Comparative analysis of antibiotic sensitivity pattern in Streptococcus mutans isolated from dental caries of different age & sex group in Dhaka city, Bangladesh

Background: Dental caries, a widespread infectious disease caused by Streptococcus mutans (S. mutans), results from acid production during sugar fermentation and biofilm formation on teeth. Despite progress in oral hygiene, it remains a major public health concern, especially in developing countries like Bangladesh. The growing antibiotic resistance among oral pathogens, including S. mutans, complicates treatment and emphasizes the need for effective antimicrobial stewardship. Objective: This study aimed to evaluate the antibiotic sensitivity patterns of S. mutans isolated from dental caries in different age and sex groups in Dhaka, Bangladesh, and to assess the prevalence of multi-drug resistance. Methods and Materials: S. mutans strains were isolated from dental caries and tested for antibiotic sensitivity using the Kirby-Bauer disc diffusion method. Nine antibiotics were evaluated: Ampicillin, Amoxiclav, Erythromycin, Penicillin, Ciprofloxacin, Streptomycin, Tetracycline, Bacitracin, and Vancomycin. Sensitivity, intermediate sensitivity, and resistance were measured and compared across age groups (children, adolescents, adults, elderly) and between sexes (male and female). Statistical analyses were performed to identify significant differences in antibiotic susceptibility. Results: S. mutans showed the highest sensitivity to Penicillin (96.5%) and Amoxiclav (88.1%), while Bacitracin (60.2%) and Ciprofloxacin (64.3%) were less effective. Multi-drug resistance was notable, with 27.5% of strains resistant to six antibiotics and 20% resistant to seven or more. Sensitivity decreased with age, with children showing the highest sensitivity (79.5%) and the elderly the lowest (62.5%). No significant differences in sensitivity between males and females were observed. Statistical analysis indicated significant variations in sensitivity across different age groups (p < 0.05). Conclusion: The study highlights the growing antibiotic resistance in S. mutans and the need for targeted, age-specific treatment strategies. Penicillin and Amoxiclav were the most effective antibiotics, while multi-drug resistance was prevalent.