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BACKGROUND Previous studies have shown substantial differences in geographic clustering of sexually transmitted infections (STI), such as chlamydia (CT) and gonorrhea (NG), conditional on epidemic phase. Chlamydia and NG have recently shown resurgent epidemiology in the northern hemisphere. This study describes the recent epidemiology of CT and NG in Winnipeg, Canada, combining traditional surveillance tools with place-based analyses, and comparing the ecological niches of CT and NG, in the context of their evolving epidemiology. METHODS Data were collected as part of routine public health surveillance between 2007 and 2016. Secular trends for CT and NG, and CT/NG coinfection were examined. Gini coefficients and population attributable fractions explored the distribution, and concentration of infections over time and space. RESULTS Rates of CT increased from 394.9/100,000 population to 476.2/100,000 population from 2007 to 2016. Gonorrhea rates increased from 78.0/100,000 population to 143.5/100,000 population during the same period. Each pathogen had its own ecological niche: CT was widespread geographically and socio-demographically, while NG was clustered in Winnipeg's inner-core. CT/NG co-infections had the narrowest space and age distribution. NG was shown to be undergoing a growth phase, with clear signs of geographic dispersion. The expansion of NG resembled the geographic distribution of CT. CONCLUSIONS We demonstrated that NG was experiencing a growth phase, confirming theoretical predictions of geographic dispersion during a growth phase. During this phase, NG occupied similar geographic spaces as CT. Knowledge of different ecological niches could lead to better targeting of resources for subpopulations vulnerable to STIs.

Real-time polymerase chain reaction (PCR) assays to detect antimicrobial resistance-associated mutations were tested on Neisseria gonorrhoeae-positive clinical samples with matched isolates. Of the nucleic acid amplification tests/cultures, 87.7% (64/73), 98.6% (72/73), and 98.4% (62/63) predicted cephalosporin, ciprofloxacin, and azithromycin susceptibilities, respectively. N. gonorrhoeae multiantigen sequence type was correctly predicted for 98.7% (79/80), and 13 of 58 N. gonorrhoeae-negative specimens showed false-positive results.

Background Often, research takes place on underserved populations rather than with underserved populations. This approach can further isolate and stigmatize groups that are already made marginalized. What Goes Around is a community-based research project that was led by community members themselves (Peers). Case presentation This research aimed to implement a community-based research methodology grounded in the leadership and growing research capacity of community researchers and to investigate a topic which community members identified as important and meaningful. Chosen by community members, this project explored how safer sex and safer drug use information is shared informally among Peers. Seventeen community members actively engaged as both community researchers and research participants throughout all facets of the project: inception, implementation, analysis, and dissemination of results. Effective collaboration between community researchers, a community organization, and academics facilitated a research process in which community members actively guided the project from beginning to end. Conclusions The methods used in What Goes Around demonstrated that it is not only possible, but advantageous, to draw from community members’ involvement and direction in all stages of a community-based research project. This is particularly important when working with a historically underserved population. Purposeful and regular communication among collaborators, ongoing capacity building, and a commitment to respect the experience and expertise of community members were essential to the project’s success. This project demonstrated that community members are highly invested in both informally sharing information about safer sex and safer drug use and taking leadership roles in directing research that prioritizes harm reduction in their communities.

ObjectivesHIV point-of-care testing (POCT) has been available in Manitoba since 2008. This study evaluated the effectiveness of POCT at identifying individuals with previously unknown HIV status, its effects on clinical outcomes and the characteristics of the populations reached.MethodsA retrospective database review was conducted for individuals who received HIV POCT from 2011 to 2014. Time to linkage to care and viral load suppression were compared between individuals who tested positive for HIV using POCT and controls identified as positive through standard screening. Testing outcomes for labouring women with undocumented HIV status accessing POCT during labour were also assessed.Results3204 individuals received POCT (1055 females (32.9%) and 2149 males (67.1%)), being the first recorded HIV test for 2205 (68.8%). Males were more likely to be targeted with POCT as their first recorded HIV test (adjusted OR (AOR) 1.40). Between the two main test sites (Main Street Project (MSP) and Nine Circles Community Health Centre), MSP tested relatively fewer males (AOR 0.79) but a higher proportion of members of all age groups over 30 years old (AOR 1.83, 2.51 and 3.64 for age groups 30–39, 40–49 and >50, respectively). There was no difference in time to linkage to care (p=0.345) or viral load suppression (p=0.405) between the POCT and standard screening cohorts. Of 215 women presenting in labour with unknown HIV status, one was identified as HIV positive.ConclusionsPOCT in Manitoba has been successful at identifying individuals with previously unknown HIV-positive status. Demographic differences between the two main testing sites support that this intervention is reaching unique populations. Given that we observed no significant difference in time to clinical outcomes, it is reasonable to continue using POCT as a targeted intervention.MeSH termsHIV infection; rapid HIV testing; vertical infectious disease transmission; community outreach; service delivery; marginalised populations.

We have identified a Salmonella enterica serotype 4,[5],12:i:- containing a mcr-3.2 in a patient who travelled to Thailand 1 month prior to the identification of it in Canada. The isolate was multidrug resistant, but remained susceptible to the carbapenems, amikacin and piperacillin/tazobactam. The mcr-3.2 was carried on a 261 Kb variant of the IncHI2 pWJ1. This report provides further evidence of the emergence of a ST34 colistin-resistant clone.

Background Alongside traditional epidemiologic tools, network analyses and molecular epidemiology offer deeper insights into the structure of STBBI epidemics. In the context of a 2014 gonorrhea (NG) outbreak, this study sought to compare molecular networks to case-contact networks constructed from public health investigations. Methods Data were from enhanced public health investigations of NG in Winnipeg, Canada. NG-MAST was used to determine the molecular subtypes of NG. Subtypes were described by socio-demographic/clinical characteristics. Multivariable logistic regression models were used to assess the association of socio-demographic/clinical characteristics, and having the most frequently reported subtype. Networks constructed from case-contact investigations were visualized; components were characterized with univariate network statistics, including degree centralization. Conditional uniform graph (CUG) tests assessed observed degree centralization. Results In total, 126 NG cases were genotyped, with 41 subtypes found. Five subtypes accounted for 51% of all subtypes, with ST-3672 (n=22) predominant. At the bivariate level, infection with ST-3672 was associated with younger age (62% of those infected were 15–19 years old, p=0.002), and chlamydia co-infection (67% vs 37%, p=0.012). In multivariable analysis, age group remained significant, while an interaction between inner-core residency and chlamydia co-infection was detected. Case-contact networks were highly-fragmented, consisting mainly of dyads and triads. Of 85 components, the largest component included 6 nodes, while 61% were dyads. CUG testing indicated in-degree centralization was lower than expected (p Conclusion Molecular data revealed connections that were not apparent from case-contact investigations alone, leading to more cases potentially linked together, and over a wider geographic area. A handful of subtypes were responsible for the majority of infections. Early identification of dominant subtypes may potentially curtail transmission of NG. Disclosure No significant relationships.

Background There are large numbers of people who inject drugs (PWID) in Pakistan, with a high and growing HIV prevalence in many cities. Cross-sectional bio-behavioural surveys conducted over fifteen years have shown heterogeneous HIV epidemic trajectories in different cities with inconsistent associations between aggregate and individual measures of behaviour and epidemic trajectories. This study triangulates behavioural, biological, and network data to gain new insights into drivers of local epidemics among PWID. Methods A questionnaire was administered to 1,439 PWID in five cities in Pakistan in 2014 and dried blood spots were collected for HIV testing and sequencing. The questionnaire collected locations where participants injected recently and these were used to construct place-based injection networks. Demographic, behavioral, geographic, and network structure data were tested for associations with HIV and HIV phylogenetic analysis was conducted to identify transmission clusters. Results HIV prevalence varied between the cities, from 8.6% to 45.3%. Although aggregate individual behaviours were not strongly associated with HIV, there were differences between cities in injecting practices and network configurations. Injection network configurations differed between cities, ranging from networks with dense sub-regions to widely dispersed networks. A city that experienced an explosive HIV outbreak showed particularly dense geospatial networks and a large phylogenetic cluster (n=52) suggesting a link between geospatial concentration and rapid HIV transmission. In a city where the use of professional injectors was associated with HIV at the individual level, there were dense network subregions and HIV+ individuals were more likely to be more centrally located in networks (p Conclusion Contextual factors shape the injection practices and network configurations among PWID in Pakistan. Factors that influence HIV transmission dynamics are more complex than individual behaviours, and include professional injectors and geographic and network clustering. Disclosure No significant relationships.

Objectives: The purpose of this study was to describe and explore potential driving factors of trends in reported chlamydia infections over time in Manitoba, Canada. Methods: Surveillance and laboratory testing data from Manitoba Health, Seniors and Active Living were analysed using SAS v9.4. Kaplan-Meier plots of time from the first to second chlamydia infection were constructed, and Cox proportional hazards regression was used to estimate the risk of second repeat chlamydia infections in males and females. Results: Overall, the number of reported infections found mirrored the number of tests conducted. From 2008 to 2014, the number of first infections found among females decreased as the number of first tests conducted among females also decreased. Between 2008 and 2012, the number of repeat tests among females increased and was accompanied by an increase in the number of repeat positive results from 2009 to 2013. From 2008 to 2016, the number of repeat tests and repeat positive results increased steadily among males. Conclusions: Chlamydia infection rates consistently included a subset composed of repeat infections. The number of cases identified appears to mirror testing volumes, drawing into question incidence calculations that do not include testing volumes. Summary Box: 1) What is the current understanding of this subject? Chlamydia incidence is high in Manitoba, particularly among young women and in northern Manitoba. 2) What does this report add to the literature? This report suggests that incidence calculated using case-based surveillance data alone does not provide an accurate estimate of chlamydia incidence in Manitoba and is heavily influenced by testing patterns. 3) What are the implications for public health practice? In general, improving testing rates in clinical practices as well as through the provision of rapid services in non-clinical venues could result in higher screening and treatment rates. In turn, this could lead to a better understanding of true disease occurrence.

RESUMEN: La intención de este artículo es evidenciar la importancia de los grupos focales de discusión como estrategia metodológica para la recolección de información en el trabajo con adolescentes institucionalizados con experiencia de vida en calle y, al mismo tiempo, mostrar su valor en el abordaje de la salud sexual con esta población, en tanto que permite una interacción flexible y reflexiva entre investigadores y participantes, así como de los participantes entre sí. El valor de esta estrategia metodológica es sustentado en este artículo mediante testimonios y resultados obtenidos durante su implementación en el estudio llevado a cabo con adolescentes institucionalizados entre 2013 y 2014 en Medellín. Se espera con este reducir las creencias de profesionales con respecto a las limitaciones de la estrategia para abordar temáticas relacionadas con la salud sexual de este grupo poblacional. Los resultados se articulan en cuatro categorías: conocimientos y percepciones sobre vih e its, salud sexual y reproductiva (ssr), el lenguaje en la ssr, y acceso y uso de las tecnologías de la información y la comunicación (tic). De esta manera, se deja de manifiesto el aporte y potencial de la estrategia para el abordaje del tema y para el acercamiento e interacción con adolescentes con experiencia de vida en calle. ABSTARCT: This paper aims to show the importance of discussion focus groups as a methodological strategy for the compilation of information in studies with institutionalized adolescents who have lived on the streets. At the same time, it aims to show the value of this technique in approaching the topic of sexual health with this population, since it allows for flexible and reflexive researcher-participant and participant-participant interaction. The value of this methodological strategy is supported in this article through accounts and results obtained during the implementation of a study conducted with institutionalized adolescents between 2013 and 2014. We expect these results will reduce the beliefs of professionals regarding the limitations of the strategy to address issues related to the sexual health of this type of population. The results are divided into four categories: knowledge and perceptions of HIV and STIs, sexual and reproductive health (SRH), the language used in SRH, and access to and use of information and communications technology (ICT). Thus, this paper clearly shows the contribution and potential of the strategy for addressing the issue, approaching and interacting with adolescents who have lived on the street. COL0019829

Mass spectrometry-based phenotypic H-antigen typing (MS-H) combined with whole-genome-sequencing-based genetic identification of H antigens, O antigens, and toxins (WGS-HOT) was used to type 60 clinical Escherichia coli isolates, 43 of which were previously identified as nonmotile, H type undetermined, or O rough by serotyping or having shown discordant MS-H and serotyping results. Whole-genome sequencing confirmed that MS-H was able to provide more accurate data regarding H antigen expression than serotyping. Further, enhanced and more confident O antigen identification resulted from gene cluster based typing in combination with conventional typing based on the gene pair comprising wzx and wzy and that comprising wzm and wzt . The O antigen was identified in 94.6% of the isolates when the two genetic O typing approaches (gene pair and gene cluster) were used in conjunction, in comparison to 78.6% when the gene pair database was used alone. In addition, 98.2% of the isolates showed the existence of genes for various toxins and/or virulence factors, among which verotoxins (Shiga toxin 1 and/or Shiga toxin 2) were 100% concordant with conventional PCR based testing results. With more applications of mass spectrometry and whole-genome sequencing in clinical microbiology laboratories, this combined phenotypic and genetic typing platform (MS-H plus WGS-HOT) should be ideal for pathogenic E. coli typing.

Understanding patterns of serological testing for hepatitis B & C, and syphilis among HIV-positive individuals, prior to HIV diagnosis, can inform HIV diagnosis, engagement and prevention strategies. This was a population-based, retrospective analysis of prior serological testing among HIV-positive individuals in Manitoba, Canada. HIV cases were age-, sex- and region-matched to HIV-negative controls at a 1:5 ratio. Conditional logistic regression was used to examine previous serological tests and HIV status. Odds ratios (ORs) and their 95% confidence intervals (95% CI) were reported. A total of 193 cases and 965 controls were included. In the 5 years prior to diagnosis, 50% of cases had at least one test, compared to 26% of controls. Compared to those who did not have serological testing in the 5 years prior to HIV infection, those who had one serological test were at twice the odds of being HIV positive (OR: 1.9, 95% CI: 1.2-2.9), while those with 2 or more tests were at even higher odds (OR: 5.5, 95%CI: 3.7-8.4). HIV cases had higher serological testing rates. Interactions between public health and other healthcare providers should be strengthened.

Background Streptococcus pneumoniaeis a major cause of community-acquired pneumonia and septicemia in adults. The global drug-susceptible capsular serotype 12F, clonal complex 218 caused several outbreaks in the United States between 1989 and 2008, as well as a recent large outbreak in Manitoba, Canada, that resulted in 36 cases of septicemia and 3 deaths. The evolutionary origin of the Canadian outbreak strain and its relationship to the historical US outbreak strains are not known. Methods Whole-genome deep sequencing was performed on isolates from the Canadian outbreak (n = 36), the US outbreaks (n = 9), and nonoutbreak surveys (n = 21). Phylogenomic analysis and comparative genomics were used to assess evolutionary relationships and to detect gene content differences between the isolates. Results The Canadian outbreak was closely related to sporadic cases that occurred preoutbreak in cross-border geographic regions in Manitoba, North Dakota, and Iowa. The emerging Canadian strain differed from US strains by acquisition of a cell-surface protein and macrolide resistance determinants via incorporation of a 5.3-kb mega cassette harboringmsrDandmefE Furthermore, during 11 months of transmission, this clone evolved rapidly and acquired fluoroquinolone resistance through precise stepwise mutations in bothparCandgyrA, and putative compensatory mutations inuraAorIMPDHunder drug selection. Alarmingly, this drug-resistant clone appears to have spread quickly to other regions of Canada and the United States, and replaced drug-susceptible strains. Conclusions Whole-genome sequencing revealed an independent emergence and secondary adaptation of a new virulent and drug-resistant pneumococcal epidemic clone. Ongoing molecular surveillance is required, and measures to prevent its spread should be developed.

Background The city of Winnipeg has experienced a surge of infectious syphilis cases since the fall of 2012, concentrated among men who have sex with men (MSM) and who use social media technologies-including phone applications-to meet sexual contacts. Objective To evaluate the acceptability, cost and effectiveness of a campaign promoting syphilis testing on popular websites and applications used by MSM in the Winnipeg Health Region (WHR). Methods The Winnipeg Regional Health Authority developed a campaign in March 2014 highlighting the syphilis outbreak and the importance of seeking testing. Over one month, advertisements appeared on four web-platforms: Grindr, Facebook, Squirt and the Gay Ad Network. When clicked, ads would direct the user to an information website. Acceptability was assessed using the number of 'clicks' elicited by advertisements on each platform. The cost of each platform's run of advertisements was compared to the number clicks elicited to produce a cost-per-click ratio for each platform. Effectiveness was assessed by comparing the number of syphilis tests ordered for male residents of the Winnipeg Health Region in the seven-week period before and after the campaign, as well as to the same time periods in 2012 and 2013. Results Out of 800,000 appearances purchased, the advertisements elicited 2,166 clicks, suggesting good acceptability. Grindr and Squirt advertisements had a better cost-per-click ratio than Facebook or the Gay Ad Network. There was no significant difference in testing before (2,049 tests) versus after (2,025 tests) the campaign and these findings were similar to testing trends in 2012 and 2013. Conclusion Although this web-based campaign showed good acceptability and low cost, it did not appear to increase syphilis testing. This may be due to a poor campaign design; it also suggests that an education campaign alone may be insufficient to change behaviour.

Background: Drug users act as reservoirs and transmission channels for hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV) infections to the general population worldwide. Periodic epidemiological studies to monitor the prevalence and genetic diversity of these infections to inform on interventions are limited. Objective of the study: The objective of this study was to determine the predictors of HIV infection and genetic diversity of HBV and HCV among drug users in Kenya. Materials and methods: A cross-sectional study on previous drug use history among drug users was conducted in three Kenyan cities using a respondent-driven sampling method between January 2011 and September 2012. Blood samples were collected and analysed for the presence of HBV, HCV and HIV serological markers and to determine the genotypes of HBV and HCV. Results: The overall prevalence of HBV, HCV and HIV among drug users was 4.3%, 6.5% and 11.1%, respectively, with evidence of HBV/HIV, HCV/HIV and HBV/HCV/HIV co-infections. The HBV circulating genotypes were A1 (69%) and D6 (19%), whereas HCV genotypes were 1a (72%) and 4a (22%). Injection drug use was a significant predictor of HIV/HCV infections. Younger age (30 years; aOR (adjusted odds ratio) = 0.50, 95% CI (confidence interval): 0.33–0.76; p < 0.001) and early sexual debut (aOR = 0.54, 95% CI: 0.40–0.82; p < 0.05) were negatively associated with detection of any of the three infections. Injecting drug use was positively associated with HCV infection (aOR = 5.37, 95% CI: 2.61–11.06; p < 0.001). Conclusion: This high level of genetic diversity exhibited by HBV and HCV isolates requires urgent implementation of harm reduction strategies and continuous monitoring for effective management of the patients.

Testing remnant Aptima specimens from women infected with Chlamydia trachomatis detected 13.4% (53/396) with Mycoplasma genitalium compared with 5.4% (22/406) in matched C. trachomatis-negative women. Overall, 9.4% (provincial ranges of 3-20%) were infected with M. genitalium and resistance mediating mutations were found in 47.3% (26/55) to macrolides and 1.9% (1/53) to fluoroquinolones by sequencing.

Drug users are increasingly recognized as a key population driving human immunodeficiency virus (HIV) spread in sub-Saharan Africa. To determine HIV-1 subtypes circulating in this population group and explore possible geographic differences, we analyzed HIV-1 sequences among drug users from Nairobi, Mombasa, and Kisumu in Kenya. We sequenced gag and env from 55 drug users. Subtype analysis from 220 gag clonal sequences from 54 of 55 participants (median = 4/participant) showed that 44.4% were A, 16.7% were C, 3.7% were D, and 35.2% were intersubtype recombinants. Of 156 env clonal sequences from 48 of 55 subjects (median = 3/participant), 45.8% were subtype A, 14.6% were C, 6.3% were D, and 33.3% were recombinants. Comparative analysis of both genes showed that 30 (63.8%) participants had concordant subtypes, while 17 (36.2%) were discordant. We identified one genetically linked transmission pair and two cases of dual infection. These data are indicative of extensive HIV-1 intersubtype recombination in Kenya and suggest decline in subtype D prevalence.

This study examined invasive Neisseria meningitidis recovered from invasive meningococcal disease (IMD) cases in Western Canada between 2009 and 2013. A total of 161 isolates from individual IMD cases were analysed for serogroup, serotype, serosubtype, PorA genotype, multi-locus sequence type and nucleotide sequence of their 4CMenB vaccine antigen genes. Sixty-nine isolates were serogroup B (MenB), 47 were serogroup Y (MenY), 22 were serogroup C (MenC), 19 were serogroup W (MenW), three were serogroup E and one was non-encapsulated. MenC, MenY and MenW were mainly clonal, represented primarily by clonal complex (cc) 11, cc23 or cc167, and cc22, respectively. In contrast, MenB were composed of eight different ccs together with 11 isolates not assigned to any known cc. Antigenic analysis and PorA genotyping confirmed the heterogeneity of MenB isolates, while such results supported the clonal nature of most MenC, MenY and MenW isolates. Thirty-four (21.1 %) isolates had at least one gene that encoded one matching vaccine protein component of the 4CMenB vaccine (i.e. PorA P1.4; fHbp variant 1.1; NHBA peptide 2; and NadA-1, -2, or -3). An additional 18 isolates had genes that encoded variant 1 or subfamily B factor H binding proteins of this same vaccine.

Background In 2010, Winnipeg, Canada, experienced a doubling of invasive pneumococcal disease (IPD) rates, with a significant increase in the number of cases due to Streptococcus pneumoniae serotype 12F, which previously had accounted for very few cases each year. Methods All serotype 12F IPD cases reported between September 2009 and January 2011 were reviewed. Pulsed-field gel electrophoresis (PFGE) and multilocus variable number tandem repeat analysis (MLVA) were conducted on all isolates. PFGE and MLVA patterns identified several possible clusters. Additional interviews were conducted to obtain information on risk factors and outcomes. Results Between September 2009 and January 2011, 169 cases of IPD were identified. The number of IPD cases due to 12F serotype increased sharply from about 3-4 cases per year (6% of IPD cases) in 2007-2009 to 28 (29%) in 2010. All 12F isolates belonged to a single sequence type (ST218), and they were generally susceptible to penicillin and fluoroquinolones but not to erythromycin. Compared with cases caused by other serotypes, patients with serotype 12F were more likely to be homeless, reside in low-income inner-city communities, and engage in substance abuse, including intravenous and crack cocaine use. Subclusters identified using MLVA had even higher rates of homelessness and substance use. Conclusions An immunization campaign targeting high-risk groups was undertaken with pneumococcal polysaccharide vaccine, and subsequently rates of serotype 12F decreased. To our knowledge, this is the largest documented community outbreak of serotype 12F IPD and the first report of an outbreak of IPD serotype 12F in a marginalized urban population in Canada.

Objectives. We assessed whether a meaningful set of latent risk profiles could be identified in an inner-city population through individual and network characteristics of substance use, sexual behaviors, and mental health status. Methods. Data came from 600 participants in Social Network Study III, conducted in 2009 in Winnipeg, Manitoba, Canada. We used latent class analysis (LCA) to identify risk profiles and, with covariates, to identify predictors of class. Results. A 4-class model of risk profiles fit the data best: (1) solitary users reported polydrug use at the individual level, but low probabilities of substance use or concurrent sexual partners with network members; (2) social–all-substance users reported polydrug use at the individual and network levels; (3) social–noninjection drug users reported less likelihood of injection drug and solvent use; (4) low-risk users reported low probabilities across substances. Unstable housing, preadolescent substance use, age, and hepatitis C status predicted risk profiles. Conclusions. Incorporation of social network variables into LCA can distinguish important subgroups with varying patterns of risk behaviors that can lead to sexually transmitted and bloodborne infections.

Gonorrhea, caused by Neisseria gonorrhoeae, is the second most commonly reported sexually transmitted infection in Canada; ≈13,000 cases occur yearly, and rates have increased from 20.1 cases/100,000 population in 2000 to 39.2 cases/100,000 in 2013 (1). The infection is also a global public health threat, with ≈106 million cases/year occurring worldwide (2). Gonococci have acquired resistance to many antimicrobial agents used for treatment (3), however, which makes it imperative to conduct surveillance programs so appropriate treatment recommendations can be determined. In 2011, the increases in MICs of cephalosporins prompted the authors of the Canadian Sexually Transmitted Infections Guidelines to update the recommended gonorrhea treatment from a single antimicrobial drug to combination therapy with ceftriaxone (250 mg intramuscularly) and azithromycin (1 g orally in a single dose) as the first-line treatment for uncomplicated anogenital and pharyngeal N. gonorrhoeae infections in adults (4). We analyzed antimicrobial drug susceptibility levels of N. gonorrhoeae to cephalosporins and azithromycin in Canada since the recommended treatments were updated in 2011.

We developed a real-time PCR assay to detect single nucleotide polymorphisms associated with ciprofloxacin resistance in specimens submitted for nucleic acid amplification testing (NAAT). All three single nucleotide polymorphism (SNP) targets produced high sensitivity and specificity values. The presence of ≥2 SNPs was sufficient to predict ciprofloxacin resistance in an organism.

Objectives Increases in case numbers for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) have been noted on a global level. This study analysed 13 years of testing data to better understand case detection trends over time. Methods Data consisted of all nucleic acid probe and nucleic acid amplification diagnostic testing for CT and NG for the population of Manitoba, Canada (1.2 million); January 2000 to December 2012. Logistic regression models were used to analyse ORs associated with positive CT and NG tests by year. Included in the model as predictor variables were test type, specimen type, patient age and residence location. Results For both male and female CT results, unadjusted OR by year mimicked absolute case counts, reflecting a general increase over time in case counts. Adjustment for laboratory-related variables altered this relationship such that a general decline in the odds of identifying a CT case over time was evident. For both male and female NG results, adjustment for laboratory and demographic variables altered the OR associated with each year, but to a lesser extent than for CT. Conclusions Temporal trends associated with CT case numbers should be interpreted after controlling, at a minimum, for the influence of laboratory-related variables. Interpretation of NG trends is feasible using only the number of reported NG cases.

A population-based study combining (i) antimicrobial, (ii) genetic, and (iii) virulence analyses with molecular evolutionary analyses revealed segregative characteristics distinguishing human clinical and bovine Escherichia coli O157 strains from western Canada. Human ( n = 50) and bovine ( n = 50) strains of E. coli O157 were collected from Saskatchewan and Manitoba in 2006 and were analyzed by using the six-marker lineage-specific polymorphism assay (LSPA6), antimicrobial susceptibility analysis, the colicin assay, plasmid and virulence profiling including the eae , ehxA , espA , iha , stx 1 , stx 2 , stx 2c , stx 2d , stx 2d-activatable , stx 2e , and stx 2f virulence-associated genes, and structure analyses. Multivariate logistic regression and Fisher's exact test strongly suggested that antimicrobial susceptibility was the most distinctive characteristic ( P = 0.00487) associated with human strains. Among all genetic, virulence, and antimicrobial determinants, resistance to tetracycline ( P < 0.000) and to sulfisoxazole ( P < 0.009) were the most strongly associated segregative characteristics of bovine E. coli O157 strains. Among 11 virulence-associated genes, stx 2c showed the strongest association with E. coli O157 strains of bovine origin. LSPA6 genotyping showed the dominance of the lineage I genotype among clinical (90%) and bovine (70%) strains, indicating the importance of lineage I in O157 epidemiology and ecology. Population structure analysis revealed that the more-diverse bovine strains came from a unique group of strains characterized by a high degree of antimicrobial resistance and high frequencies of lineage II genotypes and stx 2c variants. These findings imply that antimicrobial resistance generated among bovine strains of E. coli O157 has a large impact on the population of this human pathogen.

Introduction: Street-involved youth are one of the populations most at risk for elevated rates of sexually transmitted and bloodborne infections. This paper evaluates the suitability and success of a resource focused on health education with a population of street-involved youth in Winnipeg, Canada. Method: Using a mixed method approach, quantitative and qualitative data were collected and analysed. Surveys involving both structured and semi-structured questions were administered orally to 100 participants. Three gender-stratified focus groups (total of 23 participants) were also conducted. Focus groups were recorded and subsequently transcribed. Empirical data was used to calculate frequency distributions, supported by a general inductive analysis of qualitative data. Results: From the interview and focus group data, the majority of participants had a very positive perception of the resource. However, in terms of specific knowledge uptake, participants displayed a lack of recall of the specific items measured in the evaluation, such as local HIV testing facilities, types of HIV tests available and specific information pertaining to recent research conducted in Manitoba with street-involved populations. Conclusion: Both passive distribution of the resource through service-providing institutions and active distribution in the street were effective approaches for exposing a wide range of street-involved youth to the resource. Poor recall of specific knowledge objectives suggests alternate methods of presenting key fact-based information are necessary to increase resource efficiency. Articles must be created at an appropriate reading level for the street-involved population to improve reader engagement. The ability for the target population to identify that the resource is grounded in language, art, interests and lived-experiences of the street-involved youth was well-received and facilitated interest in looking through the resource and credibility of information.

Diez Roux has used the concept of complex systems to describe approaches for the incorporation of social factors into health research. These systems consist of heterogeneous interdependent units that also exhibit emergent properties. The latter embodies the concept that the interdependent units interact with and affect each other such that the resulting properties are not simple aggregates of the individual-level properties. This paper reviews research from Manitoba with a view towards conceptualising and phrasing the observed patterns within a complex system framework. A review of the temporal and spatial patterns seen within two large sexual network databases from Manitoba was undertaken and framed against the overlying patterns of sexually transmitted infection (STI) transmission within Manitoba. The review includes a summation of STI epidemiological patterns in Manitoba over a 5-year time frame, a comparison of temporal sexual network patterns, and an analysis of network patterns in relation to disparity in STI rates. Hypotheses are generated that focus on how individual-level behaviours and interactions create the observed complex system (network) patterns.

One hundred and twenty-two isolates of Haemophilus influenzae causing invasive disease were collected in Manitoba, Canada, from 2000 to 2006 and examined for serotype, biotype, sequence type (ST) by multilocus sequence typing and antibiotic susceptibility. Nonserotypeable (NST) isolates accounted for over half of the isolates collected (69 isolates, 56.6%). There were 36 serotype a, five serotype b, two serotype c, one serotype d, four serotype e and five serotype f isolates collected. The 69 NST isolates were found to be very diverse, with isolates representing six biotypes and 45 STs. The serotypeable isolates were more clonal, with each of the serotypes showing little diversity in their biotypes and STs. Of the 122 isolates, 17% were resistant to ampicillin due to beta-lactamase production, 10.7% were resistant to trimethoprim-sulfamethoxazole, 1.6% were resistant to clarithromycin, 2.5% were resistant to amoxicillin-clavulanic acid and none was resistant to ciprofloxacin or moxifloxacin. Antibiotic resistance was more common in the NST strains, with 37.7% showing resistance to at least one antibiotic compared to 15% in the serotypeable strains. The results of this study suggest a shift in the epidemiology of invasive H. influenzae infections in the post-Hib vaccine era, and surveillance should include all serotypeable and NST isolates.

Aims Despite the establishment of syringe exchange programmes, syringe-sharing behaviour remains common among some injection drug users (IDU). Previous studies have identified several individual- and social network-level variables associated with syringe sharing. We examine the extent to which each of these variables is related independently to this behaviour within a diverse study population. Design, setting and participants A cross-sectional survey of 435 IDU conducted between December 2003 and September 2004 in Winnipeg, Canada. Measurements Individual and social-network variables were obtained from a survey instrument administered through a personal interview. Syringe sharing was defined as receptive syringe sharing in the last 6 months. Logistic regression analysis with generalized estimating equations was used to determine simultaneously the role of individual-level and risk network member-level variables on the odds of syringe sharing. Findings Individuals' relationship to a risk network member (sex partner, OR: 15.3 95% CI: 7.6–30.8; family member, OR: 3.4 95% CI: 1.3–9.0) and difficulty of access to syringes (OR: 3.6 95% CI: 1.3–9.9) were predictive of syringe sharing. Dyads who ‘often’ pooled resources to obtain drugs were at 4.9 times (95% CI: 2.1–11.6) the odds of syringe sharing, while those who ‘sometimes’ pooled resources were at 2.8 times (95% CI: 1.1–6.7) the odds, compared to those who ‘never’ pooled resources together. Conclusions Syringe sharing in this population depended on both the availability of clean syringes and social network relationships. Adopting interventions that take into account relationships and behaviours that shape social norms present in networks/dyads would be a necessary prevention strategy alongside the provision of clean syringes.

Contexte : Le percage du haut de l'oreille, une mode qui s'etend de plus en plus, est associe a un risque accru de complications post-percage potentiellement graves, comme la perichondrite de l'oreille. Expose de cas : Une fillette de 11 ans a contracte une perichondrite grave de l'oreille apres le percage du cartilage du tiers superieur du pavillon de son oreille dans un salon de coiffure. Quatre jours apres l'intervention, elle est retournee au meme salon pour une coupe de cheveux durant laquelle le site perce a ete manipule. Elle s'est presentee chez son medecin de famille, qui lui a administre sans succes un traitement oral a la cephalexine. Elle a ensuite ete dirigee vers un consultant en maladies infectieuses, ou elle a recu des antibiotiques antipseudomonaux par voie intraveineuse qui ont gueri l'infection. Il a aussi fallu exciser et retirer le cartilage necrose. Les enqueteurs de la sante publique ont analyse les sources d'infection possibles, dont le pistolet de percage, les solutions desinfectantes et les flacons du salon de coiffure servant a pulveriser l'eau. Les derniers resultats de culture de l'aspirat du pavillon de l'oreille ont developpe des bacteries Pseudomonas aeruginosa. Ces bacteries se sont egalement developpees dans les cultures provenant d'un des flacons utilises pour mouiller les cheveux de la fillette pendant sa coupe de cheveux. Discussion : Bien que les souches pseudomonales du flacon aient ete differentes de celle ayant infecte la fillette, cette forme de contamination pourrait avoir ete une source d'infection de la plaie. La lesion du cartilage auriculaire causee par le pistolet de percage pourrait aussi avoir joue un role dans l'infection. L'antibiotherapie empirique que l'on utilise initialement pour traiter ce genre d'infection doit inclure un agent antipseudomonal. Le percage du haut de l'oreille a l'aide d'un pistolet n'est pas recommande.

A multi-province outbreak of listeriosis occurred in Canada from June to November 2008. Fifty-seven persons were infected with 1 of 3 similar outbreak strains defined by pulsed-field gel electrophoresis, and 24 (42%) individuals died. Forty-one (72%) of 57 individuals were residents of long-term care facilities or hospital inpatients during their exposure period. Descriptive epidemiology, product traceback, and detection of the outbreak strains of Listeria monocytogenes in food samples and the plant environment confirmed delicatessen meat manufactured by one establishment and purchased primarily by institutions was the source of the outbreak. The food safety investigation identified a plant environment conducive to the introduction and proliferation of L. monocytogenes and persistently contaminated with Listeria spp. This outbreak demonstrated the need for improved listeriosis surveillance, strict control of L. monocytogenes in establishments producing ready-to-eat foods, and advice to vulnerable populations and institutions serving these populations regarding which high-risk foods to avoid.

Many marginalized populations face severe health inequities in developed countries. These include people who are poor, homeless, sell sex or use alcohol or illegal drugs. In Toronto, an estimated 19% of homeless people who had a diagnosis of active tuberculosis during 1998–2007 died within 12

Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) has gained popularity in recent years for rapid bacterial identification, mostly at the genus or species level. In this study, a rapid method to identify the Escherichia coli flagellar antigen (H antigen) at the subspecies level was developed using a MALDI-TOF MS platform with high specificity and sensitivity. Flagella were trapped on a filter membrane, and on-filter trypsin digestion was performed. The tryptic digests of each flagellin then were collected and analyzed by MALDI-TOF MS through peptide mass fingerprinting. Sixty-one reference strains containing all 53 H types and 85 clinical strains were tested and compared to serotyping designations. Whole-genome sequencing was used to resolve conflicting results between the two methods. It was found that DHB (2,5-dihydroxybenzoic acid) worked better than CHCA (α-cyano-4-hydroxycinnamic acid) as the matrix for MALDI-TOF MS, with higher confidence during protein identification. After method optimization, reference strains representing all 53 E. coli H types were identified correctly by MALDI-TOF MS. A custom E. coli flagellar/H antigen database was crucial for clearly identifying the E. coli H antigens. Of 85 clinical isolates tested by MALDI-TOF MS-H, 75 identified MS-H types (88.2%) matched results obtained from traditional serotyping. Among 10 isolates where the results of MALDI-TOF MS-H and serotyping did not agree, 60% of H types characterized by whole-genome sequencing agreed with those identified by MALDI-TOF MS-H, compared to only 20% by serotyping. This MALDI-TOF MS-H platform can be used for rapid and cost-effective E. coli H antigen identification, especially during E. coli outbreaks.

The incidence of antimicrobial-resistant Neisseria gonorrhoeae continues to rise in Canada; however, antimicrobial resistance data are lacking for approximately 70% of gonorrhea infections that are diagnosed directly from clinical specimens by nucleic acid amplification tests (NAATs). We developed a molecular assay for surveillance use to detect mutations in genes associated with decreased susceptibility to cephalosporins that can be applied to both culture isolates and clinical samples. Real-time PCR assays were developed to detect single nucleotide polymorphisms (SNPs) in ponA , mtrR , penA , porB , and one N. gonorrhoeae -specific marker ( porA ). We tested the real-time PCR assay with 252 gonococcal isolates, 50 nongonococcal isolates, 24 N. gonorrhoeae -negative NAAT specimens, and 34 N. gonorrhoeae -positive NAAT specimens. Twenty-four of the N. gonorrhoeae -positive NAAT specimens had matched culture isolates. Assay results were confirmed by comparison with whole-genome sequencing data. For 252 N. gonorrhoeae strains, the agreement between the DNA sequence and real-time PCR was 100% for porA , ponA , and penA , 99.6% for mtrR , and 95.2% for porB . The presence of ≥2 SNPs correlated with decreased susceptibility to ceftriaxone (sensitivities of >98%) and cefixime (sensitivities of >96%). Of 24 NAAT specimens with matched cultures, the agreement between the DNA sequence and real-time PCR was 100% for porB , 95.8% for ponA and mtrR , and 91.7% for penA . We demonstrated the utility of a real-time PCR assay for sensitive detection of known markers for the decreased susceptibility to cephalosporins in N. gonorrhoeae . Preliminary results with clinical NAAT specimens were also promising, as they correlated well with bacterial culture results.

Newcomer and street-involved youth provided their perspective on the design and content of a sexual education workshop. Following the workshop, focus group discussions were held with 80 youth from four youth-serving agencies. Youth expressed increased levels of confidence and empowerment, consistent with recent criticism that a focus on specific behaviors as intervention outcome measures may miss important psychosocial changes in participants. Some youth views on cultural adaptation of workshops were not consistent with current views expressed by some adult educators, highlighting the need to ensure a youth perspective is captured during intervention development. Finally, the dichotomous views that youth expressed regarding workshop activities emphasizes a research gap related to how best to adapt interventions to different cognitive capacities, literacy levels, and learning styles. Information of this kind is relevant in terms of knowledge translation from youth to program planners and educators.

Fifty-two Haemophilus influenzae isolates from patients with invasive disease in the province of Manitoba, Canada, were examined for serotype, biotype, genotype, and antibiotic susceptibility. Half of the 52 isolates were found to be serotype a, and 38.5% (20 isolates) were found to be nonserotypeable (NST). There were only three serotype b strains and one each for serotypes c, d, and f. All 26 serotype a isolates belonged to biotype II and demonstrated identical or highly similar DNA fingerprints by pulsed-field gel electrophoresis. An analysis of these isolates by multilocus sequence typing showed that they belong to the clonal complex ST-23. While 69% (18 of 26) of the serotype a cases were found in males, only 9 (45%) of the 20 patients with NST isolates were males. Twenty (77%) of the 26 serotype a isolates were from patients who were ≤24 months old. Twelve (63%) of the NST isolates were from adult or adolescent patients. In contrast to the clonal nature of serotype a isolates, the 20 NST isolates were found to belong to 18 different sequence types. Most of these 18 different sequence types were unrelated to each other, with the exception of 7 sequence types grouped into three clonal groups. Two (6.25%) out of 32 serotypeable isolates (1 serotype a and 1 serotype b) and 6 (30%) of 20 NST isolates were resistant to ampicillin due to β-lactamase production. These results suggest a change in the epidemiology of H. influenzae disease, with the majority of invasive H. influenzae isolates being associated with serotype a and NST strains.

Recently, acquisition of methicillin-resistant Staphylococcus aureus (MRSA) has been increasingly seen in community settings. Beginning in 1995, we have routinely conducted pulsed-field gel electrophoresis (PFGE) of MRSA isolates received at Cadham Provincial Laboratory (CPL) in Manitoba, Canada. Our diverse collection of isolates coupled with molecular subtype information allowed us to assess the extent to which MRSA isolates in general were associated with community acquisition and whether specific PFGE types were more likely to be found in community settings. Forty percent of the MRSA isolates in our analysis were designated community associated (CA), with two of the six most common PFGE types showing a greater likelihood to be CA-MRSA. Overall, CA-MRSA were more likely to show multiple sensitivity to antibiotics and to be associated with younger age groups. Mapping of specific CA-MRSA types over successive 5-year periods showed rapid temporal shifts in prevalence in different parts of the province.

BACKGROUND: Relatively few enhanced surveillance studies have been undertaken to investigate the extent to which verotoxin-producing non-O157 serotypes ofEscherichia colioccur in stool samples received for the detection of verotoxin-producing organisms.OBJECTIVES: To describe the prevalence, molecular and epidemiological characteristics, and geographical patterns associated with non-O157 verotoxin-producingE coli(VTEC) in Manitoba.RESULTS: Thirty-two VTEC isolates consisting of 10 serogroups and 13 different serotypes were isolated over a 22-month period. Twenty-three isolates (71.8%) possessed verotoxin-encoding gene stx1 only, five isolates (15.6%) possessedstx2only, two isolates (6.3%) possessed bothstx1andstx2, and two isolates (6.3%) possessedstx2c. Only three instances of indistinguishable pulsed-field gel electrophoresis patterns were identified. The age of the individuals from whom non-O157 VTEC were isolated ranged from eight months to 87 years. Mean and median ages were 30 and 22 years of age, respectively. Some areas of the province appeared to experience a higher than expected number of non-O157E coliin comparison with the number of stools that were received from these areas.CONCLUSIONS: The present study demonstrated a large number of infections associated with non-O157 VTEC in Manitoba. Most non-O157 cases appear to result from sporadic infections, and these occur typically in rural areas. Continued enhanced surveillance is necessary to understand the temporal patterns of non-O157 VTEC and the underlying epidemiological factors driving these patterns.

We report emergence of ciprofloxacin-resistant Salmonella enterica serovar Kentucky in Canada during 2003-2009. All isolates had similar macrorestriction patterns and were multilocus sequence type ST198, which has been observed in Europe and Africa. Ciprofloxacin-resistant S. enterica serovar Kentucky represents 66% of all ciprofloxacin-resistant nontyphoidal Salmonella sp. isolates observed in Canada since 2003.

This chapter examines the persistent bacterial pathogens within the context of evolutionary ecology by addressing the functional and evolutionary aspects of the mechanisms that bacteria have developed to persist in mammalian hosts. The focus will be on antigenic variation, as this is one of the most widely studied aspects of persistence and also one of the most variable in terms of the extent to which extracellular pathogens have developed genetic mechanisms to enable variation to occur. A recent paper has provided an overview of the significance of antigenic variation in terms of the evolutionary forces driving host-pathogen coevolution. A distinction among conjugation, transduction, and transformation is that the first two processes are largely driven by factors external to the cell receiving the DNA while transformation is largely under the control of the recipient cell. Pathogenicity islands, consisting of large blocks of DNA encoding multiple, and frequently related, gene products, have been identified in some bacterial populations. The emergence of intracellular antigenic variation may be a multifactorial process, governed by the population biology of the organism, the response of the vertebrate host, and the specific bacterial interactions encountered within the host environment. Analysis of the mechanisms and population biologies of bacterial persistence within and between hosts is only one area in which a greater understanding of microbial evolution will facilitate proactive approaches for the control of infectious disease.

Objective We previously identified a high prevalence of Hepatitis C (HCV) amongst solvent-using injection drug users (S-IDU) relative to other injection drug users within the same locality. Here we incorporated social network variables to better characterize some of the behavioural characteristics that may be putting this specific subgroup of IDU at elevated disease risk. Methods A cross-sectional survey of at-risk populations was carried out in Winnipeg, Canada in 2009. Individuals reporting any history of injection drug and/or solvent use were included in the study. Associations between subgroup membership, infection with HCV and HIV and individual and social network variables were examined. Results In relation to other IDU, S-IDU were more likely to be infected with HCV, to report ever having shared a syringe, and to associate with other IDU. They were further differentiated in terms of their self-reported sexual orientation, ethnicity and in the injection drugs typically used. Conclusion Solvent use stands as a proxy measure of numerous other characteristics that put this group of IDU at higher risk of infection. Provision of adequate services to ostracized subpopulations may result in wider population-level benefits.

Background Methods for accessing large sexual networks are essential for investigating the mechanisms for the spread of sexually transmitted infections. Goal Four samples of cases were compared with the total population to determine which identified the largest networks. Study Design Individuals with positive test results for chlamydia during a 6-month period were selected from a laboratory database and linked with sex partner information from a notifiable disease registry. Sexual networks were constructed for a random sample, people with positive results from two or more tests for chlamydia, people with positive tests results for both gonorrhea and chlamydia, and the preceding two groups combined. Results The coinfected people combined with the repeaters yielded the highest proportion (47.8%) of large networks (>10 people), followed by the coinfected people, the repeaters, and finally the random sample. Conclusions People coinfected with chlamydia and gonorrhea and those with repeated chlamydial infection present ideal opportunities for both research and prevention.

A community-based, single strain cluster of methicillin-resistantStaphylococcus aureus(MRSA) is described. The cluster of cases was identified in a small rural community in southwestern Manitoba, although some spread of the MRSA strain to neighbouring communities was observed. The majority of people were otherwise healthy, had no contact with the hospital system and did not fit the profile of those at risk for MRSA infection.

The kdsA and kdsB genes from Chlamydia trachomatis encoding 3-deoxy-D-manno-octulosonate (KDO)-8-phosphate synthetase and CMP-KDO synthetase were identified by functional complementation of temperature-sensitive Salmonella typhimurium mutants, homology to known KDO-8-phosphate synthetase and CMP-KDO synthetase proteins, and in vitro enzyme activity. The kdsA gene was transcribed as part of a polycistronic mRNA with two downstream open reading frames (ORFs). One of these ORFs appeared to encode a membrane-anchored protein, while the second encoded a protein showing homology to the ATP-binding component of periplasmic binding protein-dependent ABC transporters. Transcription of kdsA and kdsB in C. trachomatis was evident within 4 h of initiation of the C. trachomatis infection process and continued throughout the chlamydial life cycle.

UNLABELLED Haemophilus influenzae serotype a (Hia) has become an important pathogen in the post-H. influenzae serotype b (Hib) vaccine era. Antibiotic resistance in H. influenzae is a global phenomenon, but few studies have looked at antibiotic resistance profiles with regard to serotype. Invasive Hia (n = 157), noninvasive Hia (n = 2) and invasive Hib (n = 42) collected over the last two decades from three Canadian Provinces were examined for resistance to several commonly prescribed antibiotics, and sequence types (STs) were determined by MLST. Only 1·9% of Hia showed antibiotic resistance, while 31% of Hib were resistant to one or more antibiotic. Resistance to ampicillin, sulfamethoxazole-trimethoprim, chloramphenicol and tetracycline was observed, with β-lactamase-mediated ampicillin resistance being the most common. Nine STs were identified for Hia with 7 STs belonging to the same clonal complex. Ten STs were observed in Hib strains, and all of them belonged to a single clonal complex. A possible correlation between sequence type and ampicillin resistance was observed for Hib, while no correlations were observed for Hia. SIGNIFICANCE AND IMPACT OF THE STUDY Despite H. influenzae serotype b (Hib) vaccine programs, invasive disease due to Hib still exists in Canada and is either second or third most common behind nontypeable and/or serotype a (Hia). Many previous studies on antibiotic resistance have focussed on respiratory isolates, and few have looked at resistance with regard to serotype. This study analysed antibiotic resistance in invasive Hia and Hib collected over 20 years from three provinces, and results found that significantly more Hib showed resistance compared to Hia. This provides a small snapshot of H. influenzae disease in Canada and highlights the importance to continually monitor antibiotic resistance profiles.

Background Respondent driven sampling (RDS) was designed for sampling “hidden” populations and intended as a means of generating unbiased population estimates. Its widespread use has been accompanied by increasing scrutiny as researchers attempt to understand the extent to which the population estimates produced by RDS are, in fact, generalizable to the actual population of interest. In this study we compare two different methods of seed selection to determine whether this may influence recruitment and RDS measures. Methods Two seed groups were established. One group was selected as per a standard RDS approach of study staff purposefully selecting a small number of individuals to initiate recruitment chains. The second group consisted of individuals self-presenting to study staff during the time of data collection. Recruitment was allowed to unfold from each group and RDS estimates were compared between the groups. A comparison of variables associated with HIV was also completed. Results Three analytic groups were used for the majority of the analyses–RDS recruits originating from study staff-selected seeds (n = 196); self-presenting seeds (n = 118); and recruits of self-presenting seeds (n = 264). Multinomial logistic regression demonstrated significant differences between the three groups across six of ten sociodemographic and risk behaviours examined. Examination of homophily values also revealed differences in recruitment from the two seed groups (e.g. in one arm of the study sex workers and solvent users tended not to recruit others like themselves, while the opposite was true in the second arm of the study). RDS estimates of population proportions were also different between the two recruitment arms; in some cases corresponding confidence intervals between the two recruitment arms did not overlap. Further differences were revealed when comparisons of HIV prevalence were carried out. Conclusions RDS is a cost-effective tool for data collection, however, seed selection has the potential to influence which subgroups within a population are accessed. Our findings indicate that using multiple methods for seed selection may improve access to hidden populations. Our results further highlight the need for a greater understanding of RDS to ensure appropriate, accurate and representative estimates of a population can be obtained from an RDS sample.

Objectives Over the last decade, a marked increase in Salmonella enterica serotype 4,[5],12:i:- with a core resistance to ampicillin, streptomycin, sulphonamides and tetracycline (ASSuT) has been observed in Europe. This study describes the emergence and characterization of isolates of multidrug-resistant Salmonella 4,[5],12:i:- in Canada. Methods Human clinical isolates of Salmonella 4,[5],12:i:- were identified by provincial laboratories from 2003 to 2010. Serotyping and phage typing were performed by standardized methodologies. MIC values were determined using broth microdilution. PCR was used to determine the presence of resistance genes. Multilocus sequence typing was performed on a selected number of isolates. Results A total of 26 251 Salmonella were submitted as part of the Canadian Integrated Program on Antibiotic Resistance Surveillance (CIPARS). Of these, Salmonella 4,[5],12:i:- accounted for a total of 766 isolates (2.9%), and the number increased significantly from 42 (1.4%) in 2003 to 164 (4.8%) in 2010. The ASSuT+ phenotype was observed in 11.9% (n = 91) of Salmonella 4,[5],12:i:- isolates and increased from two isolates in 2003 to 35 isolates in 2010. Two sequence types (STs) were observed. ST34 was mainly associated with the ASSuT isolates (n = 24; 38%), which contained blaTEM, strA-strB, tet(B) and sul2. ST19 was more likely to be associated with the ACSSuT phenotype and contained blaTEM, floR, strA-strB, sul2 and tet(A) or blaPSE-1, floR, aadA2, sul1 and tet(G). Conclusions The prevalence of Salmonella 4,[5],12:i:- has significantly increased from 2003 to 2010 and it is now the fifth most common serotype reported in Canada causing human disease. Similar antimicrobial resistance patterns, phage types and STs have been observed in Europe.

Haemophilus influenzae serotype a (Hia) is an important pathogen since the introduction of vaccines for control of disease due to serotype b strains. Using a sodC-based polymerase chain reaction, Hia can be divided into 2 phylogenetic divisions, each with their own unique multilocus sequence types. Most Canadian Hia belongs to clonal division I and the ST-23 clonal complex. The recently described hypervirulent clone of ST-4 was found in a single Canadian isolate. Therefore, surveillance of invasive H. influenzae disease should include serotyping to detect Hia and multilocus sequence typing to detect hypervirulent clones.