Distribution of oral microbial flora among the students of a tertiary institution in Nigeria: A descriptive cross-sectional study

Background: The human oral cavity harbours a diverse microbial community that influences both oral and systemic health. Disruption of this microbial balance can result in dental conditions such as tooth decay. University students are particularly at risk due to poor dietary habits and inconsistent oral hygiene. This study investigated the distribution of oral microbial flora and their association with tooth decay among students of a private tertiary institution in Nigeria. Methods: Oral swab samples were collected and cultured using standard microbiological techniques, including growth on chocolate, blood, and MacConkey agars for bacterial isolation, and Sabouraud agar for fungal isolation, and biochemical tests were performed for identification. A structured questionnaire assessed oral hygiene practices, sweet consumption, and oral health status. Data were analyzed using descriptive statistics, Chi-square tests, and binary logistic regression to identify variables. Results: The predominant microbial isolates were Streptococcus mutans (25%), Staphylococcus aureus (17%), Streptococcus sanguinis (12%), and Candida albicans (10%). Tooth decay was reported by 52% of participants and was significantly associated with S. mutans (p < 0.001), S. aureus (p = 0.006), C. albicans (p = 0.001), and S. sanguinis (p = 0.031). These microorganisms also increased the odds of tooth decay, with odds ratios (OR) of 3.27(95% CI = 1.77–6.05), 2.08(95% CI = 1.23–3.52), 1.95(95% CI = 1.06–3.58), and 2.51(95% CI = 1.40–4.50) respectively (p < 0.05). Furthermore, sweet consumption showed a significant positive correlation with tooth decay (p < 0.001). Conclusion: Streptococcus mutans , S. aureus, S. sanguinis , and Candida albicans were strongly associated with tooth decay and high sugar intake was a key risk factor.