Screening and genotyping of genital Chlamydia trachomatis in urine specimens from male and female clients of youth-health centers in Stockholm County

Therapeutic Options for Chlamydia trachomatis Infection: Present and Future

Sexually transmitted infections (STIs), such as Chlamydia trachomatis (Ct) infection, have serious consequences for sexual and reproductive health worldwide. Ct is one of the most common sexually transmitted bacterial infections in the world, with approximately 129 million new cases per year. C. trachomatis is an obligate intracellular Gram-negative bacterium. The infection is usually asymptomatic, notwithstanding, it could also be associated with severe sequels and complications, such as chronic pain, infertility, and gynecologic cancers, and thus there is an urgent need to adequately treat these cases in a timely manner. Consequently, beyond its individual effects, the infection also impacts the economy of the countries where it is prevalent, generating a need to consider the hypothesis of implementing Chlamydia Screening Programs, a decision that, although it is expensive to execute, is a necessary investment that unequivocally will bring financial and social long-term advantages worldwide. To detect Ct infection, there are different methodologies available. Nucleic acid amplification tests, with their high sensitivity and specificity, are currently the first-line tests for the detection of Ct. When replaced by other detection methods, there are more false negative tests, leading to underreported cases and a subsequent underestimation of Ct infection's prevalence. Ct treatment is based on antibiotic prescription, which is highly associated with drug resistance. Therefore, currently, there have been efforts in line with the development of alternative strategies to effectively treat this infection, using a drug repurposing method, as well as a natural treatment approach. In addition, researchers have also made some progress in the Ct vaccine development over the years, despite the fact that it also necessitates more studies in order to finally establish a vaccination plan. In this review, we have focused on the therapeutic options for treating Ct infection, expert recommendations, and major difficulties, while also exploring the possible avenues through which to face this issue, with novel approaches beyond those proposed by the guidelines of Health Organizations.

Chlamydia trachomatis as a Current Health Problem: Challenges and Opportunities

Chlamydia is one of the most common sexually transmitted bacterial infections (STIs) worldwide. It is caused by Chlamydia trachomatis (CT), which is an obligate intracellular bacterium. In some cases, it can occur in coinfection with other parasites, increasing the pathologic potential of the infection. The treatment is based on antibiotic prescription; notwithstanding, the infection is mostly asymptomatic, which increases the risk of transmission. Therefore, some countries have implemented Chlamydia Screening Programs in order to detect undiagnosed infections. However, in Portugal, there is no CT screening plan within the National Health Service. There is no awareness in the general healthcare about the true magnitude of this issue because most of the methods used are not Nucleic Acid Amplification Technology-based and, therefore, lack sensitivity, resulting in underreporting infection cases. CT infections are also associated with possible long-term severe injuries. In detail, persistent infection triggers an inflammatory milieu and can be related to severe sequels, such as infertility. This infection could also trigger gynecologic tumors in women, evidencing the urgent need for cost-effective screening programs worldwide in order to detect and treat these individuals adequately. In this review, we have focused on the success of an implemented screening program that has been reported in the literature, the efforts made concerning the vaccine discovery, and what is known regarding CT infection. This review supports the need for further fundamental studies in this area in order to eradicate this infection and we also suggest the implementation of a Chlamydia Screening Program in Portugal.

Condom use among Swedes while traveling internationally: A qualitative descriptive study

This study explores factors influencing condom use among Swedish women and men who visited a sexual health clinic after unprotected sex during international travel. Semi-structured interviews were conducted with 25 women and 25 men. The data were analyzed using conventional content analysis. The informants' narratives were categorized as strategies and barriers. Strategies found were: risk assessment, testing, and treatment for sexually transmitted infections. The barriers were characterized as technical and personal or emotional. The findings indicate that sexual behavior may be different while traveling internationally, and that a release of social constraints and increased alcohol consumption were risk factors for practicing unprotected sex. Some of the strategies may be appropriate for the prevention of sexually transmitted infections, but several strategies and most barriers were used to explain why unprotected sex was practiced. Thus, people need the opportunity to reconsider strategies and strengthen confidence in their ability to use condoms. An individual-based approach employed within routine health care may support the practice of safer sex and prevent further transmission of sexually transmitted infections.

Typing Chlamydia trachomatis: from egg yolk to nanotechnology

A historical review is provided of the various methods used for half a century to differentiate and type Chlamydia trachomatis strains. Typing of C. trachomatis is an important tool for revealing transmission patterns in sexual networks, and enabling association with clinical manifestations and pathogenicity. Serotyping using the major outer membrane protein (MOMP) has been the mainstay of epidemiological work for several decades. However, the development of nucleic acid amplification techniques (NAAT) and easy access to sequencing have shifted the focus from MOMP serotypes to omp1 genotypes. However, insufficient epidemiological resolution is achieved by characterization of both MOMP and omp1. This calls for new high-resolution genotyping methods applying for example a multilocus variable number tandem repeat assay (MLVA) or multilocus sequence typing (MLST). The futuristic nanotechnology already seems at hand to further simplify and automate the high-resolution genotyping method based on NAAT and sequencing of various targets in the C. trachomatis genome. Thereby, a high throughput can be achieved and more epidemiological information can be obtained. However, it is important to realize that culture of C. trachomatis may still be needed to detect and characterize new variants of C. trachomatis.

Efficacy of partner notification for Chlamydia trachomatis among young adults in youth health centres in Uppsala County, Sweden

BACKGROUND

The study was conducted to define the contact-tracing success rate of the partner notification services routinely provided by the community-based youth health centres and the county medical officer for communicable disease control (CMO) in Uppsala County, Sweden.

OBJECTIVE

The study had three goals, (i) to register the number of sexual partners routinely reported by each diagnosed index case with CT and the success rate in tracing and testing these partners for CT infection. (ii) To analyse the current notification practices in reporting the number of cases of unsuccessful contact tracing to the CMO. (iii) To determine the contact tracing success rate of the partner notification services provided by the CMO.

METHODS

Each diagnosed case of CT is obliged by law to participate in the contact-tracing procedure performed by the physician managing the patient or by a specialised sexually transmitted infection (STI) adviser. Successful contact-tracing is defined as the confirmed attendance of a sexual contact within 12 months of the contact with the index case.

RESULTS

The number of CT cases diagnosed by the youth health centres during the study period was 463 (299 females and 164 males). The females reported 660 male sexual contacts and the males reported 386 female contacts. Successful partner notification was achieved for 73% of all sexual contacts. 284 (190 females and 94 males) unsuccessful partner notifications were reported to the CMO of whom 98 (52%) of the female contacts and 20 (21%) of the male contacts were successfully notified by the CMO. However, for 134 (71 females and 63 males) partners, personal details given by the index case were insufficient for identification of the partner.

CONCLUSIONS

When asymptomatic, genital CT infection spreads among sexually active young adults with multiple, unidentified sexual partners, appropriate methods of partner notification are not sufficient to achieve its aims at the population level.

Genotyping of Chlamydia trachomatis from endocervical specimens in Brazil

BACKGROUND

There is no data concerning genotyping of Chlamydia trachomatis from Brazilian samples.

GOAL

To characterize the genotype of C. trachomatis detected in women assisted at a STD public clinic and establish the prevalence of this infection in that population.

STUDY DESIGN

Endocervical samples of a group of 100 women were tested for chlamydial infection with PCR directed to C. trachomatis cryptic plasmid. Genotyping of positive samples were done after omp1 amplification and sequencing.

RESULTS

The overall prevalence of C. trachomatis infection was 19%, with the highest prevalence in women between 15 and 25 years old (68.4%). Four genotypes were found associated with endocervical infections: D, E, F, and K. Sequence analysis revealed a coinfection of genotypes D and E in 1 woman.

CONCLUSIONS

To our knowledge this is the first study to characterize Brazilian C. trachomatis endocervical samples and Brazilian C. trachomatis genotype coinfection. Our results also emphasize the importance of routine diagnosis of C. trachomatis for the control of this STD.

Mailed urine samples are not an effective screening approach for Chlamydia trachomatis case finding among young men

BACKGROUND

Frequency of testing is known to be low for sexually transmitted infections (STIs) in men aged 20-24 years. The use of mailed, home-obtained urine specimens could increase the uptake of young men and facilitate screening programmes for the detection of asymptomatic Chlamydia trachomatis.

OBJECTIVE

The aim of the present study is to evaluate the home screening approach as a tool for recruitment of asymptomatic men for screening of genital C. trachomatis infections.

METHODS

Men aged 19-24 years old (n = 1936) were invited to participate in home-based testing for genital C. trachomatis infection. Persons who agreed to be tested were provided with a testing kit. Self-collected first void urine was sent for testing to the microbiology laboratory. The test result was accessible on the study's web-page 1 week after testing. Individuals with a diagnosed infection were instructed to contact the venereal disease department.

RESULTS

The response rate was 24% (462/1936). The responders' main reason for not participating was a feeling of being safe regarding STIs (87%; 159/182). The primary reason for this feeling of safety was that the responders were in a steady relationship (59%; 107/159). Having sex outside a steady relationship was reported by 36% (90/250) of the responders. The prevalence of C. trachomatis infection among the responders was 2.02% and the reported history of chlamydial infection was 36% (34/95). Out of the responders, 92% (229/249) were, to varying degrees, concerned about getting STIs; however, the majority (72%; 174/242) estimated the risk to be low.

CONCLUSION

Home screening using web-based answer management is a feasible tool for STI screening, which lowers the threshold for people at risk. In this particular population, however, the response rate was too low to be routinely introduced.

Antibiotic consumption and chlamydia prevalence in international studies

BACKGROUND

To determine whether there is an ecological association between antibiotic use and chlamydia prevalence.

METHODS

A systematic review was undertaken of international studies on chlamydia prevalence among women aged 15-25 years published between 2000 and 2005. Preference was given to studies using nucleic acid testing and representative population-based sampling methods. Data were obtained on per capita antibiotic consumption according to the defined daily dose.

RESULTS

For the 12 countries for which both antibiotic consumption and relevant prevalence data for chlamydia were available, a non-significant negative correlation was found between total antibiotic consumption per capita and chlamydia prevalence among younger women according to country (r(s) = -0.242, P = 0.449). When an outlier (from the Netherlands) was excluded, the correlation was significant (r(s) = -0.615, P = 0.044). Combined use of tetracyclines and macrolides was also associated with lower chlamydia prevalence (r(s) = -0.697, P = 0.017).

CONCLUSIONS

It is possible that antibiotics used for other reasons may have unexpectedly reduced the prevalence of chlamydia.

Correlating Chlamydia trachomatis infectious load with urogenital ecological success and disease pathogenesis

The association of infectious burden of Chlamydia trachomatis with patient characteristics and clinical disease may have implications for understanding disease pathogenesis. We examined chlamydial load from 171 urine samples where load was based on copy number of organisms per copy number of eukaryotic cells derived by real-time quantitative PCR. High- (E, F, G) and low-prevalence (Ia, H, J, Ja) genotypes in the population had similar loads, suggesting a similar propensity for replicating in vivo, despite their differential ecological success. Symptomatic and asymptomatic patients also had similar chlamydial loads, indicating that virulence differences are likely not associated with variations in replication. There was a significant difference in genotypes by age for F (<31 years; P = 0.031) and for H where the mean age was lower than for the most prevalent genotype, E (P=0.013). Also, men had a significantly lower load than women when the genotype was F (P=0.042), although there was no significant difference in load between partners. Patients with recurrent chlamydial infections had a significant reduction in load with each subsequent episode regardless of genotype (P=0.007), suggesting that immune defenses do not block chlamydial entry but may impact replication. Additionally, the probability of being infected with J was 7.7-fold higher in patients with prior chlamydial infections (P=0.016), and although the loads were lower when compared with patients without prior infection, the results did not reach statistical significance. These findings suggest that chlamydial burden could be an important marker for recurrence and host immune response, which would facilitate pathogenesis research.

Molecular genetic methods for diagnosis and characterisation of Chlamydia trachomatis and Neisseria gonorrhoeae: impact on epidemiological surveillance and interventions

One of the mainstays in the prevention of Chlamydia trachomatis and Neisseria gonorrhoeae infections is the availability of laboratory diagnostics with high sensitivity and specificity. Assays for diagnosis of C. trachomatis include cell culture and nucleic acid amplification tests (NAATs). The major target sequences for C. trachomatis diagnosis by NAATs are located at the cryptic plasmid and the major target used for characterisation is the omp1 gene. The gold standard for diagnosis of N. gonorrhoeae is culture. However, numerous NAATs for identification of N. gonorrhoeae and a number of molecular genetic methods for characterisation of N. gonorrhoeae have been developed. Probably no routine laboratory can attain as high sensitivity by culturing C. trachomatis or N. gonorrhoeae as by using NAATs. For that reason NAATs can be recommended for diagnosing C. trachomatis, but not as the only diagnostic assay for N. gonorrhoeae, due to lack of antibiotic susceptibility testing and specificity problems, most pronounced for pharyngeal and rectal samples. Genotyping of C. trachomatis or N. gonorrhoeae provides additional information for contact tracing. It is recommended for N. gonorrhoeae, at least in low prevalence geographic areas, but cannot today be recommended for C. trachomatis. This is due to the low genetic variability and hence the limited benefits for partner notification. However, genotyping of C. trachomatis may play an important role under special circumstances.

Variability of the Chlamydia trachomatis omp1 gene detected in samples from men tested in male-only saunas in Melbourne, Australia

A recent screening program in Melbourne, Victoria, Australia, has shown that Chlamydia trachomatis is an important infection among men who frequent male-only saunas. To evaluate the C. trachomatis isolates circulating in local saunas, the C. trachomatis-positive samples collected during the program underwent amplification and sequencing of the omp1 gene, and the corresponding serovars were deduced. Forty-seven C. trachomatis-positive samples collected (from October 2001 to September 2002) from 39 men were evaluated. The deduced serovars found, in descending order of prevalence, were D, G, and J; and serovars B, E, F, and H were each found in single samples. The seven different serovars identified in the study sample indicate that local saunas are a reservoir of multiple C. trachomatis strains, possibly maintained by the introduction of new patrons or regular patrons who have been exposed to C. trachomatis elsewhere. No significant genetic variants were found, as most variable positions were silent and were detected only in single samples.

Genotyping of Chlamydia trachomatis would improve contact tracing

BACKGROUND

The reported number of Chlamydia trachomatis genital infections has increased 15% annually since 1997 in Sweden. Inaccurate partner notification might be one reason.

GOAL

The goals were to determine if genotyping of C trachomatis would improve partner notification and to study the duration of infection.

STUDY DESIGN

Sexual networks were constructed. C trachomatis isolates from 231 individuals attending the Orebro STD clinic during 1 year were typed by sequencing of the omp1 gene.

RESULTS

All individuals were traced and diagnoses were established in 30 of 161 networks. More than one genotype was seen in seven networks. The mean duration of C trachomatis infection in each network was calculated to be 23 weeks.

CONCLUSION

Genotyping could be a useful tool in partner notification when there are discrepant or uncommon genotypes. Limited clinic catchment areas create information difficulties that obstruct accurate contact tracing.