Clinical features and outcomes of serotype 19A invasive pneumococcal disease in Calgary, Alberta

• Published in: The Canadian journal of infectious diseases & medical microbiology Vol. 25; no. 2; pp. e71 - e75
• Main Authors: Ricketson, Leah J, Vanderkooi, Otto G, Wood, Melissa L, Leal, Jenine, Kellner, James D
• Format: Journal Article
• Language: English
• Published: Egypt Hindawi Limited 01.03.2014; Pulsus Group Inc; Wiley
• Subjects: Clinical outcomes; Drug resistance; Epidemiology; Infectious diseases; Meningitis; Original; Streptococcus infections; Studies; Canada; Calgary Alberta Canada; Meningitis; Serotype 19A; Mortality; Antibiotic resistance; Streptococcus pneumoniae
• ISSN: 1712-9532; 1918-1493
• DOI: 10.1155/2014/196748

The recent introduction of the seven-valent pneumococcal conjugate vaccine has led to changes in the proportion of disease caused by different serotypes. The serotypes targeted by the vaccine have been reduced, and Streptococcus pneumonia serotype 19A is now the most commonly isolated serotype causing invasive pneumococcal disease. This serotype has been associated with antibiotic resistance. The authors of this article conducted a review of cases of invasive pneumococcal disease diagnosed between 2000 and 2010 in Calgary, Alberta, to examine the disease course of serotype 19A invasive pneumococcal disease compared with other serotypes. Streptoccocus pneumoniae serotype 19A (ST19A) became an important cause of invasive pneumococcal disease (IPD) after the introduction of the conjugate vaccine. To examine the severity and outcome of ST19A IPD compared with non-ST19A IPD. 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. 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. 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. ST19A is more common in younger individuals, is more antibiotic resistant and may require longer average treatment duration.