Detection of Chlamydia trachomatis-DNA in synovial fluid: evaluation of the sensitivity of different DNA extraction methods and amplification systems

Are ELISA and PCR Discrepancies in the Identification of Chlamydia pneumoniae Caused by the Presence of "Chlamydia-Related Bacteria"?

Chlamydia are Gram-negative, intracellular pathogens colonizing the epithelial mucosa. They cause primarily atypical pneumonia and have recently been associated with chronic diseases. Diagnostics rely almost exclusively on serological methods; PCR tests are used rarely because in patients with positive ELISA, it is nearly impossible to identify chlamydial DNA. To understand this issue, we elaborated a reliable and sensitive nested PCR method (panNPCR) for identifying all Chlamydiales species, not only in sputa, but also in clotted blood. Sequencing of the PCR product revealed that 41% of positive sputa samples and 66% of positive blood samples were not infected by Chlamydia but with "Chlamydia-related bacteria" such as Rhabdochlamydia sp., Parachlamydia sp., Protochlamydia sp., Neochlamydia sp., Mesochlamydia elodeae and lacustris, Piscichlamydia salmonis, and Estrella lausannensis. Consequently, we propose that there might be more than four human pathogenic Chlamydia species. We did not find any clear correlation between increased levels of antibodies and the presence of their DNA. Chlamydialles DNA was found in sputa samples from individuals positive for IgG or IgA but not in blood samples. Thus, elevated IgG and IgA levels are not reliable markers of chronic infection, and the presence of persistent forms should be proved by panNPCR. Apparently, the differences between ELISA and DNA amplification results have three main methodological reasons. The first one is the threshold occurrence of chlamydial genetic material in sputum and blood. The second one is the fact that a significant part of the samples can have DNA with sequences different from those of other species of the order Chlamydiales. The third one is the high background characteristic for ELISA, the absence of paired sera, and the vague interpretation of the gray zone.

Synoviale Veränderungen bei Erkrankungen des rheumatologischen Formenkreises und Differenzialdiagnosen

Die Untersuchung synovialer Veränderungen kann zur Diagnose von Gelenkerkrankungen und von systemischen Erkrankungen beitragen. Die Domäne der histopathologischen Diagnostik stellt die Abgrenzung tumoröser von entzündlichen Läsionen dar. Daneben können Kristallarthropathien und bestimmte Stoffwechselerkrankungen sicher diagnostiziert werden. Unter dem histologischen Bild einer granulomatösen Synovialitis können neben einer mykobakteriellen Infektion Sarkoidosen und Fremdkörperreaktionen sowie selten genetische Erkrankungen beobachtet werden. Amyloidosen können auch in der Tunica synovialis subtypisiert werden. Molekulare Methoden erlauben die schnelle und sichere Diagnostik septischer Arthritiden und eine Keimtypisierung. Mittels dieser Methoden können auch reaktive Arthritiden klassifiziert werden, da auch hier häufig DNA oder RNA bestimmter Keime in Gewebe oder Gelenkflüssigkeit nachgewiesen werden kann. Die Diagnose der rheumatoiden Arthritis basiert auf den American College of Rheumatology(ACR)-Kriterien. Molekulare Methoden, wie die Mikro-RNA-Technologie oder proteomische Methoden können die Diagnose unterstützen.

Reliable and Sensitive Nested PCR for the Detection of Chlamydia in Sputum

Chlamydia are Gram-negative, intracellular pathogens colonizing epithelial mucosa. They cause primarily atypical pneumonia and have recently been associated with chronic diseases. Diagnostics relies almost exclusively on serological methods; PCR tests are used rarely because in patients with positive ELISA, it is nearly impossible to identify chlamydial DNA. This paradox is associated with DNA degradation in sputum samples, low abundance, and low sensitivity of PCR systems. In a newly designed and validated “nested” PCR (NPCR) assay, it was possible to amplify DNA of Chlamydia known to infect humans in 31% samples. The reliability of the assay was confirmed by DNA sequencing, and all PCR products belonged exclusively to the Chlamydiales, mainly recognized as Chlamydia pneumoniae. Three samples were related to Ca. Rhabdochlamydia porcellionis and Ca. Renichlamydia lutjani, which infect arthropods. In one case, samples were taken from sick individual, indicating the potential as a human pathogen.

Putative Pathobionts in HLA-B27-Associated Spondyloarthropathy

Spondyloarthritis (SpA) is a group of immune mediated inflammatory diseases with a strong association to the major histocompatibility (MHC) class I molecule, HLA-B27. Although the association between HLA-B27 and AS has been known for almost 50 years, the mechanisms underlying disease pathogenesis are elusive. Over the years, three hypotheses have been proposed to explain HLA-B27 and disease association: 1) HLA B27 presents arthritogenic peptides and thus creates a pathological immune response; 2) HLA-B27 misfolding causes endoplasmic reticulum (ER) stress which activates the unfolded protein response (UPR); 3) HLA-B27 dimerizes on the cell surface and acts as a target for natural killer (NK) cells. None of these hypotheses explains SpA pathogenesis completely. Evidence supports the hypothesis that HLA-B27-related diseases have a microbial pathogenesis. In animal models of various SpAs, a germ-free environment abrogates disease development and colonizing these animals with gut commensal microbes can restore disease manifestations. The depth of microbial influence on SpA development has been realized due to our ability to characterize microbial communities in the gut using next-generation sequencing approaches. In this review, we will discuss various putative pathobionts in the pathogenesis of HLA-B27-associated diseases. We pursue whether a single pathobiont or a disruption of microbial community and function is associated with HLA-B27-related diseases. Furthermore, rather than a specific pathobiont, metabolic functions of various disease-associated microbes might be key. While the use of germ-free models of SpA have facilitated understanding the role of microbes in disease development, future studies with animal models that mimic diverse microbial communities instead of mono-colonization are indispensable. We discuss the causal mechanisms underlying disease pathogenesis including the role of these pathobionts on mucin degradation, mucosal adherence, and gut epithelial barrier disruption and inflammation. Finally, we review the various uses of microbes as therapeutic modalities including pre/probiotics, diet, microbial metabolites and fecal microbiota transplant. Unravelling these complex host-microbe interactions will lead to the development of new targets/therapies for alleviation of SpA and other HLA-B27 associated diseases.

Causality of Chlamydiae in Arthritis and Spondyloarthritis: a Plea for Increased Translational Research

Current molecular genetic understanding of the metabolically active persistent infection state of Chlamydia trachomatis and Chlamydia pneumoniae in the synovium in patients with arthritis and spondyloarthritis favors a causal relationship. Here, we examine how adequately the accepted criteria for that etiologic relationship are fulfilled, emphasizing the situation in which these microorganisms cannot be cultivated by standard or other means. We suggest that this unusual situation of causality by chlamydiae in rheumatic disease requires establishment of a consensus regarding microorganism-specific terminology as well as the development of new diagnostic and classification criteria. Recent studies demonstrate the value of molecular testing for diagnosis of reactive arthritis, undifferentiated spondyloarthritis, and undifferentiated arthritis caused by C. trachomatis and C. pneumoniae in clinical practice. Data regarding combination antibiotic therapy is consistent with the causative role of chlamydiae for these diseases. Observations of multiple intra-articular coinfections require more research to understand the implications and to respond to them.

Influence of storage time on DNA of Chlamydia trachomatis, Ureaplasma urealyticum, and Neisseria gonorrhoeae for accurate detection by quantitative real-time polymerase chain reaction

The shipment and storage conditions of clinical samples pose a major challenge to the detection accuracy of Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), and Ureaplasma urealyticum (UU) when using quantitative real-time polymerase chain reaction (qRT-PCR). The aim of the present study was to explore the influence of storage time at 4°C on the DNA of these pathogens and its effect on their detection by qRT-PCR. CT, NG, and UU positive genital swabs from 70 patients were collected, and DNA of all samples were extracted and divided into eight aliquots. One aliquot was immediately analyzed with qRT-PCR to assess the initial pathogen load, whereas the remaining samples were stored at 4°C and analyzed after 1, 2, 3, 7, 14, 21, and 28 days. No significant differences in CT, NG, and UU DNA loads were observed between baseline (day 0) and the subsequent time points (days 1, 2, 3, 7, 14, 21, and 28) in any of the 70 samples. Although a slight increase in DNA levels was observed at day 28 compared to day 0, paired sample t-test results revealed no significant differences between the mean DNA levels at different time points following storage at 4°C (all P>0.05). Overall, the CT, UU, and NG DNA loads from all genital swab samples were stable at 4°C over a 28-day period.

Coinfection of Chlamydiae and other Bacteria in Reactive Arthritis and Spondyloarthritis: Need for Future Research

Reactive (inflammatory) arthritis has been known for many years to follow genital infection with the intracellular bacterial pathogen Chlamydia trachomatis in some individuals. Recent studies from several groups have demonstrated that a related bacterium, the respiratory pathogen Chlamydia pneumoniae, can elicit a similar arthritis. Studies of these organisms, and of a set of gastrointestinal pathogens also associated with engendering inflammatory arthritis, have been relatively extensive. However, reports focusing on coinfections with these and/or other organisms, and the effects of such coinfections on the host immune and other systems, have been rare. In this article, we review the extant data regarding infections by multiple pathogens in the joint as they relate to engendering arthritis, and we suggest a number of research areas that must be given a high priority if we are to understand, and therefore to treat in an effective manner, such arthritides.

Optimized testing for C. trachomatis DNA in synovial fluid samples in clinical practice

AIM

No standardized polymerase chain reaction (PCR) assay is available for detection of Chlamydia trachomatis (C. tr.) in synovial fluid (SF) for diagnostic use in clinical practice. This study tested the performance of two optimized molecular biology methods, to determine which is best suited for detecting C. tr. in SF clinical samples from patients with various rheumatologic diseases.

METHODS

Two DNA extraction methods, i.e., (1) alkaline lysis and (2) QIAEX II Gel Extraction Kit® + cetyltrimethylammonium bromide (CTAB; Qiagen, Hilden, Germany), and C. tr.-omp1-152 bp PCR were tested in SF samples from a total of 329 patients with the following diagnoses: reactive arthritis (ReA; n = 10, 4 patients had posturethritic ReA), undifferentiated arthritis (UA; n = 66), rheumatoid arthritis (RA; n = 169), psoriatic arthritis (PSA; n = 12), and osteoarthritis (OA) n = 72.

RESULTS

In SF samples, C. tr.-omp1-152 bp PCR in combination with alkaline lysis DNA extraction allowed detection of more C. tr.-positive samples: 3/10 (30%) ReA patients (all with posturethritic ReA) and 20/66 (38%) UA patients were positive, compared to the 0/10 (0%) patients with ReA and 1/66 (2%) with UA detected using the QIAEX II Gel Extraction Kit® + CTAB. Moreover, 2/12 (17%) SF samples from PSA patients tested positive with alkaline lysis. All samples from patients with OA and RA tested negative.

CONCLUSION

Alkaline lysis in combination with C. tr.-omp1-152 bp PCR emerged as the most sensitive method for identification of C. tr. in clinical SF samples.

Validation of a previously developed quantitative polymerase chain reaction for the detection and quantification of Mycoplasma synoviae in chicken joint specimens

A quantitative polymerase chain reaction (qPCR) was validated for the detection of Mycoplasma synoviae (PCR equivalents of colony-forming units [CFU eq.]) in chicken joint specimens with time and compared with direct mycoplasma culture. Joint specimens were obtained from 70 layer pullets inoculated intravenously with M. synoviae at 6 weeks of age. Ten control birds were injected intra-articularly with Freund's complete adjuvant. Macroscopic joint lesions were observed in 54 infected birds, of which 11 showed positive M. synoviae culture. The specificity of direct mycoplasma culture was high (100%, 95% confidence interval [CI] = 74 to 100), but its sensitivity low (16%, 95% CI = 8 to 26). Most positive results were obtained during the first 2 weeks after onset of joint swelling using synovial fluid. The qPCR was positive in 26 of 28 synovial fluid samples and in 51 of 70 joint swabs. The sterile joint samples obtained from Freund's complete adjuvant-injected birds were negative in the mycoplasma culture. The specificity and sensitivity of the qPCR for synovial fluid samples were 100% (95% CI = 65 to 100) and 93% (95% CI = 77 to 99); for joint swabs they were 100% (95% CI = 74 to 100) and 73% (95% CI = 61 to 83), respectively. Positive qPCR results (10(0.3) (to) (4.6) CFU eq./ml) were found until the end of the experiment (12 weeks post inoculation). At the end of the study, eight out of 16 joint swabs from birds without macroscopic joints lesions were positive in the qPCR (10(2.0) (to) (2.8) CFU eq./ml). Under the conditions of this study, the sensitivity of the qPCR was higher than that of direct mycoplasma culture (P< 0.0001) during the acute, subacute and chronic stages of arthritis.

[Diagnosis and treatment of Chlamydia-induced reactive arthritis]

Urogenital chlamydia infections are the most prevalent of all sexually transmitted diseases although the number of chlamydia-induced reactive arthritis cases are generally below the estimated incidence of the disease. This may be related with the high rate of asymptomatic chlamydial infections and the lack of adequate diagnostic criteria. Polymerase chain reaction (PCR), a new system for detection of Chlamydia, is one of the most useful techniques for the diagnosis of this disease. Biologic therapy produces theoretical doubts regarding its indication and there is little information related with chlamydia induced reactive arthritis treatment efficacy. Although the usefulness of long antibiotic treatment is not clear, the use of combination antibiotics opens new therapeutic strategies for chlamydia induced reactive arthritis.

Molecular Approach by PCR is the Best Method to Detect the Presence of Chlamydia Trachomatis and to Define the True Agent of Ocular Bacterial Inflammation

Chlamydia trachomatis (Ct) is an atypical agent for acute, subclinical and chronic conjunctivitis in developed countries, as stated by the International League against Trachoma. In order to evaluate the presence of Ct, from a total of 3,520 patients visiting the consulting room of the Eye Clinic of G. d'Annunzio University of Chieti, Italy from 2006–2008, we enrolled 171 patients affected by occasional mild, moderate or severe conjunctivitis in a three-arm prospective open study, using traditional analysis such as Immune Fluorescent Assay and Enzyme–Linked Fluorescent Assay (IFA and ELFA) and molecular analysis with Polymerase Chain Reaction (PCR) procedure for Ct DNA research (Ct DNA). At the same time, microbiological culture was carried out for common germs and mycetes. These patients were analyzed at different subsequent times. In the first arm (Group A) of 82 patients with IFA and ELFA only 10 people (12.2%) resulted positive to Ct infection with both methods. The presence of Ct was never alone, but always overlapped with contaminants, like corynebacteria, staphylococci, streptococci and colonbacteria, randomly distributed, while no growth of mycetes was observed. Of these positive patients, only one 47-year-old female, suffering from a moderate form of ocular chlamydial infection, showed serological conversion against this infection; furthermore, this female had also been suffering from reactive arthritis for sometime. In the second arm (Group B) of 89 patients, we carried out PCR for Ct detection: 82 (94.25%) were found positive to Ct – DNA research, with common germ growth randomly associated, without sex or age prevalence, as in group A; no mycetes were found. The third arm (Group C) included 37 negative patients from Group A with severe or moderate chronic conjunctivitis, randomly recruited between relapsing cases, with the addition of the single previously positive seroconversion case, for a total of 38 patients, who were re-evaluated by PCR Ct-DNA analysis. All these patients, negative to IFA and ELFA, were positive to Ct-DNA analysis. These data indicate a higher rate of Ct infection in patients with severe or moderate chronic conjunctivitis, resistant to usual therapies even after eradication of common germs, thus showing the advantage of introducing this molecular technique of analysis in mild to severe chronic or recurrent conjunctivitis.