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.

Risk factors for pneumococcal endocarditis.

Bacteremia is one of the most common manifestations of invasive pneumococcal disease (IPD). One complication of bacteremia is endocarditis; yet, few studies have evaluated the overall incidence and risk factors for IPD-associated endocarditis. Thus, we evaluated the overall incidence and risk factors of endocarditis compared to those without endocarditis in a large population of IPD patients. We prospectively collected all IPD cases from 2000 to 2014 in Northern Alberta, Canada. Descriptive statistics were used to compare sociodemographic variables, clinical characteristics, and IPD-related outcomes between patients with and without endocarditis. Endocarditis complicated the course of only 28 (0.3%) of 3251 adult patients with IPD. Endocarditis patients were more likely to use illicit drugs and have a higher severity of illness at presentation (i.e., higher rate of altered mental status and rate of intensive care unit [ICU] utilization, p < 0.05); however, no other major risk factors were identified. New murmur development among endocarditis patients was common: 39.3% compared to 2.2% of non-endocarditis patients (p < 0.001). The mortality rate of 39.3% was more than twice that of the rate of 14.7% for the patients with IPD but without endocarditis. There was no pneumococcal serotype predilection for endocarditis. Endocarditis is an uncommon complication of IPD, but, when present, is associated with a significantly increased risk of mortality. Overall, few specific risk factors were identified for IPD-related endocarditis, with the exception of illicit drug use.

Invasive Pneumococcal Disease: Still Lots to Learn and a Need for Standardized Data Collection Instruments.

Background. Large studies of invasive pneumococcal disease (IPD) are frequently lacking detailed clinical information. Methods. A population-based 15-year study of IPD in Northern Alberta. Results. 2435 patients with a mean age of 54.2 years formed the study group. Males outnumbered females and Aboriginal and homeless persons were overrepresented. High rates of smoking, excessive alcohol use, and illicit drug use were seen. Almost all (87%) had a major comorbidity and 15% had functional limitations prior to admission. Bacteremia, pneumonia, and meningitis were the most common major manifestations of IPD. Almost half of the patients had alteration of mental status at the time of admission and 22% required mechanical ventilation. Myocardial infarction, pulmonary embolism, and new onset stroke occurred in 1.7, 1.3, and 1.1% of the patients, respectively; of those who had echocardiograms, 35% had impaired ventricular function. The overall in-hospital mortality was 15.6%. Conclusions. IPD remains a serious infection in adults. In addition to immunization, preventative measures need to consider the sociodemographic features more carefully. A standard set of data need to be collected so that comparisons can be made from study to study. Future investigations should target cardiac function and pulmonary embolism prevention in this population.

Interim laboratory testing guidance for the detection of non-tuberculous Mycobacterium (NTM) infections in post-operative patients exposed to heater-cooler units.

The advice contained in this document should be read in conjunction with relevant federal, provincial, territorial and local legislation, regulations, and policies. Recommended measures should not be regarded as rigid standards, but principles and recommendations to inform the development of guidance. This advice is based on currently available scientific evidence and adopts a precautionary approach where the evidence is lacking or inconclusive. It was approved for publication on December 5, 2016. It is subject to review and change as new information becomes available. The main changes to this version include additions to: Case load reported to date, Sarcoidosis-like disease as an Indicator, Whole Genome Sequencing effort, links to Provincial and Territorial Lab Services and Health Canada reporting.

Donor-derived bacteremia in liver transplant recipients despite antibiotic prophylaxis.

As the disparity between the number of candidates listed for transplant and the number of donors continues to grow, marginal organ donors are increasingly utilized. This includes bacteremic donors which may carry an increased risk of transmission of infection. It is recommended that recipients of organs from bacteremic donors receive antibiotic prophylaxis based on the susceptibilities of the donor isolate to prevent transmission. Here, we present four cases of donor-derived bacteremia, despite appropriate antimicrobial prophylaxis, in four liver transplant recipients. Transmitted pathogens included Staphylococcus aureus in two cases, and Escherichia coli and Group B Streptococcus each in one case. Interestingly, none of the nonhepatic organs (n=10) utilized from these bacteremic donors resulted in transmissions. These cases highlight the fact that risk of transmission from bacteremic donors is not eliminated with antimicrobial therapy in the donor and recipient. As no transmissions occurred in recipients of nonhepatic organs from these donors, these cases also suggest that liver recipients may be at higher risk of donor transmitted bacteremia.

Increased risk of invasive pneumococcal disease in haematological and solid-organ malignancies.

Large-scale population-based studies have reported a significant increase in invasive pneumococcal disease (IPD) in those with underlying haematological or solid-organ malignancy, but limited condition-specific data are available on rates of IPD in the adult population. A retrospective chart review of all patients with IPD (identified prospectively) in the province of Alberta, Canada (population ~3·3 million) was conducted from 2000 to 2004 to study the epidemiology of IPD. Rates of IPD in patients with various haematological and solid-organ malignancies were determined by obtaining the number of these patients at risk from the provincial cancer registry. Compared to the attack rate of IPD in the adult population aged ≥18 years (11·0 cases/100,000 per year, 95% CI 10·44-11·65), there were significantly increased rates of IPD in those with lung cancer (143·6 cases/100,000 per year, OR 13·4, 95% CI 9·3-19·4, P<0·001) and multiple myeloma (673·9 cases/100,000 per year, OR 62·8, 95% CI 39·6-99·8, P<0·001). More modestly increased rates of IPD were found in those with chronic lymphocytic leukaemia, acute myeloid leukaemia, acute lymphoblastic leukaemia, and Hodgkin's and non-Hodgkin's lymphoma. There was an increased prevalence of serotype 6A in those with these underlying malignancies, but no other serotypes predominated. Fifty-three percent (48/83) of cases were caused by serotypes in the investigational 13-valent pneumococcal conjugate vaccine (PCV13), and 57/83 (69%) of the cases were caused by serotypes in the 23-valent pneumococcal polysaccharide vaccine (PPV23). The incidence of IPD in adults with certain haematological and solid-organ malignancies is significantly greater than the overall adult population. Such patients should be routinely given pneumococcal polysaccharide vaccine; this population could also be targeted for an expanded valency conjugate vaccine.

A comparison of three real-time PCR assays for the confirmation of Neisseria gonorrhoeae following detection of N. gonorrhoeae using Roche COBAS AMPLICOR.

Three different real-time PCR assays were evaluated as confirmatory tests for Neisseria gonorrhoeae after initial screening using the COBAS AMPLICOR Chlamydia trachomatis and N. gonorrhoeae duplex assay. The target genes used for the confirmation were the gyr, cppB and 16S rRNA genes. Analytical specificity was determined by testing 60 strains belonging to different bacterial species and/or serogroups. The primers chosen from the 16S rRNA gene for confirmation of N. gonorrhoeae were highly specific, showed no cross-reactivity with other bacteria included in the study, and had an analytical sensitivity of 1 CFU. Of 192 clinical specimens that were positive for N. gonorrhoeae according to the COBAS AMPLICOR assay, 42 were confirmed as positive using the 16S rRNA gene target, 26 were confirmed using the cppB target, and 30 were confirmed using the gyr target. It was concluded that the real-time PCR assay targeting the 16S rRNA gene is a useful confirmatory assay to complement the COBAS AMPLICOR screening test for N. gonorrhoeae.

Identification of Enterococcus species and phenotypically similar Lactococcus and Vagococcus species by reverse checkerboard hybridization to chaperonin 60 gene sequences.

Data from four recent studies (S. H. Goh et al., J. Clin. Microbiol. 36:2164-2166, 1998; S. H. Goh et al., J. Clin. Microbiol. 34:818-823, 1996; S. H. Goh et al., J. Clin. Microbiol. 35:3116-3121, 1997; A. Y. C. Kwok et al., Int. J. Syst. Bacteriol. 49:1181-1192, 1999) suggest that an approximately 600-bp region of the chaperonin 60 (Cpn60) gene, amplified by PCR with a single pair of degenerate primers, has utility as a potentially universal target for bacterial identification (ID). This Cpn60 gene ID method correctly identified isolates representative of numerous staphylococcal species and Streptococcus iniae, a human and animal pathogen. We report herein that this method enabled us to distinguish clearly between 17 Enterococcus species (Enterococcus asini, Enterococcus rattus, Enterococcus dispar, Enterococcus gallinarum, Enterococcus hirae, Enterococcus durans, Enterococcus cecorum, Enterococcus faecalis, Enterococcus mundtii, Enterococcus casseliflavus, Enterococcus faecium, Enterococcus malodoratus, Enterococcus raffinosus, Enterococcus avium, Enterococcus pseudoavium, Enterococcus new sp. strain Facklam, and Enterococcus saccharolyticus), and Vagococcus fluvialis, Lactococcus lactis, and Lactococcus garvieae. From 123 blind-tested samples, only two discrepancies were observed between the Facklam and Collins phenotyping method (R. R. Facklam and M. D. Collins, J. Clin. Microbiol. 27:731-734, 1989) and the Cpn60 ID method. In each case, the discrepancies were resolved in favor of the Cpn60 ID method. The species distributions of the 123 blind-tested isolates were Enterococcus new sp. strain Facklam (ATCC 700913), 3; E. asini, 1; E. rattus, 4; E. dispar, 2; E. gallinarum, 20; E. hirae, 9; E. durans, 9; E. faecalis, 12; E. mundtii, 3; E. casseliflavus, 8; E. faecium, 25; E. malodoratus, 3; E. raffinosus, 8; E. avium, 4; E. pseudoavium, 1; an unknown Enterococcus clinical isolate, sp. strain R871; Vagococcus fluvialis, 4; Lactococcus garvieae, 3; Lactococcus lactis, 3; Leuconostoc sp., 1; and Pediococcus sp., 1. The Cpn60 gene ID method, coupled with reverse checkerboard hybridization, is an effective method for the identification of Enterococcus and related organisms.

Invasive disease due to group B streptococcal infection in adults: results from a Canadian, population-based, active laboratory surveillance study--1996. Sentinel Health Unit Surveillance System Site Coordinators.

In 1996, a population-based surveillance program for invasive adult group B streptococcal (GBS) diseases in Canada was undertaken, to define the epidemiologic and microbiologic characteristics of the disease. Nine public health units across Canada, representing 9.6% of the population, participated in the program. In total, 106 culture-positive cases of invasive adult GBS disease were reported, which represented an incidence rate 4.6 per 100,000 adults (41/100, 000 for pregnant and 4.1/100,000 for nonpregnant adults). Sixty-two (58.5%) of the 106 cases occurred in females, and, of these, 15 (14. 2%) were associated with pregnancy. Serotype V was the most common, accounting for 31% of the 90 GBS isolates typed (26.7% of nonpregnant and 4.4% of pregnant cases). This was followed by serotypes III (19%), Ia (17%), Ib (10%), II (9%), and VII (1%). Thirteen percent were nontypeable. All isolates were susceptible to penicillin, ampicillin, and vancomycin. Resistance to erythromycin and clindamycin was 6.7% and 4.4%, respectively.

Identification and characterization of IS1476, an insertion sequence-like element that disrupts VanY function in a vancomycin-resistant Enterococcus faecium strain.

The vanY gene of vancomycin-resistant enterococci encodes a D,D-carboxypeptidase. By using a PCR detection strategy, a VanA Enterococcus faecium clinical isolate was found to have an insertion sequence (IS)-like element designated IS1476 in vanY. The activity of the VanY D,D-carboxypeptidase in this isolate was decreased in a fluorometric fluoraldehyde o-phthalaldehyde assay with diacetyl-L-Lys-D-Ala-D-Ala as the substrate. This, to our knowledge, is the first report of an IS-like element in a vancomycin resistance gene.

Species identification of enterococci via intergenic ribosomal PCR.

Accurate species identification of enterococci has become important with the wide prevalence of acquired vancomycin resistance and the presence of less epidemiologically important, inherently vancomycin-resistant enterococci. Using a collection of enterococcal strains, we found that PCR amplification of the intergenic spacer (ITS-PCR) between the 16S and 23S rRNA genes can produce amplicon profiles characteristic of the enterococcus examined. The species examined were group I enterococci (Enterococcus avium, Enterococcus raffinosus, Enterococcus malodoratus, and Enterococcus pseudoavium), group II enterococci (Enterococcus faecalis, Enterococcus faecium, Enterococcus casseliflavus, Enterococcus mundtii, and Enterococcus gallinarum), and group III enterococci (Enterococcus durans and Enterococcus hirae). The enterococcal species in group I, as well as E. faecalis and two strains of E. hirae, were similar and therefore had to be differentiated from each other by Sau3A restriction digests. This produced patterns characteristic of each of these species. The remaining group II and group III enterococcal species produced amplicons characteristic of a particular species except E. gallinarum. The PCR products from E. gallinarum displayed strain-to-strain heterogeneity in the number and size of amplicons. To further test the utility of this technique, 11 phenotypically aberrant strains which had been assigned species identification based on Facklam and Collins-type strain reactions (R.R. Facklam and M.D. Collins, J. Clin. Microbiol. 27:731-734, 1989) were subjected to ITS-PCR. ITS-PCR of the phenotypically aberrant strains identified six strains with reactions consistent with those of type strains. However, five strains were characterized as follows: two strains originally identified as E. mundtii were identified by ITS-PCR as E. casseliflavus, one strain originally identified as E. raffinosus was identified by ITS-PCR as E. durans, one strain originally identified as E. hirae was identified by ITS-PCR as E. faecium [corrected]. We conclude that amplification of the intergenic 23S and 16S rRNA gene regions of enterococci provides a reliable technique for species identification of enterococci.

Crystal structure of the cell-binding B oligomer of verotoxin-1 from E. coli.

The Shiga toxin family, a group of cytotoxins associated with diarrhoeal diseases and the haemolytic uraemic syndrome, includes Shiga toxin from Shigella dysenteriae type 1 and verotoxins produced by enteropathogenic Escherichia coli. The family belongs to the A-B class of bacterial toxins, which includes the cholera toxin family, pertussis and diphtheria toxins. These toxins all have bipartite structures consisting of an enzymatic A subunit associated with a B oligomer which binds to specific cell-surface receptors, but their amino-acid sequences and pathogenic mechanisms differ. We have determined the crystal structure of the B oligomer of verotoxin-1 from E. coli. The structure unexpectedly resembles that of the B oligomer of the cholera toxin-like heat-labile enterotoxin from E. coli, despite the absence of detectable sequence similarity between these two proteins. This result implies a distant evolutionary relationship between the Shiga toxin and cholera toxin families. We suggest that the cell surface receptor-binding site lies in a cleft between adjacent subunits of the B pentamer, providing a potential target for drugs and vaccines to prevent toxin binding and effect.

Alteration of the carbohydrate binding specificity of verotoxins from Gal alpha 1-4Gal to GalNAc beta 1-3Gal alpha 1-4Gal and vice versa by site-directed mutagenesis of the binding subunit.

Verotoxin 1 (VT-1) and Shiga-like toxin II (SLT-II) bind to the glycosphingolipid (GSL), globotriaosylceramide (Gb3), whereas pig edema disease toxin (VTE) binds to globotetraosylceramide (Gb4) and to a lesser degree Gb3. Amino acids important in the GSL binding specificity of VT-1 and VTE have been identified by site-directed mutagenesis. One mutation, Asp-18----Asn, in VT-1 resulted in binding to Gb4 in addition to Gb3 in a manner similar to VTE. Several mutations in VTE resulted in the complete loss of GSL binding; however, one mutation resulted in a change in the GSL binding specificity of the VTE B subunit. The double mutation Gln-64----Glu and Lys-66----Gln (designated GT3) caused a selective loss of Gb4 binding, effectively changing the binding phenotype from VTE to VT-1. Both wild-type VTE and GT3 were purified to homogeneity and binding kinetics in vitro were determined with purified GSLs from human kidney. The cell cytotoxicity spectrum of the mutant toxin was also found to be altered in comparison with VTE. These changes were consistent with the GSL content of the target cells.

Lectinlike properties of pertussis toxin.

We have examined the lectinlike properties of pertussis toxin by binding-inhibition assays and affinity chromatography of goose erythrocyte membranes. Although pertussis toxin and wheat germ agglutinin apparently recognize similar sugar sequences on glycoproteins, the binding activities of the two lectins are not identical.