The following is a summary of “Early cytokine signatures and clinical phenotypes discriminate persistent from resolving MRSA bacteremia,” published in the February 2025 issue of BMC Infectious Diseases by Bergersen et al. 

Methicillin-resistant Staphylococcus aureus (MRSA) caused a significant proportion of life-threatening Staphylococcus aureus bacteremia (SAB), with a substantial number of patients experiencing antibiotic-persistent MRSA bacteremia (APMB) despite treatment.  

Researchers conducted a retrospective study to identify early immune signatures and clinical phenotypes distinguishing APMB from antibiotic-resolving MRSA bacteremia (ARMB) to improve therapeutic success.  

They analyzed 38 circulating cytokines and chemokines using affinity proteomics in 74 matched pairs of vancomycin-treated SAB cases classified as ARMB or APMB after 5 days of blood culture. A cohort study included hospitalized individuals with ARMB or APMB, defined as ≥5 consecutive days of MRSA bacteremia despite appropriate vancomycin (VAN) treatment. The APMB cases with available plasma or serum samples were matched to ARMB cases using stratified propensity scores based on age, sex, race, and diabetes. The focus on VAN therapy was due to its predominant use during enrollment, its status as a first-line SAB treatment, and its lower risk of inflammatory toxicity compared to daptomycin.  

The results showed that unsupervised hierarchical clustering differentiated APMB from ARMB based on IL-10, IL-12p40, IL-13, CCL4, and TGFα levels. CXCL1, CCL22, and IL-17A varied between APMB and ARMB when analyzed with diabetes, dialysis, metastatic infection, or cardiac vegetation. Integrating immune signatures with these clinical factors improved APMB outcome prediction accuracy to 79.1% using logistic regression modeling. Classification-regression tree analysis identified specific analyte thresholds linked to APMB at presentation, particularly in individuals with metastatic infection.  

Investigators concluded that distinct cytokine and chemokine signatures differentiated APMB from ARMB, and validating these biomarkers could help predict outcomes and guide early interventions to reduce persistent SAB-related complications. 

Source: bmcinfectdis.biomedcentral.com/articles/10.1186/s12879-025-10620-3