ROLE OF PHYSIOLOGICAL CONDITIONS IN THE OROPHARYNX ON THE ADHERENCE OF RESPIRATORY BACTERIAL ISOLATES TO ENDOTRACHEAL-TUBE POLY(VINYL CHLORIDE)

Pneumonia is a major problem in intensive care patients and can be ind uced by pathogenic bacteria adhering to poly(vinyl chloride) (PVC) end otracheal (ET) tubes. This study examines the influence of surface pro perties on the adherence of the respiratory isolates Staphylococcus au reus and Pseudomonas aeruginosa to PVC. In particular, the influence o f respiratory tract physiological conditions, 5% CO2 and saliva, on ad herence was investigated. In general, decreased adherence to PVC was o bserved when bacteria were grown in CO2. When these CO2-grown bacteria were treated with saliva their adherence to PVC significantly increas ed; however, their adherence was significantly reduced to saliva-treat ed PVC. Treatment of both bacterial isolates with saliva decreased the ir negative zeta potential, a factor which may directly contribute to the observed increased microbial (saliva pretreated) adherence to PVC. Cell surface hydrophobicity (CSH) was evaluated by measuring the init ial rates of microbial removal from a buffered aqueous phase, to ensur e the absence of electrostatic interactions, to an organic phase (xyle ne). Under physiological conditions, CSH did not appear to be a domina nt factor in biomaterial adherence as the CSH of S. aureus was decreas ed by saliva treatment but was unchanged for Ps. aeruginosa. Additiona lly, CSH also differed for the two isolates when grown in CO2, signifi cantly decreasing with S. aureus but remaining unaltered with Ps. aeru ginosa. Saliva treatment of PVC also decreased the advancing and reced ing contact angles of the biomaterial and its surface roughness, which may be a factor in the decreased adherence of saliva-treated bacteria to this surface. Alternative biomaterials or surface modifications ap pear necessary for the desired improvements in ET tube effectiveness. This study highlights the influence of physiological conditions on bio material and bacterial surface characteristics and subsequent interact ions. It is imperative that the physiological conditions predominating in the clinical area of biomaterial use be considered when investigat ing device biocompatibility. (C) 1997 Published by Elsevier Science Li mited.