Outbreak of invasive Streptococcus pneumoniae Serotype 12F among a marginalized inner-city population in Winnipeg, Canada (2009-2011)

Clin Infect Dis. 2014 May 19. pii: ciu366. [Epub ahead of print]

Outbreak of invasive Streptococcus pneumoniae Serotype 12F among a marginalized inner-city population in Winnipeg, Canada (2009-2011).

Schillberg E1, Isaac M2, Deng X3, Peirano G4, Wylie JL5, Van Caeseele P5, Pillai DR4, Sinnock H2, Mahmud SM6.

Abstract

BACKGROUND:

 In 2010, Winnipeg, Canada experienced a doubling of invasive pneumococcal disease (IPD) rates, with a significant increase in the number of cases due to Streptococcus pneumoniae serotype 12F, which previously had accounted for very few cases each year.

METHODS:

 All serotype 12F IPD cases reported between September, 2009 and January, 2011 were reviewed. Pulsed-field gel electrophoresis (PFGE) and multiple-locus variable number tandem repeat analysis (MLVA) were conducted on all isolates. PFGE and MLVA patterns identified several possible clusters. Additional interviews were conducted to obtain information on risk factors and outcomes.

RESULTS:

 Between September, 2009 and January, 2011, 169 cases of IPD were identified. The number of IPD cases due to 12F serotype increased sharply from about 3-4 cases/year (6% of IPD cases) in 2007-09 to 28 (29%) in 2010. All 12F isolates belonged to a single sequence type ST218, and they were generally susceptible to penicillin and fluoroquinolones but not to erythromycin. Compared to other serotypes, 12F cases were more likely to be homeless, to reside in poor inner-city communities and engage in substance abuse, including intravenous and crack cocaine use. Subclusters identified using MLVA had even higher rates of homelessness and substance use.

CONCLUSIONS:

 An immunization campaign targeting high-risk groups was undertaken with pneumococcal polysaccharide vaccine, and subsequently rates of serotype 12F decreased. To our knowledge, this is the largest documented community outbreak of serotype 12F IPD and the first report of an outbreak of IPD serotype 12F in a marginalized urban population in Canada.

© The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

PMID:  

24842908

[PubMed - as supplied by publisher]