A study on device-related infections with special reference to biofilm production and antibiotic resistance

Indwelling medical devices (IMDs) in critical patients are vulnerable to colonization by biofilm producing bacteria. Complex characteristics of bacterial biofilms promote antibiotic resistance, leading to the emergence of resistant device-related infections (DRI), which pose new challenges in their management.

The study was done on 135 hospitalized (Intensive care units) pediatric patients with IMDs (intravascular catheter, urinary catheter, and endotracheal tube) to determine the device-specific infection rates. Biofilm formations were demonstrated by the tube method and by scanning electron microscopy (SEM). Bacteria in biofilms were identified by the standard conventional methods and tested for antibiotic resistance. We also detected the presence of extended spectrum β-lactamases (ESβLs), particularly, bla(CTX-M,) in gram-negative isolates.

The rates of biofilm-based catheter-related blood stream infections (CRBSI), catheter-associated urinary tract infections (CAUTI), and Ventilator Associated Pneumonia (VAP), in our study, were 10.4, 26.6, and 20%. Biofilm formation by the tube method correlated well with the SEM findings. A majority of infections were caused by Klebsiella pneumoniae followed by Staphylococcal biofilms. A high percentage (85.7%, 95% confidence interval 64.5 to 95.8%) of biofilm producing bacterial isolates, causing infection, were multidrug resistant. Many biofilm producing gram-negative isolates were ESβLs producers, and a majority particularly harbored bla(CTX-M,) among the ESβLs genotypes.

The incidence of resistant device-related infections, predominantly caused by biofilm producing bacteria, is rising. The tube method is an effective screening method to test biofilm production, where sophisticated microscopy facilities are not available. The varying resistance pattern of organisms isolated in our setup, emphasizes the importance of studying the pattern of infection in every setting and providing antibiotic guidelines in the management of such infections.