Biofilm on Tenckhoff Catheters: A Negligible Source of Contamination

Abstract

The authors studied the presence and characterization of biofilm in the lumen of Tenckhoff chronic peritoneal dialysis catheters of 17 CAPD patients to elucidate the role of biofilm as a source of peritonitis.

At the time of investigation, all 17 patients were peritonitis-free. All used a single-use, Y -system without disinfectant. Previously eight had used the conventional system. Seven had experienced II episodes of peritonitis with their present catheter (4 episodes while on conventional systems). Ten patients had no history of peritonitis. Four samples from each catheter were obtained with aseptic technique: swabs from inside the titanium adaptor, a 5 cm proximal segment removed and sectioned longitudinally to obtain luminal scrapings, a nylon brush sample from the entire length of the catheter, and from fluid run through the catheter after introducing the brush. All samples were treated by different microbiological techniques and incubated under various conditions. In vitro control experiments were performed to recover biofilm with the brush technique. Whereas all controls were positive, 100% of the samples demonstrated no bacterial growth after two -weeks’ incubation. Five patients’ catheters (four with previous peritonitis) examined under light microscopy contained amorphous material without viable bacteria as evidenced by both growth experiments and mi croscopy. Ten catheters were examined on scanning electron microscopy: the inner surface of all were covered with a protein-Iike membra nous deposit. Occasional bacteria and various number of macrophages were observed on three catheters. On two other catheters, biofilm looked like bacterial microcolonies but this was not confirmed by gram-staining and cultures. Results suggest that biofilm is not ubiquitous in catheters of CAPD patients and that the catheter does not appear to be a bacterial reservoir that would provoke peritonitis. Biofilm might be secondary to frequent peritonitis and/or frequent asymptomatic intra-luminal catheter contaminations. The low peritonitis rate of the studied patients and the use of Y -line systems could explain the absence of a typical biofilm. Results also suggest there may be two types of biofilm -one made up of adherent bacteria and glycocalyx, and one made up of non-contaminated protein -like deposits. The presence of each type would depend of the efficacy of connectors in avoiding touch contaminations.