1444. Trends in Antimicrobial Non-susceptibility of PCV13-Type Streptococcus pneumoniae Pneumonia in Adults in the United States During 2009–2017

BACKGROUND: The routine use of 13-valent pneumococcal conjugate vaccination (PCV13) was implemented in children in 2010 and in adults (≥65 years of age) in 2014 in the United States. Trends in rates of penicillin G (PEN) antimicrobial nonsusceptibility (NS) for PCV13-type S. pneumoniae from adult pneumonia patients were assessed by age group. METHODS: Isolates were consecutively collected from pneumonia patients in 105 US sites in 40 states during 2009–2017. Isolates were identified by biochemical algorithms and/or PCR; susceptibility testing and interpretation used CLSI Methods. The cpsB sequence was obtained by PCR or whole-genome sequencing for serotype (ST) determinations. Multiplex PCR and/or Quellung reactions were also performed, as needed. RESULTS: Of 7,254 analyzed S. pneumoniae isolates, 63.6 and 36.4% were obtained from pneumonia patients aged 18–64 and ≥65 years, respectively. S. pneumoniae recovered from both age groups (18–64 and ≥65 years of age) showed a reduction in PEN-NS rates (from 12.9–14.5% in 2009 to 2.8–4.3% in 2017). The PEN-NS rates among PCV13 STs from both age groups rose to 37.7–39.9% from 2009 to 2011, decreasing in subsequent years (2012–2017) to 11.8–16.4% (Figure 1). Similar results were observed for PEN-NS rates against the STs included in PCV13 but not PCV7 (Figure 2). PEN-NS rates against PCV13 and PCV13-non-PCV7 STs from patients age 18–64 years plateaued or increased in 2015–2017, while PCV13 and PCV13-non-PCV7 STs from patients age ≥65 years declined continuously after 2012. CONCLUSION: The decrease in PEN-NS rates among PCV13 and PCV13-non-PCV7 STs may be associated with the herd effect from PCV13 vaccination in children, an effect that may have occurred as early as 2 years after PCV13 implementation. The modest differences in PEN-NS trends between age groups during 2015–2017 may reflect the US recommendation to directly vaccinate adults age ≥65 but not 18–64 years; however, this hypothesis requires further data for confirmation. [Image: see text] [Image: see text] DISCLOSURES: R. E. Mendes, T. B. Doyle, L. N. Woosley, R. K. Flamm, Pfizer Inc: Research Contractor, Research support. J. A. Suaya, Pfizer: Employee and Shareholder, Benefits and stock and Salary. B. D. Gessner, Pfizer Inc.: Employee and Shareholder, Salary. R. E. Isturiz, Pfizer, Inc: Employee and Shareholder, Salary and Stock & Stock Options.