Isolations of aerobic sporing bacilli from the tips of indwelling intravascular catheters.

Following previous reports of the isolation of aerobic sporing bacilli from intravenous catheters and infusion sets, it was decided to analyse a series of catheter tip cultures to ascertain the significance of these isolations. Those catheters from which aerobic sporing bacilli were isolated behaved statistically differently from other catheters from which organisms were isolated, but were statistically similar to sterile catheters. Using the nitroblue tetrazolium (NBT) test no significant difference was found between patients with isolates of aerobic sporing bacilli and those with sterile catheters. The NBT test readily distinguished those patients from whom other organisms were isolated. In a small number of instances some evidence of a possible pathogenic role for the aerobic sporing bacillus was found, but the results clearly indicate that in most cases these organisms can be regarded as contaminants.