Comparative analysis of in vitro biofilm formation in gram-positive and gram-negative pathogens from orthopaedic implant infections: a retrospective cross-sectional study in a tertiary care centre

Background: Orthopaedic implant infections (ODRI) remain a significant clinical challenge due to their association with persistent biofilm formation, which complicates treatment. 1.2 Objective: This study aimed to investigate the biofilm-forming potential of Gram-positive and Gram-negative pathogens isolated from orthopaedic implant infections in a tertiary care setting. Methods: A retrospective cross-sectional study was conducted at the Krishna Institute of Medical Sciences, Secunderabad, India, from February 2023 to January 2024. Clinical samples from orthopaedic implant infections, were processed for bacterial culture and biofilm formation using the Tissue Culture Plate (TCP) method in triplicates. Bacterial identification was performed using the Vitek 2 Compact system. Results: Of 87 patients diagnosed with orthopaedic implant infections, 62 (71.26%) were culture-positive, with 35 (56.45%) Gram-negative bacilli and 27 (43.54%) Gram-positive cocci. Biofilm formation was observed in 59.25% of Gram-positive isolates, with 18.51% strong biofilm producers, 40.74% moderate producers, and 40.74% weak/non-producers. Among Gram-negative isolates, 31.42% were biofilm producers, with 5.71% strong, 25.71% moderate, and 68.57% weak/non-producers. A higher prevalence of biofilm production was noted in Gram-positive organisms compared to Gram-negative bacteria. Conclusion: The study highlights the higher propensity of Gram-positive bacteria to form biofilms, which may contribute to the persistence and chronicity of orthopaedic implant infections.