Clinical prognostic factors for time to positivity in cancer patients with bloodstream infections

Purpose: Time to positivity (TTP) has been used in recent years as a simple and rapid method for the additional characterization of the degree of bacteremia. However, prognostic factors for TTP in cancer patients with bloodstream infections have rarely been studied. The aim of this study was to investigate the clinical factors for TTP involving various isolated organisms in cancer patients.

Methods: We analyzed 386 episodes of bloodstream infections (BSIs) in patients with or without cancer during a 19 month period. Information on age, gender, tumor type, ICU stay, organisms, multidrug resistance (MDR), TTP and outcome was collected. Multivariate logistic regression analysis was performed.

Results: The mean TTP of Enterobacteriaceae in patients with hepatocellular carcinoma, gastroenterological cancer, and lung cancer was shorter than in non-cancer patients (9.86 ± 3.22, 10.05 ± 3.47, 8.85 ± 2.78 vs 13.11 ± 5.37 h). The mean TTP of nonfermentative bacilli in patients with lung cancer (12.37 ± 5.96 h) and hematologic diseases (8.72 ± 4.21 h) was also shorter than in non-cancer patients (20.74 ± 2.46 h), and the mean TTP of Staphylococcus isolates was significantly different between non-cancer patients (22.06 ± 3.71 h) and hematologic disease patients (11.93 ± 5.44 h). The presence of a benign tumor was a significant prognostic factor for a long TTP only in the Staphylococci group (OR 0.076, 95 % CI 0.014-0.412), according to multivariate analysis. MDR (OR 2.178, 95 % CI 1.196-4.239) was an independent significant predictor in the Enterobacteriaceae group, with a short TTP, and it was also a significant clinical factor for a long TTP in nonfermentative bacilli and the Staphylococci group (OR 5.037, 95 % CI 1.065-23.82; OR 0.167, 95 % CI 0.059-0.474).

Conclusion: Time to positivity provides useful diagnostic and prognostic information for the differentiation of frequently isolated organisms. This information may help clinicians to use the correct antibiotics in a timely manner to treat cancer patients with BSIs based on clinical factor analysis.