Pathogenic potential and antimicrobial resistance patterns detected in facultative anaerobic microorganism in pulp and periapical lesion

Abstract

The oral cavity hosts a large microbial community whose interaction plays a crucial role in ecological balance. The establishment and persistence of microorganisms can cause various pathologies and progress to treatment failure. Microbiological isolation and documentation through culture of dental samples is not routinely performed in our country; however, the surveillance of related microorganisms in these ecological niches, resistance patterns, and association as pathogens are clinically significant. Objectives: To characterize facultative anaerobic microbiota in biological samples of pulp and periapical conditions using conventional and molecular techniques, as well as their antibiotic resistance profile, relating their association with inflammatory and infectious oral pathologies. Methodology: Biological samples of pulp and periapical conditions were analyzed in patients treated in the emergency of an university dental clinic in the Central District during the months of January-March 2025. Facultative anaerobic microbiota was isolated and identified using conventional methods such as dark field microscopy, bacteriological and biochemical identification, antibiotic resistance through disk diffusion and minimum inhibitory concentration (MIC) as well as the molecular determination of the mecA gene involved in antibiotic resistance. Results and discussion: A total of 35 biological samples of apical and periapical lesions were collected in patients diagnosed with irreversible pulpitis, pulp necrosis, previous root canal treatment failures, and previously initiated therapy. The pulp cavity showed a diverse and critically important microbiota such as Staphylococcus aureus, Enterococcus spp., Gram-negative bacilli, Candida albicans, and Spirochetes. The presence of MRSA carrying the mecA gene, which confers resistance to most betalactam antibiotics, is notable. This finding demonstrates that the dental pulp can act as a reservoir and source of antimicrobial resistance, posing both local and systemic risk, especially in vulnerable patients. Early detection and management are essential to prevent its spread in the community and hospital settings.