Diagnostica microbiologica delle infezioni associate all’utilizzo di cateteri venosi centrali (CVC): considerazioni generali e studio in pazienti immunocompromessi

Central venous catheterization today is essential for the intensive management of both medical and surgical patients (for the administration of iv fluids, medications, blood products and parenteral nutrition fluids, to monitor hemodynamic status and to provide hemodialysis). CVC infection is a serious complication of catheterization and a common type of nosocomial infection. This complication is particularly serious in oncologic, haematologic and AIDS, frequently immunocompromised, patients. To prevent CVC infection strategies were proposed, such as use of guidelines for the management of CVC or use of antimicrobialimpregnated CVC. However, despite their high frequency of occurrence and seriousness, CVC infections are often difficult to diagnose. Because of their poor specificity and sensitivity clinical findings are often unreliable for establishing a diagnosis of CVC related infection. For the past 25 years a large number of different microbiologic tests have been proposed. In this paper we report the results of some microbiologic tests (qualitative peripheral and CVC blood culture, qualitative and quantitative CVC tip culture) performed in our Laboratory, in the past 10 years, in oncologic, haematologic and AIDS patients.We report also the results of a study performed by using “quantitative cultures” and “differential time to positive cultures” of peripheral and CVC blood samples. On the basis of findings from our study, quantitative CVC tip culture,“quantitative culture” and “differential time to positive culture” of peripheral and CVC blood samples were found simple, sensitive and specific methods for the diagnosis of CVC and CVC-related infection. The microorganism most commonly associated with these infections is Staphylococcus epidermidis, but also others may be involved such as Pseudomonas aeruginosa, Enterococcus faecalis, and Candida spp.