Evaluation of Pharyngeal Commensalism by Aerobic and Capnophilic Bacteria Among Healthy Individuals Residing in and Around Northern Bihar

Background: The human pharynx harbors a diverse community of commensal microorganisms that maintain mucosal health and prevent pathogen overgrowth. Understanding the composition of normal pharyngeal flora is essential for distinguishing colonization from infection and guiding antimicrobial stewardship. Objective: To evaluate the pattern and diversity of aerobic and capnophilic bacterial flora colonizing the pharynx of healthy individuals residing in and around Northern Bihar. Materials and Methods: A cross-sectional study was conducted in the Department of Microbiology, Mata Gujri Memorial Medical College and L.S.K. Hospital, Kishanganj, Bihar, over 18 months (June 2023–December 2024). Throat swabs from 200 asymptomatic volunteers were cultured on Blood Agar (aerobic) and Chocolate Agar (capnophilic) using a candle-jar method. Isolates were identified up to the genus level by standard microbiological procedures. Data were analyzed using SPSS v26.0 with Chi-square/Fisher’s exact tests; p < 0.05 was considered significant. Results: Among 200 samples, 95% were positive for aerobic growth and 90% for capnophilic growth, with an overall combined culture positivity of 99%. Viridans group Streptococcus was the most prevalent organism (85%), followed by Neisseria spp. (55%), Staphylococcus aureus (25%), and Moraxella catarrhalis (20%). Mixed bacterial colonization was frequent, particularly between Viridans Streptococcus and Neisseria spp. Conclusion: Healthy individuals in Northern Bihar harbor a rich pharyngeal microbiota dominated by Viridans Streptococcus and Neisseria spp. The detection of potential opportunistic pathogens like S. aureus highlights the clinical importance of monitoring commensal flora. Dual aerobic and capnophilic culture methods effectively capture this microbial diversity, providing valuable baseline data for infection surveillance and antibiotic policy formulation