One controversial area in microbiology is the reliability of blood cultures drawn from an indwelling vascular catheter. In general, investigators have encountered higher rates of contamination when drawing culture specimens from vascular catheters, due to colonization of the catheter tip or other areas of the apparatus, such as the stopcock, reservoir, or hub. However, not all investigators reported substantial problems. Another controversial subject is usefulness of catheter tip culture in diagnosis of bacteremia etiology. This is especially important since it has been stated that catheter-related infections cause at least 20%-40% of all hospital-acquired bacteremias. At present, the most often recommended method for catheter tip culture is the semiquantitative procedure of Maki. However, this issue is still undecided, since some studies have reported that catheter tip culture has little impact on clinical decisions, or that catheter hub contamination and other factors are more important than catheter tip status. Also, interpretation of a positive culture of a catheter tip is frequently difficult, since even if the same organism is isolated from the blood and from the catheter tip, the tip could be secondarily colonized from a bacteremia originating from some other source. Another problem area is surface cultures from decubitus ulcers and similar chronic open wounds. These generally yield a mixed flora. The Public Health Service Communicable Disease Center believes that little clinically relevant information will be obtained from chronic open surface lesions. If for some reason a culture is necessary, they recommend culture of a tissue biopsy from the base of the lesion rather than a surface swab culture.