# Impact of prevalence of P. gingivalis and S. cristatus in oral health disparities

> **NIH NIH U54** · MEHARRY MEDICAL COLLEGE · 2020 · $297,679

## Abstract

Impact of prevalence of P. gingivalis and S. cristatus in oral health disparities 
Adult periodontitis is disproportionally distributed among races, and has a significantly higher incidence in 
African Americans (AA) compared to European Caucasians (EC), even when co-variants such as diabetes and 
other health and social factors have been taken into account. This proposal examines the potential role of two 
oral microbial biofilm components (P. gingivalis and S. cristatus) on this disparity. Titers to the oral pathogen P. 
gingivalis are reported to be higher in dentate subjects with, compared to those without periodontitis. Our 
laboratory was the first to report an intergeneric communication between S. cristatus and P. gingivalis. We 
identified a surface protein of S. cristatus, arginine deiminase (ArcA) that serves as a signal molecule to which 
P. gingivalis responds by repressing the expression of the fimA gene, which codes for the major subunit 
protein of long fimbriae. The latter is required for bacterial colonization of P. gingivalis and host cell invasion. 
Recently, we demonstrated that S. cristatus indeed inhibited colonization of P. gingivalis in the murine oral 
cavity and reduced periodontal bone loss in those mice tested. Therefore, we hypothesize that colonization of 
P. gingivalis is dependent upon the nature of the initial streptococcal biofilm, and that certain as yet unidentified 
risk factors of periodontitis are the driving force behind different streptococcal profiles of these initial microbial 
biofilms. We will first compare the prevalence of S. cristatus versus P. gingivalis in the oral cavities of 
periodontally healthy AAs, ECs and Mexican Americans (MA) versus those with periodontitis (before and after 
periodontal treatments). Our objective is to determine if there is a link between a lower prevalence ratio of oral 
S. cristatus:P. gingivalis in AAs, or MAs compared to ECs, which might help account for the higher risk of 
periodontitis in AAs and MAs. We will also then test the potential involvement of other periodontal risk factors 
in this disparity, and their role in the prevalence of S. cristatus versus P. gingivalis. Finally, we propose to 
investigate if intense education of periodontal health will promote a shift in ratio of S. cristatus versus P. 
gingivalis in periodontitis patients. We anticipate that the proposed studies will provide important information 
regarding the pathogenesis of periodontitis and the nature of the microbial biofilms found in different 
races/ethnics, and will pave the way for extended studies in future, focused on the development of appropriate 
interventional strategies targeted at eliminating of P. gingivalis colonization.

## Key facts

- **NIH application ID:** 9974586
- **Project number:** 5U54MD007586-34
- **Recipient organization:** MEHARRY MEDICAL COLLEGE
- **Principal Investigator:** HUA XIE
- **Activity code:** U54 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $297,679
- **Award type:** 5
- **Project period:** 1997-09-30 → 2022-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9974586

## Citation

> US National Institutes of Health, RePORTER application 9974586, Impact of prevalence of P. gingivalis and S. cristatus in oral health disparities (5U54MD007586-34). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9974586. Licensed CC0.

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