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19 Cards in this Set

  • Front
  • Back
General characteristics of G- anaerobes
Normal flora
opportunistic pathogens
benefit from co-infecting
many form bifilms
Common virulence factors of G- anaerobs
Anti-phagocytic capsule
Also promotes abscess formation

Tissue destructive enzymes
Lipases, proteases, collagenases that destroy tissue and promote abscess formation

Beta-lactamase production
Protects self and other species in mixed infections

Superoxide dismutase production
Protects bacteria from toxic O2 radicals as they move out of usual niche
1.5-4.5 um long
Gut normal flora
Drug resistance plasmids
Bacteroides fragilis
Pathogenesis of Bacteroides fragilis
Fimbriae and agglutinins function as adhesins
Polysaccharide capsule
Responsible for abscess formation
Stimulates leukocyte chemotaxis and migration
Contains little lipid A -> weak endotoxin activity
Oxygen tolerance
Superoxide dismutase
Degradative enzymes, eg neuraminidase, hyaluronidase, DNAses, proteases
Histolytic (tissue destruction)
Inactivation of immunoglobulins (IgA, IgM, IgG proteases)
Some drug resistance plasmids
clinical syndromes of Bacteroides fragilis
Abscess formation in normally sterile sites
Intraabdominal infections: more than 80% caused by B. fragilis
Gynecological infections: polymicrobial anaerobic infections with B. fragilis frequently causing abscesses
Skin and soft tissue infections: most commonly associated with B. fragilis; Gm- anaerobes gain access to sites via bites or trauma
Respiratory tract: polymicrobial infections including non-fragilis Bacteroides
Short coccoid rods
Produces black pigment
Requires vitamin K
Weak endotoxin
Other sp.: P. oralis
Prevotella melaninogenica
Gram negative, short, rod-shaped, pleiomorphic, anaerobic bacteria
Porphyromonas gingivalis
Virulence factors of Porphyromonas gingivalis
Fimbriae (adherence)
Capsule (antiphagocytic)
Many degradative enzymes (proteases, collagenase, hemolysin)
Pathogenesis of Porphyromonas gingivalis
Aggressive periodontal pathogen in humans and animals
Found almost exclusively at subgingival sites
Gram-negative anaerobe
Spindle shape, with sharp ends
Similar to Bacteroides
5-10um long
Butyric acid fermenters
Fusobacterium nucleatum
Gut normal flora
Pleuropulmonary infections
Tropical skin ulcers
Cause of trench mouth (common during WWI)
Ulcerative disease of the gums associated with poor oral hygiene, fatigue, malnutrition, heavy smoking, etc.
Fusobacterium nucleatum
Necrotizing infection of the pharynx
Unilateral with same side earache
Bleeding ulcer on one tonsil
Antibiotics and debridement recommended

F. nucleatum + Treponema vincentii
Vincent’s Angina
Normal throat flora
Lemierre’s syndrome
very rare today but common before penicillin
Rising incidence in children may result from encouraged reduced use of antibiotics
starts with sore throat, viral cause usually is suspected, hence rarely treated with antibiotics
Potentially leads to severe disease: high fever spikes, septicemia, abscesses on organs
Predisposition to abscess formation, in liver, spleen and muscles
Pulmonary lesions
Fusobacterium necrophorum
Gm- thin, filamentous,
non-motile bacteria
Related to Fusobacterium sp.
Aerotolerant anaerobes, fastidious slow-growers
Several species cause disease in humans:
L. amnionii
L. trevisanii
L. sanguinegens
L. buccalis
Associated disease: periodontal disease, bacteremia, serious systemic disease in immunocompromised patients, disease of reproductive tract, etc.
grows best at reduced O2 and CO2 concentrations of 10%
Motile curved rods
Single polar flagellum
Small: will pass through .65 uM filters that filter out most enteric bacteria
Many serotypes based on O (LPS O-side chain) and H (surface proteins) antigens
commensal flora of birds
many other animals serve as vehicles for human infection
usually through he consumption of contaminated food
the major cause of food-borne bacterial infection of humans
Sites of infetion of Campylobater
Small and Large intestine
Virulence factors
Ability to penetrate cells
Intracellular survival
Clinical significance
Caused mainly by C. jejuni and C. coli
Systemic infections
Usually due to C. fetus ssp. fetus
Occurs in debilitated or immunocompromised individuals