Although numerous articles have demonstrated that recommended empiric antimicrobial regimens are associated with decreased mortality at 30 days, there is controversy over whether appropriate antibiotic selection has a beneficial impact on mortality within the first 48 to 96 hours after admission. Our aim was to determine whether the use of guideline-concordant antibiotic therapy is associated with decreased mortality within the first 48 hours after admission for patients with pneumonia.

A retrospective cohort study was conducted at two tertiary teaching hospitals in San Antonio, Texas. A propensity score was used to balance the covariates associated with the use of guideline-concordant antimicrobial therapy. A multivariable logistic regression model was used to assess the association between mortality within 48 hours and the use of guideline-concordant antibiotic therapy, after adjusting for potential confounders including the propensity score.

Information was obtained on 787 patients with community-acquired pneumonia. The median age was 60 years, 79% were male, and 20% were initially admitted to the intensive care unit. At presentation 52% of subjects were low risk, 34% were moderate risk, and 14% were high risk. Within the first 48 hours, 20 patients died. After adjustment for potential confounders, the use of guideline-concordant antimicrobial therapy (odds ratio 0.37, 95% confidence interval, 0.14-0.95) was significantly associated with decreased mortality at 48 hours after admission.

Using initial empiric guideline-concordant antimicrobial therapy is associated with decreased mortality at 48 hours. Further research needs to investigate methods to ensure that patients with community-acquired pneumonia are treated with appropriate antimicrobial therapies.