Does the selection of narrow- or broad-spectrum betalactam antibiotics have any different effect in mortality of pneumococcal pneumonia? : – a retrospective register study

Abstract: Introduction: Streptococcus pneumoniae (pneumococci) is most common and has the highest mortality in community-acquired pneumonia (CAP). In vitro many antibiotics are effective against pneumococci, but recent studies suggest a favor for narrow-spectrum antibiotics. Aim: To investigate difference in mortality from pneumococcal CAP if betalactam antibiotics in monotherapy with a narrow or broad spectrum are selected initially. Methods: A retrospective national register study with cases of pneumococcal CAP 2008-2015. Cohorts of CAP were divided by severety, 0-2 and 3-4 CRB-65-points. Antibiotics and background factors were analyzed. A logistic regression model analyzed potential factors for mortality <30 days. Results: There were 34.299 cases, of which 1592 cases were included, n=1509 with 0-2 CRB-65 and n=83 with 3-4 CRB-65. Overall mortality was 2.5%. 17 out of 1025 (1.7%) died after narrow-spectrum betalactam monotherapy (NSBM), and 23 out of 567 (4.1%) died after broad-spetrum betalactam monotherapy (BSBM). In CAP with 0-2 CRB-65-points, NSBM were associated with less mortality than BSBM (p=0.007, OR 0.39; 95 % CI 0.20-0.78). Age<65 and kidney disease were associated with higher mortality, but in the logistic regression model, these factors were not associated with selected antibiotics and thus not confounders. In CAP with 3-4 CRB-65-points, no significant results were found. Conclusion: NSBM, like penicillins, seems to be safe choice and associated with less mortality than BSBM in less severe pneumococcal CAP. The reasons are unknown, but maybe because of less severe side-effects, better property to the bacteria or better empirical dosage.