Feasibility of investigating the association between bacterial pathogens and oral leukoplakia in low and middle income countries: A population-based pilot study in India.

Krithiga Shridhar,Michael Goodman,Aastha Aggarwal,Dorairaj Prabhakaran,Ravi Mehrotra,Shet Masih,Theresa W Gillespie,Ishita Rawal,Dominique S Michaud,Preet K Dhillon,Ruby Gupta,David M Ojcius

doi:10.1371/journal.pone.0251017

Abstract

BackgroundCertain oral bacterial pathogens may play a role in oral carcinogenesis. We assessed the feasibility of conducting a population-based study in India to examine the distributions and levels of Porphyromonas gingivalis, Fusobacterium nucleatum and Prevotella intermedia in relation to oral leukoplakia (a potentially malignant disorder) and other participant characteristics.MethodsThis exploratory case-control study was nested within a large urban Indian cohort and the data included 22 men and women with oral leukoplakia (cases) and 69 leukoplakia-free controls. Each participant provided a salivary rinse sample, and a subset of 34 participants (9 cases; 25 controls) also provided a gingival swab sample from keratinized gingival surface for quantitative polymerase chain reaction (qPCR).ResultsNeither the distribution nor the levels of pathogens were associated with oral leukoplakia; however, individual pathogen levels were more strongly correlated with each other in cases compared to controls. Among controls, the median level of total pathogens was the highest (7.55×104 copies/ng DNA) among persons of low socioeconomic status. Salivary rinse provided better DNA concentration than gingival swab for qPCR analysis (mean concentration: 1.8 ng/μl vs. 0.2 ng/μl).ConclusionsThis study confirms the feasibility of population studies evaluating oral microbiome in low-resource settings and identifies promising leads for future research.

Highlights

Mechanistic studies of common oral bacterial species [1,2,3], and epidemiological studies with high-throughput sequencing of oral microbiome [4,5,6,7] have identified discrete bacterial genera that may be associated with increased risk of oral cancers, influencing early [5,7,8,9,10,11] and late carcinogenesis [12]
Neither the distribution nor the levels of pathogens were associated with oral leukoplakia; individual pathogen levels were more strongly correlated with each other in cases compared to controls
To begin assessing the feasibility of such studies we explored the distribution of P. gingivalis, F. nucleatum and P. intermedia in salivary rinse samples of an urban North Indian population using real-time quantitative polymerase chain reaction

Summary

Introduction

Mechanistic studies of common oral bacterial species [1,2,3], and epidemiological studies with high-throughput sequencing of oral microbiome [4,5,6,7] have identified discrete bacterial genera that may be associated with increased risk of oral cancers, influencing early [5,7,8,9,10,11] and late carcinogenesis [12]. While the role of tobacco and betel quid in the etiology of oral malignancies is well documented [17], recent data indicate that certain regions of India experience increasing incidence of oral cancer, tongue cancer, among persons without identifiable risk factors [17,18,19,20]. These observations underscore the importance of evaluating other possible modifiable causes and mechanisms of oral cancer, including oral microbiome that may act independently of, and perhaps in synergy with, established risk factors [1,2,3,4,21]. We assessed the feasibility of conducting a population-based study in India to examine the distributions and levels of Porphyromonas gingivalis, Fusobacterium nucleatum and Prevotella intermedia in relation to oral leukoplakia (a potentially malignant disorder) and other participant characteristics

Objectives

Results

Conclusion