Chlamydia trachomatis prevalence, genotype distribution and identification of the new Swedish variant in Southern Germany.

PURPOSE: In Germany, reliable data about the prevalence of urogenital Chlamydia trachomatis infections, causative genotypes, as well as corresponding clinical, demographic and behavioural information are sparse. We, therefore, performed a prospective prevalence study including 1,003 sexually active volunteers of a Southern German city. METHODS: Study participants completed a standardised questionnaire and provided first void urine samples for analysis. Our screening strategy included the performance of two nucleic acid amplification tests with different target genes, enabling the detection of the new Swedish variant of C. trachomatis (nvCT). Direct genotyping of positive specimens was performed by sequence analysis of the ompA gene. RESULTS AND CONCLUSION: The overall prevalence of C. trachomatis infection was 4.2 % in women and 4.6 % in men. A relatively high prevalence of 8.3 % was found in men older than 25 years. Never using condoms was an independent risk factor for infection. The most common symptom was discharge; however, 64.5 % of infected females and all of the infected men were asymptomatic, supporting the need for screening programmes. The most frequently encountered genotypes were E (46.5 %), F (20.9 %) and K (14.0 %). Since the nvCT was detected in one female student, this is one of the rare studies that reports on the molecular identification of nvCT apart from Sweden.

Identification and evaluation of a combination of chlamydial antigens to support the diagnosis of severe and invasive Chlamydia trachomatis infections.

Chlamydia trachomatis is the most common sexually transmitted organism in industrialized countries. Nucleic acid amplification testing, using non-invasively collected specimens, is considered to be the method of choice for diagnosis of chlamydial infections of the urethra and the lower genital tract. Serological testing has the potential to circumvent the problem of specimen sampling in invasive C. trachomatis infections of the upper genital tract. However, only a few defined chlamydial antigens have been used in a standardized diagnostic assay format. In this study, we used serological two-dimensional proteomic analysis to broaden the spectrum of diagnostically relevant C. trachomatis proteins. The genes encoding an assortment of already known chlamydial antigens, as well as immunogenic proteins that have not been described before, were cloned, and the recombinant proteins were purified in order to compare their diagnostic usefulness in parallel with a newly developed line immunoassay. With 189 sera collected from patients with and without C. trachomatis infection, recombinant major outer membrane protein (MOMP), chlamydial protease-like activity factor (CPAF), outer membrane protein 2 (OMP2), translocated actin-recruiting protein, and polymorphic membrane protein D (PmpD) showed the highest level of diagnostic sensitivity and specificity. In patients suffering from ascending and invasive C. trachomatis infections, such as pelvic inflammatory disease and lymphogranuloma venereum, the sensitivity reached with these proteins ranged between 71% (PmpD) and 94% (OMP2), and the specificity ranged between 82% (PmpD) and 100% (MOMP and OMP2). Recombinant thio-specific antioxidant peroxidase, ribosomal protein S1 (RpsA) and hypothetical protein 17 showed lower sensitivity but comparably high specificity, ranging from 94% to 100%. The novel line immunoassay based on defined recombinant antigens has promise for improved serodiagnosis in severe and invasive C. trachomatis infections.

Rapid and standardized detection of Chlamydia pneumoniae using LightCycler real-time fluorescence PCR.

In order to meet the need of many microbiological laboratories for a standardized system for detecting Chlamydia pneumoniae in respiratory specimens, a hybridization probe-based LightCycler (Roche Diagnostics, Germany) PCR assay was developed. The assay's analytical sensitivity and specificity were evaluated according to the recommendations of the Centers for Disease Control and Prevention (USA) and Laboratory Centre for Disease Control (Canada). Seventy-four bacterial species other than Chlamydia pneumoniae, including strains of Chlamydia trachomatis, Chlamydia psittaci, and Chlamydia pecorum, tested negative. Six of six representative Chlamydia pneumoniae strains tested positive. An analytical sensitivity of 1 inclusion forming unit per ml of bronchoalveolar lavage fluid, corresponding to 0.02 inclusion forming units per PCR reaction, was observed. The assay showed 100% specificity and sensitivity for Chlamydia pneumoniae when testing DNA preparations from 12 specimens of patients with known pulmonary Chlamydia pneumoniae infection and from 78 specimens of patients with respiratory tract disease of other origin. The newly developed LightCycler assay may contribute to the urgently needed standardization of laboratory diagnosis of Chlamydia pneumoniae.

Survival of Chlamydia pneumoniae-infected Mono Mac 6 cells is dependent on NF-kappaB binding activity.

The respiratory tract pathogen Chlamydia pneumoniae has been associated with atherosclerosis. Monocytes are supposed to serve as a vehicle for systemic dissemination of intracellular C. pneumoniae from the lung to the artery vessel wall. We were therefore interested in pathogen-induced cellular events associated with NF-kappaB, a crucial transcription factor for both inflammatory cytokines and antiapoptotic molecules. In this study we demonstrate by electrophoretic mobility shift assay that C. pneumoniae infection of the human monocytic cell line Mono Mac 6 induces activation of NF-kappaB over 48 h, with a maximum level at 1 h postinfection. As shown by supershift assay, the activated NF-kappaB complex consists of the subunits RelA (p65) and NF-kappaB1 (p50). Apoptotic host cells were not detected during the early stages of the infection when maximal activation of NF-kappaB was detected. Pretreatment of Mono Mac 6 with the antioxidant and NF-kappaB inhibitor PDTC (pyrrolidine dithiocarbamate) induced activation of caspase-3 and led to apoptotic cell death. The C. pneumoniae-induced activation of the NF-kappaB complex was reduced by PDTC, which in parallel resulted in an increased apoptosis, as quantified by annexin V labeling and terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling reaction. In the complete absence of activated NF-kappaB, when Mono Mac 6 cells were pretreated with the more potent NF-kappaB inhibitors MG-132 and parthenolide a C. pneumoniae-mediated rescue of cells from induced apoptosis could not be achieved. Our results indicate that activation of NF-kappaB in C. pneumoniae-infected Mono Mac 6 cells is associated with protection of Mono Mac 6 cells against apoptosis and might thereby contribute to systemic spread of the pathogen.

Decontamination of a Mycoplasma-infected Chlamydia pneumoniae strain by pulmonary passage in SCID mice.

We describe a procedure to eliminate contaminating Mycoplasma from Chlamydia pneumoniae (C. pneumoniae) cultures by pulmonary passage in severe combined immunodeficiency mice (SCID). Four weeks after experimental infection only C. pneumoniae could be cultured from the lungs of the infected animals while Mycoplasma could not be detected any longer, as shown by PCR, culture and transmission electron microscopy (TEM).

Analysis of the humoral immune response to Chlamydia pneumoniae by immunoblotting and immunoprecipitation.

Chlamydia pneumoniae is a widely spread agent of respiratory tract infections in humans. A reliable serodiagnosis of the disease is hampered by the poor knowledge about immunodominant antigens in C. pneumoniae infections. We applied a novel strategy to identify immunogenic proteins of C. pneumoniae TW183 combining metabolic radiolabeling of de novo-synthesized chlamydial antigens with immunoprecipitation. By this technique C. pneumoniae antigens of approximately 160, 97 to 99, 60 to 62, 40, 27, and 15 kDa were detected in the vast majority of sera from patients with a current C. pneumoniae infection. By immunoblotting purified elementary bodies of C. pneumoniae TW183 with the same sera, only the 60- to 62-kDa antigen could be detected consistently. Sequential immunoprecipitation performed at different stages of the chlamydial developmental cycle revealed that the 60- to 62-kDa antigen is strongly upregulated after 24 to 48 h of host cell infection and is presented as a major immunogen in both C. pneumoniae-infected patients and mice. We conclude that, due to its high sensitivity and concurrent preservation of conformational epitopes, metabolic radiolabeling of chlamydial antigens combined with immunoprecipitation may be a useful method to reveal important immunogens in respiratory C. pneumoniae infection which might have been missed by immunoblot analysis.

Clearance of Chlamydia trachomatis-induced polyserositis in SCID mice requires both CD4+ and CD8+ cells.

To characterize the role of specific lymphocyte subsets in Chlamydia trachomatis infection, we established a murine model using the mouse pneumonitis agent (MoPn) of C. trachomatis and C.B-17 scid/scid (SCID) mice which lack functional B and T cells. After intraperitoneal inoculation with the bacteria, SCID mice developed polyserositis with pleuritis, pericarditis, and perihepatitis. Within 8 weeks post infection, SCID mice succumbed to the disease, whereas immunocompetent congenic C.B-17+/+ mice resolved the infection. Adoptive transfer of immune spleen cells into MoPn-infected SCID mice resulted in a complete elimination of the agent and prevention of polyserositis as measured by quantitative chlamydial culture, direct immunofluorescence and histopathological analysis. Selective reconstitution of MoPn-infected SCID mice with immune B lymphocytes, CD4+ T cells or CD8+ T cells alone did not influence the chlamydial load in the lung and liver of infected SCID animals, resulting in a polyserositis as observed in untreated MoPn-infected SCID mice. However, co-transfer of both CD4+ T cells and CD8+ T cells led to a significant reduction of chlamydiae in quantitative organ culture coupled with unremarkable histopathology. These data confirm that T cell-mediated immune responses are essential for immune protection in chlamydial infection, although total eradication of the agent could not be achieved. Further experiments are needed to stress the importance of a concerted action of B and T lymphocytes, as indicated by the complete protective efficacy of transferred splenocytes.

Infection of Acanthamoeba castellanii by Chlamydia pneumoniae.

Chlamydia pneumoniae is an intracellular respiratory pathogen, which, similar to Legionella, might have developed mechanisms to escape the intracellular bactericidal activity of both human host cells and amoeba. We therefore investigated the intracellular growth and survival of C. pneumoniae in Acanthamoeba castellanii by using cell culture, immunofluorescence microscopy, and electron microscopy. A castellanii was incubated with purified elementary bodies of C. pneumoniae TW 183 at a concentration of 10(6) inclusion-forming units (IFU)/ml to give a ratio of approximately 1 IFU of C. pneumoniae per amoeba. Quantitative determination of chlamydial growth within A. castellanii revealed viable and infective C. pneumoniae in the range of 10(4) to 10(5) IFU/ml between days 7 and 14 postinfection. Immunofluorescence analysis and transmission electron microscopy with subsequent immunogold staining confirmed evidence of infection of the amoebae by C. Pneumoniae and additionally revealed that C. pneumoniae entered the typical growth cycle. Our results show that amoebae allow the survival of C. pneumoniae, suggesting that amoebae may serve as an additional reservoir for Chlamydia or Chlamydia-related organisms.

Growth of Chlamydia pneumoniae induces cytokine production and expression of CD14 in a human monocytic cell line.

Chlamydia pneumoniae was able to survive and to multiply in the human monocytic cell line Mono Mac 6. Growth of C. pneumoniae induced production of tumor necrosis factor alpha, interleukin 1beta, and interleukin 6, as well as up-regulation of the CD14 molecule in a time-dependent manner. Infection of monocytic cells and a proinflammatory cytokine response may be important in C. pneumoniae pathogenesis.