Streptococcus pneumoniae did not grow more resistant to penicillin after the introduction of 13-valent pneumococcal conjugate vaccine, though geographic differences remained, according to Cheryl P. Andam, Ph.D., and her associates.
Data from the Active Bacterial Core surveillance system on 285 patients before introduction of PCV13 and from 339 patients after PCV13 introduction were used in the study. Patients were from California, Colorado, Connecticut, Georgia, Maryland, Minnesota, New Mexico, New York, Oregon, and Tennessee. New Mexico, Maryland, and Georgia saw the largest increases in penicillin-nonsusceptible pneumococcus (PNSP) rates, while Colorado, New York, and Connecticut saw decreases. No change was seen in the nationwide PNSP rate.
Preintroduction of PCV13, geographic heterogeneity in serotype distribution, and serotype-specific differences in penicillin resistance were equally responsible for geographic variation in PNSP rates. Although no significant change was seen after introduction, influence of serotype-specific differences did decrease slightly while geographic heterogeneity of PSNP serotypes increased.
“Further long-term nationwide surveillance of serotype dynamics is required to assess the multiple ecologic factors that influence antibiotic resistance in the pneumococcus in the conjugate vaccine era,” the investigators concluded.
Find the full research letter in Emerging Infectious Diseases (doi: 10.3201/eid2306.161331).