Actinobacillus actinomycetemcomitans - MegaMicro

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Actinobacillus actinomycetemcomitans

Microbiology > Bacteriology > Gram-negative bacteria > Gram-negative bacilli > HACEK organisms
Actinobacillus actinomycetemcomitans
a. "A" of HACEK group

b. Structure
i. Gram-negative
1. Contains LPS
ii. Rod-shaped
iii. Non-capsulated

c. Pathobiology
i. Physiology:
1. Facultative anaerobe
a. Can grow under aerobic and anaerobic conditions
2. Facultative nonmotile
3. Catalase positive
4. Oxidase negative (except for few strains)
5. Able to ferment
a. glucose, fructose, maltose and mannose
6. Unable to ferment
a. Galactose, lactose, sucrose, and sorbitol

ii. Virulence factors:
1. Leukotoxin
a. Defense against PMNs and monocytes
2. LPS
3. Cytolethal distending toxin

iii. Host: humans

d. Epidemiology
i. Part of the normal flora of the oral cavity
ii. Located within biofilms on teeth

e. Laboratory diagnosis
i. Difficult to grow from blood cultures
1. Ranges from 2-9 days; time to culture

f. Disease manifestations:
i. Periodontitis
1. Bacterial infection of tooth-supporting structures
2. Increases risk of cardiovascular disease
ii. Bacterial endocarditis

g. Therapy
1. Cefamandole and ceftriaxone combination therapy
2. If allergic to beta lactam antibiotics then; fluoroquinoline
3. Tetracycline
4. Variable Susceptibility to penicillin, amoxicillin, ampicillin
5. Resistant to clindamycin, erythromycin, and vancomycin

h. Prevention and control
i. Good oral hygiene
ii. Routine dental check ups
iii. Removal of bacterial plaques via dental surgical and cleaning tools

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