Impact of multidrug resistance in cancer patients with bloodstream infections caused by Gram-negative bacilli: results from a multicentre study

Objective: To evaluate the impact of multidrug resistance (MDR) on the mortality of cancer patients with bloodstream infection (BSI) by Gram-negative bacilli (GNB). Patients and methods: This was a prospective observational multicentre study including cancer patients with BSI caused by GNB (June 2018–January 2020). The primary outcome was 30-day mortality. The secondary outcome was mortality attributable to MDR organisms, including extended-spectrum beta-lactamase (ESBL)producing Enterobacterales, carbapenem-resistant (CR) Enterobacterales and CR non-fermenting GNB (CR-NFGNB). A multivariable regression analysis identified factors associated with 30-day mortality. Adjusted odds ratio (aOR) with 95% confidence intervals (95% CI) were calculated. Attributable mortality was estimated according to DRIVE-AB Consortium’s formula. Results: Of 347 cancer patients, 232 (66.9%) had BSI caused by MDR-GNB. Thirty-day mortality was 27.2% in patients with BSI caused by MDR organisms compared to 7% in those with BSI by susceptible GNB (P<0.001). In the multivariable analysis, MDR-GNB including ESBL-producing Enterobacterales (aOR 8.734, 95% CI 1.411–54.077, P=0.02), KPC-producing Enterobacterales (aOR 8.548, 95% CI 1.296–56.411, P=0.026), metallo-βlactamases (MBL)-producing Enterobacterales (aOR 15.802, 95% CI 1.408–68.667, P=0.022) and CR-NFGNB (aOR 53.373, 95% CI 5.104–89.146, P<0.001) as compared to susceptible GNB were independently associated with 30-day mortality. Mortality attributable to MDR-GNB was 43%. According to causative pathogens, attributable mortality was 33% in ESBL, 32% in KPC, 47% in MBL and 73% in CR-NFGNB. Conclusions: In cancer patients, BSIs due to MDR-GNB are associated with excess mortality compared to BSI by susceptible GNB. Strategies to reduce the spread of MDR-GNB and to promote optimal management of affected patients are urgently needed.