Minimum spread of the new Swedish variant of Chlamydia trachomatis and distribution of C. trachomatis ompA genotypes in three geographically distant areas of Spain, 2011-2012

Genome organization and genomics in Chlamydia: whole genome sequencing increases understanding of chlamydial virulence, evolution, and phylogeny

The genus Chlamydia contains important obligate intracellular bacterial pathogens to humans and animals, including C. trachomatis and C. pneumoniae. Since 1998, when the first Chlamydia genome was published, our understanding of how these microbes interact, evolved and adapted to different intracellular host environments has been transformed due to the expansion of chlamydial genomes. This review explores the current state of knowledge in Chlamydia genomics and how whole genome sequencing has revolutionised our understanding of Chlamydia virulence, evolution, and phylogeny over the past two and a half decades. This review will also highlight developments in multi-omics and other approaches that have complemented whole genome sequencing to advance knowledge of Chlamydia pathogenesis and future directions for chlamydial genomics.

Genetic Characterization of Non-Lymphogranuloma venereum Chlamydia trachomatis Indicates Distinct Infection Transmission Networks in Spain

Chlamydia trachomatis infection is an important public health problem. Our objective was to assess the dynamics of the transmission of this infection, analysing the distribution of circulating ompA genotypes and multilocus sequence types of C. trachomatis in Spain as a function of clinical and epidemiological variables. During 2018 and 2019, we genetically characterized C. trachomatis in tertiary hospitals in six areas in Spain (Asturias, Barcelona, Gipuzkoa, Mallorca, Seville and Zaragoza), with a catchment population of 3.050 million people. Genotypes and sequence types were obtained using polymerase chain reaction techniques that amplify a fragment of the ompA gene, and five highly variable genes (hctB, CT058, CT144, CT172 and pbpB), respectively. Amplicons were sequenced and phylogenetic analysis was conducted. We obtained genotypes in 636/698 cases (91.1%). Overall and by area, genotype E was the most common (35%). Stratifying by sex, genotypes D and G were more common among men, and genotypes F and I among women (p < 0.05). Genotypes D, G and J were more common in men who have sex with men (MSM) than in men who have sex with women (MSW), in whom the most common genotypes were E and F. The diversity index was higher in sequence typing (0.981) than in genotyping (0.791), and the most common sequence types were ST52 and ST108 in MSM, and ST30, ST148, ST276 and ST327 in MSW. Differences in genotype distribution between geographical areas were attributable to differences in population characteristics. The transmission dynamics varied with sexual behaviour: the predominant genotypes and most frequent sequence types found in MSM were different to those detected in MSW and women.

An Asymptomatic Patient with Fatal Infertility Carried a Swedish Strain of Chlamydia trachomatis with Additional Deletion in The Plasmid orf1 that Belonged to A Different MLST Sequence Type

Here, we present the first case of asymptomatic genital Chlamydial infection caused by the new emerging Chlamydia trachomatis (C.t.) ST13 strain genovar E, which has a double deletion of 377 bp and 17 bp in orf1 gene of the cryptic plasmid (ddCT). This case occurred in an infertile patient (case-patient) with a detectable level of Chlamydial antibodies and a spermatozoa deficiency known as azoospermia. Additionally, the ddCT strain showed the presence of a duplication of 44 bp in the plasmid orf3 and SNP in orf4, which were known as the typical characteristics of the Swedish variant of C.t. (nvCT) genovar E. Multilocus sequence typing (MLST) determined a significant difference between ddCT and nvCT in four alleles (oppA, hfiX, gitA and enoA). Both ddCT and nvCT were assigned to different genetic lineages and could be allocated to two different non-overlapping clonal complexes. Furthermore, ddCT demonstrated a considerable difference among 4–5 alleles in comparison with other C.t. strains of genovar E of ST4, ST8, ST12, and ST94, including the founder of a single relevant cluster, wtCT E/SW3 (Swedish genetic lineage). In contrast to other genovar E strains, ddCT had identical alleles with seven out of seven loci found in ST13 strains of genovars D and G, including the founder for this clonal group, D/UW-3/CX, and six out of seven loci found in its derivatives, such as ST6, ST10, and ST95 of genovars G and H. Nevertheless, MSTree V2 showed that ddCT and nvCT could have a common early ancestor, which is a parental C.t. G/9301 strain of ST9. A significant difference between ddCT and nvCT of genovar D (nvCT-D) that was recently found in Mexico was also determined as: (i) ddCT belonged to genovar E but not to genovar D; (ii) ddCT had a 44 bp duplication within the orf3 of the plasmid typical for nvCT; (iii) ddCT possessed an additional 17 bp deletion in the orf1. In conclusion, improved case management should include the clinical physician’s awareness of the need to enhance molecular screening of asymptomatic Chlamydia patients. Such molecular diagnostics might be essential to significantly reducing the global burden of Chlamydial infection on international public health.

Infections caused by Chlamydia trachomatis (including lymphogranuloma venereum) and Mycoplasma genitalium

Sexually transmitted infections caused by Chlamydia trachomatis, including lymphogranuloma venereum and Mycoplasma genitalium have increased in last decade. This epidemiological scenario presents new challenges in order to improve and strengthen our control and prevention strategies. The routine clinical diagnosis of urethritis and cervicitis must be combined with the active search for the causal agent in men with symptoms of dysuria or proctitis, and in women with pelvic inflammatory disease. We should also include sexually transmitted infections screening in asymptomatic patients with sexual risk behaviours or sexual contact with patients diagnosed with an sexually transmitted infection. The microbiological diagnosis must be based on molecular techniques capable of detecting Chlamydia trachomatis (discriminating between L genotypes associated with lymphogranuloma venereum and other genotypes) and Mycoplasma genitalium (ideally including the identification of macrolide-resistant strains). A faster and specific diagnosis will allow for a targeted treatment with a suitable antibiotic regimen. We also recommend including contact tracing of sexual partners and, occasionally, a cure test. Finally, sexually transmitted infection screening must be widely implemented in those population groups with a high prevalence of sexually transmitted infections.

Identification of a new variant of Chlamydia trachomatis in Mexico

INTRODUCTION

Chlamydia trachomatis is one of the main etiological agents of sexually transmitted infections worldwide. In 2006, a Swedish variant of C. trachomatis (Swedish-nvCT), which has a deletion of 377bp in the plasmid, was reported. In Latin America, Swedish-nvCT infections have not been reported. We investigated the presence of Swedish-nvCT in women with infertility in Mexico.

METHODS

Swedish-nvCT was searched in 69C. trachomatis positive samples from 2339 endocervical specimens. We designed PCR primers to identify the deletion in the plasmid in the ORF1, and the presence of a repeated 44bp in the ORF3. The sample with the deletion was genotyped with the genes of the major outer membrane protein A (ompA) and the polymorphic membrane protein (pmpH).

RESULTS

The deletion was detected in one of the 69 samples positive C. trachomatis of 2339 endocervical exudates. The nucleotide sequence analysis of the ompA shows a high degree of similarity with the Swedish nvCT (98%), however the variant found belongs to serovar D. The nucleotide sequence of the pmpH gene associates to the variant found in the genitourinary pathotype of the Swedish-nvCT but in different clusters.

CONCLUSIONS

Our results revealed the presence of a new variant of C. trachomatis in Mexican patients. This variant found in Mexico belongs to serovar D based on the in silico analysis of the ompA and pmpH genes and differs to the Swedish-nvCT (serovars E). For these variants of C. trachomatis that have been found it is necessary to carry out a more detailed analysis, although the role of this mutation has not been demonstrated in the pathogenesis.

Chlamydia trachomatis genotypes A and B from urogenital specimens of patients in Spain: molecular characterization

OBJECTIVES

Chlamydia trachomatis ompA genotypes A and B, primarily associated with trachoma, were unexpectedly detected in urogenital samples of patients in Spain, a trachoma-free country. In this study, we aimed to explain this finding using analysis of organotropism-related genes and a multilocus sequence typing (MLST) technique.

METHODS

C. trachomatis genotypes A or B were detected in 8/930 (0.9%) infection episodes between 2006 and 2012. In these strains, organotropism-related genes (polymorphic membrane protein gene H, tryptophan synthase gene A, CTA0934, and cytotoxin) were studied. Further, the strains were analysed by MLST, using a polymerase chain reaction that amplifies five highly variable genomic loci (hctB, CT058, CT144, CT172, and pbpB). Amplicons were sequenced and phylogenetic analysis was conducted.

RESULTS

Seven strains were detected in the eight infection episodes (in one patient, an identical strain being found in two episodes). Analysis of organotropism-related genes showed that these strains shared genetic features characteristic of genitotropic genotypes but not of trachoma strains. Three strains of genotype A showed a unique and new MLST-sequence type (ST551, allele profile 8-8-2-27-69). The four strains of genotype B belonged to ST138.

CONCLUSIONS

C. trachomatis ompA genotypes A and B associated with trachoma, but detected sporadically in urogenital samples in trachoma-free countries, may be the result of recombination between strains adapted to trachoma and strains adapted to sexual transmission.

Ten years transmission of the new variant of Chlamydia trachomatis in Sweden: prevalence of infections and associated complications

OBJECTIVES

In 2006, a new variant of Chlamydia trachomatis (nvCT) was discovered in Sweden. It has a deletion in the plasmid resulting in failed detection by the single target systems from Abbott and Roche used at that time, whereas the third system used, from Becton Dickinson (BD), detects nvCT. The proportion of nvCT was initially up to 65% in counties using Abbott/Roche systems. This study analysed the proportion of nvCT from 2007 to 2015 in four selected counties and its impact on chlamydia-associated complications.

METHODS

C. trachomatis-positive specimens collected from 2007 to 2015 were analysed by a specific PCR to identify nvCT cases. Genotyping was performed by multilocus sequence typing (MLST) and ompA sequencing. Ectopic pregnancy and pelvic inflammatory disease records were extracted from the national registers.

RESULTS

In total, 5101 C. trachomatis-positive samples were analysed. The nvCT proportion significantly decreased in the two counties using Roche systems, from 56% in 2007 to 6.5% in 2015 (p<0.001). In the two counties using BD systems, a decrease was also seen, from 19% in 2007 to 5.2% in 2015 (p<0.001). Fifteen nvCT cases from 2015 and 102 cases from 2006 to 2009 had identical MLST profiles. Counties using Roche/Abbott systems showed higher mean rates of ectopic pregnancy and pelvic inflammatory disease compared with counties using BD systems.

CONCLUSIONS

The nvCT proportion has decreased in all counties and converged to a low prevalence irrespective of previous rates. Genotyping showed that nvCT is clonal and genetically stable. Failing detection only marginally affected complication rates.

Opportunities and pitfalls of molecular testing for detecting sexually transmitted pathogens

In the last 20 years, nucleic acid amplification tests (NAATs) have gradually replaced traditional methods for the detection of sexually transmitted infections. NAAT technology comes with some considerable benefits for diagnosis, including increased sensitivity, rapid result turnaround and suitability for high throughput screening of asymptomatic individuals using more-readily available specimens. However, the transition to NAAT has not come without its problems. False-negative and false-positive results have been reported owing to various technical issues. Furthermore, increased reliance on NAATs for diagnosis have created the need to develop NAAT-based methods to inform treatment, being an area that presents its own set of challenges. In this review article, we explore NAAT-based detection of Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma genitalium and Trichomonas vaginalis. In doing so, we consider the benefits and limitations of NAAT-based technology and highlight areas where further research and development is in need.

Evaluation of a dilution method for non-evaluable results in the detection of Chlamydia trachomatis and Neisseria gonorrhoeae with the Cobas 4800 platform

INTRODUCTION

A variable percentage of samples analysed using the Cobas 4800 assay can give an invalid result by PCR inhibition or erroneous due to incorrect DNA extraction with the Cobas 4800 CT/NG test.

METHOD

An analysis was performed using the vortex agitation and dilution protocol on the original sample (swab or urine) for a total of 116 samples. In order to analyse the sensitivity of this method, 100 samples (swabs and urine) with known results were retested.

RESULTS

A total of 98.3% (114/116) of the samples analysed were resolved with this protocol with 100% agreement after reviewing clinical data, Gram stain, and other samples analysed in parallel from the same patient.

DISCUSSION

The data indicate no loss of sensitivity with this protocol; thus Cobas 4800 users could use this method without the need for alternative methods.

Comparison of the CT OligoGen kit with cobas 4800 assay for detection of Chlamydia trachomatis

INTRODUCTION

A prospective study was designed to assess the performance of the new CT OligoGen kit and the cobas 4800 assay for detection of Chlamydia trachomatis.

METHODS

A set of samples that included urine samples (n=212), endocervical (n=167), rectal (n=53), pharyngeal (n=7) and urethral swabs (n=3). The samples were sent from a regional sexually transmitted diseases (STD) clinic in Seville, Spain, and were collected from 261 men and 181 women. Discordant results were re-analyzed and clinical data and other tests were reviewed in order to resolve them.

RESULTS

Sensitivity, specificity, positive predicative value (PPV), negative predictive value (NPV) and kappa value for C. trachomatis detection using the CT OligoGen kit were 98.5%, 100%, 100%, 95.4% and 0.97, respectively.

CONCLUSIONS

This new kit had a high sensitivity, specificity, PPV and NPV for C. trachomatis, therefore the performance profile confirms the usefulness and reliable results of this new assay.