Introduction:
The aim of the study was to evaluate inflammatory markers (neutrophil to lymphocyte ratio [NLR], platelet to lymphocyte ratio [PLR], platelet to mean platelet volume [PLT/MPV], C-reactive protein [CRP], CRP/albumin) in hospitalized patients with bacterial community-acquired pneumonia (CAP) and to differentiate between Gram-positive and Gram-negative groups and between admission and discharge findings.

Material and methods:
A total of 170 adult patients hospitalized with bacterial CAP due to Gram-positive (n = 130) and Gram-negative (n = 40) pathogens were included in this retrospective study. Complete blood count (CBC) and inflammatory markers (NLR, PLR, platelet/MPV ratio, CRP, albumin) were recorded.

Results:
Gram-negative vs. Gram-positive pneumonia was associated with significantly higher likelihood of being hospitalized at the ICU (70.0% vs. 2.3%, p < 0.001), mortality (20.0% vs. 2.3%, p < 0.001) and sepsis (27.5% vs. 0.0%, p < 0.001). Neutrophil to lymphocyte ratio, PLR and PLT/MPV at admission or discharge showed no significant difference between study groups. A significant decrease in NLR (p < 0.001 and p = 0.026, respectively), CRP (p < 0.001 and p = 0.013, respectively) and CRP/albumin ratio (p = 0.021 and p = 0.037, respectively) was noted from admission to discharge in both groups.

Conclusions:
In conclusion, our findings in a retrospective cohort of hospitalized CAP patients revealed no significant role of NLR, PLR, PLT/MPV or CRP in differential diagnosis of Gram-negative versus Gram-positive etiology and thus no additional benefit of these markers in faster implementation of appropriate treatment in accordance with the Gram stain.