T20 Anaerobic Bacteria

fill in the blank: 1

Peptococcus

fill in the blank: 2-9

Clostridium perfringens, Clostridium botulinum, Clostridium tetani, Clostridioides difficile, Cutibacterium acens, Bifidobacterium, Lactobacillus, Actinomyces

fill in the blank: 10

Veillonella

fill in the blank: 11-15

Fusobacterium, Gardnerella, Bacteroides, Porphyromonas, Prevotella

enzymes that allow aerotolerance

• catalase

• peroxidase

• superoxide dismutase

• superoxide reductase

anaerobic specimen transport

jar with sodium bicarbonate and sodium borohydride with methylene blue indicator

anaerobic bacteria - mediums

• cook meat

• thioglycolate broth

• stuart’s amies with inert gas

symptoms of anaerobic bacteria infection

• foul-smelling discharge from short-chain fatty acid

• infection near mucosal surface

• gas in tissues

• polymicrobial

Peptococcus - normal flora

skin, oral cavity, respi, GI, female genitourinary

Peptococcus - diseases

• deep skin and soft tissue infection: necrotizing fasciitis

• brain abscess

Peptococcus - treatment

penicillin, carbapenems

Clostridium - common characteristic

endospore

Clostridium - reservoir

soil, water, sewage, GI

Clostridium perfringens - morphology

• gram variable

• single/pairs boxcar shape

• subterminal oval spores

Clostridium perfringens - virulence factors

• toxin: alpha and enterotoxin

• endospore

Clostridium perfringens - toxin effects

• RBC, WBC lysis

• increase vascular permeability

• decrease bp

• *swelling, muscle and tissue death

Clostridium perfringens - endospore invasion

only invades wounded skin

Clostridium perfringens - disease

gas gangrene (necrotizing fasciitis) with *foul-smell, crepitus, myonecrosis leading to shock, kidney failure, death within a week

Clostridium perfringens - diagnosis

• litmus milk: stormy clot

• target hemolysis

• reverse CAMP test: S. agalactiae + C. perfringens = arrowhead

• Nagler (Lecithinase) test: precipitating zone

Clostridium perfringens - treatment

• debridement

• hyperbaric oxygen therapy

Clostridium botulinum - found in

canned food

Clostridium botulinum - virulence factors

• endospore

• toxin AB

Clostridium botulinum AB toxin

inhibit muscle contraction (cleave SNARE → vesicle can’t fuse) → *flaccid paralysis

Clostridium botulinum - diseases

• foodborne botulism

• iatrogenic botulism

Clostridium botulinum - diagnosis

ELISA, lateral flow for toxin antigen

Clostridium botulinum - treatment

• trivalent antitoxin

• heat at more than 80 degrees for 20 minutes to destroy

Clostridium tetani - virulence factors

• VAMP (synaptobrevin)

• tetanospasmin

• tetanolysin

• endospore

tetanospasmin

inhibit inhibitory neurotransmitter (GABA)

tetanolysin

hemolysis

Clostridium tetani - disease

tetanus (lock jaw)

tetanus (lock jaw)

*masseter trismus (can’t open mouth) → intermittent spasms of respiratory and swallowing muscles → back contractions (opisthotonos) → respiratory failure

Clostridium tetani - treatment

• antitoxin: only for unbound toxin

• benzodiazepines

• DPT vaccine

Clostridioides difficile - location

intestinal

Clostridioides difficile - virulence factors and effect

• toxin A&B (TcdA&B)

• hyaluronidase

• lead to hemorrhagic death of intestine = *explosive diarrhea

Clostridioides difficile - disease

pseudomembranous colitis

pseudomembranous colitis - pathogenesis

ingestion of spore → bile salt induce germination → colonization → TcdA & B → inflammation and mucosal damage → pseudomembrane → colon wall slough → perforation → toxic megacolon

Clostridioides difficile - diagnosis

• NAAT

• enzyme immunoassay if have symptoms (toxins, glutamate dehydrogenase)

• CCNA

Clostridioides difficile - agar

• cycloserine cefoxitin frucose agar: vero cell spindle → round

• requires heat shock at 80 degrees for 10 minutes to get rid of others

Clostridioides difficile - treatment

fecal transplant, nontoxigenic C. difficile for competitive exclusion

Cutibacterium acnes - characteristics

• produce propionic acid

• opportunistic nosocomial

Cutibacterium acnes - normal flora

skin, hair follicle

Cutibacterium acnes - disease

acne

acne - pathogenesis

shed keratin and sebum accumulate in follicle → P. acnes proliferation → inflammation

Cutibacterium acnes - treatment

erythromycin, clindamycin

probiotic bacteria

• Bifidobacterium

• Lactobacillus

Lactobacillus - normal flora

vagina and intestine

Lactobacillus - disease

• dental caries: L. acidophilus

• transient bacteremia: after birth, gynecologist

• endocarditis

Lactobacillus - treatment

penicillin, aminoglycoside

Actinomyces - gram

gram-positive

Actinomyces - normal flora

oral cavity

Actinomyces - disease

• granulomatous

• cervicofacial: jaw/oral infections after dental caries

• cervicothoracic/thoracoabdominopelvic infections (chronic empyema, fistulas)

Actinomyces infection characteristic

discharge with sulfur granules (yellow clumps)

Actinomyces - treatment

prolonged antibiotics

anaerobic gram-negative bacilli - treatment regimen

• resist penicilin and cephalosporin

• use: azthreonam, imipenem, ceftrixone

• or: beta-lactamase inhibitors: clavulonate, sulbactam

Bacteroides fragilis - aerotolerance

superoxide dismutase

Bacteroides - virulence factors

• NOT LPS: no lipid A so not toxic

• enzymes: collagenase, fibrinolysin, heparinase, hyaluronidase

• B. fragilis toxin (zinc metalloprotease) → *diarrhea

Bacteroides - diseases

• appendicitis

• endocarditis

• intra-abdominal abscess

Bacteroides - agar

• brain-heart infusion agar (BHIS): with vitamin K and hemin

• bacterioides bile esculin agar (BBE): brown

Bacteroides - treatment

metronidazole

Porphyromonas - diseases

• periodontitis

• arthritis: cross reaction to joint

• breast, axillary, perianal, male genital infections

Prevotella melaninogenica - disease

upper respiratory and oral infections

Prevotella bivia, Prevotella disiens - disease

female genital infections

Prevotella - disease

brain, lung abscess, empyema, pelvic inflammation

Fusobacterium necrophorum - morphology

long rod

Fusobacterium nucleatum - morphology

fusiform

Fusobacterium - disease

• fusospirochetosis: combine with Treponema vincentii

• Vincent’s angina/Trench mount

• Lemierre’s disease (Fusobacterium necrophorum)

Vincent’s angina/Trench mount

acute necrotizing ulcerative gingivitis

Lemierre’s disease

septic emboli after infections of head and neck

Gardnerella - gram

gram variable

Gardnerella - virulence factors

• surface hydrophobicity: attachment

• metalloprotease: digestive enzyme 

• vaginolysin

Gardnerella - disease

bacterial vaginosis

bacterial vaginosis - criteria

Amsel criteria

• clue cells (vaginal epithelium covered with many gram variable bacilli) >20%

• thin mucus discharge pH > 4.5

• fish odor when + 10% KOH → whiff test

bacterial vaginosis - caused by

decreased lactobacilli, trichomonad, yeast

Gardnerella - treatment

metronidazole