Increase in ST-11 serogroup W Neisseria meningitidis invasive meningococcal disease in Canada, 2016-2018.

BACKGROUND: Many countries have experienced increases in invasive meningococcal disease (IMD) due to a serogroup W Neisseria meningitidis (MenW) strain of the multilocus sequence type (ST)-11 clonal complex (CC). MenW ST-11 was first reported in Ontario, Canada, in 2014. By 2016, this strain caused IMD in five provinces and was responsible for 18.8% of the IMD cases in Canada. OBJECTIVE: To provide an update on invasive MenW disease in Canada including the strain characteristics, specimen source of isolates, age, sex and geographic distribution of cases. METHODS: N. meningitidis from culture-positive IMD cases are routinely submitted to the National Microbiology Laboratory (NML) for serogroup, serotype, serosubtype and sequence type analysis. The data from January 1, 2016 to December 31, 2018 were analyzed by calculating the proportion of IMD cases caused by MenW compared with other serogroups. In addition, trends based on age, sex and geographic distribution of cases and specimen source of isolates were analyzed based on information on specimen requisition forms. RESULTS: Over the 3-year period, 292 individual IMD case isolates were analyzed. The percentage of IMD case isolates typed as MenW more than doubled from 19% (n=15) to 44% (n=51) in 2018 when MenW became the most common serogroup, exceeded the number of MenB, MenC or MenY. In total, 93 MenW case isolates were identified, 91% (n=85) belonged to the ST-11 CC. The increase in MenW affected all age groups (but was most common in those older than 60) and both sexes, and occurred across the country but most prevalent in western Canada. The most common specimen source was blood. CONCLUSION: In 2018, MenW was the most common serogroup for isolates received by the NML from culture-positive IMD cases in Canada. Over 90% of the MenW serogroup isolates belonged to the ST-11 CC. The quadrivalent ACWY meningococcal conjugate vaccine protects against IMD caused by strains in the A, C, W or Y serogroups and therefore may protect against IMD caused by the new MenW ST-11 strain; however, more research is needed. The emergence of variant strains highlight the importance of strain characterization in IMD surveillance and research.

Multidrug-resistant and extensively drug-resistant Neisseria gonorrhoeae in Canada, 2012-2016.

BACKGROUND: Neisseria gonorrhoeae have acquired resistance to many antimicrobials, including third generation cephalosporins and azithromycin, which are the current gonococcal combination therapy recommended by the Canadian Guidelines on Sexually Transmitted Infections. OBJECTIVE: To describe antimicrobial susceptibilities for N. gonorrhoeae circulating in Canada between 2012 and 2016. METHODS: Antimicrobial resistance profiles were determined using agar dilution of N. gonorrhoeae isolated in Canada 2012-2016 (n=10,167) following Clinical Laboratory Standards Institute guidelines. Data were analyzed by applying multidrug-resistant gonococci (MDR-GC) and extensively drug-resistant gonococci (XDR-GC) definitions. RESULTS: Between 2012 and 2016, the proportion of MDR-GC increased from 6.2% to 8.9% and a total of 19 cases of XDR-GC were identified in Canada (0.1%, 19/18,768). The proportion of isolates with decreased susceptibility to cephalosporins declined between 2012 and 2016 from 5.9% to 2.0% while azithromycin resistance increased from 0.8% to 7.2% in the same period. CONCLUSION: While XDR-GC are currently rare in Canada, MDR-GC have increased over the last five years. Azithromycin resistance in N. gonorrhoeae is established and spreading in Canada, exceeding the 5% level at which the World Health Organization states an antimicrobial should be reviewed as an appropriate treatment. Continued surveillance of antimicrobial susceptibilities of N. gonorrhoeae is necessary to inform treatment guidelines and mitigate the impact of resistant gonorrhea.

Canadian recommendations for laboratory interpretation of multiple or extensive drug resistance in clinical isolates of Enterobacteriaceae, Acinetobacter species and Pseudomonas aeruginosa.

The goal of this document was to provide Canadian laboratories with a framework for consistent reporting and monitoring of multidrug resistant organisms (MDRO) and extensively drug resistant organisms (XDRO) for common gram-negative pathogens. This is the final edition of the interim recommendations, which were modified after one year of broad consultative review. This edition represents a consensus of peer-reviewed information and was co-authored by the Canadian Public Health Laboratory Network and the Canadian Association of Clinical Microbiology and Infectious Diseases. There are two main recommendations. The first recommendation provides standardized definitions for MDRO and XDRO for gram-negative organisms in clinical specimens. These definitions were limited to antibiotics that are commonly tested clinically and, to reduce ambiguity, resistance (rather than non-susceptibility) was used to calculate drug resistance status. The second recommendation identifies the use of standardized laboratory reporting of organisms identified as MDRO or XDRO. Through the broad consultation, which included public health and infection prevention and control colleagues, these definitions are ready to be applied for policy development. Both authoring organizations intend to review these recommendations regularly as antibiotic resistance testing evolves in Canada.

Microcolony culture techniques for tuberculosis diagnosis: a systematic review.

BACKGROUND: There is considerable demand for quicker and more affordable yet accurate diagnostic tools for tuberculosis (TB). The microscopic observation drug susceptibility (MODS) assay and the thin-layer agar (TLA) assay are inexpensive, rapid microcolony-based culture methods. METHODS: A systematic review and meta-analysis was performed to assess the accuracy and other test characteristics of MODS and TLA compared to a reference standard of traditional solid or liquid culture. Pooled estimates of sensitivity and specificity and their 95% confidence intervals were estimated with an exact binomial likelihood random effects meta-analysis. RESULTS: A total of 21 eligible studies were identified, 12 that evaluated MODS, seven that evaluated TLA and two that evaluated both. The overall pooled sensitivity and specificity of MODS were respectively 92% (95%CI 87-97) and 96% (90-100), and for TLA they were respectively 87% (95%CI 79-94) and 98% (95%CI 94-100), although there was considerable heterogeneity of results. When the studies were restricted to those assessing accuracy of MODS in sputum samples only, the sensitivity was 96% (95%CI 94-98) and the specificity 96% (95%CI 89-100). The mean intervals from reception of specimens to results were 9.2 days with MODS and 11.5 days with TLA; contamination rates averaged 6.6% with MODS and 12.3% with TLA; materials and supplies costs averaged US$1.48 for MODS and US$2.42 for TLA. CONCLUSIONS: MODS and TLA appear to be accurate and rapid yet inexpensive diagnostic tools for active TB. However, this review did not find sufficient evidence on the feasibility and costs of implementation of these tests, nor on the impact of these tests on patient outcomes.

Systematic review and meta-analysis of antigen detection tests for the diagnosis of tuberculosis.

Tests that detect Mycobacterium tuberculosis antigens in clinical specimens could provide rapid direct evidence of active disease. We performed a systematic review to assess the diagnostic accuracy of antigen detection tests for active tuberculosis (TB) according to standard methods and summarized test performance using bivariate random effects meta-analysis. Overall, study quality was a concern. For pulmonary TB (47 studies, 5,036 participants), sensitivity estimates ranged from 2% to 100% and specificity from 33% to 100%. Lipoarabinomannan (LAM) was the antigen most frequently targeted (23 studies, 49%). The pooled sensitivity of urine LAM was higher in HIV-infected than HIV-uninfected individuals (47%; 95% confidence interval [CI], 26 to 68% versus 14%; 95% CI, 4 to 38%); pooled specificity estimates were similar: 96%; 95% CI, 81 to 100% and 97%; 95% CI, 86 to 100%, respectively. For extrapulmonary TB (21 studies, 1,616 participants), sensitivity estimates ranged from 0% to 100% and specificity estimates from 62% to 100%. Five studies targeting LAM, ESAT-6, Ag85 complex, and the 65-kDa antigen in cerebrospinal fluid, when pooled, yielded the highest sensitivity (87%; 95% CI, 61 to 98%), but low specificity (84%; 95% CI, 60 to 95%). Because of the limited number of studies targeting any specific antigen other than LAM, we could not draw firm conclusions about the overall clinical usefulness of these tests. Further studies are warranted to determine the value of LAM detection for TB meningitis in high-HIV-prevalence settings. Considering that antigen detection tests could be translated into rapid point-of-care tests, research to improve their performance is urgently needed.

Diagnosing tuberculosis with urine lipoarabinomannan: systematic review and meta-analysis.

Lipoarabinomannan (LAM) is a potential marker of active tuberculosis (TB). We performed a systematic review and meta-analysis regarding use of urinary LAM assays for diagnosing active TB. We systematically searched for published and unpublished studies that evaluated urinary LAM for active TB diagnosis. Extracted data were pooled using bivariate random effects models and hierarchical summary receiver operating characteristic curves. Heterogeneity was explored through subgroup analysis and meta-regression. Quality was assessed according to standardised QUADAS (Quality Assessment of Diagnostic Accuracy Studies) criteria. In seven studies that assessed test accuracy in microbiologically confirmed cases only, estimates of sensitivity ranged from 13% to 93%, while specificity ranged from 87% to 99%. In five studies that assessed accuracy in clinical and confirmed TB cases, sensitivity ranged from 8% to 80%, while specificity ranged from 88% to 99%. In five studies with results stratified by HIV status, sensitivity was 3-53% higher in HIV-positive than HIV-negative subgroups; sensitivity was highest with advanced immunosuppression. The LAM urinary assay has several characteristics that make it attractive for diagnosing active TB, but has suboptimal sensitivity for routine clinical use. Further studies are needed to evaluate the potential value of the LAM assay in individuals with advanced HIV or for diagnosis of paediatric TB.

Evaluation of light emitting diode-based fluorescence microscopy for the detection of mycobacteria in a tuberculosis-endemic region.

OBJECTIVES: To evaluate fluorescence microscopy (FM) using light emitting diode (LED) technology for the detection of acid-fast bacilli at a tertiary referral centre in Mumbai, India, a tuberculosis-endemic country. DESIGN: LED FM was introduced into a laboratory experienced with Ziehl-Neelsen (ZN) microscopy but unfamiliar with FM. It was evaluated in parallel with routine ZN microscopy services and compared with mycobacterial culture as a reference standard. RESULTS: A total of 1357 pulmonary and 917 extra-pulmonary specimens were examined during the study. LED FM had 78.3% sensitivity and 92.0% specificity against mycobacterial culture when using pulmonary specimens, and 34.0% sensitivity and 88.8% specificity for extra-pulmonary specimens. The mean time per smear examination was 2.48 min for ZN vs. 1.41 min for LED FM. Several biases in study design and operation identified during analysis, which are likely to lead to underestimates of LED FM accuracy, are discussed in the context of future LED FM evaluations. CONCLUSIONS: Although LED FM has significant benefits over both ZN microscopy and conventional FM, its implementation and validation may be prone to difficulties which could hamper evaluation of its performance. Adequate training and detailed standard operating procedures are important to maximise accuracy.

Bacteriophage assays for rifampicin resistance detection in Mycobacterium tuberculosis: updated meta-analysis.

OBJECTIVE: To update a previously reported meta-analysis of evidence regarding the diagnostic accuracy and performance characteristics of commercial and non-commercial phage-based assays for the detection of rifampicin (RMP) resistant tuberculosis (TB). DESIGN AND OUTCOMES: We conducted a systematic review and meta-analysis of test accuracy using bivariate random effects regression and hierarchical summary receiver operating characteristics (HSROC) analysis. Tests included the commercial FASTPlaque assays, luciferase reporter phage (LRP) assays, and in-house phage amplification tests. Sensitivity and specificity for RMP resistance were the main outcomes. RESULTS: By updating previous literature searches, a total of 31 studies (with 3085 specimens) were included in this meta-analysis. Evaluations of commercial phage amplification assays yielded more variable estimates of sensitivity (range 81-100%) and specificity (range 73-100%) compared to evaluations of in-house amplification assays (sensitivity range 88-100%, specificity range 84-100%). LRP evaluations yielded the most consistent estimates of diagnostic accuracy, with seven of eight studies reporting 100% sensitivity and four of eight reporting 100% specificity. Estimates of accuracy failed to capture a major failing of the commercial assay, i.e., the rate of contaminated and indeterminate results. These ranged from 3% to 36% in studies looking at direct detection of RMP resistance from patient specimens (mean 20%). CONCLUSION: Phage-based assays will require further development to maximise interpretable results and reduce technical failures. Once technical issues are resolved, impact on patient-important outcomes and cost-effectiveness need to be determined to inform policy for widespread use.