Bacteremia in Cancer Patients. Comparison between Solid and Hematological Tumors and Impact on 30-day Mortality

Background: The characteristics and outcomes of bacteremia in cancer patients can be different depending if the underlying disease is a solid tumor (ST) or a hematological tumor (HT). The objective of this study is to compare the characteristics and outcomes of episodes of bacteremia in these patients according to their underlying disease.

Methods: Prospective, multicenter study. Episodes of bacteremia in adult patients with cancer were included in 10 centers in Argentina, from July 2014 to January 2016. The 30-day mortality was examined by the Kaplan-Meier method with the log-rank test and the Cox regression model was used to test statistical significance.

Results: 370 episodes of bacteremia were included, 291 (78.6%) had HT and 79 (21.4%) ST. Gram Negative Rods (GNR) were isolated in 246 episodes (66.5%), being Escherichia coli (21.4%) and Klebsiella spp. (21.1%) the most frequent. In 137 (37%) Gram Positive Cocci (GPC) were identified, being Staphylococcus aureus (11.4%) and Coagulase-negative staphylococci (CoNS) (10,8%) the most common. Multidrug-resistant bacteria (MDRB) were isolated in 166 episodes (44.9%), being the most frequent extended spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae (13.5%). ST group had higher Charlson scores (median) (6 vs 2, p=0.0001), higher PITT scores (median) (1 vs 0, p=0.015) and more GPC bacteremia (46.8 vs 34.4%, p=0.04). HT group had more MDRB bacteremia (51.2 vs 21.5%, p=0.001), especially ESBL-producing Enterobacteriaceae (15.5 vs 6.3%, p=0.035) and were more frequently neutropenic (68 vs 27.8%, p=0.0001). APACHE II scores were similar in both groups (median) (ST: 13 vs HT:12, p=0.59). Frequency of adequate empirical treatment was similar (82,3 vs 74,9%, p=0.17), although empirical carbapenem use was more frequent in HT group (43.3%  vs 19, p=0.0001). 30-day mortality was higher in ST group (31.6 vs 19.6%, p=0.017) (Kaplan-Meier, Figure 1). However, in multivariate analysis risk factors for 30-day mortality were a high Charlson score (>4) (HR=2,06, IC95% 1.04-4,1, p=0.03), a high APACHE II score (>24) (HR=2,69, IC95% 1.37-5.27, p=0.004), a high PITT score (>4) (HR=4,25, IC95% 2.3-7.9, p=0.001) and having a MDRB bacteremia (HR=2.15, IC95% 1.2-3.7, p=0.006).

Conclusion: Patients with ST and bacteremia had a higher risk of death compared to HT, secondary to more comorbidites and more severe infections, even though HT patients had more MDRB bacteremia.