontalis, gingivalis

  • aggressive periodontitis; heart disease, atherosclerosis, diabetes

  • biofilms plaques

  • root canals, sinusitis

• p. asaccharolytica: GI/GU tracts

porphyromonas presumptive ID

• anaBAP: small translucent/opaque

  • brown/black pigment

  • fluoro brick red (except gingivalis)

  • no LKV: S to V

• tiny GN ccb

• no BBE

• indole pos

f. nucleatum

• most commonly isolated fuso

• oral cavity, URT, GU, GI tracts

• sole pathogen in pleuropulmonary

f. necrophorum

• URT infections following pharyngotonsillitis, IM, bacterial pharyngitis

• virulence factors: endotoxin, leucocidin, hemolysin, hemagglutinin

• cause lemierre’s syndrome and vincent’s angina

• large pleomorphic cells

• pos lipase

lemeirre’s syndrome

• after pharyngitis

• endotoxins spread bacteria into jugular vein

• inflammation, plt aggregation, clot formation in vein

• persistent fever, acute pharyngitis, sepsis, neck tenderness, swelling

vincent’s angina

• acute necrotizing ulcerative gingivitis, trench mouth

• bad breath, blunting of interdental papilla, necrotic sloughing of gingiva

• very painful, bleeding

f. mortiferum, varium

• found in polymicrobial intra abd infections

• mortiferum: bizarre, round bodies, neg indole

• varium: large, rounded ends

f. nucleatum presumptive ID

• anaBAP: opalescent bread crumb w chartreuse fluoro

  • no growth on LKV

• fusiform thin pointed GNR

• no growth BBE

• indole pos

bile resistance - fusobacterium

R: mortiferum, varium

S: nucleatum, necrophorum

veillonella

• normal oral, GU, resp, GI tract flora

• rare sole pathogen in meningitis, joints, pleuropulmonary, bacteremia, endocarditis

veillonella presumptive ID

• anaBAP/LKV: small transparent/opaque colonies

  • red fluoro that fades rapidly

• tiny GN dcc

• no growth BBE

• neg indole

vanc susceptible GN

porphyromonas

kanamycin susceptible

bacteroides (not frag), bilophila, fuso, veillonella

colistin susceptible

bacteroides (not frag), bilophila, fuso, veillonella, prevotella