C-Reactive Protein as a Predictor of Early Antibiotic Treatment Failure in Hospitalized Patients With Community-Acquired Pneumonia

Background: Community-acquired pneumonia (CAP) is one of the leading causes of hospitalization and infectious mortality worldwide. Identifying factors associated with early response to antibiotic treatment may improve clinical outcomes. Methods: This retrospective, analytical, observational study included 230 adult patients hospitalized with CAP at Regional General Hospital No. 1 of the Mexican Social Security Institute in Chihuahua, Mexico, between June 2024 and December 2025. Clinical variables, comorbidities, inflammatory biomarkers, and severity scores were evaluated. Statistical analysis included chi-square tests and binary logistic regression. Results: A total of 230/230 (100%) patients were included. The mean age was 63.9 ± 12.7 years, and 121/230 (52.6%) patients were male and 109/230 (47.4%) were female. A favorable response to the initial antibiotic regimen was observed in 143/230 (62.2%) patients, whereas 87/230 (37.8%) required therapeutic escalation. Mortality was higher among patients requiring escalation than those who did not (31/87 (35.6%) vs. 18/143 (12.6%), χ²=15.8, df=1, p<0.001, Cramér’s V=0.26). In multivariable analysis, higher baseline C-reactive protein (CRP) levels were independently associated with non-response to initial antibiotic therapy (OR=1.98; 95% CI: 1.10-3.55; p=0.022). Conclusions: Higher baseline CRP levels were independently associated with non-response to the initial antibiotic regimen in patients with CAP.