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Seven valent pneumococcal conjugate vaccine immunization in two Boston communities: changes in serotypes and
Stephen I Pelton1, Anita M Loughlin, Colin D Marchant
1Department of Pediatrics, Boston University School of Medicine and Boston Medical Center, Boston, MA, USA.
Insights
The seven valent pneumococcal conjugate vaccine (PCV7) significantly reduced vaccine-type Streptococcus pneumoniae colonization in young children. However, non-vaccine serotypes increased, with no major shifts in antimicrobial resistance observed.
Area of Science:
- Pediatrics
- Infectious Diseases
- Vaccinology
Background:
- The seven valent pneumococcal conjugate vaccine (PCV7) was introduced in 2000 for child immunization.
- PCV7 targets common Streptococcus pneumoniae serotypes responsible for childhood infections.
Purpose of the Study:
- To assess the impact of PCV7 on Streptococcus pneumoniae colonization.
- To evaluate changes in antimicrobial susceptibility of S. pneumoniae post-PCV7 introduction.
Main Methods:
- A surveillance study monitored nasopharyngeal carriage of S. pneumoniae in children aged 2-24 months.
- Nasopharyngeal cultures were collected during well-child and illness visits.
- S. pneumoniae isolates were serotyped and tested for susceptibility to key antibiotics.
Main Results:
- Nasopharyngeal colonization with PCV7 serotypes decreased from 22% to 2% over three years.
- Colonization by non-vaccine serotypes increased from 7% to 16%.
- Antibiotic resistance rates for penicillin, amoxicillin, azithromycin, and trimethoprim-sulfamethoxazole were 29.3%, 2.2%, 26.5%, and 28.1%, respectively.
Conclusions:
- PCV7 immunization effectively reduced carriage of vaccine-targeted pneumococcal serotypes.
- A rise in non-vaccine serotype prevalence was observed.
- No significant changes in antimicrobial susceptibility patterns were noted during the study period.
Background:
Seven valent pneumococcal conjugate vaccine (PCV7) was licensed and introduced in 2000 for universal administration of children younger than 2 years of age and for selective immunization of children 2-5 years of age.
Specific Aims:
To identify changes in colonization and antimicrobial susceptibility among Streptococcus pneumoniae organisms after introduction of PCV7.
Methods:
Infants and children ages 2-24 months were enrolled in surveillance study of nasopharyngeal carriage of S. pneumoniae. Nasopharyngeal cultures for S. pneumoniae were performed at all well child visits and illness visits of children with acute otitis media. S. pneumoniae organisms were serotyped, and antimicrobial susceptibilities to penicillin, amoxicillin, trimethoprim-sulfamethoxazole and azithromycin were performed.
Results:
During the 3-year period (October 2000 through September 2003), nasopharyngeal colonization with vaccine serotypes declined from 22% to 2%, and nonvaccine serotypes increased from 7% to 16%. Rates of antibiotic resistance of S. pneumoniae isolates to penicillin, amoxicillin, azithromycin and trimethoprim-sulfamethoxazole were 29.3, 2.2, 26.5 and 28.1%, respectively.
Conclusions:
PCV7 immunization produces a marked decline in vaccine serotypes carried in the nasopharynx of young children, with a coincident rise in the prevalence of nonvaccine serotypes. Important shifts in antimicrobial susceptibility have not been observed to date.
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