Browsing by Author "Vanderkooi, Otto G"

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    Antimicrobial Susceptibility of Invasive and Lower Respiratory Tract Isolates of Streptococcus pneumoniae, 1998 to 2007
    (2009-01-01) Vanderkooi, Otto G; McConnell, Athena; Church, Deirdre L; Kellner, James D
    Previous surveys of antimicrobial resistance in Streptococcus pneumoniae have found differences depending on source of isolate (eg, higher resistance in lower respiratory tract [LRT] versus invasive isolate) and age (higher resistance in children versus adults). Susceptibility profiles in the Calgary Health Region (approximately 1.25 million population) over a 10-year period were studied. Prospective laboratory-based population surveillance for S pneumoniae disease has been conducted since 1998. Patient demographics and susceptibility testing were analyzed. In total, 2382 patient isolates were available for analysis from 1998 to 2007. Of these, 1170 isolates were invasive while 496 were LRT. Patient age distribution was: younger than five years, 14%; five to 17 years, 6%; 18 to 64 years, 56%; and 65 years or older, 24%. Mean patient age was 44.8 years and 60.0% were male. The overall incidence of nonsusceptibility was: penicillin, 8.2%; amoxicillin, 0.3%; cefuroxime, 6.2%; ceftriaxone, 1.7%; erythromycin, 8.8%; trimethoprim-sulfamethoxazole (TMP-SMX), 25.6%; clindamycin, 2.3%; and levofloxacin, 0.2%. Overall resistance rates were stable, except for increasing erythromycin resistance from 5.4% (1998) to a high of 14.2% (2004) (P=0.007). Isolates that were nonsusceptible to penicillin or TMP-SMX were more likely to be multidrug resistant (Pud_less_than0.001) compared with penicillin- or TMP-SMX-susceptible isolates. Compared with invasive isolates, LRT isolates showed more resistance to penicillin, TMP-SMX, cefuroxime and erythromycin, and were more likely to be multidrug resistant. Isolates from children younger than five years of age are more likely to be multidrug resistant and resistant to erythromycin and cefotaxime. Ongoing surveillance of S pneumoniae isolates is important because resistance rates vary by source and patient age among health care regions.
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    Clinical Features and Outcomes of Serotype 19A Invasive Pneumococcal Disease in Calgary, Alberta
    (2014-01-01) Ricketson, Leah J; Vanderkooi, Otto G; Wood, Melissa L; Leal, Jenine; Kellner, James D
    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%; Pud_less_than0.001). 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 ud_less_than18 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.
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    Invasive Streptococcus pneumoniae Infection Causing Hemolytic Uremic Syndrome in Children: Two Recent Cases
    (2003-01-01) Vanderkooi, Otto G; Kellner, James D; Wade, Andrew W; Jadavji, Tajdin; Midgley, Julian P; Louie, Thomas; Tyrrell, Gregory J
    INTRODUCTION: Streptococcus pneumoniae is an uncommon cause of hemolytic uremic syndrome (HUS) with a unique pathophysiology that differs from Shiga toxin-related HUS.METHODS: Case descriptions for each patient are provided. Each strain of S pneumoniae was subjected to a pulsed-field gel electrophoresis (PFGE) analysis, Shiga toxin assay and polymerase chain reaction to detect Shiga toxin genes. A review of the current literature was conducted.CASE PRESENTATIONS: Two patients with S pneumoniae-related HUS that presented to the Alberta Children's Hospital, Calgary, Alberta, within four weeks of each other in 2001 are described. Both presented with pneumonia and empyema with associated HUS. Both patients required dialysis, one patient for 10 days and the other for 18 days. Neither patient demonstrated evidence of Shiga toxin-related disease. S pneumoniae isolated from blood or pleural fluid was penicillin susceptible. One isolate was serotype 3 and the other was serotype 14. The two strains had different PFGE patterns. Both patients recovered well with no persistent renal dysfunction.CONCLUSIONS: S pneumoniae continues to be an uncommon but important cause of HUS. Most cases can be confirmed or at least considered probable without performing a renal biopsy.