Phenotypic Detection of Antimicrobial Resistance Patterns in Microorganisms Isolated From the Primary Molars of Pediatric Dental Patients Undergoing Pulp Therapy.

Background Pulp necrosis is a prevalent complication following dental caries in primary dentition. Certain bacteria exhibit increased adaptability to adverse conditions and possess virulence factors that enable more effective colonization of dental tissues. The invasion of the root canal system (RCS) by pathogenic microorganisms, compounded by the rising concern of antimicrobial resistance (AMR), emphasizes the necessity for a culture-driven and evidence-based approach to antibiotic selection in pediatric endodontics, wherein the therapeutic efficacy of root canal treatment is inherently dependent on the comprehensive elimination of endodontic microbiota. Aim To isolate, identify, and analyze the antimicrobial susceptibility and resistance profiles of microorganisms associated with endodontic infections in the deciduous teeth of children undergoing pulp therapy. Materials and methods One hundred systemically healthy children aged four to nine years with carious teeth and without direct endodontic exposure were enrolled following Strengthening the Reporting of Observational studies in Epidemiology (STROBE) guidelines at the Department of Pediatric and Preventive Dentistry, University College of Medical Sciences (UCMS) & Guru Teg Bahadur Hospital (GTBH), Delhi, India. Root canal samples from infected or necrotic primary teeth were aseptically collected and cultured on blood, chocolate, and MacConkey agar. Bacterial isolates were identified via Gram staining and standard biochemical assays. Statistical evaluation was conducted using IBM SPSS Statistics for Windows, Version 21 (Released 2012; IBM Corp., Armonk, New York, United States). Results Bacterial growth was detected in 68 samples (68%), predominantly involving Gram-positive cocci (n=48; 48%). Enterococcus faecalis (n=25; 25%) was the most common isolate, followed by Staphylococcus aureus (n=17; 17%) and a smaller proportion of Gram-negative bacilli, including Enterobacter cloacae, Escherichia coli, and Klebsiella pneumoniae. All isolates showed complete sensitivity to vancomycin, teicoplanin, linezolid, amikacin, and imipenem, while variable resistance to macrolides, clindamycin, fluoroquinolones, and β-lactams was observed. No extended-spectrum β-lactamase (ESBL) or carbapenem-resistant strains were identified. Conclusion Enterococcus faecalis remains the predominant pathogen in pediatric endodontic infections, with its increasing multidrug resistance presenting significant therapeutic challenges. Nevertheless, β-lactam and glycopeptide antibiotics continue to demonstrate reliable clinical efficacy. These findings highlight the importance of culture-guided therapy and rational antimicrobial stewardship in pediatric dental practice.