OBJECTIVES: This study aimed to evaluate the correlation between antimicrobial susceptibility profiles of S. pneumoniae and disease severity outcomes in older adults hospitalized with invasive pneumococcal disease (IPD).

METHODS: We conducted a retrospective chart review of adults ≥ 60 y.o. hospitalized with IPD at three tertiary hospitals from 2016 to 2018 in Sao Paulo, Brazil. Antibiogram data provided the S. pneumoniae susceptibility profile. The main disease severity outcomes evaluated were hospital stay length, intensive care unit stay, antimicrobial resistance (AMR), sequelae, and complications (respiratory, cardiovascular, central nervous system (CNS), renal). Statistical comparisons were made using Chi-Square or Fisher Exact tests for categorical variables and Kruskal-Wallis or Mann-Whitney tests for continuous variables, following non-normal distributions. The association between the length of hospital stay and age was assessed by Spearman correlation. All statistical tests were two-sided considering a significance level of 5%.

RESULTS: Ninety of the 94 patients underwent antimicrobial susceptibility testing. During the study period, AMR was observed in 43.3% of isolates. Resistance to a single antibiotic or ≥ 2 antibiotic classes was observed in 21.1% and 22.2%, respectively. Following statistical analysis, limited demographic or clinical outcome data were associated with AMR. In contrast, patients with new-onset seizures experienced higher AMR rates (12.8% vs 0.0%, p=0.026).

CONCLUSIONS: Our study showed high rates of AMR in older adults with IPD. It was observed that there may be a relationship between AMR and the development of new-onset seizures. Further research is needed to explore the impact of AMR on clinical outcomes and provide supporting evidence on the potential value of implementing prevention strategies to avoid infection-related complications.