Microbiological Analysis of Bloodstream Infections in Patients with Acute Leukemia and the Association with Prognosis
Authors: Ge Rui , Huang Yanqing , Song Chunhua , Ge Zheng 
Published: December 2024

Background
Bloodstream infection (BSI) is defined as the presence of systemic signs of infection in patients with positive blood cultures, which can be primary or secondary (Timsit JF, 2020). Patients with acute leukemia (AL) constitute a prominent cohort in the susceptible populations of BSI. Studies have indicated that the infection rate of AL patients can be as high as 86.9% during induction chemotherapy (Tang Y, 2018； Kato H,2018), and 6% to 36% of AL patients succumb to death following the onset of BSI (Peri AM, 2022； Gustinetti G, 2016). This study aims to analyze the microbial distribution, in vitro antimicrobial susceptibility profiles of major pathogens, and the therapeutic effects of administering sensitive drugs in AL patients with BSI. The association of risk factors with the prognosis was also analyzed in the patients.
Methods
This study recruited 122 patients with AL complicated by BSI from the Hospital Information System of Zhongda Hospital between January 2016 and June 2024. Statistical analysis was performed using SPSS software. To compare pre- and post-treatment patient data, paired-sample t-tests were employed for continuous variables that met the criteria of normal distribution and homogeneity of variance; otherwise, paired-sample Wilcoxon signed-rank tests were applied. Univariate analysis utilized the χ2 test, while multivariate analysis employed Logistic regression analysis, with the level of significance set at α=0.05.
Results
A total of 130 pathogenic strains were detected in the BSI of 122 patients, the strains with high detection rates are Klebsiella Pneumoniae (30.8% 40/130), Escherichia coli (14.6%, 19/130), Staphylococcus (14.6%, 19/130), Pseudomonas aeruginosa (13.1 %, 17/130). 62.5% (25/40) of patients with Klebsiella Pneumoniae were sensitive to carbapenems in vitro. 20/25 patients received carbapenem-based antimicrobial therapy and showed a statistically significant decrease in body temperature, C-reactive protein (CRP), and Procalcitonin (PCT) compared to pre-treatment (P&lt;0.05); 11 of them appeared no detectable pathogens in bacteriological cultures after the treatment. Similar results were also observed in the carbapenem-based treatment for 19 patients with Escherichia coli BSI, 13 of the 17 patients with Pseudomonas aeruginosa BSI. 19 patients with Staphylococcus BSI are sensitive to either vancomycin or linezolid and appeared significant efficacy upon their treatment.
Among the 122 patients, there were 94 cases (77%) of AML, 26 cases (21.3%) of ALL, and 2 cases (1.6%) of acute mixed lineage leukemia (AMLL). The prolonged and frequent intensive chemotherapy in AL leads to prolonged granulocytopenia, further elevating their risks of infection and mortality. In our cohort, the duration of neutropenia ≥7 days in the patients with BSI occupied 64.8%, which outnumbered those with a duration of &lt;7 days (35.2%). Notably, the duration of neutropenia ≥7 days exhibited a significant difference between the survival group and the non-survival group (P=0.009). Moreover, we conducted a multivariate analysis of the clinical covariates between the 30-day survival and non-survival groups among patients with AL complicated by BSI. Results revealed that relapse/refractory status (P=0.001), detection of drug-resistant bacteria in blood cultures (P=0.011), Charlson Comorbidity Index（CCI）&gt; 4 (P=0.022), Pitt Bacteremia Score（PBS）&gt; 3 (P=0.001) were independent risk factors for 30-day mortality in patients with acute leukemia complicated by BSI.
Conclusions
Our study showed that K. pneumoniae, E. coli, and P. aeruginosa are highly detected bacteria strains in BSI, sensitive to carbapenems in vitro, and carbapenems have effective therapeutic effects on their bloodstream infection. Our results also indicated that vancomycin or linezolid is an effective therapy for BSI of Staphylococcus, another highly-detected strain. The duration of neutropenia lasting for ≥7 days in the AL patient with BSI revealed a potential correlation with adverse patient outcomes. Our data also indicated that the drug-resistant bacteria in blood cultures and PBS score, similar to other co-variates such as relapse/refractory status and the CCI score, are important prognosis factors in AL patients with BSI.