In vitro Demonstration of Biofilm Formation on Catheter Materials by Candida Species Isolated from Blood Stream Infections

Abstract

In recent years, a progressive increase in the frequency of nosocomial candidaemia has been observed. Candidaemia due to vascular catheters are on the rise. There are many associated risk factors such as the type of patient, catheter location, frequency of change of cannulae, duration of catheterization, etc. Candida species produce biofilms on synthetic materials, which facilitate adhesion of the organisms to devices and render them relatively refractory to medical therapy. This study is an attempt to determine whether the clinical association of Candida species with bloodstream and/or device-associated infections can be attributed to a higher degree of adherence of Candida non-albicans than C. albicans to two types of catheters in vitro. A total of 153 Candida isolates were obtained from blood samples collected from intensive care unit (ICU) patients. The majority were Candida non-albican strains. Biofilms were allowed to form on the surfaces of polyether block amide (PBA) and polyvinyl chloride (PVC) catheters. Adherence was measured by counting the number of adhering viable cells. Adherence of the Candida non-albican was significantly greater on both types of catheters than C. albicans. Intraspecific differences in adherence, mostly related to more invasive strains, were noted. A connection between adherences in vitro, the ability to produce a biofilm in vivo and catheter-associated infection is suggested here. The study also proves that the chemical nature of catheter material plays an important role in the pathogenesis of device-associated infections.