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Changing serotypes causing childhood invasive pneumococcal disease: Massachusetts, 2001-2007
Katherine K Hsu1, Kimberly M Shea, Abbie E Stevenson
1Section of Pediatric Infectious Diseases, Boston University School of Public Health, Boston University Medical Center, Boston, MA 02118, USA. khsu@bu.edu
The Pediatric Infectious Disease Journal
|November 26, 2009
Summary
Invasive pneumococcal disease (IPD) caused by non-PCV7 serotypes, particularly 19A, increased in Massachusetts children from 2001-2007. Antibiotic resistance also rose, necessitating ongoing surveillance for vaccine strategies.
Area of Science:
- Pediatric Infectious Diseases
- Vaccinology
- Antimicrobial Resistance
Background:
- The heptavalent pneumococcal conjugate vaccine (PCV7) was introduced in the US in 2000 and Massachusetts in 2000 for children.
- Statewide surveillance began in 2001 to monitor invasive pneumococcal disease (IPD) in children.
Purpose of the Study:
- To monitor the incidence, serotypes, antimicrobial susceptibility, and risk factors of childhood IPD in Massachusetts.
- To assess the impact of PCV7 on IPD epidemiology.
Main Methods:
- Enhanced passive surveillance of microbiology laboratory reports for pediatric IPD cases (<18 years).
- Serotyping and antimicrobial susceptibility testing of Streptococcus pneumoniae isolates.
- Demographic and clinical data collection via provider interviews.
- Incidence rate calculation using Census 2000 denominators.
Main Results:
- 586 IPD cases reported from 2001-2007; 74% had isolates available for serotyping.
- 85% of typed isolates were non-PCV7 serotypes, with 19A being the most common (28%).
- IPD incidence remained stable due to a decrease in PCV7 serotypes offset by an increase in non-PCV7 serotypes. Ceftriaxone non-susceptible isolates increased to ~20% since 2005. 8 fatalities occurred.
Conclusions:
- Non-PCV7 serotype IPD, especially 19A, increased significantly from 2001-2007.
- Ceftriaxone non-susceptibility also rose, particularly after 2005.
- Ongoing surveillance is crucial for informing vaccination strategies and antibiotic choices for critically ill children.
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