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Canadian Journal of Infectious Diseases and Medical Microbiology
Volume 25, Issue 2, Pages e71-e75
Original Articles

Clinical Features and Outcomes of Serotype 19A Invasive Pneumococcal Disease in Calgary, Alberta

Leah J Ricketson,1 Otto G Vanderkooi,1,2,3,4 Melissa L Wood,1 Jenine Leal,1 and James D Kellner1,2

1Department of Pediatrics, University of Calgary, and Alberta Health Services – Calgary Zone, University of Calgary, Calgary, Alberta, Canada
2Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
3Department of Microbiology and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada
4Department of Pathology and Laboratory Medicine, University of Calgary, Calgary, Alberta, Canada

Copyright © 2014 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


BACKGROUND: Streptoccocus pneumoniae serotype 19A (ST19A) became an important cause of invasive pneumococcal disease (IPD) after the introduction of the conjugate vaccine.

OBJECTIVE: To examine the severity and outcome of ST19A IPD compared with non-ST19A IPD.

METHODS: The Calgary Area Streptococcus pneumoniae Epidemiology Research (CASPER) study collects clinical and laboratory data on all IPD cases in Calgary, Alberta. Analysis was performed on data from 2000 to 2010 comparing ST19A and non-ST19A IPD cases. Adjusted linear and logistic regression models were used to examine outcomes of duration of appropriate intravenous antibiotic therapy and intensive care unit admission, respectively.

RESULTS: ST19A tended to cause disease in younger patients. ST19A isolates were more often multidrug resistant (19% versus 0.3%; P<0.001). Adjusted logistic regression showed no difference in intensive care unit admission between ST19A and non-ST19A IPD cases (OR 1.4 [95% CI 0.8 to 2.7]). An adjusted linear regression model showed patients <18 years of age with a diagnosis of bacteremia and no risk factors infected with ST19A were, on average, treated with antibiotics 1.4 times (95% CI 1.1 to 1.9) as long as patients with non-19A IPD and the same baseline characteristics.

DISCUSSION: ST19A IPD was associated with an increase in average time on antibiotics. Although many of the infecting strains of ST19A were within the threshold for susceptibility, they may be sufficiently resilient to require a longer duration of antibiotic therapy or higher dose to clear the infection.

CONCLUSIONS: ST19A is more common in younger individuals, is more antibiotic resistant and may require longer average treatment duration.