Chlamydia trachomatis serovar distribution and other concurrent sexually transmitted infections in heterosexual men with urethritis in Italy

Main etiological agents identified in 170 men with urethritis attended at the Fundação Alfredo da Matta, Manaus, Amazonas, Brazil

Background

Sexually transmitted infections (STI) are a global public health problem. Urethritis are among the most common STIs, and can cause several complications and facilitate the transmission of the HIV virus.

Objectives

To investigate the main etiologic agents of urethritis in 170 men treated at Fundação Alfredo da Matta.

Methods

To identify the agents, urethral exudate and urine were collected. Gram and culture tests were performed in Thayer-Martin medium for Neisseria gonorrhoeae and polymerase chain reaction for Neisseria gonorrhoeae, Chlamydia trachomatis, Trichomonas vaginalis, Ureaplasma urealyticum, Ureaplasma parvum, Mycoplasma hominis, Mycoplasma genitalium, and herpes simplex types 1 and 2.

Results

N. gonorrhoeae were identified in 102 (60.0%) patients, C. trachomatis in 50 (29.4%), U. urealyticum in 29 (17.0%), M. genitalium in 11 (6.5 %), U. parvum in ten (5.9%), and M. hominis in seven (4.1%). Herpes simplex type 2 was diagnosed in 24 (21.6%) of the 111 patients who underwent PCR for this pathogen. In 69 cases there was co-infection; the most frequent were: N. gonorrhoeae and C. trachomatis in 21 (14.7%) patients; N. gonorrhoeae and C. trachomatis in 21 (12.4%) patients; N. gonorrhoeae and herpes simplex type 2 in 11 (6.5%), and N. gonorrhoeae and U. urealyticum in nine (5.3%).

Study limitations

Not relevant.

Conclusion

N. gonorrhoeae, C. trachomatis, U. urealyticum, and herpes simplex type 2 were the pathogens most frequently identified in the present study. The main coinfection found was N. gonorrhoeae and C. trachomatis. T. vaginalis and herpes simplex type 1 were not identified in any of the patients.

Gender differences in risk taking behaviors for Chlamydia trachomatis

Chlamydia trachomatis (CT) is a global problem. We compared the risk taking behaviors for CT infection between men and women. Adults (2299 females, 5559 males) were administered the Risk Behavior Assessment. In women, CT was associated with candidiasis, in men with gonorrhea, genital warts, and syphilis. Risk factors for both genders were trading sex for money, use of marijuana for women, and use of Ecstasy and Viagra for men. Those with CT had higher risk perception for HIV infection and were more likely to obtain HIV testing. Patient teaching and concurrent testing for HIV and CT are imperative.

Distribution of Chlamydia trachomatis omp A genotypes in patients attending a sexually transmitted disease outpatient clinic in New Delhi, India

Background & objectives:

Limited data are available on the typing of Chlamydia trachomatis in India. Serovars D to K of C. trachomatis are chiefly responsible for urogenital infections. Thus, this study was conducted to determine the distribution of C. trachomatis serovars in patients with urogenital infections and to characterize ompA gene of the detected C. trachomatis isolates by sequence analysis. Presence of other co-infections was also evaluated.

Methods:

Endocervical swabs were collected from 324 women and urethral swabs/urine were collected from 193 men attending the sexually transmitted diseases outpatient clinic. The samples were screened for C. trachomatis by cryptic plasmid PCR and ompA gene PCR. Genotyping was performed by PCR-restriction fragment length polymorphism (RFLP) and sequencing of the ompA gene. Samples were screened for genital mycoplasmas, Neisseria gonorrhoeae, Treponema pallidum and human immunodeficiency virus (HIV).

Results:

C. trachomatis was found in 15.0 per cent men and 10.8 per cent women. Serovar D was the most prevalent followed by serovars E, F, I and G. Twenty two C. trachomatis isolates were selected for ompA gene sequencing. No mixed infection was found. Variability in ompA sequences was seen in 31.8 per cent cases. Both PCR-RFLP and ompA gene sequencing showed concordant results. The presence of Ureaplasma spp. and Mycoplasma hominis was observed in 18.7 and 9.5 per cent patients, respectively. Co-infection of C. trachomatis was significantly associated with Ureaplasma urealyticum and HIV.

Interpretation & conclusions:

The high occurence of C. trachomatis infections warrants its screening in addition to other sexually transmitted infections namely U. urealyticum and HIV. Genotyping of the ompA gene may provide additional information for vaccine development.

The influence of centrifugation and incubation temperatures on various veterinary and human chlamydial species

The Chlamydiaceae are Gram-negative bacteria causing diseases in humans and in both, endothermic (mammals and birds) and poikilothermic (e.g. reptiles, amphibians) animals. As most chlamydial species described today were isolated from humans and endothermic animals, the commonly used culturing temperature in vitro is 37 °C, although the centrifugation temperature during experimental infection, a technique necessary to improve the infection rate, may vary from 25 to 37 °C. The aim of this study was to investigate the influence of different centrifugation (28° or 33 °C) and incubation temperatures (28 °C or 37 °C) on the average inclusion size, infectivity and ultrastructural morphology of human and animal chlamydial strains, as well as two recently described species originating from snakes, C. poikilothermis and C. serpentis, in LLC-MK2 cells at 48 h post infection. Infectivity and average inclusion size was reduced at an incubation temperature of 28 °C compared to 37 °C for all strains including C. poikilothermis, although the latter formed larger, fully matured inclusions at 28 °C in comparison to the other investigated Chlamydia species. C.psittaci displayed a shorter developmental cycle than the other species confirming previous studies. Higher centrifugation temperature increased the subsequent inclusion size of C. trachomatis, C. abortus and C. suis but not their infectivity, while the incubation temperature had no discernable effect on the morphology, inclusion size and infectivity of the other chlamydial strains. In conclusion, we found that all Chlamydia species are viable and can grow at low incubation temperatures, although all strains grew better and more rapidly at 37 °C compared to 28 °C.

Growth kinetics of Chlamydia trachomatis in primary human Sertoli cells

Chlamydia trachomatis (Ct) is the leading cause of bacterial sexually transmitted infections worldwide and has been associated with male infertility. Recently, it was hypothesized that Ct may infect the epithelium of the seminiferous tubule, formed by Sertoli cells, thus leading to impaired spermatogenesis. To date, there is a lack of data on Ct infection of the seminiferous epithelium; therefore, we aimed to characterize, for the first time, an in vitro infection model of primary human Sertoli cells. We compared Ct inclusion size, morphology and growth kinetics with those in McCoy cells and we studied F-actin fibres, Vimentin-based intermediate filaments and α-tubulin microtubules in Sertoli and McCoy cells. Our main finding highlighted the ability of Ct to infect Sertoli cells, although with a unique growth profile and the inability to exit host cells. Furthermore, we observed alterations in the cytoskeletal fibres of infected Sertoli cells. Our results suggest that Ct struggles to generate a productive infection in Sertoli cells, limiting its dissemination in the host. Nevertheless, the adverse effect on the cytoskeleton supports the notion that Ct may compromise the blood-testis barrier, impairing spermatogenesis.

Hepatitis B virus core antigen as a carrier for Chlamydia trachomatis MOMP multi-epitope peptide enhances protection against genital chlamydial infection

Chlamydia trachomatis (Ct) is the leading cause of sexually transmitted diseases worldwide. There is no safe and effective vaccine to control the spread of Ct. In development of Ct vaccine, selection of appropriate candidate antigens and an effective delivery system may be the main challenges. Multi-epitope of major outer membrane protein (MOMPm) is the most suitable candidate for a Ct vaccine, while hepatitis B virus core antigen (HBcAg) has unique advantages as vaccine delivery system. Therefore, in this study, we evaluated the immunogenicity and protective immune response of a novel candidate vaccine in a murine model of chlamydial genital infection. This candidate vaccine comprises MOMPm peptide delivered with HBcAg. Our results of Ct-specific serum IgG and secretory IgA assay, cytokine assay, and cytotoxic T-lymphocyte assay revealed that immunogenicity of the candidate vaccine was much better than that of the corresponding synthetic MOMPm peptide. Furthermore, the protective effect of the candidate vaccine was also shown much better than that of the synthetic peptide by calculating the isolation of Chlamydia from vaginal swabs and histopathological analysis. Taken together, our results indicate that HBcAg carrying Ct MOMPm could be an effective immune prophylactic for chlamydial infection.

A Multi-Component Prime-Boost Vaccination Regimen with a Consensus MOMP Antigen Enhances Chlamydia trachomatis Clearance

BACKGROUND

A vaccine for Chlamydia trachomatis is of urgent medical need. We explored bioinformatic approaches to generate an immunogen against C. trachomatis that would induce cross-serovar T-cell responses as (i) CD4(+) T cells have been shown in animal models and human studies to be important in chlamydial protection and (ii) antibody responses may be restrictive and serovar specific.

METHODS

A consensus antigen based on over 1,500 major outer membrane protein (MOMP) sequences provided high epitope coverage against the most prevalent C. trachomatis strains in silico. Having designed the T-cell immunogen, we assessed it for immunogenicity in prime-boost regimens. This consensus MOMP transgene was delivered using plasmid DNA, Human Adenovirus 5 (HuAd5) or modified vaccinia Ankara (MVA) vectors with or without MF59(®) adjuvanted recombinant MOMP protein.

RESULTS

Different regimens induced distinct immune profiles. The DNA-HuAd5-MVA-Protein vaccine regimen induced a cellular response with a Th1-biased serum antibody response, alongside high serum and vaginal MOMP-specific antibodies. This regimen significantly enhanced clearance against intravaginal C. trachomatis serovar D infection in both BALB/c and B6C3F1 mouse strains. This enhanced clearance was shown to be CD4(+) T-cell dependent. Future studies will need to confirm the specificity and precise mechanisms of protection.

CONCLUSION

A C. trachomatis vaccine needs to induce a robust cellular response with broad cross-serovar coverage and a heterologous prime-boost regimen may be an approach to achieve this.

A mouse model for Chlamydia suis genital infection

A mouse model for Chlamydia suis genital infection was developed. Ninety-nine mice were randomly divided into three groups and intravaginally inoculated with chlamydia: 45 mice (group 1) received C. suis purified elementary bodies (EBs), 27 (group 2) were inoculated with C. trachomatis genotype E EBs and 27 mice (group 3) with C. trachomatis genotype F EBs. Additionally, 10 mice were used as a negative control. At seven days post-infection (dpi) secretory anti-C. suis IgA were recovered from vaginal swabs of all C. suis inoculated mice. Chlamydia suis was isolated from 93, 84, 71 and 33% vaginal swabs at 3, 5, 7 and 12 dpi. Chlamydia trachomatis genotype E and F were isolated from 100% vaginal swabs up to 7 dpi and from 61 and 72%, respectively, at 12 dpi. Viable C. suis and C. trachomatis organisms were isolated from uterus and tubes up to 16 and 28 dpi, respectively. The results of the present study show the susceptibility of mice to intravaginal inoculation with C. suis. A more rapid course and resolution of C. suis infection, in comparison to C. trachomatis, was highlighted. The mouse model could be useful for comparative investigations involving C. suis and C. trachomatis species.

Identification of linear B-cell epitopes within Tarp of Chlamydia trachomatis

Chlamydia trachomatis is one of the most prevalent sexually transmitted pathogens. There is currently no commercially available vaccine against C. trachomatis. Chlamydial translocated actin-recruiting phosphoprotein (Tarp) can induce cellular and humoral immune responses in murine models and has been regarded as a potential vaccine candidate. In this report, the amino acid sequence of Tarp was analyzed using computer-assisted techniques to scan B-cell epitopes, and six possible linear B-cell epitopes peptides (aa80-95, aa107-123, aa152-170, aa171-186, aa239-253 and aa497-513) with high predicted antigenicity and high conservation were investigated. Sera from mice immunized with these potential immunodominant peptides was analyzed by ELISA, which showed that epitope 152-170 elicited serum immunoglobulin G (IgG) response and epitope 171-186 elicited both serum IgG and mucosal secretory immunoglobulin A response. The response of immune sera of epitope 171-186 to endogenous Tarp antigen obtained from the Hela229 cells infected with C. trachomatis was confirmed by Western blot and indirect fluorescence assay. In addition, binding of the antibodies against epitope 171-186 to endogenous Tarp was further confirmed by competitive ELISA. Our results demonstrated that the putative epitope (aa171-186) was an immunodominant B-cell epitope of Tarp. If proven protective and safe, this epitope, in combination with other well-documented epitopes, might be included into a candidate epitope-based vaccine against C. trachomatis.

A multi-epitope vaccine based on Chlamydia trachomatis major outer membrane protein induces specific immunity in mice

We evaluated the immunogenicity and efficacy of a candidate vaccine comprising the major outer membrane protein (MOMP) multi-epitope of Chlamydia trachomatis. A short gene of multi-epitope derived from MOMP containing multiple T- and B-cell epitopes was artificially synthesized. The recombinant plasmid pET32a(+) containing codon optimized MOMP multi-epitope gene was constructed. Expression of the fusion protein Trx-His-MOMP multi-epitope in Escherichia coli was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and western blot analysis. Balb/c mice were inoculated with the purified fusion protein subcutaneously three times with 2-week intervals. Results showed that the MOMP multi-epitope elicited not only strong humoral immune responses to C. trachomatis by generating significantly high levels of specific antibodies (IgG1 and IgG2a), but also a cellular immune response by inducing robust cytotoxic T lymphocyte responses in mice. Furthermore, the MOMP multi-epitope substantially primed secretion of IFN-γ, revealing that this vaccine could induce a strong Th1 response. Finally, the mice vaccinated with the MOMP multi-epitope displayed a reduction of C. trachomatis shedding upon a chlamydial challenge and an accelerated clearance of the infected C. trachomatis. In conclusion, the MOMP multi-epitope vaccine may have the potentiality for the development of effective prophylactic and therapeutic vaccines against the C. trachomatis infection.

Hepatitis B virus surface antigen as delivery vector can enhance Chlamydia trachomatis MOMP multi-epitope immune response in mice

Chlamydia trachomatis is the leading cause of sexually transmitted infections worldwide. There is currently no commercially available vaccine against C. trachomatis. Major outer membrane protein (MOMP) of C. trachomatis is considered to be an ideal candidate for prophylactic vaccine. We designed a MOMP multi-epitope containing T- and B-cell epitope-rich peptides and developed hepatitis B surface antigen (HBsAg) as antigen delivery vehicle. In order to study the immunogenicity and efficacy of the candidate vaccine in a murine model of chlamydial genital infection, we engineered a recombinant plasmid expressing HBsAg and MOMP multi-epitope genes. Results of reverse transcription polymerase chain reaction and immunofluorescence assay revealed successful expression of the recombinant HBsAg/MOMP multi-epitope gene at both the transcription and translation levels. Intramuscular administration in mice was able to elicit not only antibodies against Chlamydia and HBsAg but also cytotoxic T lymphocyte activity against Chlamydia. In addition, mice inoculated with the rHBsAg were highly resistant to C. trachomatis genital infection. The rHBsAg DNA with MOMP multi-epitope appended at the C terminus of the HBsAg stimulated a stronger immune response and protective response than that appended at the N terminus. Together, our results suggested that use of a recombinant HBsAg encoding the MOMP multi-epitope could be a powerful approach to developing a safe and immunogenic C. trachomatis vaccine.

Host defense peptides: general overview and an update on their activity against Chlamydia spp

Chlamydiae are obligate intracellular bacteria that cause serious diseases in a wide range of hosts. Chlamydia trachomatis is one of the leading sexually transmitted pathogens in the world. Because vaccines are not currently available, effective drugs are essential. In both animals and humans, chlamydial infections are often treated with tetracycline or its derivatives. A stable tetracycline-resistant phenotype was described in Chlamydia suis strains from pigs in the USA and in Europe. In humans, there are reports of tetracycline treatment failure and the in vitro adaptability of C. trachomatis to evolve to antibiotic resistance has been described, suggesting the pressing need to search for alternative and effective classes of antimicrobial drugs. Host defense peptides (HDPs) are known as direct antimicrobial agents as well as innate immune modulators. Being active against multidrug-resistant bacteria, HDPs are attractive candidates as templates for new drugs. A number of studies evaluated the activity of natural and synthetic HDPs against Chlamydia spp., showing C. trachomatis to be the most sensitive among chlamydia species tested. Protegrins and α-helical peptides were the most active among the HDPs assessed.

Chlamydia trachomatis genovar distribution in clinical urogenital specimens from Tunisian patients: high prevalence of C. trachomatis genovar E and mixed infections

Background

This epidemiological study was carried out in Sfax (south of Tunisia) and focused on genital Chlamydia trachomatis (C. trachomatis) genovar distribution.

Methods

One hundred and thirty seven genital samples from 4067 patients (4.2%) attending the Habib Bourguiba University hospital of Sfax over 12 years (from 2000 to 2011) were found to be C. trachomatis PCR positive by the Cobas Amplicor system. These samples were genotyped by an in house reverse hybridization method.

Results

One hundred and eight (78.8%) samples contained only one genovar and 29 (21.2%) samples contained two or three genovars. Genovar E was the most prevalent (70.8%) single genovar and it was detected in 90.6% of all the cases. Genovars J, C and L1-L3 were not detected in our samples whereas ocular genovars A and B were in 5 cases. All the five cases were mixed infections. Men had more mixed infections than women (p=0.02) and were more frequently infected by genovars F and K (p<0.05). No associations between current infection, infertility and the genovar distribution were observed. Patients coinfected with Neisseria gonorrhoeae were also significantly more frequently infected with mixed genovars (p=0.04).

Conclusions

In conclusion, we have reported a high prevalence of genovar E and of mixed infections in our study population. Such data could have implications for the control and vaccine development of C. trachomatis in Tunisia.

Evaluation of the new test VERSANT CT/GC DNA 1.0 assay for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae in urine specimens

Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC) are the two most common sexually transmitted bacterial infections in developed countries. The purpose of the present study was evaluating a new system for CT/GC detection in urine specimens. A total of 700 urine specimens were obtained from patients attending the STD Outpatients Clinic of St. Orsola University Hospital, Bologna, Italy. Samples were tested by VERSANT® CT/GC DNA 1.0 Assay (Siemens Healthcare Diagnostics Inc., Tarrytown, NY), a multiplex Real-Time PCR assay, for simultaneous CT/GC detection. Results obtained by VERSANT assay were compared with those obtained by culturing genital secretions of the same patients. Moreover, urine specimens testing positive in VERSANT assay were retested by in-house PCR assays, used as confirmatory tests. VERSANT® CT/GC DNA 1.0 Assay performed with 99.4% and 99.2% of specificity for GC and CT detection, respectively, whereas sensitivity was 100% both for CT and GC. Culture methods were 100% specific, but far less sensitive than VERSANT assay. VERSANT® CT/GC DNA 1.0 Assay demonstrated to be a highly sensitive and specific technique for CT/GC detection.

Distribution of Chlamydia trachomatis serotypes in clinical urogenital samples from north-eastern Croatia

The purpose of this study was to determine prevalence of Chlamydia trachomatis (Ct) urogenital infection and its serotype distribution from clinical samples in north-eastern Croatia. During a 3-year period, 2,379 urogenital samples were analyzed by real-time polymerase chain reaction (A group), while 4,846 genital swabs were analyzed by direct fluorescent antibody test (B group). 132 Ct positive specimens were genotyped by omp1 gene sequencing. The prevalence rate of Ct was 3.2 % in A and 1 % in B group. The most prevalent chlamydial genotype was E (44 %), followed by F (33 %), K (11.5 %), G (8 %), J/UW (5.3 %), D-IC (4.4 %), D-B120 (1.8 %), and B/IU, J/IU, Ia/IU (0.9 % each) serotypes. Single-nucleotide polymorphisms (SNPs) of omp1 gene were detected in E, K, and G serotypes. Some of these SNPs (C/T at position 272 and G/A at position 813 in E strain; C/T at position 884 in D strain) might represent novel omp1 variants.

Identification of immunodominant linear B-cell epitopes within the major outer membrane protein of Chlamydia trachomatis

Chlamydia trachomatis is one of the most prevalent sexually transmitted pathogens. Chlamydial major outer membrane protein (MOMP) can induce strong cellular and humoral immune responses in murine models and has been regarded as a potential vaccine candidate. In this report, the amino acid sequence of MOMP was analyzed using computer-assisted techniques to scan B-cell epitopes, and three possible linear B-cell epitopes peptides (VLKTDVNKE, TKDASIDYHE, TRLIDERAAH) with high predicted antigenicity and high conservation were investigated. The DNA coding region for each potential epitope was cloned into pET32a(+) and expressed as Trx-His-tag fusion proteins in Escherichia coli. The fusion proteins were purified by Ni-NTA agarose beads and followed by SDS-PAGE and western blot analysis. We immunized mice with these three fusion proteins. The sera containing anti-epitope antibodies from the immunized mice could recognize C. trachomatis serovars D and E in ELISA. Antisera of these fusion proteins displayed an inhibitory effect on invasion of serovar E by in vitro neutralization assays. In addition, serum samples from convalescent C. trachomatis-infected patients were reactive with the epitope fusion proteins by western blot assay. Our results showed that the epitope sequences selected by bioinformatic analysis are highly conserved C. trachomatis MOMP B-cell epitopes, and could be good candidates for the development of subunit vaccines, which can be used in clinical diagnosis.

Antibiotic resistance in Chlamydiae

There are few documented reports of antibiotic resistance in Chlamydia and no examples of natural and stable antibiotic resistance in strains collected from humans. While there are several reports of clinical isolates exhibiting resistance to antibiotics, these strains either lost their resistance phenotype in vitro, or lost viability altogether. Differences in procedures for chlamydial culture in the laboratory, low recovery rates of clinical isolates and the unknown significance of heterotypic resistance observed in culture may interfere with the recognition and interpretation of antibiotic resistance. Although antibiotic resistance has not emerged in chlamydiae pathogenic to humans, several lines of evidence suggest they are capable of expressing significant resistant phenotypes. The adept ability of chlamydiae to evolve to antibiotic resistance in vitro is demonstrated by contemporary examples of mutagenesis, recombination and genetic transformation. The isolation of tetracycline-resistant Chlamydia suis strains from pigs also emphasizes their adaptive ability to acquire antibiotic resistance genes when exposed to significant selective pressure.

Chlamydia trachomatis serovar distribution and Neisseria gonorrhoeae coinfection in male patients with urethritis in Greece

The distribution of Chlamydia trachomatis serovars and Neisseria gonorrhoeae coinfection was studied in a group of 100 C. trachomatis-positive males with urethritis in Greece. The serovar distribution revealed that apart from the predominant worldwide types E and F, the relatively uncommon type G is also prevalent. Gonococcal coinfection was frequent (30%) and was associated with genovariant Ja (75%, P = 0.008).