Abstract
Objectives
Antimicrobial resistance in Streptococcus pneumoniae has increased in recent decades. We linked two surveillance programs to evaluate trends in incidence, serotype distribution, and antimicrobial resistance in invasive pneumococcal disease (IPD) since the heptavalent pneumococcal conjugate vaccine (PCV7) was introduced in BC in 2003.
Methods
IPD case reports for BC from 2002–2005 from the BC Centre for Disease Control were linked to serotype and antimicrobial susceptibility results from the National Centre for Streptococcus (NCS).
Results
There was a significant decrease in IPD incidence in children <5 from 54/100,000 in 2002 to 16/100,000 population in 2005 (70% decrease, p<0.001). The most dramatic decline was in children aged 1 year, where the rate fell from 135/100,000 to 15/100,000 (89% decrease, p for trend <0.001). Overall, 728/1288 (56.5%) reported cases of IPD were referred to NCS. For all matched cases, the proportion of isolates of PCV7 preventable serotypes decreased from 68.9% to 43.8% (p for trend <0.001) between 2002 and 2005. In children <2 years, this proportion decreased from 83.0% (39/47 cases) to 16.7% (1/6 cases) (p=0.006). The prevalence of non-susceptible isolates was highest for trimethoprim-sulfamethoxazole (15.3%, 111/725 tested), penicillin (9.1%, 66/728), and erythromycin (9.1%, 66/727). 10.3% (75/728) were non-susceptible to ≥2 classes of antimicrobials. Children <15 years of age had the highest proportion of non-susceptible isolates.
Discussion
The incidence of IPD in children has decreased significantly since the introduction of PCV7. Comprehensive serotype and antimicrobial susceptibility can aid in evaluating the impact of immunization programs.
Keywords: Pneumococcal infections, antimicrobial drug resistance, pneumococcal vaccines, Canada
Résumé
Objectifs
Depuis quelques décennies, la résistance aux antimicrobiens contre Streptococcus pneumoniae est en hausse. Nous avons relié deux programmes de surveillance afin d’évaluer les tendances relatives à l’incidence, à la distribution des sérotypes et à la résistance aux antimicrobiens pour les maladies invasives à pneumocoques (MIP) depuis l’introduction du vaccin antipneumococcique conjugué heptavalent (VCP7) en Colombie-Britannique en 2003.
Méthode
Les cas de MIP déclarés en Colombie-Britannique de 2002 à 2005, obtenus du BC Centre for Disease Control, ont été liés aux résultats par sérotype et par sensibilité aux antimicrobiens du Centre national pour le streptocoque (CNS).
Résultats
Nous avons observé une diminution significative de l’incidence des MIP chez les enfants de moins de 5 ans, qui est passée de 54 p. 100 000 en 2002 à 16 p. 100 000 en 2005 (soit une baisse de 70 %, p<0,001). La chute la plus spectaculaire a été observée chez les enfants d’1 an, chez qui les taux sont passés de 135 p. 100 000 à 15 p. 100 000 (soit une baisse de 89 %, p<0,001). Globalement, 728 des 1 288 cas déclarés de MIP (56,5 %) ont été dirigés vers le CNS. Pour tous les cas assortis, la proportion des isolats de sérotypes évitables par le VCP7 a diminué, passant de 68,9 % à 43,8 % (p<0,001) entre 2002 et 2005. Chez les enfants de moins de 2 ans, cette proportion est passée de 83 % (39 cas sur 47) à 16,7 % (1 cas sur 6) (p=0,006). La prévalence des isolats résistants était la plus élevée pour le triméthoprime-sulfaméthoxazole (15,3 %, 111/725), la pénicilline (9,1 %, 66/728) et l’érythromycine (9,1 %, 66/727). Une proportion de 10,3 % (75/728) des isolats étaient résistants à 2 classes ou plus d’antimicrobiens. Les enfants de moins de 15 ans avaient la proportion la plus élevée d’isolats résistants.
Discussion
L’incidence des MIP chez les enfants a diminué de façon significative depuis l’introduction du VCP7. L’inclusion de tous les sérotypes et la sensibilité aux antimicrobiens sont deux éléments qui peuvent faciliter l’évaluation des impacts des programmes d’immunisation.
Motsclés: infections à pneumocoques, résistance aux antimicrobiens, vaccins antipneumococciques, Canada
Footnotes
Source of funding: M. Winters was funded by the Canadian Institutes for Health Research (CIHR), the Bridge CIHR/MSFHR Training Program, and the Paetzold Fellowship through the University of British Columbia
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