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 (US). 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 20092017. 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 (1864 and ≥65 years of age) showed a reduction in PEN-NS rates (from 12.914.5% in 2009 to 2.84.3% in 2017). The PEN-NS rates among PCV13 STs from both age groups rose to 37.739.9% from 2009 to 2011, decreasing in subsequent years (20122017) to 11.816.4% (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 1864 years plateaued or increased in 20152017, 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 20152017 may reflect the US recommendation to directly vaccinate adults age ≥65 but not 18-64 years; however, this hypothesis requires further data for confirmation.
R. E. Mendes,
T. B. Doyle, Pfizer Inc: Research Contractor , Research support .
L. N. Woosley, Pfizer Inc: Research Contractor , Research support .
R. K. Flamm, Pfizer Inc: Research Contractor , Research support .
B. D. Gessner, Pfizer Inc.: Employee and Shareholder , Salary .
R. E. Isturiz, Pfizer, Inc: Employee and Shareholder , Salary and Stock & Stock Options .