Biofilm Formation and Antibiotic Resistance in Orthopaedic Implant Infections: A Molecular Analysis of icaA, icaD, and mecA Genes in an Indian Cohort.

Verma, Sheetal; Khan, Asma; Venkatesh, Vimala; Waliullah, Shah; Kumar, Deepak · Indian J Orthop · 2026

cross_sectional · Level IV

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Abstract

Orthopaedic implant-related infections (OIRIs) are a major clinical challenge, contributing to increased morbidity, prolonged hospitalisation, and higher healthcare costs. This study investigated the prevalence of biofilm-associated genes (<i>icaA</i>, <i>icaD</i>) in <i>Staphylococcus</i> spp., antimicrobial resistance patterns, and the relationship between implant material, infection rates, and treatment outcomes. This was a cross-sectional study of 200 clinical samples from patients with suspected OIRIs. Pathogens were identified using MALDI-TOF MS, and antimicrobial susceptibility was tested according to CLSI 2023 guidelines. Biofilm formation was assessed by a modified microtiter plate assay, and <i>icaA</i>, <i>icaD</i>, and <i>mecA</i> genes were detected by PCR. Statistical analysis, including chi-square tests and logistic regression, was performed to explore associations between implant material, biofilm genes, and infection risk. The mean patient age was 37.99 ± 18.17 years, with males comprising 74%. Fractures were the leading cause of OIRIs (72.5%), predominantly affecting the lower limb (62.5%). <i>Staphylococcus epidermidis</i> (30.2%) and <i>Escherichia coli</i> (15.1%) were the most frequent isolates, with 98% of infections being monomicrobial. Methicillin resistance was common, with 57% of MRSA and 45% of MRSE producing strong biofilms. The <i>icaD</i> gene was significantly associated with biofilm formation (79% in MRSA, 45% in MRSE), whereas <i>icaA</i> showed no such link. Steel implants had the highest infection rate (41.5%), though analysis indicated surgical and patient factors as primary drivers. MDR Gram-negative bacteria displayed high resistance to cephalosporins and fluoroquinolones, with carbapenems and colistin remaining effective. OIRIs are strongly influenced by biofilm formation and methicillin resistance. Management should prioritize biofilm-targeted therapies, precision antibiotic use, and implant surface innovations to reduce infection risk and improve outcomes.