Peritoneal dialysis is a form of therapy, when the kidneys have ceased their functions. This form of therapy is used mainly in the end-stage renal insufficiency. In peritoneal dialysis, the peritoneum is used as a semi-permeable dialysis membrane and through a catheter, the dialysis solution flows into the abdominal cavity. The dialysate remains for a few hours in the abdominal cavity until the liquid saturated with urinary metabolites. During the peritoneal dialysis, it can come to complications, the most serious complication is the peritoneal dialysis-associated peritonitis. This infection is often associated with biofilms, which complicate the therapy significantly, because microorganisms embedded in biofilms are more resistant to antibiotics. In this work, firstly, the question is processed, how the biofilm formation behaves in commercially available peritoneal dialysis fluids (PDF) and in the control fluid. Secondly, the question should be treated how the in vitro activity of teicoplanin behaves on biofilm formation in different solutions. Method: The biofilm testing of the 10 MRSA blood stream isolate is carried out according to a modified Christensen method. A crystal violet assay for in vitro evaluation of biofilms in 96-well microtiter plates by staining with 2% crystal violet. The measurement is done with a microplate photometer at 620 nm. Results: The results collected in this study show a significant difference between biofilm formation of MRSA blood stream isolates, of the control fluid and the commercially available PDF. In connection with the Teicoplanin therapy, no significant difference in TSB, in Extraneal® and Physioneal® could be shown within the antibiotic concentrations. Conclusion: The data show that Teicoplanin has a good efficacy in the control solution, but has no significant effect in the PDF. Part of the future research should especially be in vivo studies, which occupy with the duration of therapy and the antimicrobial efficacy of the various antibiotics.