180. Impact of Pneumococcal Conjugative Vaccine on Antibiotic Resistant Invasive Pneumococcal Disease in the United States

BACKGROUND: Antibiotic-nonsusceptible invasive pneumococcal disease (NS-IPD) in the United States declined dramatically following the introduction of pneumococcal conjugative vaccines (7-valent, PCV7 in 2000, replaced by the 13-valent, PCV13 in 2010). We evaluated the long-term impact of PCV13 on NS-IPD. METHODS: IPD cases were identified through CDC’s Active Bacterial Core surveillance during 2005−2018. We applied 2012 Clinical and Laboratory Standards Institute breakpoints to minimum inhibitory concentrations determined by broth microdilution (2005−2014) or whole genome sequencing (2015−2018) and classified non-susceptible isolates as those intermediate or resistant to ≥1 antibiotic class. Isolates were serotyped and classified as PCV13 or non-vaccine type (NVT). Incidence rates (cases per 100,000) were calculated using United States Census Bureau population denominators. RESULTS: From 2005 to 2018, NS IPD incidence decreased from 8.5 to 3.2 among children < 5 years old and from 13.0 to 9.4 among adults ≥ 65 years old. Incidence of vaccine-type NS-IPD decreased in all age groups (Figure 1), while incidence of NVT NS-IPD increased in all age groups (Figure 2). The greatest absolute increase in NVT NS-IPD occurred among adults ≥ 65 years from 4.7 in 2005 to 7.2 in 2018. PCV13 serotypes contributed to 62% of NS-IPD (36% of NS-IPD caused by serotype 19A alone) in 2005−2009, and 27% of NS-IPD in 2014−18 (8% of NS-IPD caused by 19A). During 2014–18, NVTs 35B (11%), 33F (9%), 22F (9%), and 15A (9%) were the most common NS-IPD serotypes. Figure 1. Incidence of vaccine type antibiotic non-susceptible invasive pneumococcal disease by age group, 2005−2018. [Image: see text] Figure 2. Incidence of non-vaccine type antibiotic non-susceptible invasive pneumococcal disease by age group, 2005−2018. [Image: see text] CONCLUSION: NS-IPD incidence decreased following PCV13 use in the United States, driven by reductions in PCV13 serotypes. Recent increases in NVT NS-IPD, most pronounced among older adults, have started to erode PCV impact on NS-IPD. PCVs in development that contain serotypes 22F and 33F could help to further reduce NS-IPD. DISCLOSURES: Lee Harrison, MD, GSK (Consultant)Merck (Consultant)Pfizer (Consultant)Sanofi Pasteur (Consultant)