A definition of catheter-related infection.

There is controversy about the definitions of catheter-related infection. The term "infection" implies a physiological reaction by the patient to a pathogenic microorganism. However, the organism has no pathognomonic infectious reaction to a colonised catheter, with the exception of a local exit-site infection. Therefore, suggestions have been made that the definition of catheter-related infection should be based solely on the degree of bacterial colonisation, i.e. the number of colony forming units recovered from the catheter. Although this method does not define catheter-related infections in the strict sense, the approach may be useful for comparing various studies carried out on this topic. However, various methods are used to analyse intraluminal and/or extraluminal colonisation, and comparison of data across studies is difficult. Ideally studies addressing this issue should use a combination of different methods to analyse catheter colonisation. On the basis of microbiological semi-quantitative or quantitative analysis of bacterial colonisation, an attempt should be made to correlate the clinical symptoms of infection to these culture results in order to define useful cutoff values.