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A particular clone (JP2) of Actinobacillus actinomycetemcomitans with increased leukotoxin production has been isolated from individuals with early-onset periodontitis (EOP). The aim of this study was to determine the frequency of carriers of this clone and its association with EOP in Moroccan schoolchildren. Of 217 plaque samples, 131 (60.4%) were culture-positive for A. actinomycetemcomitans. A total of 19 of these isolates had a 530-bp deletion in the leukotoxin promoter region characteristic of the JP2 clone. A strong association between the presence of A. actinomycetemcomitans with the 530-bp deletion and EOP was found (adjusted OR = 29.4; 95% CI 8.3 -104.4; p < 0.0005), while no association could be demonstrated between the presence of A. actinomycetemcomitans without the deletion and EOP (adjusted OR =1.3; 95% CI =0.5 -2.9; p = .750). The study demonstrates that the endemic presence, in a human population, of the highly leukotoxic JP2 clone may result in an unusually high prevalence of EOP. [ABSTRACT FROM AUTHOR]

The JP2 clone of Aggregatibacter actinomycetemcomitans is strongly associated with aggressive periodontitis. To obtain information about colonization dynamics of the JP2 clone, we used PCR to examine its presence in 365 Moroccan juveniles from whom periodontal plaque samples were collected at baseline and after one and two years. Periodontal attachment loss was measured at baseline and at the two-year follow-up. At baseline, 43 (12%) carriers of the JP2 clone were found. Nearly half (44 %) of these were persistently colonized with the clone. The relative risk for the development of aggressive periodontitis, adjusted for the concomitant presence of other genotypes of A. actinomycetemcomitans, was highest for individuals continuously infected by the JP2 clone (RR = 13.9; 95% CI, 9.0 to 21.4), indicating a relationship between infectious dose and disease, which further substantiates the evidence for the JP2 clone as a causal factor in aggressive periodontitis.

Background: Periodontitis is a loss of supporting connective tissue and alveolar bone around teeth, and if it occurs in an aggressive form it can lead to tooth loss before the age of 20 years. Although the cause of periodontitis in general remains elusive, a particular clone (JP2) of the gram-negative rod Aggregatibacter (Actinobacillus) actinomycetemcomitans is considered a possible aetiological agent of the aggressive form in adolescents living in or originating from north and west Africa, where the disease is highly prevalent. We did a population-based longitudinal study of adolescents to assess the role of the JP2 clone in the initiation of aggressive periodontitis., Methods: A total of 700 adolescents from public schools in Rabat, Morocco, were enrolled in the study. We used PCR to detect A actinomycetemcomitans in plaque samples (taken from molar and incisor sites) and to differentiate between the JP2 clone and other non-JP2 genotypes of the bacterium. 18 individuals were found to already have periodontitis and were excluded. The 682 periodontally healthy adolescents (mean age 12.5 years; SD 1.0) were classified according to their A actinomycetemcomitans carrier status at baseline. After 2 years, 428 (62.8%) individuals returned for re-examination, which included recording of periodontal attachment loss measured from the cemento-enamel junction to the bottom of the periodontal pockets of all teeth present., Findings: Individuals who carried the JP2 clone of A actinomycetemcomitans alone (relative risk 18.0; 95% CI 7.8-41.2, p<0.0001) or together with non-JP2 clones of A actinomycetemcomitans (12.4; 5.2-29.9, p<0.0001) had a significantly increased risk of periodontal attachment loss. A much less pronounced disease risk was found in those carrying non-JP2 clones only (3.0; 1.3-7.1, p=0.012)., Interpretation: The JP2 clone of A actinomycetemcomitans is likely to be an important aetiological agent in initiation of periodontal attachment loss in children and adolescents. Co-occurrence of non-JP2 clones of A actinomycetemcomitans reduces the risk of development of periodontitis, suggesting competition for the ecological niche between the JP2 and non-JP2 clones of this species.

Background/aims: Actinobacillus actinomycetemcomitans is frequently detected in dental plaque collected from Moroccan adolescents, and has been shown to be associated with clinical attachment loss in this population. The aim of this study was to assess whether behaviors such as the sharing of toothbrushes, and eating and drinking habits were associated with the presence of A. actinomycetemcomitans in Moroccan adolescents., Materials and Methods: A total of 121 adolescents were clinically examined. Interviews regarding sharing of toothbrushes, eating and drinking habits were performed, and plaque samples were collected and analyzed for A. actinomycetemcomitans with different leukotoxin promoter types by polymerase chain reaction. Based on eating and drinking habits, the study population was divided in a low risk behavior group (LRB) and a high risk behavior group (HRB)., Results: No association was found between the sharing of toothbrushes and the presence of A. actinomycetemcomitans. The odds ratios between the HRB and LRB group for being positive for the JP2 type, for non-JP2 types, and for any type of A. actinomycetemcomitans were 4.74 (95% CI 0.55; 40.71), 2.49 (95% CI 1.03; 5.97), and 2.97 (95% CI 1.28; 6.91), respectively. The difference in the mean number of teeth with a clinical attachment loss of > or = 3 mm between the HRB and the LRB group was 0.91(95% CI 0.09; 1.72)., Conclusion: Sharing of toothbrushes does not seem to be associated with the presence of A. actinomycetemcomitans in young Moroccans. Eating and drinking habits conducive to exchange of saliva are positively associated with presence of A. actinomycetemcomitans, and with a higher level of clinical attachment loss.

Background: A clone of Actinobacillus actinomycetemcomitans (JP2) with increased leukotoxin production and characterized by a 530-bp deletion in the leukotoxin gene operon is endemically present in Morocco and strongly associated with the presence of early onset periodontitis (EOP)., Objectives: To compare patterns of attachment loss among EOP-patients with or without JP2-type of A. actinomycetemcomitans in dental plaque., Material and Methods: Among 45 Moroccan adolescents with EOP (i.e. one or more teeth with attachment loss >/= 3 mm) 39 had cultivable plaque samples. Fifteen (38.5%) were culture-positive for A. actinomycetemcomitans of the JP2-type as determined by PCR, and 24 (61.5%) were not (mean age 16.5 years in both groups)., Results: EOP-patients culture-positive for A. actinomycetemcomitans of the JP2-type had significantly more teeth with attachment loss (mean 5.1, median 4.0) than EOP-patients not culture-positive for A. actinomycetemcomitans of the JP2-type (mean 2.8 teeth, median 1.0) (p = 0.02), and higher attachment loss (mean 4.3 mm vs. 3.4 mm; median 4.0 mm vs. 3.0 mm) (p = 0.01). No major differences could be detected between the two groups in the pattern of affected teeth in the dentition., Conclusions: The study demonstrates increased periodontal destruction among EOP-patients culture-positive for A. actinomycetemcomitans of the JP2-type compared with EOP-patients without the JP2-clone.