We made a retrospective cohort study of a primary bloodstream infection outbreak in patients of a cancer unit in a general hospital, evaluated the impact of intervention measures and investigated the predisposing factors. The targeted predisposing factors were selected based on the medical literature. The data were treated with univariate analysis to calculate the relative risk, and statistical significance was set at p<0.05. The presence of a long-term totally-implanted central venous catheter appears to be a predisposing factor, while a peripheral venous catheter appears to have offered protection from infection. This is reinforced by fact that intervention measures controlled the outbreak, suggesting cross-contamination from a common source. These findings corroborate the fundamental role of the hospital infection control service in early intervention and reinforce the need for continued training of health professionals that perform this type of care.