Bloodstream infections in immunocompromised adult patients

Bloodstream infections (BSIs) are a major cause of morbidity and mortality in immunocompromised hosts, particularly those with malignancies, transplants, or autoimmune diseases. Epidemiologic surveillance is critical to optimize empirical antimicrobial therapy. Our aims were to describe the frequency, clinical and microbiological characteristics of BSIs in immunocompromised patients treated at two hospitals in Córdoba, Argentina. We conducted a retrospective study at two tertiary care centers in Córdoba, Argentina, including adult immunocompromised patients with microbiologically confirmed BSIs between January 2019 and December 2022. Underlying immunosuppression included malignancy, neutropenia, transplantation, or immunosuppressive therapy. Clinical data were analyzed over a 30-day period, and microbiological isolates were characterized. A total of 181 BSI episodes were included; 97 (53.6%) were hospital-acquired (HA-BSI) and 84 (46.4%) community-acquired (CA-BSI). Median age was 62 years (IQR 54.5-71.5), and 101 (55.8%) were male patients. Active malignancy was the most common immunosuppressive condition (n=124, 68.5%). Primary bacteremia occurred in 51 cases (28.2%). Urinary (n=34, 18.8%), intra-abdominal (n=30, 16.6%), and catheter-related infections (n=24, 13.3%) were the leading sources. Gram-negative bacilli (GNB) predominated (n=150, 75.8%), with Escherichia coli (n=71, 35.9%) and Klebsiella pneumoniae (n=30, 15.2%) being the most frequent isolates. Multidrug-resistant organisms (MDRO) were identified in 67 (33.8%) episodes, more commonly in HA-BSI than CA-BSI (37 [46.3%] vs 15 [21.4%], p=0.001). The overall 30-day mortality rate was 24.8% (n=45). This study demonstrated that, in this cohort of immunocompromised adults, BSIs were slightly more often hospital-acquired and associated with substantial mortality. One-third of the isolates were multidrug-resistant organisms (MDROs).