Abstract

Streptococcus pneumoniae, a natural constituent of nasopharyngeal flora in young children, is an important pathogen involved in various respiratory and invasive infections. Extensive antibiotic use has reduced morbidity and mortality associated with pneumococcal infections but has also led to non-susceptibility of some serotypes. Implementation of pneumococcal conjugate vaccine (PCV) programmes results in reduced antibiotic usage and decreased antibiotic resistance. In California, the Kaiser Permanente study demonstrated a 7.8% reduction in otitis media (OM) visits from 1995 to 1998 following seven-valent PCV (PCV7) administration while decreasing antibiotic prescriptions by 5.4%. An Israeli study in day-care centres recorded a 17% reduction in antibiotic use in children given nine-valent PCV. Similarly, a US study showed a 41.9% reduction in antibiotic prescriptions for acute OM (AOM) when comparing pre-PCV7 to post-PCV7 utilization. In France, a comprehensive PCV7 vaccination programme showed a decrease in antibiotic treatment of AOM from 51.8% to 40.9% over 2 years. Carriage of penicillin-resistant pneumococci dropped from 15.4% to 6.7%. A similar reduction from 47.7% to 30.4% was seen in penicillin-non-susceptible pneumococci. Other studies demonstrated a shift in serotype distribution. Carriage of vaccine-serotype pneumococci declined from 44.3% to 28.9% over a 2-year period, while carriage of non-vaccine serotypes increased from 9.6% to 15.8%. During 6 years of follow-up surveillance, prevalence of serotype 19A increased from 8.6% to 12.6%, while highly penicillin-resistant strains decreased from 15.6% to 1.1%; no new serotype emergence was observed. Implementation of PCV programmes should be accompanied by supportive education on restricting the use of antibiotics.