Aims: To evaluate whether the presence of hypoxemia could influence the systemic inflammatory response (C-reactive protein, CRP) in bacteremic pneumococcal pneumonia (Pn-CAP).

Material and methods: We analyzed the relationship between the presence of hypoxemia (PaO₂/FiO₂ <300) and other clinical parameters and systemic inflammatory response measured by PCR in a series of bacteremic pneumococcal pneumonia. We performed a multiple linear regression analysis considering CRP levels as a dependent variable and other physiological parameters and comorbidities as independent variables.

Results: We analyzed 297 cases of bacteremic pneumococcal pneumonia. The mean PaO2/FiO2 was 277.7 (IQR: 233.3-323.8), and 44.8% (133) showed PaO₂/FiO₂<300. CRP mean was 27.6 mg/dl (IQR: 15.7-39.2). Linear regression analysis showed that pneumonia severity (PSI score) (regression coefficient: -0.21, p = 0.047), PaO₂/FiO₂ (regression coefficient: -0.21, p = 0.037) and the presence of some immunosuppressant factor (regression coefficient: -0.29, p = 0.002) were independently associated with CRP levels. The model showed a correlation of 0.353 with r² of 0.125.

Conclusions: In our series, we observed that the degree of hypoxemia, the severity of pneumonia and the presence of some immunosuppressant factors correlates with the systemic inflammatory response measured by CRP in bacteremic pneumococcal pneumonia.