Pre- & post-vaccine trends in pneumococcal serotypes & antimicrobial resistance patterns

Area of Science:

• Microbiology
• Vaccinology
• Infectious Diseases

Background:

• Pneumococcal vaccines were introduced in India's Universal Immunization Programme (UIP) in 2021.
• Limited data exists on serotype shifts post-vaccine introduction in India.
• This study assesses serotype and antimicrobial resistance changes before and after vaccine rollout.

Purpose of the Study:

• To estimate changes in pneumococcal serotypes and antimicrobial resistance patterns.
• To compare pre- and post-vaccine introduction data from a tertiary care center.
• To evaluate the impact of pneumococcal vaccination on circulating strains.

Main Methods:

• Analysis of clinical isolates from pre-vaccine (Jan 2015-Jul 2021) and post-vaccine (Aug 2021-Mar 2023) eras.
• Antimicrobial susceptibility testing via disc diffusion or VITEK2.
• Serotyping using Quellung test or multiplex PCR; statistical analysis with Chi-square, Fisher exact, and z-tests.

Main Results:

• Increased resistance rates for most antibiotics in the post-vaccine era.
• Proportions of serotypes 19F and 15B/C increased; 23F and 14 decreased.
• Majority of persistent 19F and 19A isolates were multidrug-resistant.

Conclusions:

• Pneumococcal vaccination reduced the burden of many vaccine serotypes.
• A slight increase in non-vaccine serotypes was observed.
• Persistent vaccine serotypes (19F, 19A) in the post-vaccine era exhibited significant drug resistance.