Can Platelet Indices Predict Gram-Positive Bacterial Infections in ICU Patients: A Cross-Sectional Study

Background Until now, blood culture remains the gold standard for diagnosis of bloodstream infections (BSI). We investigated the diagnostic accuracy of complete blood count (CBC), particularly platelet indices, as a less expensive and more rapid alternative for the diagnosis of BSI, which allows for early proper antibiotic administration. Methods A total of 169 patients admitted to the Intensive Care Unit (ICU) from July 2023 to July 2025 who had suspected BSI and were tested via blood culture (BC). Patients were classified into a BSI group (n = 143) and a non-BSI group (n = 26). The BSI group was further classified into three subgroups as Gram negative bacteremia (n = 87), Gram positive bacteremia (n = 46) and candidemia (n = 10). Demographic parameters and hematological parameters were recorded and compared between the groups. To evaluate sensitivity and specificity, we constructed receiver operating characteristic (ROC) curves. Results Patients with positive blood culture had significantly higher PCT, CRP, Neutrophil, PDW, MPV, MPV/PLT, PDW/PLT, and lower PWR, MPV/PCT, PDW/PCT & PLT/PCT compared to patients with negative blood culture. PLT/PCT, PCT, MPV/PCT, CRP, PDW & PDW/PCT have the highest AUCs (AUCs were 0.73, 0.71, 0.70, 0.69, 0.69 & 0.68, respectively). RDW, MPV/PLT, and PDW/PLT significantly increase, and platelet count significantly decreases among patients with Gram-positive compared to patients with Gram-negative bacterial infection. RDW, platelet, MPV/PLT & PDW/PLT have the highest AUC and accuracy in diagnosis of Gram-positive bacteria (AUC were 0.64, 0.62, 0.62 & 0.62, respectively). Conclusion The RDW, platelet count, MPV/PLT, and PDW/PLT demonstrated the greatest accuracy in predicting Gram-positive bacterial infections.