Investigation of Biofilm Formation and Antimicrobial Resistance in Bacteria Isolated from Hospital Medical Devices

Background: Medical device-associated infections represent a major component of healthcare-associated infections. Biofilm formation promotes microbial persistence on device surfaces, reduces antimicrobial susceptibility, and contributes to multidrug resistance (MDR), complicating diagnosis and treatment. Materials and Method: This study investigated biofilm production and antimicrobial resistance in microorganisms recovered from 100 indwelling and implantable medical devices, including urinary and venous catheters, urethral stents, catheter tips, and orthopedic or prosthetic materials, collected at a tertiary-care hospital (AOU "San Giovanni di Dio e Ruggi d'Aragona", Salerno, Italy). Microbiological cultures were performed using direct and enrichment methods. Microbial identification was carried out by MALDI-TOF MS, antimicrobial susceptibility testing by VITEK^® (bioMérieux, Marcy-l'Étoile, France) 2 according to EUCAST criteria, and biofilm production was assessed using the crystal violet tissue culture plate assay. MDR status was defined according to international guidelines. Results: Microbial growth was detected in the majority of analized devices, frequently with polymicrobial contamination. Within the study cohort, coagulase-negative staphylococci (CoNS) were the most frequently recovered microorganisms (20%), followed by Klebsiella pneumoniae (10%), Candida albicans (9%), Staphylococcus aureus (9%), Enterococcus faecalis (8%), and Escherichia coli (8%). A significant association was observed between multidrug resistance and biofilm production, with MDR isolates showing a markedly higher likelihood of being biofilm producers compared with non-MDR isolates (OR 9.50; 95% CI 2.72-42.96; p < 0.005). Biofilm formation also differed significantly among device types (p = 0.028). Conclusions: These findings indicate a high prevalence of biofilm-producing MDR microorganisms among isolated recovered from medical devices in our cohort and highlight a significant association between MDR phenotype and biofilm production. These results provide a microbiological characterization of device-associated isolates that may support future studies on infection dynamics and control strategies.