Demonstration of chlamydial RNA and DNA during a culture-negative state

Chlamydia Persistence: A Survival Strategy to Evade Antimicrobial Effects in-vitro and in-vivo

The Chlamydiaceae comprise a group of highly adapted bacterial pathogens sharing a unique intracellular lifestyle. Three Chlamydia species are pathogenic to humans: Chlamydia trachomatis, Chlamydia pneumoniae, and Chlamydia psittaci. C. trachomatis is the leading bacterial cause of sexually-transmitted infections and infectious blindness worldwide. Chlamydia pneumoniae is a major cause of community-acquired atypical pneumonia. C. psittaci primarily affects psittacine birds and can be transmitted to humans causing psittacosis, a potentially fatal form of pneumonia. As opposed to other bacterial pathogens, the spread of clinically relevant antimicrobial resistance genes does not seem to be a major problem for the treatment of Chlamydia infections. However, when exposed to stressing conditions, like those arising from exposure to antimicrobial stimuli, these bacteria undergo a temporary interruption in their replication cycle and enter a viable but non-cultivable state known as persistence. When the stressing conditions are removed, Chlamydia resumes replication and generation of infectious particles. This review gives an overview of the different survival strategies used by Chlamydia to evade the deleterious effects of penicillin and IFNγ, with a focus on the different models used to study Chlamydia persistence, their contribution to elucidating the molecular basis of this complex phenomenon and their potential implications for studies in animal models of infection.

Evaluation of direct immunofluorescence assay and cytological examination in comparison to polymerase chain reaction of conjunctival swabs in patients with adult inclusion conjunctivitis

PURPOSE

To evaluate PCR, direct immunofluorescence assay (DIA) and cytological test of conjunctival swabs for the diagnosis of adult follicular conjunctivitis (AFC).

METHODS

Eighty-three adult patients with chronic conjunctivitis and sixteen healthy individuals were included. Conjunctival scrapings underwent PCR, DIA and cytological analysis. Exams were repeated two weeks after treatment application. Sensitivity, specificity and agreement rate with PCR of DIA and Cytology were evaluated and correlated with clinical symptoms/signs.

RESULTS

Cytology test was more sensitive than DIA and presented an acceptable agreement with PCR (K=0.44) in treatment-naïve patients, concerning especially the combination of both conventional exams (K = 0.77). Inferior diagnostic performance of was detected post-treatment, considering the combination as well (K=0.40). Negative post-treatment PCR correlated well with significant relief of symptoms/signs.

CONCLUSION

Combination of Cytology and DIA seems to be a useful diagnostic option for treatment naïve AFC patients. However, PCR remains the most reliable test for post-treatment evaluation.

Characterization of in vitro Chlamydia muridarum persistence and utilization in an in vivo mouse model of Chlamydia vaccine

PROBLEM

Chlamydia trachomatis genital tract infections are easily treated with antibiotics; however, the majority of infections are asymptomatic and therefore untreated, highlighting the need for a vaccine. Because most infections are asymptomatic, vaccination could potentially be administered to individuals who may have an acute infection at that time. In such individuals, the effect of vaccination on the existing infection is unknown; however, one potential outcome could be the development of a persistent infection. In vitro chlamydial persistence has been well characterized in various strains; however, there have been no reported studies in C. muridarum.

METHOD OF STUDY

We performed ultrastructural characterization and transcriptome analysis of selected genes. We then used the transcriptional profiles of the selected genes to examine whether intranasal immunization of mice during an active genital infection would induce persistence in the upper reproductive tract of female mice.

RESULTS AND CONCLUSIONS

We found that persistence developed in the oviducts of mice as a result of immunization. This is a significant finding, not only because it is the first time that C. muridarum persistence has been characterized in vitro, but also due to the fact that there is a minimal characterization of in vivo persistence of any chlamydial species. This highlights the importance of the timing of vaccination in individuals.

Chlamydia muridarum enters a viable but non-infectious state in amoxicillin-treated BALB/c mice

In culture, exposure to penicillin and other stressors induce chlamydiae to enter a non-infectious but viable state termed persistence. Chlamydiae may reenter their normal developmental cycle after stressor removal. Though aberrant RB similar to those present in culture models of persistence have been observed within infected tissues, the existence of persistent chlamydiae has not been definitively demonstrated in vivo. As a result, the role of persistent organisms in pathogenesis is undefined. In order to establish an experimentally tractable model of in vivo persistence, Chlamydia muridarum vaginally-infected mice were gavaged with either water or amoxicillin (amox). Vaginal swabs were collected for chlamydial titration and RNA isolated for quantification of pre-16s rRNA. Uterine tissue was analyzed by transmission electron microscopy (TEM). Although amox-treatment reduced vaginal shedding by >99%, C. muridarum pre-16s rRNA accumulation was unchanged by treatment. These data indicate that the amox-exposed organisms were viable but not infectious. Furthermore, TEM analyses demonstrated that inclusions in amox-treated animals contained primarily large, aberrant RB, but those observed in untreated control animals were normal. Collectively, these data suggest that amoxicillin treatment induces C. muridarum to enter the persistent state in vivo. This model also represents the first experimentally tractable animal model of chlamydial persistence.

Inhibition of indoleamine 2,3-dioxygenase activity by levo-1-methyl tryptophan blocks gamma interferon-induced Chlamydia trachomatis persistence in human epithelial cells

Gamma interferon (IFN-γ) induces expression of the tryptophan-catabolizing enzyme indoleamine 2,3-dioxygenase (IDO1) in human epithelial cells, the permissive cells for the obligate intracellular bacterium Chlamydia trachomatis. IDO1 depletes tryptophan by catabolizing it to kynurenine with consequences for C. trachomatis, which is a tryptophan auxotroph. In vitro studies reveal that tryptophan depletion can result in the formation of persistent (viable but noncultivable) chlamydial forms. Here, we tested the effects of the IDO1 inhibitor, levo-1-methyl-tryptophan (L-1MT), on IFN-γ-induced C. trachomatis persistence. We found that addition of 0.2 mM L-1MT to IFN-γ-exposed infected HeLa cell cultures restricted IDO1 activity at the mid-stage (20 h postinfection [hpi]) of the chlamydial developmental cycle. This delayed tryptophan depletion until the late stage (38 hpi) of the cycle. Parallel morphological and gene expression studies indicated a consequence of the delay was a block in the induction of C. trachomatis persistence by IFN-γ. Furthermore, L-1MT addition allowed C. trachomatis to undergo secondary differentiation, albeit with limited productive multiplication of the bacterium. IFN-γ-induced persistent infections in epithelial cells have been previously reported to be more resistant to doxycycline than normal productive infections in vitro. Pertinent to this observation, we found that L-1MT significantly improved the efficacy of doxycycline in clearing persistent C. trachomatis forms. It has been postulated that persistent forms of C. trachomatis may contribute to chronic chlamydial disease. Our findings suggest that IDO1 inhibitors such as L-1MT might provide a novel means to investigate, and potentially target, persistent chlamydial forms, particularly in conjunction with conventional therapeutics.

Immunopathogenic consequences of Chlamydia trachomatis 60 kDa heat shock protein expression in the female reproductive tract

Chlamydia trachomatis is an obligate intracellular bacterium that infects chiefly urogenital and ocular epithelial cells. In some infected women the microorganism migrates to the upper reproductive tract resulting in a chronic, but asymptomatic, infection. The immune response to this infection, production of interferon-gamma and pro-inflammatory cytokines, results in interruption of chlamydial intracellular replication. However, the Chlamydia remains viable and enters into a persistent state. In this form, most chlamydial genes are inactive. An exception is the gene coding for the 60 kDa heat shock protein (hsp60), which is synthesized in increased amounts and is released into the extracellular milieu. The chronic release of chlamydial hsp60 induces a local pro-inflammatory immune response in fallopian tube epithelia and results in scar formation and tubal occlusion. In addition, long-term exposure of the maternal immune system to the chlamydial hsp60 eventually results in the release of tolerance and generation of an immune response that recognizes regions of the chlamydial hsp60 that are also present in the human hsp60. Production of cross-reacting antibodies and cell-mediated immunity to the human hsp60 is detrimental to subsequent pregnancy outcome and may also possibly increase susceptibility to atherosclerosis, autoimmune disorders, or malignancies.

Immune pathogenesis of asymptomatic chlamydia trachomatis infections in the female genital tract

Chlamydia trachomatis (CT) infections of the female genital tract, although frequently asymptomatic, are a major cause of fallopian-tube occlusion and infertility. Early stage pregnancy loss may also be due to an unsuspected and undetected CT infection. In vitro and in vivo studies have demonstrated that this organism can persist in the female genital tract in a form undetectable by culture. The mechanism of tubal damage as well as the rejection of an embryo may involve an initial immune sensitization to the CT 60 kD heat shock protein (HSP), followed by a reactivation of HSP-sensitized lymphocytes in response to the human HSP and the subsequent release of inflammatory cytokines. The periodic induction of human HSP expression by various microorganisms or by noninfectious mechanisms in the fallopian tubes of women sensitized to the CT HSP may eventually result in tubal scarring and occlusion. Similarly, an immune response to human HSP expression during the early stages of pregnancy may interfere with the immune regulatory mechanisms required for the maintenance of a semiallogeneic embryo.

Pregnancy outcome following pelvic infection

To determine whether a previous pelvic infection has an effect on the outcome of a subsequent pregnancy, we identified women with a diagnosis of pelvic inflammatory disease (PID), amnionitis, and postpartum or postabortal endometritis-salpingitis by a retrospective chart review of all patients admitted to the Department of Obstetrics and Gynecology at The New York Hospital-Cornell Medical Center between 1975 and 1977 and between 1985 and 1988. Antimicrobial regimens effective against Chlamydia trachomatis were initiated in 1985. Controls were randomly selected patients presenting during the same time period for routine examinations who had normal Pap smears and no infections. Both groups were comparable for age, race, gravity, and parity. Differences were evaluated by chi square analysis, using the Yates correction factor. We identified 183 women with a history of the above infections who subsequently conceived, and 82 controls. There were no differences in outcome between the two index groups. Term vaginal deliveries occurred in 14.2% of the women with a prior pelvic infection and in 56% of the controls (P < 0.001). Among the 97 women who had had PID, 21 (21.6%) had a spontaneous abortion in the subsequent pregnancy, as opposed to 6 (7.3%) of the controls (P = 0.013). In addition, eight of the women with PID (but no controls) went into preterm labor (P = 0.021). An increased incidence of preterm labor (P = 0.001) was also observed in women with a history of amnionitis. A history of endometritis was not associated with an increased prevalence of abnormal outcome in subsequent pregnancies. PID and amnionitis may adversely affect the outcome of subsequent pregnancies.

A real-time quantitative polymerase chain reaction assay for the detection of Chlamydia in the mouse genital tract model

Chlamydia trachomatis is a human pathogen that infects genital tracts in women. Disease control may be achieved through development of an efficacious vaccine. A mouse genital tract model serves as a tool for evaluation of vaccine candidates. Currently, assessment of infection in mice is performed by enumeration of inclusion-forming units (IFUs) through microscopic counting of fluorescently stained bacteria. We have developed a highly sensitive real-time quantitative polymerase chain reaction (RT-qPCR) assay for enumeration of Chlamydia from mouse genital tracts to increase assay sensitivity, remove subjectivity, and improve sample throughput. The qPCR assay uses a 16S ribosomal gene sequence that is conserved across Chlamydia species and serovars, resulting in detection of multiple serovars of C. trachomatis, as well as Chlamydia muridarum and Chlamydia pneumoniae. The PCR assay provided results similar to IFU enumeration (94% agreement between the 2 assays) and is highly sensitive and specific with less inherent subjectivity than traditional enumeration methods.

Chlamydia trachomatis infection: host immune responses and potential vaccines

Chlamydia trachomatis causes genital tract infections that affect men, women, and children on a global scale. This review focuses on innate and adaptive immune responses in the female reproductive tract (FRT) to genital tract infections with C. trachomatis. It covers C. trachomatis infections and highlights our current knowledge of genital tract infections, serovar distribution, infectious load, and clinical manifestations of these infections in women. The unique features of the immune system of the FRT will be discussed and will include a review of our current knowledge of innate and adaptive immunity to chlamydial infections at this mucosal site. The use of animal models to study the pathogenesis of, and immunity to, Chlamydia infection of the female genital tract will also be discussed and a review of recent immunization and challenge experiments in the murine model of chlamydial FRT infection will be presented.

Survival of Chlamydia muridarum within dendritic cells

Immune responses to Chlamydia trachomatis underlay both immunity and immunopathology. Immunopathology in turn has been attributed to chronic persistent infection with persistence being defined as the presence of organisms in the absence of replication. We hypothesized that dendritic cells (DCs) play a central role in Chlamydia immunity and immunopathology by favoring the long-term survival of C. muridarum. This hypothesis was examined based on (i) direct staining of Chlamydia in infected DCs to evaluate the development of inclusions, (ii) titration of infected DCs on HeLa cells to determine cultivability, and (iii) transfer of Chlamydia-infected DCs to naive mice to evaluate infectivity. The results show that Chlamydia survived within DCs and developed both typical and atypical inclusions that persisted in a subpopulation of DCs for more than 9 days after infection. Since the cultivability of Chlamydia from DCs onto HeLa was lower than that estimated by the number of inclusions in DCs, this suggests that the organisms may be in state of persistence. Intranasal transfer of long-term infected DCs or DCs purified from the lungs of infected mice caused mouse lung infection, suggesting that in addition to persistent forms, infective Chlamydia organisms also developed within chronically infected DCs. Interestingly, after in vitro infection with Chlamydia, most DCs died. However, Chlamydia appeared to survive in a subpopulation of DCs that resisted infection-induced cell death. Surviving DCs efficiently presented Chlamydia antigens to Chlamydia-specific CD4+ T cells, suggesting that the bacteria are able to both direct their own survival and still allow DC antigen-presenting function. Together, these results raise the possibility that Chlamydia-infected DCs may be central to the maintenance of T-cell memory that underlies both immunity and immunopathology.

Development and validation of a rotor-gene real-time PCR assay for detection, identification, and quantification of Chlamydia trachomatis in a single reaction

A multitarget real-time PCR (MRT-PCR) for detection of Chlamydia trachomatis DNA was developed and validated. There were three targets for amplification in a single reaction: the cryptic plasmid (CP), the major outer membrane protein (MOMP) gene, and an internal control. The assay had the following characteristics: (i) detection and confirmation of the presence of C. trachomatis DNA in a single reaction, (ii) detection of all genovars of C. trachomatis without any cross-reactivity with pathogenic bacteria or commensal organisms of the oropharynx and genital tract, (iii) a 95% probability of detection with three copies of MOMP and one copy of CP per reaction mixture, (iv) identification of the inhibition of amplification, (v) a quantitative dynamic range of 25 to 250,000 genome copies per reaction mixture, (vi) high intra- and interassay reproducibilities, and (vii) correct identification of all samples in the validation panel. There were 146 COBAS Amplicor PCR (Amplicor PCR)-positive samples and 122 Amplicor PCR-negative samples in the panel. MRT-PCR detected CP DNA alone in 6 (4%) Amplicor PCR-positive samples and both CP and MOMP DNAs in 140 (96%) of 146 Amplicor PCR-positive samples. The quantity of MOMP DNA in 95 (68%) of 140 samples was within the dynamic range of the assay. The median C. trachomatis load in these samples was 321 genome copies per reaction mixture (range, 26 to 40,137 genome copies per reaction mixture). Due to the inclusion of two different C. trachomatis-specific targets, the assay confirmed 259 (97%) of 268 results in a single reaction. This assay could be used in the qualitative format for the routine detection of C. trachomatis and in the quantitative format for study of the pathogenesis of C. trachomatis-associated diseases. The assay demonstrated the potential to eliminate the need for confirmatory testing in almost all samples, thus reducing the turnaround time and the workload.

Diagnosis and assessment of trachoma

Trachoma is caused by Chlamydia trachomatis. Clinical grading with the WHO simplified system can be highly repeatable provided graders are adequately trained and standardized. At the community level, rapid assessments are useful for confirming the absence of trachoma but do not determine the magnitude of the problem in communities where trachoma is present. New rapid assessment protocols incorporating techniques for obtaining representative population samples (without census preparation) may give better estimates of the prevalence of clinical trachoma. Clinical findings do not necessarily indicate the presence or absence of C. trachomatis infection, particularly as disease prevalence falls. The prevalence of ocular C. trachomatis infection (at the community level) is important because it is infection that is targeted when antibiotics are distributed in trachoma control campaigns. Methods to estimate infection prevalence are required. While culture is a sensitive test for the presence of viable organisms and nucleic acid amplification tests are sensitive and specific tools for the presence of chlamydial nucleic acids, the commercial assays presently available are all too expensive, too complex, or too unreliable for use in national programs. There is an urgent need for a rapid, reliable test for C. trachomatis to assist in measuring progress towards the elimination of trachoma.

The occurrence of antibodies against chlamydia species in patients with monoarthritis and chronic closed lock of the temporomandibular joint

PURPOSE

The study goal was to investigate the occurrence of serum antibodies to Chlamydia trachomatis, Chlamydia pneumoniae, and Chlamydia psittaci in patients with temporomandibular joint (TMJ) monoarthritis or chronic closed lock and in control subjects.

PATIENTS AND METHODS

An indirect microimmunofluorescence test for detecting antibodies against C trachomatis was used. Twenty-three patients (12 with monoarthritis and 11 with chronic closed lock) and 42 control subjects were evaluated.

RESULTS

Six patients with monoarthritis, 5 patients with chronic closed lock of the TMJ, and 6 control individuals were considered to have had a past C trachomatis infection based on their immunoglobulin G titers. Corresponding groups for C pneumoniae investigation included 3 patients with monoarthritis, 4 patients with chronic closed lock, and 17 control subjects, and for C psittaci, 1 patient with monoarthritis, 2 patients with chronic closed lock, and 1 control subject. Statistically significant differences between patients and control subjects were found for C trachomatis only; monoarthritis versus control (P =.016), chronic closed lock versus control (P =.038), and all patients versus control (P =.007). Patients with monoarthritis did not differ from patients with chronic closed lock with regard to antibodies against C trachomatis.

CONCLUSION

The occurrence of serum antibodies to C trachomatis was significantly higher in patients than in control subjects, but this occurrence did not correlate with severity of observed tissue changes. Nevertheless, an association may exist between the presence of C trachomatis and TMJ disease.

Differential expression of genes encoding membrane proteins between acute and continuous Chlamydia pneumoniae infections

Chlamydia pneumoniae is associated with several chronic human diseases, including chronic obstructive pulmonary disease and atherosclerotic cardiovascular disease. During chronic disease, organisms are believed to exist in a persistent phase that is not well understood at the genetic level. Long-term in vitro continuous infections are spontaneously persistent and are less susceptible than in vitro acute infections to treatment with antibiotics, and are therefore particularly relevant as an in vitro model of in vivo chronic disease. Real-time reverse transcriptase-PCR (r-t RT-PCR) was used to quantitate transcript copy numbers of 13 genes in continuous and acute infections with C. pneumoniae. The set of genes studied encodes proteins with known or predicted functions in the cell membrane, the inclusion membrane, cell division, metabolism, and immunopathology. Significant upregulation was seen for five genes (CPn0483, nlpD, ompA, pmp1 and porB) in continuous cultures. The genes omcB, pmp1, and porB, all of which encode membrane proteins, shared similar patterns of expression over both acute and continuous profiles. These results show that Chlamydia in the long-term continuous model of persistence have a unique transcription profile, adding to our knowledge of regulation of this important stage of chlamydial growth.

Chlamydia trachomatis persistence in the female mouse genital tract: inducible nitric oxide synthase and infection outcome

It was previously reported that female mice resolve a primary Chlamydia trachomatis urogenital infection independent of inducible nitric oxide synthase (iNOS). We now report that although iNOS-deficient (NOS2(-/-)) mice resolve culture-apparent infection in a fashion similar to that of normal control (NOS2(+/+)) mice, they sustain significantly increased rates of disease, as assessed by hydrosalpinx formation. PCR amplification of ompA followed by Southern blot detection of amplicands revealed the presence of chlamydial DNA in the lower genital tracts of both NOS2(-/-) and NOS2(+/+) mice at > or =120 days postinfection and in upper genital tract tissues at >120 days postinfection. However, only NOS2(-/-) mice shed low numbers of viable chlamydiae from the lower genital tract after immunosuppressive treatment at 120 days postinfection. When cultured primary murine lung fibroblasts were activated in the presence of gamma interferon (IFN-gamma), inhibition of chlamydial growth occurred in both NOS2(+/+) and NOS2(-/-) cells, but the inhibition was reversible after removal of the cytokine in the NOS2(-/-) primary cell culture only. The iNOS-independent inhibition was microbistatic but was independent of 2,3-indoleamine dioxygenase activity. We conclude that chlamydial DNA and antigens persist in mice subsequent to culture-apparent resolution. In addition, IFN-gamma induces in vivo inhibition of chlamydial growth through microbistatic mechanisms in the absence of iNOS activity, but in the presence of iNOS activity, IFN-gamma is microbicidal and effects eradication.

Chlamydia pneumoniae antigens, rather than viable bacteria, persist in atherosclerotic lesions

AIMS

To evaluate the nature of the presence of Chlamydia pneumoniae or of other members of the order Chlamydiales in atherosclerotic lesions.

METHODS

Consecutive sections of 13 carotid artery specimens obtained at necropsy and of C pneumoniae infected HEp2 cells were analysed using: (1) immunocytochemistry (ICC) to detect C pneumoniae membrane protein; (2) in situ hybridisation (ISH) using a polymerase chain reaction (PCR) fragment of the omp1 gene to detect C pneumoniae specific DNA; (3) ISH using an oligonucleotide probe to detect Chlamydiales specific 16S rRNA; (4) PCR to detect C pneumoniae 16S rDNA; and (5) in situ DNA nick and labelling (TUNEL) to detect fragmented DNA.

RESULTS

Staining by ICC and ISH of infected HEp2 cells showed characteristic inclusions. Chlamydia pneumoniae membrane protein was demonstrated in macrophages in advanced atherosclerotic lesions (six of six), but not in fatty streaks (none of two), or normal arteries (none of five). ISH assays using both probes and PCR were all negative, indicating the absence of both specific C pneumoniae DNA and Chlamydiales specific 16S rRNA. Only after treatment with DNAse I were uniformly sized dots demonstrated by the TUNEL assay in inclusions of infected HEp2 cells. The TUNEL assay showed a similar staining pattern in macrophages in five carotid artery specimens, of which four were also positive for C pneumoniae membrane protein. Both macrophage populations were morphologically similar and were similarly distributed.

CONCLUSIONS

No evidence was obtained for the involvement of other members of the order Chlamydiales in atherosclerosis. The presence of C pneumoniae antigen in the absence of DNA and 16S rRNA suggests that antigens, rather than viable bacteria, persist in atherosclerotic lesions.

Chlamydial development is adversely affected by minor changes in amino acid supply, blood plasma amino acid levels, and glucose deprivation

This study has demonstrated the extreme sensitivity of Chlamydia trachomatis growing in McCoy cells to small changes in external amino acid supply. In the absence of cycloheximide, a decrease in the amino acid concentration of medium to 75% of control values was sufficient to induce the growth of enlarged chlamydial forms of reduced infectivity. Morphology became more distorted and the yield of infectious particles from inclusions declined as medium amino acid levels were further reduced. These events correlated with a general decline in intracellular amino acids, as measured by high-performance liquid chromatography, suggesting that chlamydiae require a minimum concentration of each amino acid for normal development. Cycloheximide enhanced the production of normal organisms and increased infectivity yield in media, suggesting that the drug increased the available pool of amino acids. This was supported by intracellular amino acid analyses. Aberrant forms with reduced infectivity were also induced during supply of infected cell cultures with medium containing blood plasma amino acid concentrations, supporting the proposal that nutrient levels in vivo could promote abnormal chlamydial development. Markedly abnormal forms were also observed during glucose deprivation, providing further evidence that aberrant development is a general stress-related response.

Antimicrobial susceptibility testing of Chlamydia trachomatis using a reverse transcriptase PCR-based method

The conventional method for antimicrobial susceptibility testing of Chlamydia trachomatis is subjective and potentially misleading. We have developed a reverse transcriptase PCR (RT-PCR)-based method which is more sensitive and less subjective than the conventional method. Using 16 strains of C. trachomatis in triplicate assays, we found the RT-PCR method consistently more sensitive than the conventional technique for all eight antimicrobials tested, with resultant MICs determined by RT-PCR ranging from 1.6-fold higher (erythromycin) to >/=195-fold higher (amoxicillin).

Detection of Chlamydia trachomatis DNA in cervical samples with regard to infection by human papillomavirus

OBJECTIVE

The correlation between human papillomavirus (HPV) and Chlamydia, trachomatis infections was evaluated in 144 patients with normal cytology or with atypical squamous cells of undetermined significance (ASCUS).

METHODS

Cervical samples were analysed using polymerase chain reaction (PCR) and non-radioactive Southern blot analysis. Specificity and sensitivity of two C. trachomatis PCR systems: major outer membrane protein (MOMP)-PCR and plasmid-PCR were determined. Southern blot hybridization of the PCR amplicons was done using 5' and 3' biotinylated oligonucleotide probes.

RESULTS

All cervical samples were tested by the plasmid-PCR due to a 10 times higher sensitivity compared to the MOMP-PCR. To determine the specificity of our C. trachomatis primer sets different bacteria and viruses which can cause urogenital infections were analysed. Comparison of the probes revealed an increased sensitivity of the 5' and 3' double-biotinylated probe vs. the 5' biotinylated probe. The infection rate of C. trachomatis in cervical samples of HPV-positive patients was 10.3% (three out of 29) vs. 1.7% (two out of 115; P< or =0.05) in HPV-negative patients. In patients HPV-X (unsequenced HPV-types) positive the rate was 14.3% (one out of seven) vs. 2.9% (four out of 137: P = 0.2) in HPV-X negative patients. In high risk (HR) HPV-positive cervical samples the infection rate was 9.1% (two out of 22) vs. 2.5% (three out of 122; P = 0.14) in HR HPV-negative samples. Chlamydia trachomatis frequency of patients with cytological changes (ASCUS) was 27.3% (three out of 11) vs. 1.5% (two out of 1 33) in patients with normal cytology (P = 0.003). The highest prevalence rate of C. trachomatis-positive cervical samples (50%; one out of two) was found in HR HPV-positive patients with cytological changes (ASCUS) vs. 5% (one out of 20) in HR HPV-positive patients with normal cytology (P = 0.17). Patients negative for HPV and positive for ASCIIS have a C. trachomatis rate of 22.2% (two out of nine) vs. HPV-negative patients with normal cytology (none out of 106; P = 0.006) and vs. HR HPV-negative patients with normal cytology (0.9%; one out of 113; P = 0.014).

CONCLUSIONS

There appears to be a correlation between cervical HPV and cervical C. trachomatis infections. The prevalence rate of C. trachomatis was significantly higher in patients with abnormal cytology (ASCUS) vs. normal cytology.

In situ hybridisation and direct fluorescence antibodies for the detection of Chlamydia trachomatis in synovial tissue from patients with reactive arthritis

BACKGROUND

Chlamydia trachomatis is associated with Reiter's syndrome and reactive arthritis but the form in which the organism survives in synovial cells is unclear.

AIM

To compare in situ hybridisation with direct fluorescence in the detection of inapparent chlamydial infection in synovial tissue.

METHODS

Synovial tissue from four patients with reactive arthritis patients was examined using biotin labelled probes for chlamydial DNA and fluorescein isothiocyanate (FITC) labelled monoclonal antibodies against the major outer membrane protein.

RESULTS

In two of the four patients, evidence of chlamydial infections was detected by in situ hybridisation in parallel sections but not with FITC labelled monoclonal antibodies.

CONCLUSIONS

Detection of chlamydial DNA by in situ DNA hybridisation may be a better way to identify chlamydial infection in synovial tissue than phenotype targeting with FITC conjugated antibodies, which is used as a standard procedure for screening clinical specimens for chlamydia.

Detection of Chlamydia trachomatis in genital swabs: comparison of commercial and in house amplification methods with culture

AIMS

To evaluate the sensitivity of the Roche Cobas, Roche Amplicor plate kit, ligase chain reaction (LCR), and an in house polymerase chain reaction (PCR) by titration of purified elementary bodies (EB) and also to test 245 urethral and endocervical specimens for Chlamydia trachomatis by the four assays as well as conventional culture.

STUDY DESIGN

EB titrations were run in duplicate in each commercial assay and six times in the in house PCR. Clinical samples were aliquoted and tested by each assay and were considered positive if C trachomatis was detected by two or more separate tests or if the sample was either culture or immunofluorescence positive. Major outer membrane protein (MOMP) specific primers were used as a confirmatory assay for the in house PCR.

RESULTS

The in house PCR, Roche Cobas Amplicor, LCR, and Amplicor plate kit gave detection limits of approximately 1, 1-2, 2, and 2-4 EBs respectively. By the criteria described above for definition of a C trachomatis positive result in clinical samples we identified 23 true positives among the 245 clinical specimens. The in house PCR detected all 23 giving a sensitivity of 100% and a specificity of 98%. The Roche Cobas Amplicor, Roche Amplicor plate kit, and LCR detected 21, 19, and 19 of these respectively giving sensitivities of 87.5%, 82%, and 82% respectively and specificities of 99.5%, 99%, and 100% respectively. The culture gave a sensitivity of 78% and specificity of 100%.

CONCLUSION

All four amplification assays had a greater sensitivity than the culture used routinely in this laboratory. The in house plasmid PCR had the greatest sensitivity and when combined with confirmation by immunofluorescence detected the greatest number of positives. This increased sensitivity is likely to have been achieved by the use of a DNA purification step and of nested primers in the amplification stage and their combined use in routine diagnostic assays for chlamydia might increase the frequency of C trachomatis detections. However, this assay is much less user friendly than the two semiautomated commercial assays investigated in this study.

Reactivation of chlamydial genital tract infection in mice

A model was developed to study chlamydial quiescence in C3H/HeN (C3H) and C57BL/6N (C57) mice following genital tract infection by Chlamydia trachomatis MoPn. Reactivation of chlamydial shedding following immunosuppression indicated that viable MoPn remained in the genital tract for up to 4 or 5 weeks after the apparent clearance of a primary infection. Either cyclophosphamide or cortisone acetate treatment could cause reactivation, but cyclophosphamide was more effective. However, the frequency of reactivation by either drug diminished with time in both mouse strains. Progesterone treatment prior to infection of C57 mice greatly reduced the frequency of reactivation by cyclophosphamide and also correlated with the development of marked fluid accumulation and distension of the uterine horns in the vast majority of those animals. This pathology was apparent by 5 to 7 weeks postinfection and was consistently seen through 110 days postinfection. Neither of these phenomena was observed in C57 mice that had not been treated with progesterone or in C3H mice under any conditions tested. The infecting dose of MoPn did not clearly influence the frequency of reactivation in either inbred strain as defined by this model.

Lack of evidence for rotavirus by polymerase chain reaction/enzyme immunoassay of hepatobiliary samples from children with biliary atresia

The purpose of this study was to analyze hepatobiliary samples of patients with biliary atresia for rotavirus groups. A, B, and C, because group A rotavirus had been used to produce an animal model of the disease and group C rotavirus had been found in hepatobiliary samples from one group of patients. Biliary remnants and liver tissue from 10 biliary atresia and 14 control patients with other liver diseases were examined for rotavirus groups A, B, and C using nonisotopic, reverse transcriptase polymerase chain reaction enzyme immunoassay. Biliary atresia patients had a median age of 3 mo and were from a confined geographic area. Rotaviral stocks from groups A and C were used as polymerase chain reaction-positive controls. The limits of detection for rotaviral RNA from these two groups were respectively, 5 plaque-forming units and 50 tissue culture infectious doses (ID50). Tissue culture was 100-fold less sensitive for groups A and C than the polymerase chain reaction. The nested nonisotopic probes hybridized in solution only with their homologous target DNAs as determined by the enzyme immunoassay, or by Southern blot hybridization. Although it was possible to detect mRNA from a beta-actin housekeeping gene in all of the hepatobiliary samples, no evidence of rotaviral RNA was found in either the biliary atresia or the negative control group. In conclusion, rotavirus is not a common viral etiology of biliary atresia.

Interferon-gamma and interleukin-5 production by mice in response to genital infection by the mouse pneumonitis agent of Chlamydia trachomatis

BACKGROUND AND OBJECTIVES

Mice sensitized with a chlamydial detergent extract and then genitally infected by Chlamydia trachomatis have increased genital inflammation characterized by elevated eosinophils, but do not have increased protective immunity. In contrast, mice infected previously by C. trachomatis show strong protective immunity. The authors studied interferon-gamma levels (associated with protective immunity) and interleukin-5 levels (the major cytokine responsible for eosinophilia).

GOALS

To evaluate protective and nonprotective immune responses to chlamydial infection.

STUDY DESIGN

The authors examined interferon-gamma and interleukin-5 levels in the genitalia during chlamydial genital infection among three groups of mice: extract-sensitized, sham-sensitized, and infected previously.

RESULTS

Interferon-gamma levels peaked between 24 and 72 hours after chlamydial infection and then declined among all groups of mice. Overall, interleukin-5 levels increased throughout infection. Interleukin-5 levels apparently continued to increase over the 5-week period after primary infection.

CONCLUSIONS

Increased interferon-gamma levels were associated with an early response to chlamydial genital infection. Increased interleukin-5 levels were associated with a more persistent immune response.

Case report: in situ hybridization for detection of inapparent infection with Chlamydia trachomatis in synovial tissue of a patient with Reiter's syndrome

The authors have shown that protein antigens, RNA, and DNA from Chlamydia trachomatis are present in synovial tissues of patients with Reiter's syndrome (RS). However, those studies gave no insight into the host cell type involved or the precise tissue location of the bacteria. To address such issues, the authors developed an in situ hybridization system to detect chlamydia, and they used that system to examine synovial biopsies from a patient with RS and a patient without RS. The in situ system uses a previously described digoxigenin-labeled DNA probe that hybridizes with chlamydial 16S rRNA sequences in paraformaldehyde-fixed samples. Control studies with chlamydia-infected and uninfected HeLa cells confirmed that the in situ system is as sensitive as is direct fluorescence cytology for detection of the organism. Morphology of host and chlamydia cells is preserved after hybridization. Studies using synovial tissue from an osteoarthritis patient produced no in situ hybridization signal, but similar hybridization to tissue from a culture-/direct fluorescence cytology- negative RS patient had a strong intracellular signal for chlamydia within a subsynovial cell layer. These in situ hybridization results confirm the extensive presence of chlamydia in synovia and extend the authors' earlier observation that chlamydia RNA is present in the synovia of patients with RS. The data also confirm their electron microscopy studies, indicating that chlamydia are intracellular in synovial tissue, and they further show that infected host cells are located beneath the synovial lining.

Q-beta replicase-amplified assay for detection of Mycobacterium tuberculosis directly from clinical specimens

We report the results of a study conducted to evaluate the performance of manual Q-Beta replicase-amplified Mycobacterium tuberculosis complex assay compared with that of culture for detecting M. tuberculosis directly from digested sputum pellets. A total of 261 specimens submitted to three tuberculosis testing laboratories were analyzed. Culture and acid-fast bacillus smear results were provided by the tuberculosis testing laboratories. Of these 261 specimens, 34 (13% prevalence rate) were positive for M. tuberculosis by culture. The samples were digested and decontaminated by the testing laboratories by using their standard digestion and decontamination procedures. An aliquot of the digested and decontaminated pellet was sent to GENE-TRAK. The digested and decontaminated pellet was neutralized by washing it with 0.067 M phosphate buffer (pH 6.8), and the bacteria present in the washed pellet were heat inactivated at 100 degrees C for 15 min. The samples were combined with sample processing buffer containing GuSCN and were treated for 6 min in the GENE-TRAK Sample Processing Instrument to release the nucleic acids. The release rRNA was analyzed in a manual Q-Beta replicase assay format which incorporates elements of sandwich hybridization, reversible target capture, and Q-beta replicase signal amplification technologies. In comparison with culture, the overall assay sensitivity and specificity were 97.1 and 96.5%, respectively. The positive predictive value was 80.5%, and the negative predictive value was 99.5%. After analysis of discrepant results, the assay sensitivity and specificity were 97.3 and 97.8, respectively, and the prevalence rate was 14%. The positive predictive value and the negative predictive value were 87.8 and 99.5%, respectively. The Q-Beta replicase assay is rapid sensitive, semiquantitative, and specific for the direct detection of M. tuberculosis from clinical specimens.

Effects of two antibiotic regimens on course and persistence of experimental Chlamydia pneumoniae TWAR pneumonitis

We studied the effects of two antibiotic regimens on the course of Chlamydia pneumoniae infection in the lungs of Swiss Webster mice. After intranasal challenge with isolates AR-388 (1.3 x 10(7) inclusion-forming units per mouse) and AR-39 (1.5 x 10(6) inclusion-forming units per mouse), groups of animals were treated with either doxycycline (10 mg/kg of body weight once a day for 3 days), azithromycin (10 mg/kg [single dose]), or saline. Responses were assessed by the isolation of organisms in cell culture, detection of TWAR DNA in lung tissues by PCR, and lung histology. Both regimens were effective in clearing infections induced by AR-388 (P = 0.02 and 0.007 for doxycycline and azithromycin, respectively) compared with controls. TWAR DNA was detected in 77 and 25% of culture-negative lungs 2 weeks after treatment of AR-388 and AR-39 infections, respectively. Histological changes showed interstitial pneumonitis and were similar over time for all groups. Single-dose azithromycin produced drug levels in lung tissues above the MICs for the test strains for a period three times longer than that of single-dose doxycycline. We concluded that short-term antibiotic regimens were successful for the treatment of experimental TWAR pneumonitis in mice. TWAR DNA was frequently recovered from lung tissues after apparently successful treatment.

Comparison of characteristics of Q beta replicase-amplified assay with competitive PCR assay for Chlamydia trachomatis

In order to study infections due to Chlamydia trachomatis, we have compared semiquantitative PCR and Q beta replicase-amplified assays for detection of this organism. The PCR assay was directed against the C. trachomatis 16S rRNA gene. Quantitation was accomplished by adding known amounts of a plasmid containing a truncated segment of the 16S rRNA gene target to chlamydia-containing samples and then amplifying with a common primer set. The Q beta replicase assay consisted of reversible target capture of C. trachomatis 16S rRNA, which was followed by amplification of an RNA detector probe in the presence of the enzyme Q beta replicase. In a clinical matrix, the lower limit of detection of both the PCR and Q beta replicase assays was five elementary bodies. The Q beta replicase and PCR assays were quantitative over 10,000- and 1,000-fold ranges of organisms, respectively. Analysis of the effects of endocervical matrix on amplification was accomplished by examining 94 endocervical specimens by each technique. Both assays detected five of six culture-confirmed specimens as well as three culture-negative specimens. PCR inhibitors were detected in 13 specimens. The Q beta replicase assay, in contrast, showed no evidence of sample inhibition. The Q beta replicase and PCR assays should allow quantitative investigation of infections due to C. trachomatis. In addition, because it targets highly labile RNA, the Q beta replicase assay may facilitate investigations into the role of active persisting infection in culture-negative inflammatory conditions.

Reactivation of persistent Chlamydia trachomatis infection in cell culture

Gamma interferon induces persistent chlamydial infections in cell culture. These infections are characterized by altered morphologic and biochemical features of the pathogen. These persistent forms are abnormally large and noninfectious and undergo unusual structural and functional changes, including production of a paucity of outer envelope constituents and normal levels of the chlamydial hsp60, an immunopathological antigen. The current investigation evaluates the events that occur during reactivation of infectious Chlamydia trachomatis from persistently infected cell cultures. Transfer of persistent chlamydial organisms to gamma interferon-free medium resulted in recovery of infectivity accompanied by an increase in levels of structural membrane proteins and reorganization of aberrant organisms to morphologically typical elementary bodies. In addition, reactivation of infectious organisms from persistent chlamydiae that were maintained in culture for several weeks was demonstrated. These studies show that persistent C. trachomatis maintains viability for extended periods, illustrate the reversibility of immunologically mediated persistent infections, and characterize reactivation at the ultrastructural and biochemical levels.

Persistent chlamydiae: from cell culture to a paradigm for chlamydial pathogenesis

Chlamydiae are medically important bacteria responsible for a wide range of human infections and diseases. Repeated episodes of infection promote chronic inflammation associated with detrimental immune system-mediated pathologic changes. However, the true nature of chlamydial pathogenesis may encompass repeated infection superimposed upon persistent infection, which would allow for heightened immune reactivity. During the course of chlamydial infection, numerous host elaborated factors with inhibitory or modifying effects may cause alterations in the chlamydia-host cell relationship such that the organism is maintained in a nonproductive stage of growth. Abnormal or persistent chlamydiae have been recognized under a variety of cell culture systems. The numerous factors associated with altered growth suggest an innate flexibility in the developmental cycle of chlamydiae. This review evaluates in vitro studies of chlamydial persistence and correlates these model systems to features of natural chlamydial disease.

Molecular epidemiology of trachoma in a Gambian village

The application of a diagnostic and genotyping technique based on the polymerase chain reaction (PCR) to the study of trachoma epidemiology in the Gambian village of Jali is reported. PCR based on the major outer membrane protein (MOMP) gene of Chlamydia trachomatis appears to be more sensitive than either isolation or antigen detection by enzyme immunoassay; it had a specificity of 95% and sensitivity of 51% against clinical signs. PCR genotyping identified genotypes A and B of Chlamydia trachomatis circulating in Jali. Sequencing revealed a Pst1 restriction endonuclease site in the amplified MOMP gene of some B strains but not others; Pst1 digestion of the PCR product proved an easy method of distinguishing these strains. The distribution of serotypes and B strain variants shows a significant degree of household clustering (p < 0.001). PCR based genotyping combined with strain typing provides a new and powerful epidemiological tool for the study of transmission events in trachoma.

Unsuspected Chlamydia trachomatis infection and in vitro fertilization outcome

OBJECTIVE

Chlamydia trachomatis infections of the female genital tract, although a major cause of infertility, are often asymptomatic and undetected. Since many infertile women now seek in vitro fertilization, a procedure whereby fertilization and embryo implantation are precisely timed, we sought to determine the relation between an unsuspected C. trachomatis infection and the ability of embryos to implant and develop after their transfer to the uterus.

STUDY DESIGN

At the time of oocyte aspiration, endocervical samples were obtained from 216 women and assayed by enzyme-linked immunoassay for immunoglobulin A antibodies to C. trachomatis structural membrane components and to recombinant C. trachomatis heat shock protein. The presence of C. trachomatis in the cervices was assessed by the polymerase chain reaction. The outcome of each in vitro fertilization cycle was then ascertained.

RESULTS

Oocytes from 198 (91.7%) of the women were fertilized in vitro and subsequently transferred to the uterus. Term deliveries of healthy infants occurred after 68 (34.3%) of these transfers. Cervical immunoglobulin A antibodies to chlamydial heat shock protein were detected in 5 (7.3%) of the women with term births, and 1 (1.5%) also had immunoglobulin A antibody to chlamydial structural components; 3 (4.4%) were positive by the polymerase chain reaction for C. trachomatis. In contrast, among the 130 women whose embryo transfers did not result in an ongoing pregnancy, 36 (27.7%) had cervical antiheat shock protein immunoglobulin A (p = 0.0007) and 24 (18.5%) had antichlamydial structural component immunoglobulin A (p = 0.0002); 15 (11.5%) of these women had positive results of polymerase chain reaction for C. trachomatis. The majority of women with cervical antibodies to chlamydial structural antigens were also positive for antibody to heat shock protein. However, only 35% of the women with antibodies to heat shock protein were also positive for the other chlamydial antibodies. C. trachomatis was detected by polymerase chain reaction in 29.2% of women with anti-C. trachomatis antibodies and 7.8% of women with anti-heat shock protein antibodies. Women positive for antichlamydial immunoglobulin A were more likely to be undergoing a repeat in vitro fertilization cycle than were women who were antibody negative (p = 0.007).

CONCLUSION

Unsuspected C. trachomatis infection or reactivation of an immune response to the C. trachomatis heat shock protein may induce an inflammatory reaction in the uterus that impairs embryo implantation and/or facilitates immune rejection after uterine transfer of in vitro fertilized embryos.

Identification of individual genotypes of Chlamydia trachomatis from experimentally mixed serovars and mixed infections among trachoma patients

Genetic polymorphisms in the major outer membrane protein gene (omp-1) of Chlamydia trachomatis B and Ba serovars have been demonstrated in Tunisian isolates. A total of 15 of 27 unique sequence signatures or omp-1 genotypes were identified. However, differentiation of unique signatures from sequences that reflect those of strains involved in a mixed infection is necessary to define the molecular epidemiology of chlamydial ocular infections. We devised a strategy for identifying mixed infections by characterizing their effects on omp-1 genotyping. Various ratios of elementary bodies from organisms of serovars A, B, Ba, and C that cause trachoma were amplified by PCR and were subjected to automated and manual sequencing. Serovar-specific primers were also designed so that each serovar could be individually amplified and its omp-1 genotype unequivocally determined. One of 27 Tunisian samples showed a mixed infection with sequences comparable to those of serovars B and D. The omp-1 genotypes of organisms involved in mixed infections can be accurately identified by automated sequencing and will be useful for molecular epidemiologic studies of populations worldwide who live where trachoma is endemic.

Intracellular location of inapparently infecting Chlamydia in synovial tissue from patients with Reiter's syndrome

Culture of Chlamydia trachomatis from synovial tissues/fluids from Reiter's syndrome (RS) patients frequently yields negative results. However, we have identified chlamydial RNA at that site in such patients, suggesting that viable organisms may be present. Here we define the cellular location of chlamydia within the synovium via in situ hybridization. Using a chlamydial ribosomal RNA-directed probe, we show that synovial tissue from culture-negative RS patients gives strong hybridization which is often localized to a subsynovial cell layer, rather than to the synovial lining; in some cases, hybridizing cells are dispersed through the synovium. All hybridization signal is located within host cells, indicating that infectious extracellular elementary bodies are rare or absent. These data confirm the extensive intracellular presence of inapparent chlamydia in the synovia of RS patients and provide some insight into the usual culture negativity of synovial tissues for the organism.

Repeated and persistent infection with Chlamydia and the development of chronic inflammation and disease

Chlamydia trachomatis is an important human pathogen that mediates disease processes capable of inflicting permanent damage. Aggressive inflammatory responses to repeated infections, and to a persistent form of this intracellular bacterium, are thought to initiate the pathogenic events that lead to the debilitating sequelae of blinding trachoma and infertility.

Use of a commercial PCR kit for detecting Chlamydia trachomatis

AIMS

To evaluate a commercial polymerase chain reaction (PCR) kit for the detection of Chlamydia trachomatis.

METHODS

Two hundred and fifty seven genital specimens, which had been submitted in 2SP medium for chlamydial isolation and subsequently stored at -70 degrees C, were retrospectively examined by a commercial PCR kit which detects chlamydial plasmid DNA. Culture negative, PCR positive specimens were examined by immunofluorescence and an in-house major outer membrane protein (MOMP)-PCR.

RESULTS

All 49 specimens which were culture positive were also PCR positive. Another 14 specimens were also PCR positive. After resolution of these results by immunofluorescence and a PCR assay for MOMP the sensitivity for PCR was 98.4% and that of culture 79%. The specificities were 99.5% and 100%, respectively.

CONCLUSIONS

This kit, which is highly sensitive and specific, is straightforward to use and has a built-in safeguard against cross contamination. The role of this test in the examination of routine genital specimens from patients with uncomplicated chlamydial infection is questionable due to its expense. It may have a place in the investigation of trachoma or infertility, however, where it has been shown that DNA can be detected when culture is unsuccessful.

Sensitive detection and typing of Chlamydia trachomatis using nested polymerase chain reaction

OBJECTIVES

A method based on a nested polymerase chain reaction (PCR) was developed to detect and to type Chlamydia trachomatis from low titre samples by amplifying a large portion of the major outer membrane protein gene. The sensitivity of this procedure was evaluated in urogenital clinical samples in comparison with culture.

SPECIMENS

A series of 787 urogenital specimens, including 37 (4.7%) positive by culture, together with 227 other samples that had been found to yield less than 25 chlamydial inclusions in culture were tested.

METHODS

Samples were pelleted, resuspended in 1 mM NaOH, heated and amplified without further purification. After 40 cycles of PCR, 1 microliters of product was amplified by a further 30 cycles of PCR using a second set of primers nested within the initial pair. Positives were detected by agarose gel electrophoresis and confirmed by repeating the PCR analyses and determining the serovar of both amplified samples by restriction fragment length polymorphism.

RESULTS

Nested PCR allowed detection of 96% and culture 77% of positives with only three samples repeatedly positive by PCR but considered false positives because a different serovar was identified in the two amplifications. Of culture-positive samples with less than 11 chlamydia inclusion-forming-units 97% could be detected by nested PCR and most still gave a positive signal when diluted hundred fold.

CONCLUSIONS

Nested PCR provided the basis for a very sensitive C trachomatis detection and typing strategy. Repetition and typing positive samples facilitated detection of false-positive PCR specimens resulting from contamination of the PCR process or any reagent except the original sample.

Comparison of plasmid- and chromosome-based polymerase chain reaction assays for detecting Chlamydia trachomatis nucleic acids

Several laboratories have demonstrated that the polymerase chain reaction (PCR) is more sensitive than culture or enzyme immunoassay (EIA) for detecting Chlamydia trachomatis in genitourinary tract specimens when various DNA targets are used for amplification, including the cryptic plasmid, major outer membrane protein (MOMP), or rRNA genes. We compared the performances of five different PCR assays, including assays with two plasmid, two MOMP, and one rRNA targets, by amplifying serial dilutions of C. trachomatis DNA and testing genitourinary tract specimens. By using published procedures, two different plasmid primers had sensitivities of 0.1 fg for C. trachomatis plasmid DNA and 10 fg for total cellular DNA. The sensitivities of the assays with the two MOMP primers were 0.1 and 10 pg, and the sensitivity for the assay with the rRNA primers was 1 pg for cellular DNA. Both plasmid-based assays detected 38 of 38 confirmed Chlamydiazyme-positive specimens, whereas the assays with the MOMP and rRNA primers detected 36 of 38 and 29 of 38 confirmed Chlamydiazyme-positive specimens, respectively. Six of 18 Chlamydiazyme-negative specimens collected from individuals whose specimens were positive by culture or immunofluorescence were positive by both plasmid-based PCRs; 4 of these were positive by PCR with the MOMP primers and 3 were positive by PCR with the rRNA primers. The results obtained with both purified DNA and genitourinary tract specimens indicated that the plasmid-based PCRs are more sensitive than bacterial chromosome-based PCRs for detecting C. trachomatis.

Detection of Chlamydia trachomatis in semen by the polymerase chain reaction in male members of infertile couples

OBJECTIVE

Our objective was to evaluate the presence of asymptomatic Chlamydia trachomatis infection by means of the polymerase chain reaction in male members of couples with previously undiagnosed infertility.

STUDY DESIGN

Twenty-eight infertile-couples who had negative cultures or negative results when tested by deoxyribonucleic acid probe for Chlamydia trachomatis in semen and cervical samples were studied. Semen samples were tested for Chlamydia trachomatis by means of the polymerase chain reaction. Sera from both partners were diluted 1:128 and tested for immunoglobulin M antibodies to Chlamydia. Sera and ejaculated sperm were evaluated for the presence of antisperm antibodies. Semen analyses were also performed.

RESULTS

Chlamydia trachomatis was identified in semen from 11 (39.3%) of the male partners. Its detection correlated with the presence in the ejaculate of motile sperm containing antisperm antibodies (p < 0.01). Either antisperm immunoglobulin G, immunoglobulin A, or both were located on sperm only from 5 (45.5%) of the 11 men whose results were positive when tested for Chlamydia trachomatis. Similarly, immunoglobulin G or immunoglobulin A antibodies to sperm were only detected in 5 (45.5%) of the spouses of men with Chlamydia in semen. Immunoglobulin M antibody to Chlamydia trachomatis was identified in only one of the men. However, antichlamydial immunoglobulin M antibodies were present in sera from 6 (54.5%) female partners of men with seminal Chlamydia trachomatis but in none of the other 17 women (p < 0.01).

CONCLUSION

Although undetected by culture of deoxyribonucleic acid probe of semen samples, Chlamydia trachomatis was nevertheless identified in semen of some symptom-free men by the polymerase chain reaction. This is probably a result of the increased sensitivity of the polymerase chain reaction to detect Chlamydia trachomatis. The increased prevalence of an autoimmune response to sperm in men with this organism in their semen suggests that a subclinical chlamydial infection may activate an immune response to sperm. A similar association between Chlamydia trachomatis in semen and circulating antisperm antibodies in female partners indicates that Chlamydia may also induce an immune response to sperm in women. Infertility in these couples may be the result of a direct inflammatory response in the cervix or endometrium to repeated Chlamydia exposure or of the ability of Chlamydia to evoke an immune response to spermatozoa.