Introduction ofChlamydia trachomatisscreening for young women in Germany

Informative array testing with multiplex assays

High-volume testing of clinical specimens for sexually transmitted diseases is performed frequently by a process known as group testing. This algorithmic process involves testing portions of specimens from separate individuals together as one unit (or "group") to detect diseases. Retesting is performed on groups that test positively in order to differentiate between positive and negative individual specimens. The overall goal is to use the least number of tests possible across all individuals without sacrificing diagnostic accuracy. One of the most efficient group testing algorithms is array testing. In its simplest form, specimens are arranged into a grid-like structure so that row and column groups can be formed. Positive-testing rows/columns indicate which specimens to retest. With the growing use of multiplex assays, the increasing number of diseases tested by these assays, and the availability of subject-specific risk information, opportunities exist to make this testing process even more efficient. We propose specific specimen arrangements within an array that can reduce the number of retests needed when compared with other array testing algorithms. We examine how to calculate operating characteristics, including the expected number of tests and the SD for the number of tests, and then subsequently find a best arrangement. Our methods are illustrated for chlamydia and gonorrhea detection with the Aptima Combo 2 Assay. We also provide R functions to make our research accessible to laboratories.

Age specific evaluation of sexual behavior, STI knowledge and infection among asymptomatic adolescents and young adults

OBJECTIVES

Adolescents and young adults account for 50% of new infections with sexually transmitted infection (STI), while representing only 25% of the sexually active population. An evaluation of sexual behavior, STI knowledge and infection among youth of different age groups is relevant to formulate effective sexual health strategies.

METHODS

In this monocentric, open, prospective cross-sectional study, 268 asymptomatic subjects (14-30 years) were partitioned into three cohorts I: 14-19 (n=42), II: 20-25 (n=147) and III: 25-30 (n=79) years. A comparative analysis of their sexual behavior and STI knowledge was performed using a 21-item questionnaire at the WIR-Center for Sexual Health and Medicine. Prevalence of chlamydia and gonococcal infections were tested, using the Cepheid Xpert® CT/NG assay.

RESULTS

The three age-specific cohorts showed statistically significant differences in their relationship status, their sexual contacts and the number of life-time sexual partners. Independent of age, men who have sex with men had greater number of sexual partners across all age groups. Although >95% of participants were aware of HIV in all age groups, the corresponding awareness of non-HIV STI was consistently lower in cohort I. The awareness of trichomonas, mycoplasma and candida in particular was <50% across all agedemographies. Chlamydia screening remains poor despite current chlamydia infection among cohort I, II & III being 7.1%, 5.4%, & 11.4% respectively.

CONCLUSION

Our study demonstrates a demographic divide in the knowledge on most frequent STI apart from HIV. Current education, screening and vaccination programs for STI among the younger demographic should be improved.

The objective function controversy for group testing: Much ado about nothing?

Group testing is an indispensable tool for laboratories when testing high volumes of clinical specimens for infectious diseases. An important decision that needs to be made prior to implementation is determining what group sizes to use. In best practice, an objective function is chosen and then minimized to determine an optimal set of these group sizes, known as the optimal testing configuration (OTC). There are a few options for objective functions, and they differ based on how the expected number of tests, assay characteristics, and testing constraints are taken into account. These varied options have led to a recent controversy in the literature regarding which of two different objective functions is better. In our paper, we examine these objective functions over a number of realistic situations for infectious disease testing. We show that this controversy may be much ado about nothing because the OTCs and corresponding results (eg, number of tests and accuracy) are largely the same for standard testing algorithms in a wide variety of situations.

[Sexually transmitted infections in Germany : The current epidemiological situation]

Sexually transmitted infections (STIs) can impair sexual health. Surveillance and study data were used to provide an overview over STIs in Germany. We estimated 3900 new HIV diagnoses in 2015. Of newly diagnosed infections, 57% were attributed to men who have sex with men (MSM). It was further estimated that there were 3200 new HIV infections and 84,700 people living with HIV in 2015. A total of 6834 syphilis infections were recorded in 2015, which corresponds to an increase of 149% since 2009. The incidence in men was 16-times higher than in women. Of syphilis infections, 85% could be attributed to MSM. Antimicrobial resistance of gonococci against the broad-spectrum antibiotic cefixime decreased between 2014 and 2016 after a change of therapy guidelines and remained stable on a low level regarding the antibiotic ceftriaxone. After an increase of resistance against the antibiotic azithromycin to 11.3% in 2015, we observed a decreasing trend in 2016. Between 2013 and 2015, 2,355,336 chlamydia tests were reported through the chlamydia sentinel network. Of these, 92.5% of samples were from women. Uptake for screening for women <25 years was 11.3% in 2015, with 5.0% positive chlamydia tests. In a cross-sectional study among women aged 20-25 years, a prevalence of human papilloma virus (HPV) of 38.1% was observed. A total of 30.5% of 15-year-old women were vaccinated against HPV in 2014. Data suggest that STIs represent a high burden of disease. Knowledge of STI prevention should be improved by targeted education campaigns. Extending existing offers for counselling and testing through cooperation between different health sectors would improve early diagnosis and treatment of STIs.

Not again! Effect of previous test results, age group and reason for testing on (re-)infection with Chlamydia trachomatis in Germany

Background

Infection with Chlamydia trachomatis (Ct) is the most commonly reported sexually transmitted infection in Europe. In Germany, Ct screening is offered free of charge to pregnant women since 1995 and to women < 25 years of age since 2008. For symptomatic individuals, testing is covered by statutory health insurance. Study results have shown that repeat Ct infection occurs in 10–20% of previously infected women and men. Our aim was to describe persons tested for Ct and to investigate the determinants of (repeat) Ct infection in women and men in Germany.

Methods

We analysed Ct test results from men and women tested between 2008 and 2014 in laboratories participating in the German Chlamydia trachomatis Laboratory Sentinel surveillance. Reinfection was defined as at least 2 positive laboratory tests within more than 30 days. We performed logistic regression stratified by sex and, for women, reason for testing to determine the effect of previous test results and age group on subsequent test results.

Results

In total, 2,574,635 Ct tests could be attributed to 1,815,494 women and 123,033 men. 5% of women and 14% of men tested positive at least once. 15–19- and 20–24-year-old women tested positive at least once respectively in 6.8 and 6.0%, while men respectively in 16.6 and 21.2%. Altogether, 23.1% of tested women and 11.9% of tested men were tested repeatedly between 2008 and 2014. Among those who previously tested positive, reinfection occurred in 2.0% of women and 6.6% of men. Likelihood to be tested Ct positive was higher in women and men with a positive Ct test in the past compared to previously tested Ct negative, odds ratios 4.7 and 2.6 (p < 0.01) respectively. Odds ratios ranged by age group and test reason.

Conclusion

A history of Ct infection increased the likelihood of infection with Ct in women and men taking into account the result of the previous test. Health education, safer sex and treatment of partners are necessary for women and men who have tested positive to prevent reinfection and complications and to interrupt the chain of transmission. To identify potential reinfection repeat testing after treatment should be performed.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3323-2) contains supplementary material, which is available to authorized users.

STI Knowledge in Berlin Adolescents

Sexually transmitted infections (STIs) pose a significant threat to individual and public health. They disproportionately affect adolescents and young adults. In a cross-sectional study, we assessed self-rated and factual STI knowledge in a sample of 9th graders in 13 secondary schools in Berlin, Germany. Differences by age, gender, migrant background, and school type were quantified using bivariate and multivariable analyses. A total of 1177 students in 61 classes participated. The mean age was 14.6 (SD = 0.7), 47.5% were female, and 52.9% had at least one immigrant parent. Knowledge of human immunodeficiency virus (HIV) was widespread, but other STIs were less known. For example, 46.2% had never heard of chlamydia, 10.8% knew of the HPV vaccination, and only 2.2% were aware that no cure exists for HPV infection. While boys were more likely to describe their knowledge as good, there was no general gender superiority in factual knowledge. Children of immigrants and students in the least academic schools had lower knowledge overall. Our results show that despite their particular risk to contract an STI, adolescents suffer from suboptimal levels of knowledge on STIs beyond HIV. Urgent efforts needed to improve adolescent STI knowledge in order to improve the uptake of primary and secondary prevention.

Establishment of a voluntary electronic Chlamydia trachomatis laboratory surveillance system in Germany, 2008 to 2014

Chlamydia trachomatis (CT) infections are not reportable in Germany and limited data on prevalence are available. CT screening has been offered free of charge to pregnant women since 1995 and to all women under 25 years since 2008. For symptomatic women and men, diagnostic testing is covered by statutory health insurance. We describe the establishment of a nationwide, laboratory-based, voluntary sentinel that electronically collects information on all performed CT tests with test results, test reason and patient information. The sentinel represents one third of all performed CT tests in Germany. In the period from 2008 to 2014, 3,877,588 CT tests were reported, 93% in women. Women aged 20–24 years and men aged 25–29 years were the most frequently tested age groups. The overall proportion of positive tests (PPT) among women was 3.9% and among men 11.0%. The highest PPT among women was in the age groups 15–19 (6.8%) and 20–24 years (5.9%), and among men in the age groups 20–24 (19.2%), 15–19 (15.4%) and 25–29 years (14.8%). The PPT for CT was high among women and men younger than 25 years. Prevention is urgently needed. Monitoring of CT infection in Germany should be continued.

[Epidemiological developments of selected sexually transmitted infections in Germany]

The number of people living with HIV infection has been increasing since the mid 1990s and is expected to rise further in the coming years. The HIV epidemic in Germany is still most affected by developments in the group of men who have sex with men (MSM). In this group, the number of newly diagnosed HIV infections has increased in recent years especially in large cities. Despite increased efforts to motivate HIV-infected people, who were not previously diagnosed, to be tested as early as possible and to seek medical treatment, the number of undiagnosed HIV-infected persons has increased. There are more people infected with HIV than those who have been tested positive for HIV and subsequently receive antiretroviral treatment. However, early testing and treatment alone are not sufficient to effectively contain the infection. Increased efforts are required to more effectively prevent new HIV infections by combining all the available options. In Germany as in all other developed countries, a stronger increase in the number of syphilis infections among MSM is reported, which is primarily due to a higher willingness to risk unprotected contacts, whereby the risk of HIV infection is also increased. The public prevention messages available for HIV are only partially effective against syphilis. More frequent examinations and optimized therapy management are necessary in addition to the use of condoms to prevent the spread of syphilis, gonorrhea, and Chlamydia trachomatis. Sustainable containment of new HIV infections must, therefore, be accompanied by both containment of sexually transmitted infections (STI) and use of public prevention messages for HIV/STI.

Optimal retesting configurations for hierarchical group testing

Hierarchical group testing is widely used to test individuals for diseases. This testing procedure works by first amalgamating individual specimens into groups for testing. Groups testing negatively have their members declared negative. Groups testing positively are subsequently divided into smaller subgroups and are then retested to search for positive individuals. In our paper, we propose a new class of informative retesting procedures for hierarchical group testing that acknowledges heterogeneity among individuals. These procedures identify the optimal number of groups and their sizes at each testing stage in order to minimize the expected number of tests. We apply our proposals in two settings: 1) HIV testing programs that currently use three-stage hierarchical testing and 2) chlamydia and gonorrhea screening practices that currently use individual testing. For both applications, we show that substantial savings can be realized by our new procedures.

Risk factors for Chlamydia trachomatis infection in adolescents: results from a representative population-based survey in Germany, 2003-2006

Infections with Chlamydia trachomatis (CT) can lead to severe sequelae; however, they are not notifiable in Germany. We tested urine samples from participants of KiGGS (German Health Interview and Examination Survey for Children and Adolescents) for CT infections and linked the results to demographic and behavioural data from 1,925 participants (girls aged 15-17 years and boys aged 16-17 years) to determine a representative prevalence of CT infection in adolescents in Germany and to assess associated risk factors. Prevalence of CT infection was 2.2% (95% CI: 1.4-3.5) in girls and 0.2% (95% CI: 0.1-0.7) in boys. CT infection in girls was associated with higher use of alcohol, marijuana and cigarettes, lower social status, oral contraceptive use, pregnancy, repeated lower abdominal pain and higher rates of doctors' consultations within the preceding three months and consultation of gynaecologists within the last 12 months. In multiple logistic regression, we identified two predictors for CT infection: marijuana consumption often or several times within the last 12 months (F(1,164)=7.56; p<0.05) and general health status less than 'very good' (F(1,164)=3.83; p=0.052). Given our findings, we recommend enhancing sex education before sexual debut and promoting safe sex practices regardless of the contraceptive method used. Well-informed consumption of alcohol should be promoted, the risky behaviour of people intoxicated through consumption of marijuana highlighted and doctors' awareness of CT screening enhanced.

Chlamydia trachomatis infection of the male genital tract: an update

Chlamydia trachomatis (CT) is the most prevalent cause of sexually transmitted diseases. Although the prevalence of chlamydial infection is similar in men and women, current research and screening are still focused on women, who develop the most severe complications, leaving the study of male genital tract (MGT) infection underrated. Herein, we reviewed the literature on genital CT infection with special focus on the MGT. Data indicate that CT certainly infects different parts of the MGT such as the urethra, seminal vesicles, prostate, epididymis and testis. However, whether or not CT infection has detrimental effects on male fertility is still controversial. The most important features of CT infection are its chronic nature and the presence of a mild inflammation that remains subclinical in most individuals. Chlamydia antigens and pathogen recognition receptors (PRR), expressed on epithelial cells and immune cells from the MGT, have been studied in the last years. Toll-like receptor (TLR) expression has been observed in the testis, epididymis, prostate and vas deferens. It has been demonstrated that recognition of chlamydial antigens is associated with TLR2, TLR4, and possibly, other PRRs. CT recognition by PRRs induces a local production of cytokines/chemokines, which, in turn, provoke chronic inflammation that might evolve in the onset of an autoimmune process in genetically susceptible individuals. Understanding local immune response along the MGT, as well as the crosstalk between resident leukocytes, epithelial, and stromal cells, would be crucial in inducing a protective immunity, thus adding to the design of new therapeutic approaches to a Chlamydia vaccine.

Group testing regression model estimation when case identification is a goal

Group testing is frequently used to reduce the costs of screening a large number of individuals for infectious diseases or other binary characteristics in small prevalence situations. In many applications, the goals include both identifying individuals as positive or negative and estimating the probability of positivity. The identification aspect leads to additional tests being performed, known as "retests", beyond those performed for initial groups of individuals. In this paper, we investigate how regression models can be fit to estimate the probability of positivity while also incorporating the extra information from these retests. We present simulation evidence showing that significant gains in efficiency occur by incorporating retesting information, and we further examine which testing protocols are the most efficient to use. Our investigations also demonstrate that some group testing protocols can actually lead to more efficient estimates than individual testing when diagnostic tests are imperfect. The proposed methods are applied retrospectively to chlamydia screening data from the Infertility Prevention Project. We demonstrate that significant cost savings could occur through the use of particular group testing protocols.

Pooled-testing procedures for screening high volume clinical specimens in heterogeneous populations

Pooled testing is a procedure commonly used to reduce the cost of screening a large number of individuals for infectious diseases. In its simplest form, pooled testing works by compositing a set of individual specimens (e.g., blood or urine) into a common pool. If the pool tests negative, all individuals within it are diagnosed as negative. If the pool tests positive, retesting is needed to decode the positive individuals from the negative individuals. Traditionally, pooled testing has assumed that each individual has the same probability of being positive. However, this assumption is often unrealistic, especially when known risk factors can be used to measure distinct probabilities of positivity for each individual. In this paper, we investigate new pooled-testing algorithms that exploit the heterogeneity among individual probabilities and subsequently reduce the total number of tests needed, while maintaining accuracy levels similar to standard algorithms that do not account for heterogeneity. We apply these algorithms to data from the Infertility Prevention Project, a nationally implemented program supported by the Centers for Disease Control and Prevention.

Group testing in heterogeneous populations by using halving algorithms

Group (pooled) testing is often used to reduce the total number of tests that are needed to screen a large number of individuals for an infectious disease or some other binary characteristic. Traditionally, research in group testing has assumed that each individual is independent with the same risk of positivity. More recently, there has been a growing set of literature generalizing previous work in group testing to include heterogeneous populations so that each individual has a different risk of positivity. We investigate the effect of acknowledging population heterogeneity on a commonly used group testing procedure which is known as 'halving'. For this procedure, positive groups are successively split into two equal-sized halves until all groups test negatively or until individual testing occurs. We show that heterogeneity does not affect the mean number of tests when individuals are randomly assigned to subgroups. However, when individuals are assigned to subgroups on the basis of their risk probabilities, we show that our proposed procedures reduce the number of tests by taking advantage of the heterogeneity. This is illustrated by using chlamydia and gonorrhoea screening data from the state of Nebraska.