Kirsten Gravningen

Global Multilocus Sequence Type Analysis of Chlamydia trachomatis Strains from 16 Countries

ABSTRACT The Uppsala University Chlamydia trachomatis multilocus sequence type (MLST) database (http://mlstdb.bmc.uu.se) is based on five target regions (non-housekeeping genes) and the ompA gene. Each target has various numbers of alleles—hctB, 89; CT058, 51; CT144, 30; CT172, 38; and pbpB, 35—derived from 13 studies. Our aims were to perform an overall analysis of all C. trachomatis MLST sequence types (STs) in the database, examine STs with global spread, and evaluate the phylogenetic capability by using the five targets. A total of 415 STs were recognized from 2,089 specimens. The addition of 49 ompA gene variants created 459 profiles. ST variation and their geographical distribution were characterized using eBURST and minimum spanning tree analyses. There were 609 samples from men having sex with men (MSM), with 4 predominating STs detected in this group, comprising 63% of MSM cases. Four other STs predominated among 1,383 heterosexual cases comprising, 31% of this group. The diversity index in ocular trachoma cases was significantly lower than in sexually transmitted chlamydia infections. Predominating STs were identified in 12 available C. trachomatis whole genomes which were compared to 22 C. trachomatis full genomes without predominating STs. No specific gene in the 12 genomes with predominating STs could be linked to successful spread of certain STs. Phylogenetic analysis showed that MLST targets provide a tree similar to trees based on whole-genome analysis. The presented MLST scheme identified C. trachomatis strains with global spread. It provides a tool for epidemiological investigations and is useful for phylogenetic analyses.

Multilocus Sequence Typing of Genital Chlamydia trachomatis in Norway Reveals Multiple New Sequence Types and a Large Genetic Diversity

Background The Chlamydia trachomatis incidence rate in Finnmark, the most northern and sparsely populated county in Norway, has been twice the national average. This population based cross-sectional study among Finnmark high school students had the following aims: i) to examine distribution of multilocus sequence types (STs) of C. trachomatis in a previously unmapped area, ii) to compare chlamydia genetic diversity in Finnmark with that of two urban regions, and iii) to compare discriminatory capacity of multilocus sequence typing (MLST) with conventional ompA sequencing in a large number of chlamydia specimens. Methodology ompA sequencing and a high-resolution MLST system based on PCR amplification and DNA sequencing of five highly variable genetic regions were used. Eighty chlamydia specimens from adolescents aged 15–20 years in Finnmark were collected in five high schools (n = 60) and from routine clinical samples in the laboratory (n = 20). These were compared to routine clinical samples from adolescents in Tromsø (n = 80) and Trondheim (n = 88), capitals of North and Central Norway, respectively. Principal Findings ompA sequencing detected 11 genotypes in 248 specimens from all three areas. MLST displayed 50 STs providing a five-fold higher resolution. Two-thirds of all STs were novel. The common ompA E/Bour genotype comprised 46% and resolved into 24 different STs. MLST identified the Swedish new variant of C. trachomatis not discriminated by ompA sequencing. Simpsons discriminatory index (D) was 0.93 for MLST, while a corrected Dc was 0.97. There were no statistically significant differences in ST genetic diversity between geographic areas. Finnmark had an atypical genovar distribution with G being predominant. This was mainly due to expansion of specific STs of which the novel ST161 was unique for Finnmark. Conclusions/Significance MLST revealed multiple new STs and a larger genetic diversity in comparison to ompA sequencing and proved to be a useful tool in molecular epidemiology of chlamydia infections.

Early sexual behaviour and Chlamydia trachomatis infection - a population based cross-sectional study on gender differences among adolescents in Norway.

BackgroundEarly sexual behaviour has been shown to differ significantly between genders, but few studies have addressed this topic to explain the commonly observed differences in chlamydia rates between adolescent girls and boys. Our study aimed to determine chlamydia prevalence in adolescents aged 15–20 years in a high-incidence area in Norway, and to identify gender-specific early sexual behaviours associated with infection.MethodsA population based cross-sectional study was conducted among all high school students in five towns in Finnmark county in 2009, using a web-based questionnaire and real-time Chlamydia trachomatis PCR in first-void urine samples (participation rate 85%, 800 girls/818 boys, mean age 17.2 years). Crude and multivariable logistic regression models were applied with chlamydia test result as dependent variable.ResultsPrevalence of chlamydia infection was 5.7% (95% confidence interval, CI, 4.4–7.3%). Girls were twice as likely to be infected as boys (7.3%, 5.3–9.7 vs 3.9%, 2.3–6.0). Girls reported earlier sexual debut, older partners, higher lifetime number of partners, and were poorer condom users. In girls, higher maternal education (odds ratio, OR, 2.2, 95% CI 1.1–4.4), ≥2 sexual partners past 6 months (OR 3.6, 1.8–7.3), and partner meeting venue at a private party, bar or disco (OR 5.0, 1.1–22.7) increased the odds of infection in the multivariable model. In boys, condom use at first intercourse (OR 0.06, 0.01–0.42) decreased the odds of infection, while having an older last sexual partner (OR 3.7, 1.3–11.0) increased the odds. In all participants, the risk of infection increased if residence outside the family home during school year (OR 2.0, 1.2–3.6), and decreased if condom was used at last intercourse (OR 0.2, 0.1–0.8).ConclusionsWe detected significant gender differences in chlamydia prevalence and sexual behaviours, and accordingly differing independent risk factors for chlamydia infection. We suggest that accumulation of essentially different experiences in the early sexually active years contribute to gender disparities in chlamydia risk in individuals this age. Gender-specific approaches may be the best alternative to control chlamydia infection in age group 15–20 years.

High-Resolution Genotyping of Chlamydia trachomatis by Use of a Novel Multilocus Typing DNA Microarray

ABSTRACT Typing of Chlamydia trachomatis is important to understanding its epidemiology. Currently used methods such as DNA sequencing of the ompA gene and multilocus sequence typing (MLST) either offer limited epidemiological resolution or are laborious and expensive, or both. DNA microarray technology using the ArrayStrip format is an affordable alternative for genotyping. In this study, we developed a new multilocus typing (MLT) DNA microarray, based on the target regions of a high-resolution MLST system as well as software for easy analysis. Validation of the array was done by typing 80 previously MLST-typed clinical specimens from unselected adolescents in school. The MLT array showed 100% specificity and provided 2.4-times-higher resolution than ompA sequencing, separating the commonly predominating ompA E/Bour genotype into 7 MLT array genotypes. The MLT array reproduced epidemiological findings revealed by the MLST system and showed sufficient sensitivity to work with clinical specimens. Compared to MLST analysis, the expenses needed for testing a sample with the MLT array are considerably lower. Moreover, testing can be completed within 1 working day rather than 3 or 4 days, with data analysis not requiring highly specialized personnel. The present MLT array represents a powerful alternative in C. trachomatis genotyping.

Meeting sexual partners online: associated sexual behaviour and prevalent chlamydia infection among adolescents in Norway: a cross-sectional study

Objectives Evidence is mixed as to whether meeting sexual partners online (‘internet-partners’) is associated with risky sexual behaviour and/or sexually transmitted infection transmission. Accordingly, we sought to estimate the prevalence of reporting various online romantic and sexual activities among Norwegian adolescents, including internet-partners, and the reason for meeting them and to examine differences in sexual behaviour, partnership characteristics and chlamydia infection prevalence among those reporting internet-partners versus those reporting only offline partners. Methods Population-based cross-sectional survey among sexually experienced girls and boys, 15–20 years, using electronic questionnaires and collecting urine samples for Chlamydia trachomatis PCR testing (79% provided both, n=1023). We used logistic regression to examine associations, adjusting for potentially confounding variables. Results Overall, 30% of both genders reported internet-partners (ever). Boys (but not girls) with internet-partners had higher chlamydia prevalence than those reporting meeting sexual partners only offline (8.1%, 95% CI 4.3% to 13.7% vs 1.6%, 0.5% to 3.7%). Two-thirds of girls and 37% of boys reported meeting their most recent internet-partner to start a romantic relationship, while the remainder did so with the specific intention of having sex. Among both genders, reporting sexual (vs romantic) reasons for meeting their most recent internet-partners was associated with reporting several risky sexual behaviours, including multiple recent sex partners (adjusted OR girls: 3.27, boys: 2.48) and three-fold higher chlamydia prevalence. Conclusions This population-based study suggests that internet-partners are common among adolescents in Norway, and the reason for meeting them was more strongly associated with additionally reporting sexual risk behaviours and prevalent chlamydia infection than the internet itself as a meeting venue.

Sexual identity, attraction and behaviour in Britain: The implications of using different dimensions of sexual orientation to estimate the size of sexual minority populations and inform public health interventions.

Background Sexual orientation encompasses three dimensions: sexual identity, attraction and behaviour. There is increasing demand for data on sexual orientation to meet equality legislation, monitor potential inequalities and address public health needs. We present estimates of all three dimensions and their overlap in British men and women, and consider the implications for health services, research and the development and evaluation of public health interventions. Methods Analyses of data from Britain’s third National Survey of Sexual Attitudes and Lifestyles, a probability sample survey (15,162 people aged 16–74 years) undertaken in 2010–2012. Findings A lesbian, gay or bisexual (LGB) identity was reported by 2·5% of men and 2·4% of women, whilst 6·5% of men and 11·5% of women reported any same-sex attraction and 5·5% of men and 6·1% of women reported ever experience of same-sex sex. This equates to approximately 547,000 men and 546,000 women aged 16–74 in Britain self-identifying as LGB and 1,204,000 men and 1,389,000 women ever having experience of same-sex sex. Of those reporting same-sex sex in the past 5 years, 28% of men and 45% of women identified as heterosexual. Interpretation There is large variation in the size of sexual minority populations depending on the dimension applied, with implications for the design of epidemiological studies, targeting and monitoring of public health interventions and estimating population-based denominators. There is also substantial diversity on an individual level between identity, behaviour and attraction, adding to the complexity of delivering appropriate services and interventions.

Illicit drug use and its association with key sexual risk behaviours and outcomes: Findings from Britain's third National Survey of Sexual Attitudes and Lifestyles (Natsal-3)

Objectives We explore the hypothesis that using illicit drugs other than, or in addition to, cannabis is associated with sexual risk behaviour and sexual health outcomes in the British population. Methods We analysed data, separately by gender, reported by sexually-active participants (those reporting > = 1 partners/past year) aged 16–44 years (3,395 men, 4,980 women) in Britain’s third National Survey of Sexual Attitudes and Lifestyles (Natsal-3), a probability survey undertaken 2010–12 involving computer-assisted personal-interview and computer-assisted self-interview. Analyses accounted for the stratification, clustering and weighting of the data. Multivariable logistic regression was used to calculate adjusted odds ratios. Results Use of illicit drugs other than, or in addition to, cannabis in the past year was reported by 11.5% (95%CI:10.4%-12.8%) of men and 5.5% (4.8%-6.3%) of women. Use of these types of drugs was more common among those <35 years, those who reported poor general and/or sexual health behaviours, e.g. binge drinking > = weekly (age-adjusted ORs, aAORs, 10.91 (6.27–18.97) men; 9.95 (6.11–16.19) women); having > = 2 condomless partners in the past year (aAOR:5.50 (3.61–8.39) men; 5.24 (3.07–8.94) women). Participants reporting illicit drug use were more likely (than those who did not) to report sexual health clinic attendance (ORs after adjusting for age, sexual identity and partner numbers: 1.79 (1.28–2.51) men; 1.99 (1.34–2.95) women), chlamydia testing (1.42 (1.06–1.92) men; 1.94 (1.40–2.70) women), unplanned pregnancy (2.93 (1.39–6.17) women), and among men only, sexually transmitted infection diagnoses (3.10 (1.63–5.89)). Conclusions In Britain, those reporting recent illicit drug use were more likely to report other markers of poor general and sexual health. They were also more likely to attend sexual health clinics so these should be considered appropriate settings to implement holistic interventions to maximise health gain.

Self-perceived risk and prevalent chlamydia infection among adolescents in Norway: a population-based cross-sectional study

Objectives Risk judgements are key factors in adolescents’ decisions related to sexual health. We examine the associations between self-perceived risk and prevalent chlamydia infection, and sexual behaviours related to risk perception in a general adolescent population in Norway. Methods Population-based cross-sectional study among 1028 sexually experienced girls and boys, age 15–20 years (85% participation), including web questionnaires and urine samples for Chlamydia trachomatis PCR testing. Participants rated self-perceived risk as: no/low/medium/high/very high. We used binary and ordinal logistic regressions to examine associations with chlamydia prevalence and self-perceived risk, respectively, adjusting for potentially confounding variables. Results Chlamydia prevalence increased with increasing risk perception. Although girls had twice the chlamydia prevalence of boys (7.3% vs 3.9%), their risk distribution was similar and 65% of both genders rated their risk as no/low with half of infections detected in this group. In multivariable analyses, reporting multiple sexual risk behaviours, non-steady relationship, previous chlamydia testing and treatment, and urogenital symptoms increased self-perceived risk. More boys overestimated their personal risk whereas more girls underestimated it (52% vs 30%, respectively, and 15% vs 31%, p<0.001). The main reasons for perceiving no/low risk were: ‘I have a steady partner’ and ‘I trust my partner will tell me about an infection’. Conclusions These sexually experienced adolescents acknowledged their chlamydia infection risk, but wrong beliefs were incorporated in their assessments, and more than half had incorrect risk perception. We suggest that sexually transmitted infection prevention programmes should be directed at closing the gap between perceived and actual risk and focus on how context may bias personal judgement.

Finding sexual partners online: prevalence and associations with sexual behaviour, STI diagnoses and other sexual health outcomes in the British population

Objectives Online venues might facilitate sexual encounters, but the extent to which finding partners online is associated with sexual risk behaviour and sexual health outcomes is unclear. We describe use of the internet to find sexual partners in a representative sample in Britain. Methods The third National Survey of Sexual Attitudes and Lifestyles (Natsal-3) was a cross-sectional probability survey of 15 162 adults (aged 16–74 years) undertaken 2010–2012. We estimated prevalence of, and identified factors associated with, finding sexual partners online among those reporting ≥1 new sexual partners in the past year. Results Finding sexual partners online in the past year was reported by 17.6% (95% CI 15.6 to 19.9) of men and 10.1% (8.5–11.9) of women, and most common among those aged 35–44 years. After age-adjustment, those reporting a non-heterosexual identity were more likely to report this. Finding partners online was also associated with reporting sexual risk behaviours: condomless sex with ≥2 partners (adjusted OR (aOR) men: 1.52 (1.03 to 2.23); women: 1.62 (1.06 to 2.49)), concurrent partnerships (aOR men: 2.33 (1.62 to 3.35); women: 2.41 (1.49 to 3.87)) and higher partner numbers (reporting ≥5 partners aOR men: 5.95 (3.78 to 9.36); women: 7.00 (3.77 to 13.00)) (all past year). STI diagnoses and HIV testing were more common among men reporting finding partners online (adjusted for age, partner numbers, same-sex partnerships), but not women. Conclusions Finding partners online was associated with markers of sexual risk, which might be important for clinical risk assessment, but this was not matched by uptake of sexual health services. Online opportunities to find partners have increased, so these data might underestimate the importance of this social phenomenon for public health and STI control.

Reported reasons for breakdown of marriage and cohabitation in Britain: Findings from the third National Survey of Sexual Attitudes and Lifestyles (Natsal-3)

Objectives Breakdown of marriage and cohabitation is common in Western countries and is costly for individuals and society. Most research on reasons for breakdown has focused on marriages ending in divorce and/or have used data unrepresentative of the population. We present prevalence estimates of, and differences in, reported reasons for recent breakdown of marriages and cohabitations in Britain. Methods Descriptive analyses of data from Britain’s third National Survey of Sexual Attitudes and Lifestyles (Natsal-3), a probability sample survey (15,162 people aged 16–74 years) undertaken 2010–2012, using computer-assisted personal interviewing. We examined participants’ reported reasons for live-in partnership breakdown in the past 5 years and how these varied by gender and partnership type (married vs. cohabitation). Results Overall, 10.9% (95% CI: 9.9–11.9%) of men and 14.1% (13.2–15.0%) of women reported live-in partnership breakdown in the past 5 years. Mean duration of men’s marriages was 14.2 years (95% CI: 12.8–15.7) vs. cohabitations; 3.5 years (3.0–4.0), and for women: 14.6 years (13.5–15.8) vs. 4.2 years (3.7–4.8). Among 706 men and 1254 women reporting experience of recent breakdown, the reasons ‘grew apart’ (men 39%, women 36%), ‘arguments’ (27%, 30%), ‘unfaithfulness/adultery’ (18%, 24%, p<0.05), and ‘lack of respect/appreciation’ (17%, 25%, p<0.05) were the most common, irrespective of partnership type. A total of 16% of women vs. 4% of men cited domestic violence. After adjusting for age at interview and duration of partnership, there were no significant differences in reasons given for breakup by partnership type, except that men more commonly cited ‘moving due to changing circumstances’ as a reason for a cohabitation ending than for a marriage (AOR = 3.78, 95% CI: 1.08–13.21); and among women, ‘not sharing housework’ (0.54, 0.35–0.83) and ‘sexual difficulties’ (0.45, 0.25–0.84) were less commonly cited as reasons for cohabitation ending than marriage. Conclusion These representative data on recently ended marriages and cohabitations among men and women in Britain show that there were more similarities than differences in the reasons reported for breakdown across partnership type. For both marriages and cohabitations, cited reasons relating to communication and relationship quality issues were most common, followed by unfaithfulness/adultery. Our findings support a focus on relationship quality, including communication and conflict resolution, in preventive and therapeutic interventions addressing breakdown of live-in partnerships.