Evaluation of the Formation of Single- and Double-Species Biofilms on Intraventricular Catheters by Strains of Staphylococcus aureus, Listeria monocytogenes and Escherichia coli with K1 Antigen

Intraventricular catheters (IVCs) are an important diagnostic and therapeutic tool. They are used in patients after traumatic brain injury, intracranial haemorrhage, ventricular, or hydrocephalus. However, the use of IVCs may lead to the development of bacterial brain and cerebrovascular infections associated with the presence of microorganisms in cerebrospinal fluid (ventriculitis). What is especially dangerous for the patients health is the formation of biofilms by microorganisms on the catheters.
The aim of the study was to evaluate the intensity of single- and double-species biofilms formation on IVCs by Staphylococcus aureus (SAU), Escherichia coli (ECO) with K1 antigen, and Listeria monocytogenes (LMO).
The research material was 15 strains of S. aureus, L. monocytogenes, and E. coli with K1 antigen, each. Evaluation of biofilm formation was performed on sterile fragments of IVCs with 1 cm length. The intensity of biofilm formation by the tested strains was determined with the quantitative method using sonication for removal of bacteria from IVCs surface. Biofilm formation ability was verified individually for each of the tested bacteria strain and for SAU LMO, SAU ECO, LMO ECO combinations. Randomly selected fragments of biofilm-coated catheters were subjected to scanning electron microscopy (SEM).
The number of bacteria isolated from single-species biofilms on the IVCs surface ranged from 3.79 × 107 do 8.95 × 107 CFU × cm-2, depending on the species of microorganism. The strongest biofilm formed ECO with K1 antigen strains and the weakest - LMO strains. The scomposition of multi-species biofilms significantly influences the intensity of biofilm formation by strains from the examined species. In the SAU LMO combination, strains from both species formed biofilm more intensively than in single-species variant. In turn, ECO has shown a significant inhibitory effect on biofilm formation by other tested species.
It was stated that bacteria form biofilm on IVCs and it is a significant medical problem. The species composition of multi-species biofilms significantly influences the number of individual bacteria recovered from this biofilm.