Aggregatibacter actinomycetemcomitans in African Americans with Localized Aggressive Periodontitis

Abstract

This study aims to investigate the prevalence of the highly leukotoxic JP2 sequence versus the minimally leukotoxic non-JP2 sequence of Aggregatibacter actinomycetemcomitans within a cohort of 180 young African Americans, with and without localized aggressive periodontitis (LAP), in north Florida. The study included patients aged 5 to 25 y: 60 LAP patients, 60 healthy siblings (HS), and 60 unrelated healthy controls (HC). Subgingival plaque was collected from LAP sites-diseased (PD ≥5 mm with bleeding on probing) and healthy (PD ≤3 mm with no bleeding on probing)-and from healthy sites of HS and HC. Plaque DNA was extracted and analyzed by polymerase chain reaction for the detection of the JP2 and non-JP2 sequences of A. actinomycetemcomitans. Overall, 90 (50%) subjects tested positive for the JP2 sequence. Fifty (83.33%) LAP subjects were carriers of the highly leukotoxic JP2 sequence, detected in 45 (75%) diseased sites and 34 (56.67%) healthy sites. Additionally, JP2 carriage was found in 16 HS (26.67%) and 24 HC (40%; P < 0.0001, among groups). The non-JP2 sequence was detected in 26 (14.44%) total subjects: 17 (28.33%) LAP patients detected in equal amounts of diseased and healthy sites (n = 11, 18.33%), 6 (10%) HS sites, and 3 (5%) HC sites (P < 0.05, among groups). The JP2 sequence was strongly associated with LAP-diseased sites in young African Americans, significantly more so than the non-JP2 (ClinicalTrials.gov NCT01330719). Knowledge Transfer Statement: Clinicians may use the results of this study to identify susceptible individuals to aggressive periodontitis, potentially leading to more appropriate selection of therapeutic choices.

Keywords: bacteria; bacterial virulence; children; inflammation; juvenile periodontitis; microbiology.

Figure 1.

Presence of JP2 and non-JP2 among groups. (a) Presence of JP2 sequence among groups, P < 0.0001 (chi-square exact test). Fisher’s exact test shows a trend difference between LAPd and LAPh sites (⁺P = 0.054) and a significant difference between LAPd sites and HS (****P < 0.0001) and HC (***P < 0.001). (b) Presence of Aggregatibacter actinomycetemcomitans minimally leukotoxic sequence among groups. Fisher’s exact test shows difference between HC and LAPd sites (*P < 0.05) and LAPh sites (*P < 0.05). HC, healthy unrelated controls; HS, healthy siblings; LAP, localized aggressive periodontitis (d, diseased sites; h, healthy siblings).

Figure 2.

Localized aggressive periodontitis (LAP) versus healthy participant sites: JP2, ****P < 0.0001; non-JP2, *P < 0.05 (Fisher’s exact test). Aa, Aggregatibacter actinomycetemcomitans.

Figure 3.

Comparison of pocket depth (PD) and clinical attachment level (CAL) in diseased sites within localized aggressive periodontitis (LAP; a, c) and in all healthy and diseased sites in LAP (*P < 0.05; b, d). Mann-Whitney test showed significance for PD difference between JP2-positive and JP2-negative sites (P = 0.034; b) and a significant difference in mean CAL values between those sites (P = 0.019; d). Boxes indicate means; whiskers, SEM.

Figure 4.

Comparisons of pocket depth (PD), clinical attachment level (CAL), and JP2 presence alone or with non-JP2, in terms of localized aggressive periodontitis (LAP diseased sites only (LAPd; a, c) or all diseased and healthy sites in LAP patients (b, d). No difference was found on PD by analysis of variance among the 3 categories of JP2 (b), but Mann-Whitney test comparing only presence versus absence of JP2 was significant (*P < 0.05). Kruskal-Wallis with Dunn’s multiple comparisons test showed a difference in mean CAL between JP2-positive and JP2-negative sites in all LAP sites (d; *P < 0.05), specifically between sites negative for JP2 and sites with only JP2.