Canadian Public Health Laboratory Research Articles

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.

Canadian Public Health Laboratory Network position statement: Non-culture based diagnostics for gastroenteritis and implications for public health investigations.

As clinical laboratories transition to using culture-independent detection test (CIDT) panels for cases of acute gastroenteritis, culture of clinical specimens is becoming less common. The reduction in bacterial cultures available for public health activities is expected to hinder surveillance and outbreak response by public health laboratories at the local, provincial, national and international levels. These recommendations are intended to serve as guidelines for the implementation of CIDT panels in frontline laboratories in Canada. The United States of America has already seen a significant reduction in culture of stool specimens despite the Association of Public Health Laboratories recommendation to perform reflex culture on positive CIDT specimens. Priority public health organisms addressed in these Canadian guidelines include Shiga toxin-producing Escherichia coli, Shigella and Salmonella and, under regional circumstances, other organisms such as Campylobacter jejuni/coli and Yersinia enterocolitica. These recommendations suggest active engagement between primary diagnostic laboratories and provincial public health laboratories to determine the workflow and protocols for reflex or parallel culture. Consequently, notifiable disease definitions will also need modification, with consultation of all stakeholders. Stakeholders need to work together to enhance recovery of bacterial isolates with best practices used for stool transport and storage.

Canadian Public Health Laboratory Network position statement: Nonculture based diagnostics for gastroenteritis and implications for public health investigations

Canadian Public Health Laboratory Network position statement: Nonculture based diagnostics for gastroenteritis and implications for public health investigations

Respiratory Outbreak Investigations: How Many Specimens Should Be Tested?

To determine the optimal number of specimens for virus detection in a respiratory outbreak, laboratory results from 2 Canadian public health laboratories were reviewed. The evidence suggests that 3 specimens are sufficient for detection of a virus in >95% of outbreaks, thereby reducing laboratory costs.

Canadian Public Health Laboratory Network laboratory guidelines for the diagnosis of neurosyphilis in Canada.

Neurosyphilis refers to infection of the central nervous system by Treponema pallidum, which may occur at any stage. Neurosyphilis has been categorized in many ways including early and late, asymptomatic versus symptomatic and infectious versus non-infectious. Late neurosyphilis primarily affects the central nervous system parenchyma, and occurs beyond early latent syphilis, years to decades after the initial infection. Associated clinical syndromes include general paresis, tabes dorsalis, vision loss, hearing loss and psychiatric manifestations. Unique algorithms are recommended for HIV-infected and HIV-uninfected patients, as immunocompromised patients may present with serologic and cerebrospinal fluid findings that are different from immunocompetent hosts. Antibody assays include a VDRL assay and the FTA-Abs, while polymerase chain reaction for T. pallidum can be used as direct detection assays for some specimens. This chapter reviews guidelines for specimen types and sample collection, and identifies two possible algorithms for use with immunocompromised and immunocompetent hosts using currently available tests in Canada, along with a review of treatment response and laboratory testing follow-up.

Canadian Public Health Laboratory Network laboratory guidelines for the use of direct tests to detect syphilis in Canada.

Treponema pallidum subsp. pallidum and/or its nucleic acid can be detected by various methods such as microscopy, rabbit infectivity test or polymerase chain reaction (PCR) tests. The rabbit infectivity test for T. pallidum, although very sensitive, has been discontinued from most laboratories due to ethical issues related to the need for animal inoculation with live T. pallidum, the technically demanding procedure and long turnaround time for results, thus making it impractical for routine diagnostic use. Dark-field and phase-contrast microscopy are still useful at clinic- or hospital-based laboratories for near-bedside detection of T. pallidum in genital, skin or mucous lesions although their availability is decreasing. The lack of reliable and specific anti-T. pallidum antibodies and its inferior sensitivity to PCR may explain why the direct fluorescent antibody test for T. pallidum is not widely available for clinical use. Immunohistochemical staining for T. pallidum also depends on the availability of specific antibodies, and the method is only applicable for histopathological examination of biopsy and autopsy specimens necessitating an invasive specimen collection approach. With recent advances in molecular diagnostics, PCR is considered to be the most reliable, versatile and practical for laboratories to implement. In addition to being an objective and sensitive test for direct detection of Treponema pallidum subsp. pallidum DNA in skin and mucous membrane lesions, the resulting PCR amplicons from selected gene targets can be further characterized for antimicrobial (macrolide) susceptibility testing, strain typing and identification of T. pallidum subspecies.

Canadian Public Health Laboratory Network laboratory guidelines for the use of point-of-care tests for the diagnosis of syphilis in Canada.

Syphilis point-of-care tests (POCT) are widely available in developing countries enabling early diagnosis, treatment and support. The majority of commercially available tests use treponemal antigens and the presence of antibodies does not distinguish between current and past infection, which may lead to unnecessary antibiotic use and stigmatization of having a current STI. In hard-to-reach populations, the benefits may outweigh the risks. Available studies show reasonable performance of POCT with median sensitivity of 86%, specificity of 99% and positive predictive values >80% when prevalence was >0.3%. Although no syphilis POCT are approved in Canada at this time, a single study in an outreach setting in Alberta showed limited benefit due to a high prevalence of previous infection but more studies are needed. Newer dual tests employing treponemal and nontreponemal antigens look promising.

Canadian Public Health Laboratory Network National Syphilis Laboratory Testing Recommendations: Introduction

Canadian Public Health Laboratory Network National Syphilis Laboratory Testing Recommendations: Introduction

Canadian Public Health Laboratory Network laboratory guidelines for congenital syphilis and syphilis screening in pregnant women in Canada.

Despite universal access to screening for syphilis in all pregnant women in Canada, cases of congenital syphilis have been reported in recent years in areas experiencing a resurgence of infectious syphilis in heterosexual partnerships. Antenatal screening in the first trimester continues to be important and should be repeated at 28 to 32 weeks and again at delivery in women at high risk of acquiring syphilis. The diagnosis of congenital syphilis is complex and is based on a combination of maternal history and clinical and laboratory criteria in both mother and infant. Serologic tests for syphilis remain important in the diagnosis of congenital syphilis and are complicated by the passive transfer of maternal antibodies which can affect the interpretation of reactive serologic tests in the infant. All infants born to mothers with reactive syphilis tests should have nontreponemal tests (NTT) and treponemal tests (TT) performed in parallel with the mother's tests. A fourfold or higher titre in the NTT in the infant at delivery is strongly suggestive of congenital infection but the absence of a fourfold or greater NTT titre does not exclude congenital infection. IgM tests for syphilis are not currently available in Canada and are not recommended due to poor performance. Other evaluation in the newborn infant may include long bone radiographs and cerebrospinal fluid tests but all suspect cases should be managed in conjunction with sexually transmitted infection and/or pediatric experts.

Canadian Public Health Laboratory Network laboratory guidelines for the use of serological tests (excluding point-of-care tests) for the diagnosis of syphilis in Canada.

Syphilis, caused by the bacterium Treponema pallidum subsp. pallidum, is an infection recognized since antiquity. It was first reported at the end of the 15th century in Europe. Infections may be sexually transmitted as well as spread from an infected mother to her fetus or through blood transfusions. The laboratory diagnosis of syphilis infection is complex. Because this organism cannot be cultured, serology is used as the principal diagnostic method. Some of the issues related to serological diagnoses are that antibodies take time to appear after infection, and serology screening tests require several secondary confirmatory tests that can produce complex results needing interpretation by experts in the field. Traditionally, syphilis screening was performed using either rapid plasma reagin or Venereal Disease Research Laboratory tests, and confirmed by treponemal tests such as MHA-TP, TPPA or FTA-Abs. Currently, that trend is reversed, ie, most of the laboratories in Canada now screen for syphilis using treponemal enzyme immunoassays and confirm the status of infection using rapid plasma reagin or Venereal Disease Research Laboratory tests; this approach is often referred to as the reverse algorithm. This chapter reviews guidelines for specimen types and sample collection, treponemal and non-treponemal tests utilized in Canada, the current status of serological tests for syphilis in Canada, the complexity of serological diagnosis of syphilis infection and serological testing algorithms. Both traditional and reverse sequence algorithms are recommended and the algorithm used should be based on a combination of local disease epidemiology, test volumes, performance of the proposed assays and available resources.

MERS-CoV- Low risk to Canadians.

Middle East respiratory syndrome - Coronavirus (MERS-CoV) -- is a novel coronavirus that has caused a number of community-acquired cases and health care associated outbreaks in Saudi Arabia and the United Arab Emirates (UAE) as well as sporadic cases in other countries, especially in the Middle East. The evidence to date links MERS-CoV cases with exposure to camels, including camel products or to probable or confirmed human cases of MERS-CoV. It typically presents as an acute respiratory illness and is associated with a 35% mortality rate. Based on available information at this time, the current risk to Canadians for acquiring MERS-CoV infections is considered low. However, the International Health Regulations Committee concerning MERS-CoV has cautioned that the upsurge of cases seen this past spring (2014) may be predictive of an increase in cases related to the Hajj - an annual pilgrimage to Mecca in Saudi Arabia that took place in early October 2014. Although the overall risk is low, the Public Health Agency of Canada and its National Microbiology Laboratory (NML) in close collaboration with provincial and territorial partners, the Canadian Public Health Laboratory Network (CPHLN) and infection prevention and control experts have developed a number of preparedness guidance documents and protocols to address the risk of an imported case of MERS-CoV in Canada.

Lyme Borreliosis: An Update for Canadian Dermatologists

Lyme borreliosis is a multisystemic tick-borne spirochetosis, which may result in dermatologic, musculoskeletal, cardiovascular, and neurologic manifestations. Patients with suspected acute Lyme borreliosis infection may be referred for urgent dermatologic review. Canadian dermatologists should be aware of the latest information regarding the diagnosis and management of Lyme borreliosis. This review is based on a PubMed database search combining the word "Lyme" with variations of the word "Canada." Data sources included articles from the fields of ecology, epidemiology, laboratory diagnostics, and clinical management. In this review, the ecological basis of spirochete transmission by tick vectors is described. The latest available Canadian epidemiologic data are summarized. North American clinical manifestations of Lyme borreliosis are contrasted with European presentations. The Canadian Public Health Laboratory Network's diagnostic guidelines are summarized. Finally, treatment recommendations are outlined.

Canadian Multicenter Laboratory Study for Standardized Second-Line Antimicrobial Susceptibility Testing of Mycobacterium tuberculosis

The purpose of this study was to establish a standardized protocol for second-line antimicrobial susceptibility testing of Mycobacterium tuberculosis using the Bactec MGIT 960 system in Canadian laboratories. Four Canadian public health laboratories compared the susceptibility testing results of 9 second-line antimicrobials between the Bactec 460 and Bactec MGIT 960 systems. Based on the data generated, we have established that the Bactec MGIT 960 system provides results comparable to those obtained with the previous Bactec 460 method. The critical concentrations established for the testing of the antimicrobials used are as follows: amikacin, 1 μg/ml; capreomycin, 2.5 μg/ml; ethionamide, 5 μg/ml; kanamycin, 2.5 μg/ml; linezolid, 1 μg/ml; moxifloxacin, 0.25 μg/ml; ofloxacin, 2 μg/ml; p-aminosalicylic acid, 4 μg/ml; rifabutin, 0.5 μg/ml.

Not So Good Old Summertime

Not So Good Old Summertime

Introducing the Sixth Edition of theCanadian Tuberculosis Standards

The sixth edition of the Canadian Tuberculosis Standards will soon be available in hard copy through the offices of the Canadian Lung Association (CLA), and the individual provincial and territorial lung associations, and in PDF format at . Historically, the Standards became important when effective treatment of tuberculosis became available and sanatoria closed. In contrast to the first (1972), second (1981), third (1988) and fourth (1996) editions, which were products of the Canadian Thoracic Society (CTS)/CLA alone, the fifth (2000) and sixth editions of the Standards were jointly produced by the CTS/CLA and Health Canada (fifth), and the Public Health Agency of Canada (PHAC) (sixth). The evolution of the Standards as a document dependent on the CTS for medical and scientific input, and on the PHAC for public health and policy input, was part of a broader shift from nongovernmental to governmental organization of tuberculosis prevention and control activity in Canada. The Tuberculosis Prevention and Control Program of the PHAC is the sponsor of the Canadian Tuberculosis Committee, a national committee with representation from each province and territory, Citizenship and Immigration Canada, First Nations and Inuit Health Branch of Health Canada, Correctional Service Canada, Canadian Public Health Laboratory Network, Association of Medical Microbiology and Infectious Disease, CLA, CTS and PHAC (both the National Microbiology Laboratory and the Tuberculosis Prevention and Control Program). It also houses the Canadian Tuberculosis Surveillance System and the Canadian Tuberculosis Laboratory Surveillance System, as well as represents Canada internationally. The major role of the Tuberculosis Committee of the CTS is now the preparation of the Standards. In fact, the membership of the CTS Tuberculosis Committee and the editorial committee of the Standards are one and the same; the editors of the Standards are the Chair of the CTS Tuberculosis Committee and the Manager of the Tuberculosis Prevention and Control Program of the PHAC. The sixth edition of the Standards is a substantial revision to its predecessor the fifth edition (see below). Chapters or appendixes already in the fifth edition were redacted, and new chapters and appendixes were added (Chapters 14, 15 and 18; Appendixes D, E, F, G, H and J) after a systematic survey of end-user satisfaction with the fifth edition undertaken by the CTS. In addition to the chapter-specific table of contents and expanded bibliographies, the text is populated with a series of Web resources that will be regularly updated by PHAC and other agencies. As in the fifth edition, treatment recommendations are rated using a roman numeral (I, II or III), which indicates the quality of evidence supporting the recommendation (1). The Standards are meant to be a definitive resource on issues pertaining to tuberculosis prevention and control in Canada. In contrast to provincial and territorial guidelines, which describe how an action is to be accomplished and how the structure of care is framed, the Canadian Tuberculosis Standards, like the International Standards for Tuberculosis Care (available at ), provide the foundation on which care can be based, presenting what should be done.

Introducing the Sixth Edition of the Canadian tuberculosis standards

The sixth edition of the Canadian Tuberculosis Standards will soon be available in hard copy through the offices of the Canadian Lung Association (CLA), and the individual provincial and territorial lung associations, and in PDF format at . Historically, the Standards became important when effective treatment of tuberculosis became available and sanatoria closed. In contrast to the first (1972), second (1981), third (1988) and fourth (1996) editions, which were products of the Canadian Thoracic Society (CTS)/CLA alone, the fifth (2000) and sixth editions of the Standards were jointly produced by the CTS/CLA and Health Canada (fifth), and the Public Health Agency of Canada (PHAC) (sixth). The evolution of the Standards as a document dependent on the CTS for medical and scientific input, and on the PHAC for public health and policy input, was part of a broader shift from nongovernmental to governmental organization of tuberculosis prevention and control activity in Canada. The Tuberculosis Prevention and Control Program of the PHAC is the sponsor of the Canadian Tuberculosis Committee, a national committee with representation from each province and territory, Citizenship and Immigration Canada, First Nations and Inuit Health Branch of Health Canada, Correctional Service Canada, Canadian Public Health Laboratory Network, Association of Medical Microbiology and Infectious Disease, CLA, CTS and PHAC (both the National Microbiology Laboratory and the Tuberculosis Prevention and Control Program). It also houses the Canadian Tuberculosis Surveillance System and the Canadian Tuberculosis Laboratory Surveillance System, as well as represents Canada internationally. The major role of the Tuberculosis Committee of the CTS is now the preparation of the Standards. In fact, the membership of the CTS Tuberculosis Committee and the editorial committee of the Standards are one and the same; the editors of the Standards are the Chair of the CTS Tuberculosis Committee and the Manager of the Tuberculosis Prevention and Control Program of the PHAC. The sixth edition of the Standards is a substantial revision to its predecessor the fifth edition (see below). Chapters or appendixes already in the fifth edition were redacted, and new chapters and appendixes were added (Chapters 14, 15 and 18; Appendixes D, E, F, G, H and J) after a systematic survey of end-user satisfaction with the fifth edition undertaken by the CTS. In addition to the chapter-specific table of contents and expanded bibliographies, the text is populated with a series of Web resources that will be regularly updated by PHAC and other agencies. As in the fifth edition, treatment recommendations are rated using a roman numeral (I, II or III), which indicates the quality of evidence supporting the recommendation (1). The Standards are meant to be a definitive resource on issues pertaining to tuberculosis prevention and control in Canada. In contrast to provincial and territorial guidelines, which describe how an action is to be accomplished and how the structure of care is framed, the Canadian Tuberculosis Standards, like the International Standards for Tuberculosis Care (available at ), provide the foundation on which care can be based, presenting what should be done.

The Laboratory Diagnosis of Lyme Borreliosis: Guidelines from the Canadian Public Health Laboratory Network

Lyme borreliosis is uncommonly seen in Canada. Most cases have occurred in close proximity to small geographical areas where infected ticks have become established. Although few cases are seen, thousands of patients are tested yearly. Unless patients are carefully selected and an appropriately sensitive and specific testing algorithm is applied, large numbers of patients without Lyme borreliosis will be incorrectly diagnosed. The Canadian Public Health Laboratory Network has developed the present guidelines to assist physicians in assessing patients for Lyme borreliosis, and to help guide the choice and interpretation of laboratory testing.

Canadian Listeriosis Reference Service

Listeria monocytogenes, a psychrotrophic organism capable of growing at refrigeration temperatures, is of major concern in extended shelf life, refrigerated foods. Considering that as much as 80-90% of human listeriosis cases are linked to the ingestion of contaminated food, human cases are predominantly seen in high-risk individuals, including organ-transplant recipients, patients with AIDS and HIV-infected individuals, pregnant women, cancer patients, and the elderly. In 2001, the Canadian Listeriosis Reference Service (LRS) was created by the Bureau of Microbial Hazards (Health Canada) and the National Microbiology Laboratory (now part of the Public Health Agency of Canada). Major goals of the LRS include investigation of listeriosis cases and maintenance of a national collection of isolates. The LRS intends to create a comprehensive molecular epidemiological database of all isolates in Canada for use as a resource for outbreak investigations, research and other microbiological investigations. The PFGE profiles are being established and stored for clinical, food, environmental, and possibly animal strains of L. monocytogenes. The LRS pursues research activities for investigation and implementation of other molecular methods for characterizing L. monocytogenes isolates. Ribotyping, Multi-locus Sequence Typing (MLST), Variable Number of Tandem Repeats (VNTR), Multi-locus virulence sequence typing (MLVA), microarray- based technologies and sequence-based typing schemes, are being investigated on selected diversity sets. The LRS has also used PFGE typing for outbreak investigations. The molecular epidemiological data, timely coordination and exchange of information should help to reduce the incidence of listeriosis in Canada. In Canada, listeriosis is not a national notifiable disease, except for the province of Quebec, where it has been since 1999. The LRS, Canadian Public Health Laboratory Network, and federal epidemiologists are currently working on making human listeriosis notifiable throughout Canada.

Epidemiological study of hepatitis B virus infection in Manitoba, Canada, 1992–2003

In comparison with other Canadian provinces and most Western countries, the province of Manitoba maintains a different vaccination policy for hepatitis B. This policy provides selective antenatal screening for hepatitis B in women and an inoculation program for hepatitis B vaccination for fourth-grade pupils. There has been increasing concern for this policy with regard to its influence on secular trends of acute hepatitis B incidence in Manitoba. This created a need to summarise the epidemiological characteristics of hepatitis B virus (HBV) infection in Manitoba and to allocate finances and human resources for future prevention programs. The Cadham Provincial Laboratory in Winnipeg, a Canadian Public Health Laboratory, is responsible for testing all specimens for diagnosis of various common infectious diseases in Manitoba. During the period from 1 January 1992 to 31 December 2003, a total of 285,946 clinical specimens were submitted to this laboratory, which confirmed 310 cases of acute HBV and 7,556 cases of chronic HBV infection. A total of 18,168 individuals were identified as having vaccine-induced immune status. The incidence rate of acute HBV infection has significantly decreased from 6.52/100,000 person-years in 1996 to 0.86/100,000 person-years in 2003. Annual prevalence rates of chronic HBV infection in Manitoba increased slightly from 42.96 cases/100,000 population in 1992 to 71.47 cases/100,000 population in 2003. Incidence rates were generally higher in men than in women at all age groups, with values of 2.65 and 1.65 per 100,000 population, respectively (chi-square=15.768, p value <0.001). The highest incidence rate for both males and females was observed in the age group 30-34 years. The North Eastman and Winnipeg Regional Health Authorities showed significantly higher incidence rates of acute hepatitis B compared with the other nine Regional Health Authorities. Selective hepatitis B vaccination programs for children in Manitoba had achieved the greatest success in the prevention of vertical and horizontal transmission. There is an urgent need to develop cost-effective harm-reduction strategies for hepatitis B prevention among adults (aged 30-34) and groups at risk in Manitoba.

A comparison of six different plating media used in the isolation of salmonella

Seventeen Canadian Federal, Provincial and Public Health Laboratories took part in different phases of a comparative/collaborative study that evaluated rapid methods to the standard Health Protection Branch (HPB) method for the detection of Salmonella. A variety of commercial media were tested, including Brilliant Green Sulpha Agar, Bismuth Sulphite Agar, Hektoen Enteric Agar, Xylose Lysine Deoxycholate Agar, EF-18 Agar and Rambach Agar. Each laboratory compared up to six of these different plating media. Plating of 123 salmonellae culttures and 28 artificially-inoculated foods showed the recovery of Salmonella spp. on the six plating media to be within one log. Therefore, quantitative testing of the media showed them to be comparable in the recovery of salmonellae. Qualitative testing of the six media during the comparative/collaborative study of various methods showed that EF-18 Agar recovered the greatest number of isolates. Hektoen Enteric Agar ranked second, with the other agars being comparable in their recovery of Salmonella spp. Problems with the various media are summarized. Based on our results and those of other researchers, it is recommended that Bismuth Sulphite Agar be compulsory and that at least one other agar be used for newly developed cultural procedures.