Shirley Brown

Use of Bordetella pertussis BP3385 To Establish a Cutoff Value for an IS481-Targeted Real-Time PCR Assay

ABSTRACT This study utilized the Bordetella pertussis single-copy PCR target BP3385 as a means of confirming IS481 PCR-positive reactions with cycle threshold (CT) values of >35. IS481 PCRs with CT values of >35 cycles may represent PCR conditions where there is <1 CFU of B. pertussis per PCR.

Rapid identification of herd effects with the introduction of serogroup C meningococcal conjugate vaccine in Ontario, Canada, 2000-2006.

In 2001, Canadas National Advisory Committee on Immunization endorsed a meningococcal serogroup C conjugate vaccine, which appears to provide durable serogroup-specific immunity while reducing nasopharyngeal carriage. With reference to direct and indirect effects on case occurrence, we sought to evaluate recent trends in the incidence of invasive meningococcal disease (IMD) in Ontario. Analyses included all IMD cases reported between 2000 and 2006 to the Ontario Central Public Health Laboratory. Poisson models incorporating terms for age, sex and seasonal oscillation identified a significant downward trend in disease occurrence, which was strongest in serogroup C cases and not evident when serogroup C strains were excluded from the analysis. Among age groups not targeted by the vaccine program serogroup C, IMD displayed a pattern of decreasing incidence that was not present in non-serogroup C disease. These apparent dramatic effects of conjugate C vaccine (both direct and indirect) may be important in the implementation and evaluation of vaccine policy in other jurisdictions.

VanG-Type Vancomycin-Resistant Enterococcus faecalis Strains Isolated in Canada

ABSTRACT Enterococcus faecalis G1-0247 (vancomycin MIC, 16 μg/ml) was found to harbor a vanG operon 99% identical to the vanG operon in E. faecalis BM4518. E. faecalis N03-0233 (vancomycin MIC, 16 μg/ml) was found to harbor a novel vanG operon, vanG2, on an element in a different chromosomal location than the vanG-harboring elements in G1-0247 and BM4518.

Outbreak of Serogroup C Meningococcal Disease Caused by a Variant of Neisseria meningitidis Serotype 2a ET-15 in a Community of Men Who Have Sex with Men

ABSTRACT We describe an outbreak, in a community of men who have sex with men, of serogroup C meningococcal disease caused by a genetic variant of the serotype 2a ET-15 Neisseria meningitidis characterized by a point mutation in the gene coding for the serotype 2a antigen. A microbiological characterization of the outbreak strain is presented in this report.

Genetic analysis of Bordetella pertussis in Ontario, Canada reveals one predominant clone

OBJECTIVE To characterize Bordetella pertussis isolates in Ontario, Canada in order to understand the clonal diversity of strains present in this province. METHODS A total of 521 isolates from the period 1998-2006 were analyzed by serotyping, pulsed-field gel electrophoresis (PFGE), and DNA sequencing of their virulence factors of pertactin, fimbriae 3, pertussis toxin subunit 1, and pertussis toxin gene promoter. Characteristics of the Ontario isolates were compared to those described for isolates from Europe and Australia. RESULTS A single predominant clone was identified in Ontario, Canada, represented by 83.5% of the 521 isolates analyzed. This clone was characterized by the genotype fim3B, prn2, ptxS1A, and ptxP3 (sequence type (ST)-1), and 72.9% of this clone displayed three closely related PFGE profiles of BpSR11, BpSR5, and BpSR12. Pertussis isolates in Europe with these PFGE profiles and virulence factor genotype are reported as common. The Australian epidemic clone was previously reported to have the genotype prn2 and ptxP3. CONCLUSION The finding of one predominant B. pertussis clone in Ontario, Canada, with characteristics identical to strains involved in epidemics in Europe and Australia, suggests a potential link of this strain to the resurgence of pertussis in this province.

Epidemiology of Invasive Meningococcal Disease with Decreased Susceptibility to Penicillin in Ontario, Canada, 2000 to 2006

ABSTRACT Neisseria meningitidis has been relatively slow to acquire resistance to penicillin. We previously reported an increase in the incidence of invasive meningococcal disease (IMD) strains with decreased susceptibility to penicillin (DSP) in Ontario. Our objectives were to evaluate trends in IMD with DSP, to identify case-level predictors of IMD with DSP, and to evaluate the relationship among DSP, bacterial phenotype, and the likelihood of a fatal outcome. All IMD isolates received in Ontario between 2000 and 2006 were submitted to the Public Health Laboratories, Toronto, for confirmation of the species, serogroup determination, and susceptibility testing. Isolates were considered to be IMD strains with DSP if the penicillin MIC was ≥0.125 μg/ml. Temporal trends were evaluated using multivariable Poisson regression models. Correlates of diminished susceptibility and fatal outcome were evaluated with multivariable logistic regression models. The overall rate of IMD caused by strains with DSP in Ontario was approximately 1.20 cases per million population annually (95% confidence interval [95% CI], 0.99 to 1.46). Seventy-nine strains (21.7%) were IMD strains with DSP. There was no year-to-year trend in the incidence of IMD with DSP. IMD with DSP was strongly associated with strains of serogroups Y (odds ratio [OR], 6.3; 95% CI, 3.6 to 11.1) and W-135 (OR, 8.2; 95% CI, 4.0 to 16.7). Infection with serogroup B or C strains was associated with a marked increase in the risk of mortality (OR, 3.07; 95% CI, 1.39 to 6.75); however, no association between IMD with DSP and mortality was observed. In contrast to trends of the 1990s, the incidence of IMD with DSP was stable in Ontario between 2000 and 2006. In Ontario, the serogroup rather than the penicillin MIC is the microbiological parameter most predictive of mortality.

Contamination of bone marrow products with an actinomycete resembling Microbacterium species and reinfusion into autologous stem cell and bone marrow transplant recipients.

Bacterial contamination of bone marrow or peripheral blood stem cell transplant products typically occurs with skin flora or, rarely, gram-negative organisms. We describe a clonal outbreak of contamination in transplant products caused by contamination with an aerobic actinomycete that occurred at our institution during the summer of 2001. From 1 July through 12 September 2001, 73 peripheral blood or bone marrow stem cell products were obtained from 39 patients, and 34 products were found to be contaminated with the outbreak strain. Fourteen patients were reinfused with contaminated cells, and the outbreak strain was isolated from the blood cultures for one patient. Investigation revealed multiple potential sources for contamination during the product cryopreservation process. The outbreak of contamination was aborted upon modification of the cryopreservation process.

Evaluation of CLSI Agar Dilution Method and Trek Sensititre Broth Microdilution Panel for Determining Antimicrobial Susceptibility of Streptococcus pneumoniae

ABSTRACT Both the CLSI agar dilution method and Trek Sensititre broth microdilution panel for Streptococcus pneumoniae antimicrobial susceptibility testing were evaluated against the reference CLSI broth microdilution method using the most recently published CLSI breakpoints. While agar dilution was not an optimal method, the commercial panel appeared to be an acceptable method, with minor errors encountered for ceftriaxone, penicillin, and meropenem.