Increased prevalence of pediatric pneumococcal serotypes in elderly adults.
BACKGROUND
Pneumococcal disease is most prevalent among young children and elderly adults. We explored whether similarities exist in the serotypes that cause disease in these 2 high-risk groups.


METHODS
With use of US population-based data from 1998-1999 (before the introduction of the 7-valent pneumococcal conjugate vaccine [PCV7] as routine immunization for infants) from the Centers for Disease Control and Prevention's Active Bacterial Core surveillance, we evaluated whether the rate of invasive pneumococcal disease caused by the pediatric serotypes (6B, 9V, 14, 19F, and 23F) increased among elderly persons. We adjusted for potential confounders in multivariable logistic regression.


RESULTS
We analyzed 2987 pneumococcal isolates recovered from adults. The risk of infection with pediatric serotypes increased from 32.5% in 35-49-year-old persons to 51.2% in > or = 85-year-old persons (P < .001). Compared with 35-49-year-old persons, the risk of infection with pediatric serotypes was significantly elevated among 65-74-year-old persons (relative risk [RR], 1.68; 95% confidence interval [CI], 1.29-2.20) and increased progressively among persons aged 75-84 years (RR, 1.82; 95% CI, 1.41-2.36) and > or = 85 years (RR, 2.29; 95% CI, 1.72-3.05), with adjustment for sex, race, geographic location, underlying illness, and penicillin resistance. The rate of penicillin resistance was also elevated in the elderly population but was not significant after adjustment for serotype and race.


CONCLUSIONS
The increased proportion of severe pneumococcal disease caused by pediatric serotypes in the elderly population might indicate opportunities for prevention with use of PCV7.
Feikin
Daniel R
DR
Division of Bacterial and Mycotic Diseases, National Center for Infectious Disease, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
Klugman
Keith P
KP
Facklam
Richard R
RR
Zell
Elizabeth R
ER
Schuchat
Anne
A
Whitney
Cynthia G
CG
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010403:Penicillin Resistance; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000382:microbiology*; D015995:Prevalence; D012307:Risk Factors; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification*; D014481:United States / Q000453:epidemiology