Objective: To elucidate the preventive effect of 23-valent pneumococcal polysaccharide vaccine (PV) on drug-resistant Streptococcus pneumoniae.
Methodology: Participants (outpatients, over 60 years of age, and with chronic lung disease) were interviewed and divided into two groups: the PV-vaccinated group (n=722) and the non-vaccinated group (n=872). The antimicrobial susceptibility and the genotype of antibiotic-resistant genes among the isolated pneumococcal strains from sputum before and after vaccination were studied.
Results: The number of the isolated strains was as follows: prior to the vaccination, 24 isolates in the vaccinated group, 18 isolates in the non-vaccinated group; after vaccination (within 5 years), 53 isolates in the vaccinated group, 46 isolated in the non-vaccinated group. The PV decreased the frequency of Penicillin G-resistant strains successfully (from 16.7 to 7.5%) in the vaccinated group while the frequency increased (from 5.5 to 15.2%) in the non-vaccinated group during the same period. In genetic analysis, the rates of strains with altered pbpla, pbp2x and pbp2b were decreased in the vaccinated group than the non-vaccinated group (28.6% versus 53.3%).
Conclusions: The 23-valent pneumococcal polysaccharide vaccine may have a preventive effect against drug-resistant Streptococcus pneumoniae.