Actinobacillus actinomycetemcomitans - MegaMicro

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