Gram-positive rods prevailing in teeth with apical periodontitis undergoing root canal treatment.
OBJECTIVE
To identify Gram-positive rods from root canals of teeth with apical periodontitis and to examine their associations with other species.


METHODS
Consecutive root canal samples (RCSs) from 139 teeth undergoing root canal treatment were analyzed prospectively for cultivable microbes. Gram-positive rods in the first RCS submitted after chemo-mechanical preparation were categorised to genus level by selective media and gas-liquid chromatography (GLC), and identified to species level by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Associations between organisms were measured by odds ratios (OR).


RESULTS
In the first samples submitted a total of 158 Gram-positive rods, 115 Gram-positive cocci, 26 Gram-negative rods and 9 Gram-negative cocci, were identified. At genus levels Gram-positive rods were classified into: Lactobacillus spp. (38%), Olsenella spp. (18%), Propionibacterium spp. (13%), Actinomyces spp. (12%), Bifidobacterium spp. (13%) and Eubacterium spp. (6%). The most frequent species were Olsenella uli, Lactobacillus paracasei and Propionibacterium propionicum. In subsequent samples taken during treatment, Gram-positive rods were also identified, although the number of strains was considerably reduced. Positive associations were observed between members of the genus lactobacilli and Gram-positive cocci (OR>2).


CONCLUSIONS
Olsenella uli and Lactobacillus spp. predominated over other Gram-positive rods. A possible association exists between Lactobacillus spp. and Gram-positive cocci in root canals of teeth with apical periodontitis receiving treatment.
Department of Oral Microbiology, Faculty of Odontology, The Sahlgrenska Academy at Göteborg University, Göteborg, Sweden. luis.chavez.de.paz@odontologi.gu.se
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Chávez de Paz
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Molander
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Dahlén
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015373:Bacterial Typing Techniques; D015169:Colony Count, Microbial; D003786:Dental Pulp Cavity / Q000382:microbiology*; D019232:Dental Restoration Failure; D024881:Drug Resistance, Bacterial; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006095:Gram-Positive Cocci / Q000145:classification / Q000472:pathogenicity; D016987:Gram-Positive Rods / Q000145:classification* / Q000472:pathogenicity*; D006801:Humans; D007778:Lactobacillus / Q000145:classification / Q000472:pathogenicity; D008297:Male; D008875:Middle Aged; D010485:Periapical Periodontitis / Q000382:microbiology* / Q000628:therapy; D011446:Prospective Studies; D012390:Root Canal Therapy