Detection of Chlamydia trachomatis by the polymerase chain reaction in swabs and urine from men with non-gonococcal urethritis

MicroRNA mediated regulation of oxidative stress and cytokines in Chlamydia trachomatis-infected recurrent spontaneous abortion: A case-control study

PROBLEM

Increased oxidative stress (OS) and inflammatory responses are major underlying factors behind Chlamydia trachomatis-associated recurrent spontaneous abortion (RSA). miRNAs are known to regulate inflammation and OS and their dysregulation has been associated with compromised pregnancies. Therefore, aim of this study was to investigate the expression/correlation of OS biomarkers, cytokines and miRNAs in C. trachomatis-associated RSA.

METHOD OF STUDY

Urine and non-heparinized blood samples were collected from RSA patients with history of >3 consecutive abortions (cases) and non-pregnant women with history of >2 successful deliveries (controls) attending Department of Obstetrics and Gynaecology, Safdarjung hospital, New Delhi. C. trachomatis detection was done in urine by PCR. miRNA expression was studied by microarray analysis and validated by real time-PCR. Evaluation of cytokines and antioxidant genes expression were done by real-time PCR. Level of OS biomarkers 8-hydroxy guanosine (8-OHdG) and 8-isporostane (8-IP) were measured by ELISA.

RESULTS

Fifty circulating miRNAs were differentially expressed in infected patients compared with controls. Of these, four were overexpressed and 46 downregulated. Thirteen differentially expressed circulating miRNAs were selected to validate microarray results. miRs-8069, -3663-3p showed maximum upregulation/downregulation in infected versus control group. Expression of cytokines (IL-8, TNF-α, IFN-γ), antioxidant genes SOD2 and OS biomarkers (8-OHdG,8-IP) were increased while SOD1 was decreased in infected patients. miR-8069 showed significant positive correlation with cytokines, SOD2, 8-OHdG and 8-IP. miR-3663-3p showed significant positive correlation with SOD1.

CONCLUSIONS

Overall results indicate circulating miRNAs are involved in pathogenesis of C. trachomatis-associated RSA and are potential modulators of cytokine signalling and OS in infected RSA.

Progesterone-mediated immunoregulation of cytokine signaling by miRNA-133a and 101-3p in Chlamydia trachomatis-associated recurrent spontaneous abortion

miRNAs regulate the expression of various genes involved in cellular and metabolic pathways in pregnancy related complications including recurrent spontaneous abortion (RSA). Modulation of progesterone and associated pro-inflammatory cytokines by miRNAs in Chlamydia trachomatis-associated RSA is still under investigation. Present study aimed to evaluate the expression/correlation of serum-circulating miRNAs-133a, 101-3p, 320b, 146b-5p, 24, 559, progesterone and few cytokines in C. trachomatis-positive spontaneous aborters. Non-heparinized blood and urine was collected from 120 patients with history of RSA (Group I) and 120 patients with ≥ 2 successful deliveries (Group II) attending Department of Obstetrics and Gynecology, Safdarjung hospital, New Delhi, India. C. trachomatis detection was performed by PCR and chlamydial load by real time PCR. Progesterone concentration was estimated by ELISA. miRNAs and cytokine expression was studied by quantitative real-time PCR and correlated with progesterone expression. Twenty six patients were found to be positive for C. trachomatis. miRNAs- 133a, 101-3p showed maximum upregulation in infected versus control patients. miRNA expression showed positive correlation with chlamydial load. Progesterone concentration showed significant decrease while cytokines (IL-6, IFN-γ, TNF-α) were significantly upregulated in C. trachomatis-positive patients. Positive correlation was observed between expression of miRNAs-133a and 101-3p and cytokines while negative correlation was observed with progesterone in infected RSA patients. Correlation between progesterone and cytokines was found to be significantly negative in infected RSA patients. Although further validation is required, the study concludes that miR-133a and 101-3p are of clinical importance and have a role in immunoregulation of progesterone and cytokines in infection associated RSA.

Immune regulation by activation markers at feto-maternal interface in infection-associated spontaneous preterm birth

BACKGROUND

Spontaneous preterm birth (sPTB) is a global health concern. Studies reveal infections are majorly responsible for sPTB and immune activation markers play a role in regulation of maternal immune responses against pathogens during sPTB.

AIM

To study the mRNA expression and correlation of activation markers (CD66a, ICAM1, ITGB1, TIM3, CD25, CD95) and associated cytokines (IL-1β and IL-17)/prostaglandin receptors (EP2 and IP) in the placenta of Chlamydia trachomatis, Mycoplasma hominis, Ureaplasma urealyticum-infected sPTB women.

METHODS

Placental samples were collected from 160 sPTB and 160 term birth women. PCR was used for the detection of C. trachomatis, M. hominis, U. urealyticum. The mRNA expression of activation markers, cytokines and prostaglandin receptors was evaluated by real-time qPCR.

RESULTS

The fold-change expression of CD66a, ICAM1, TIM3, CD25 and CD95 was 2.89, 5.5, 4.95, 6.44 and 6.95-fold (p < 0.001), respectively; while for cytokines- IL-1β and IL-17 was 5.41 and 4.71-fold (p < 0.001), respectively and for prostaglandin receptors- EP2 and IP was 5.5 and 5-fold (p < 0.001) upregulated, respectively in infected sPTB women. Significant positive correlation was obtained among ICAM-1 and IL-1β/EP2/IL-17, TIM3 and IP/IL-17. Significant negative correlation was obtained between CD66a and EP2/IL-17, CD25 and IL-1β/EP2, CD95 and IL-1β/EP2 in infected sPTB women.

CONCLUSIONS

CD66a, ICAM1 and TIM3 may play role in inflammation and have potential for the clinical beginning of preterm labour during infection while CD25 and CD95 are possibly involved in immunotolerance at feto-maternal interface during C. trachomatis, M. hominis and U. urealyticum infection.

Microarray profiling of serum micro-RNAs in women with Chlamydia trachomatis-associated recurrent spontaneous abortion: A case control study

Chlamydia trachomatis infection is a major cause of sexually transmitted diseases and adverse pregnancy outcomes such as recurrent spontaneous abortion (RSA). Micro-RNAs (miRNAs) have been known to be upregulated/downregulated in various reproductive-associated diseases such as ectopic pregnancy, preterm birth and pre-eclampsia. However, there is paucity of literature on miRNA profile in C. trachomatis-infected RSA. The present study aimed to determine the profile of serum miRNAs followed by their validation in C. trachomatis-infected RSA and to find target genes involved in biological pathways. Non-heparinized blood and first void urine were collected from 30 non-pregnant women with RSA and 30 non-pregnant women with ≥2 successful deliveries (controls) attending Department of Obstetrics and Gynaecology, Safdarjung hospital, New Delhi, India. C. trachomatis detection was done in urine by PCR and chlamydial load was determined by quantitative real-time PCR (qRT-PCR). miRNA expression was studied by microarray analysis followed by in vitro validation by qRT-PCR. Analysis of target genes/pathways was characterized in silico. 06 RSA patients were infected with C. trachomatis, while chlamydial load was found to be 6000-12,000 copies/ml. 110 circulating miRNAs were expressed differentially in infected RSA patients compared with controls. Of these, 16 were overexpressed and 94 downregulated. 06 differentially expressed circulating miRNAs were selected to validate the microarray results. qRT-PCR data confirmed the reliability of the microarray results: miR-4443, -5100, -7975 showed statistically significant upregulation, while miR-6808-5p, -3148, -6727-5p were significantly downregulated in infected RSA patients versus controls. Chlamydial load was positively correlated with these upregulated miRNAs. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that target genes of miRNAs in RSA are involved in AMPK, Akt and mTOR signaling pathways. Overall results indicate that differentially expressed circulating miRNAs are involved in pathogenesis of C. trachomatis-associated RSA and have the potential to be used as biomarkers for predicting RSA.

Intronic variants of LGALS13 gene encoding placental protein (PP13) are linked with increased risk of infection-associated spontaneous preterm birth

PROBLEM

Spontaneous preterm birth (sPTB) is a global health issue. Studies suggest infection and infection-based inflammatory responses are major risk factors for sPTB. Considering the important role of anti-inflammatory proteins in pregnancy, the study aimed to find the association between anti-inflammatory LGALS13 gene variants IVS2-22 A/G (rs2233706) and IVS3+72 T/A (rs2233708) and the risk of sPTB during Chlamydia trachomatis, Mycoplasma hominis and Ureaplasma urealyticum infection in Indian population.

METHOD OF STUDY

Placental samples of 160 sPTB and 160 term women were collected. Pathogens were detected by PCR. The genotyping of LGALS13 gene variants IVS2-22 A/G (rs2233706) and IVS3+72 T/A (rs2233708) was done by qualitative real-time PCR using allelic discrimination method (VIC- and FAM-labeled).

RESULTS

The frequency of AG or GG genotype of LGALS13 IVS2-22A/G polymorphism (rs2233706) was 75.5% in infected sPTB cases and 14.4% in uninfected sPTB cases and 7.3% in term birth controls (p < .0001), while the frequency of TA or AA genotype of LGALS13 IVS3+72T/A polymorphism (rs2233708) was 83.6% in infected sPTB cases and 18% in uninfected sPTB cases and 12.7% in term birth controls (p < .0001). The genotypic frequencies for both the variants of LGALS13 were statistically significant (p < .0001) in the infected sPTB versus uninfected sPTB and term birth controls.

CONCLUSIONS

Study reveals strong association between the presence of immunological gene variants LGALS13 IVS2-22 A/G (rs2233706) and LGALS13 IVS3+72 T/A (rs2233708) and risk of sPTB during C. trachomatis, M. hominis and U. urealyticum infection.

Immunomodulation of cytokine signalling at feto-maternal interface by microRNA-223 and -150-5p in infection-associated spontaneous preterm birth

Spontaneous preterm birth (sPTB) is a global health concern and it is the most prevalent cause of infant mortality and morbidity with occurrence rate of 5 - 18% worldwide. Studies suggest infection and infection-driven activation of inflammatory responses are the potential risk factors for sPTB. MicroRNAs (miRNAs) are thought to control the expression of several immune genes, making them crucial components of the intricate immune regulatory network and the dysregulation of miRNAs in placenta has been associated to several pregnancy-related complications. However, studies on possible role of miRNAs in immunomodulation of cytokine signalling in infection-associated sPTB are scarce. Present study aimed to investigate expression/ correlation of a few circulating miRNAs (miR-223, -150-5p, -185-5p, -191-5p), miRNA target genes and associated cytokines in sPTB women found infected with Chlamydia trachomatis/ Mycoplasma hominis/ Ureaplasma urealyticum. Non-heparinized blood and placental sample were collected from 140 sPTB and 140 term women visiting Safdarjung hospital, New Delhi (India) for conducting PCR and RT-PCR for pathogen detection and miRNA/ target gene/ cytokine expression, respectively. Common target genes of differentially expressed miRNAs were obtained from databases. The correlation between select target genes/ cytokines and serum miRNAs was determined by Spearman's rank correlation. 43 sPTB were infected with either pathogen and a significant upregulation of serum miRNAs was observed. However, miR-223 and 150-5p showed maximum fold-change (4.78 and 5.58, respectively) in PTB versus control group. IL-6ST, TGF-β R3 and MMP-14 were important target genes among 454 common targets, whereas, IL-6 and TGF-β were associated cytokines. miR-223 and 150-5p showed significant negative correlation with IL-6ST/ IL-6/ MMP-14 and positive correlation with TGF-β R3/ TGF-β. A significant positive correlation was found between IL-6ST and IL-6, TGF-β R3 and TGF-β. However, miR-185-5p and 191-5p were not significantly correlated. Although post-transcriptional validation is required, yet on the basis of mRNA findings, the study concludes that miR-223 and 150-5p are apparently of clinical importance in regulation of inflammatory processes during infection-associated sPTB.

Galectins are critical regulators of cytokine signalling at feto-maternal interface in infection-associated spontaneous preterm birth

INTRODUCTION

Spontaneous preterm birth (sPTB) is a global health issue. Studies suggest infections are chiefly associated with sPTB and galectins (gals) play a role in regulation of innate and adaptive maternal immune response against pathogens during sPTB. The aim of this study was to describe the gene expression of gal -1, -3, -8, -9, -13 in relation to gene expression of cyclooxygenase-2 (COX-2) and the cytokines IL-8, IL-10, TNF-α, IFN-ϒ in the setting of sPTB and confirmed infection with Chlamydia trachomatis, Mycoplasma hominis, and Ureaplasma urealyticum.

METHODS

Placental samples were collected from 120 term control and 120 sPTB pregnancies. PCR was used to detect specific pathogens. Gene expression of galectins, cytokines, and COX-2 was performed using real time qPCR.

RESULTS

Fold-change expression of gal -1, -3, -8, -9, -13 was 5.13, 6.11, 1.14, 5.23 and 7.16 (p<0.001), respectively; while IL-10, IL-8, TNF-α, IFN-ϒ and COX-2 was 6.29, 6.55, 6.35, 6.36 and 2.73-fold upregulated (p<0.05), respectively in infected sPTB. Gal-1 was positively correlated with IL-10 (r=0.49, p=0.003) while gal-3 showed significant correlation with IL-8 (r=0.42, p=0.0113), TNF-α (r=0.65, p=< 0.001) and COX-2 (r=0.72, p=0.001). However, gal-8 was not significantly correlated with any cytokine. Gal-9, -13 were negatively correlated with IFN-ϒ (r=-0.45, p=0.006) and IL-8 (r=-0.39, p=0.018).

DISCUSSION

Gal-1, -9, -13 are anti-inflammatory and might play role in immune-tolerance while gal-3 is pro-inflammatory and possibly responsible for immunogenic response, having potential to anticipate the clinical beginning of preterm labour during infection.

Association of functional superoxide gene polymorphism with chlamydia trachomatis-associated recurrent spontaneous abortion

BACKGROUND

Oxidative stress generated by Chlamydia trachomatis infection is associated with reproductive complications such as recurrent spontaneous abortion. Aim of prospective study was to evaluate whether single nucleotide polymorphisms (SNPs) of SOD1 and SOD2 gene are associated with C. trachomatis-infected recurrent spontaneous abortion (RSA).

METHODS

150 patients with history of RSA and 150 patients with history of successful deliveries were recruited from Department of Obstetrics and Gynecology, Safdarjung hospital, New Delhi, India. Urine and non-heparinized blood samples were collected and C. trachomatis was detected by polymerase chain reaction (PCR). Using qualitative real time PCR, SNPs rs4998557 (SOD1) and rs4880 (SOD2) were screened in enrolled patients. Level of 8-hydroxyguanosine (8-OHdG), 8-isoprostane (8-IP), progesterone and estrogen was determined by enzyme-linked immunosorbent assays and correlated with SNPs.

RESULTS

Significant differences were found in frequency of AA genotype of SOD1 gene among RSA patients versus controls, (82% and 54.66%, respectively; p = 0.02; OR 0.40; CI 95%). Frequency of AA genotype of SOD1 gene among RSA patients with C. trachomatis infection was 87.33%, while in uninfected RSA patients was 71.33% (p < 0.0001; OR 8; CI 95%). No significant relation was found between SOD2 (rs4880) genotype and RSA. Furthermore, significant increase in 8-OHdG, 8-IP and estrogen and significant decrease in progesterone was observed among patients carrying AA genotype.

CONCLUSIONS

Findings suggest the clinical importance of AA genotype along with 8-OHdG, 8-IP and estrogen and progesterone in screening C. trachomatis-infected RSA women.

Aberrant gene expression of superoxide dismutases in Chlamydia trachomatis-infected recurrent spontaneous aborters

Study aimed to characterize the expression of antioxidant genes SOD1 and SOD2 in Chlamydia trachomatis-induced recurrent spontaneous aborters and further determine their role by in silico analysis. First void urine was collected from 130 non-pregnant women with history of recurrent spontaneous abortion (RSA) (Group I) and 130 non-pregnant women (Group II; control) attending Obstetrics and Gynecology Department, SJH, New Delhi, India. C. trachomatis detection was performed by conventional PCR in urine. Gene expression of SOD1 and SOD2 was performed by quantitative real-time PCR. Further, its interacting partners were studied by in silico analysis. 22 patients were positive for C. trachomatis in Group I. Significant upregulation was observed for SOD2 gene in C. trachomatis-infected RSA patients while SOD1 was found to be downregulated. Increased concentration of oxidative stress biomarkers 8-hydroxyguanosine and 8-isoprostane was found in C. trachomatis-infected RSA patients. Protein–protein interaction (PPI) of SOD proteins and its interacting partners viz.; CCS, GPX1, GPX2, GPX3, GPX4, GPX5, GPX7, GPX8, CAT, PRDX1, TXN, SIRT3, FOXO3, and AKT1 were found to be involved in MAPK, p53 and foxo signaling pathways. Molecular pathways involved in association with SODs indicate reactive oxygen species (ROS) detoxification, apoptotic pathways and cell cycle regulation. Overall data revealed alleviated levels of SOD2 gene and decreased expression of SOD1 gene in response to C. trachomatis-infection leading to production of oxidative stress and RSA.

Differential expression of urine-circulating micro-RNAs in Chlamydia trachomatis-induced recurrent spontaneous aborters

Studies behind mechanisms of Chlamydia trachomatis-induced recurrent spontaneous abortion is still in its infancy. Possible strategy for preventing recurrent spontaneous abortion at molecular level is needed. Despite its multifactorial aetiology, Chlamydia trachomatis is important cause of RSA. However, mechanism leading to RSA in C. trachomatis-positive patients is not understood and novel strategies are needed. It is hypothesized that microRNAs play important role in RSA regulation during infection. Study aimed to elucidate expression/role of urine-circulating miRs-320b, 221-3p, 146b-5p,-16,-24,-559 in recurrent spontaneous aborters with C. trachomatis infection and to find their target genes by bioinformatic analysis. First-void urine was collected from 30 non-pregnant women with RSA (Group I) and 30 non-pregnant women with ≥2 successful deliveries (Group II; Controls) attending Department of Obstetrics and Gynaecology, Vardhman Mahavir Medical College, Safdarjung hospital, New Delhi (India). PCR was performed to detect C. trachomatis. Expression of miRNAs was studied by quantitative real-time PCR while target genes/functional annotations were predicted by GO/KEGG databases. Data was statistically evaluated. 05 RSA patients were C. trachomatis-positive. Group I was subdivided into Group Ia (C. trachomatis-positive RSA; n = 5) and Group Ib (C. trachomatis-negative RSA; internal controls). miR-320b, -221-3p, -146b-5p, -16, -24 were significantly upregulated (miR-16 showed maximum 4.3 fold-change) while miR-559 was downregulated (0.5 fold-change) in Group Ia versus controls ('p'<0.001). Bioinformatic analysis revealed that target genes of miRNAs in RSA are involved in apoptosis and AMPK signalling pathways. Results showed differential expression of miRNAs implyingmiR-16 and miR-559 as potential biomarkers of RSA in infected women. Furthermore, network of genes of differentially expressed miRNAs regulates RSA by targeting gene function in apoptosis, cell adhesion and angiogenesis.

Does tumour necrosis factor alpha-induced cyclooxygenase-2 expression lead to spontaneous abortion in Chlamydia trachomatis-infected women

Cytokines might be involved in spontaneous abortion by triggering inflammatory mediators (Cyclooxygenases (Cox)) leading to spontaneous abortion in Chlamydia trachomatis (Ct)-infected women. Study aimed to quantitate the expression of pro-inflammatory cytokines (TNF-α, IFN-γ, IL-8) and Cox-2 in endometrial curettage tissue (ECT) of Spontaneous Aborters (SA). SA (n = 135) and 120 age-matched controls were enrolled from SJH, New Delhi, India. PCR was performed for detection of Ct MOMP gene (537 bp) in ECT. mRNA expression of pro-inflammatory cytokines and Cox-2 was assessed by real-time qPCR. Data was statistically evaluated. 14.8% SA were diagnosed as Ct-positive. Elevated expression of TNF-α, IFN-γ, IL-8 and Cox-2 was observed in Ct-infected SA. Ct-positive recurrent aborters showed significantly higher cytokine expression. Significant positive correlation was found between expression of Cox-2 and TNF-α in infected SA. Data suggested an increased expression of Th-1 cytokines, particularly TNF-α that induced Cox-2 expression in ECT, leading to spontaneous abortion in Ct-infected pregnant women.

Differential expression of circulating Th1/ Th2/ Th17 cytokines in serum of Chlamydia trachomatis-infected women undergoing incomplete spontaneous abortion

The study aimed to elucidate role of Th1/Th2/Th17 cytokines in the immunopathogenesis of spontaneous abortion in Chlamydia trachomatis (Ct)-positive first-trimester aborters. Endometrial curettage tissue and serum were collected from 145 aborters (spontaneous abortion (SA) group, n = 85; recurrent miscarriage (RM) group, n = 60) and 120 controls attending Department of Obstetrics & Gynecology at Safdarjung hospital, New Delhi (India). Polymerase chain reaction was used to detect Ct plasmid/MOMP, while commercial cytometric bead array kit was utilized to estimate circulating serum cytokines. 13.7% aborters were Ct-positive, however, none was found to be infected among controls. IFN-γ, TNF-α, IL-2, IL-6 and IL-17A cytokines were significantly increased in SA group/RM group (Ct-infected) versus controls. IL-4 showed no difference between groups, while IL-10 was significantly elevated in controls versus Ct-infected subjects in SA group/RM group. Furthermore, IFN-γ, TNF-α, IL-6, IL-17A cytokines were significantly elevated in Ct-positive RM group versus Chlamydia-infected SA group. However, IL-2, IL-4 and IL-10 cytokines showed no significant difference between Ct-positive SA group versus infected RM group. Positive correlation was found between few cytokines (TNF-α and IFN-γ/IL-17A; IL-17A and IFN-γ/IL-6) in Ct-positive aborters. Our study clearly established the role of Th1/Th2/Th17 cytokines in the pathogenesis of spontaneous abortion in Ct-infected subjects and found that Chlamydia-positive recurrent aborters had a predominant Th1/Th17 bias.

Diagnosis of sexually transmitted infections (STI) using self-collected non-invasive specimens

Paramount in control of transmission of sexually transmitted infections (STIs) is their prompt recognition and appropriate treatment. In countries where definitive diagnoses are difficult, a 'syndromic approach' to management of STIs is recommended and practiced, yet many STIs have common symptoms or are asymptomatic and therefore go undetected and untreated. This is of particular concern with the recognition that HIV transmission is increased with co-existent STIs: the attributable risk for each STI varying with the prevalence within a particular population. Hence, HIV public health prevention approaches must include STI preventative strategies to be effective. Even then, microbiological screening is incorporated into STI control strategies; lack of access to appropriate services (especially in rural and remote areas), reluctance of at-risk populations to attend for treatment, fear of invasive genital examinations, and lower sensitivities of conventional diagnostic assays reduces the effectiveness of such programmes. Therefore, accurate, cost-effective, reliable diagnostic assays (preferably those which can be used in the field) are needed to impact on the incidence of the various STIs, as well as HIV. With the advent of molecular technologies, including target and signal amplification methods, diagnoses of STIs have been revolutionised and allow the use of non or minimally invasive sampling techniques, some of which are self-collected by the patient, e.g. first-void urine, cervico-vaginal lavage, low vaginal swabs, and tampons. Most studies evaluating such self-sampling with molecular diagnostic techniques have demonstrated an equivalent or superior detection of STIs as compared to conventional sampling and detection methods. These sampling methods can also be used to determine prevalence of STIs in various populations, but particularly those with difficult access to medical care. In this article, the utility of self-sampling collection devices for detection of various STIs, particularly in women, is reviewed as one step towards formulating appropriate strategies in control of STIs, and which are especially suited for remote areas.

Role of Mycoplasma genitalium and Ureaplasma urealyticum in acute and chronic nongonococcal urethritis

One hundred fourteen heterosexual men with acute nongonococcal urethritis (NGU) and 64 patients without NGU were studied. We determined that Chlamydia trachomatis and Mycoplasma genitalium were strongly associated with acute NGU after controlling, by means of multivariate analysis, for age, race, sexual lifestyle, and coinfection (odds ratio [OR], 13.0, 95% confidence interval [CI], 2.6-64.5; and OR, 17.9, 95% CI, 2.0-160, respectively). Eighty-six men with acute NGU reattended at least once 10-92 days after treatment; 59 (69%) of these 86 men had urethritis. Seven men had M. genitalium detected during 10-92 days of follow-up, and all had urethritis. Ureaplasmas were not associated with acute NGU in multivariate analysis, but their detection was associated with the presence of urethritis during follow-up (P=.014). Ureaplasmas or M. genitalium were associated with both chronic NGU, which was defined as urethritis that occurred 30-92 days after the commencement of treatment (P=.028), and chronic NGU with symptoms or signs (P=.005).

An algorithm to detect Chlamydia trachomatis by polymerase chain reaction on specimens extracted for enzyme immunoassay

Amplification assays for detecting Chlamydia trachomatis have been shown to be more sensitive than enzyme immunoassay (EIA) by many investigators. In this study, we have developed an algorithm for performing PCR (COBAS AMPLICOR) on selected specimens extracted for EIA (ACCESS) with sample-to-cutoff (s/co) values between 0.25 and 0.99. Furthermore, we have shown that these specimens can be utilized for PCR without encountering any inhibition problems. In our investigation, 230 out of 6,558 urethral and cervical swabs submitted for C. trachomatis screening by EIA over a period of 9 months, had s/co values ranging between of 0.25 and 0.99. Ninety (39.1%) of these specimens tested positive by PCR. These specimens were stable and gave reproducible PCR results before and after storage for a period of 9 months. This testing algorithm offers an effective way of detecting C. trachomatis with selective use of PCR while increasing the sensitivity of the EIA screening system.

Pooling urine samples for ligase chain reaction screening for genital Chlamydia trachomatis infection in asymptomatic women

The accuracy of pooling urine samples for the detection of genital Chlamydia trachomatis infection by ligase chain reaction (LCR) was examined. A model was also developed to determine the number of samples to be pooled for optimal cost savings at various population prevalences. Estimated costs included technician time, laboratory consumables, and assay costs of testing pooled samples and retesting individual specimens from presumptive positive pools. Estimation of population prevalence based on the pooled LCR results was also applied. After individual urine specimens were processed, 568 specimens were pooled by 4 into 142 pools and another 520 specimens were pooled by 10 into 52 pools. For comparison, all 1,088 urine specimens were tested individually. The sample-to-cut-off ratio was lowered from 1.0 to 0.2 for pooled samples, after a pilot study which tested 148 samples pooled by 4 was conducted. The pooling algorithm was 100% (48 of 48) sensitive when samples were pooled by 4 and 98.4% (61 of 62) sensitive when samples were pooled by 10. Although 2.0% (2 of 99) of the negative pools of 4 and 7.1% (1 of 14) of the negative pools of 10 tested presumptive positive, all samples in these presumptive-positive pools were negative when retested individually, making the pooling algorithm 100% specific. In a population with 8% genital C. trachomatis prevalence, pooling by four would reduce costs by 39%. The model demonstrated that with a lower prevalence of 2%, pooling eight samples would reduce costs by 59%. Pooling urine samples for detection of C. trachomatis by LCR is sensitive, specific, and cost saving compared to testing individual samples.

Multiplex AMPLICOR PCR screening for Chlamydia trachomatis and Neisseria gonorrhoeae in women attenting non-sexually transmitted disease clinics. The European Chlamydia Epidemiology Group

A new PCR kit (AMPLICOR CT/NG; Roche Diagnostic Systems, Inc., Branchburg, N.J.) was used as a screening tool for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae in first-void urine (FVU) specimens from 3,340 asymptomatic women attending European health care units for contraceptive advice or pregnancy termination. All samples were kept frozen (-20 degrees C) prior to testing. Chlamydia-positive samples were retested once by the plasmid-based PCR kit and also by a major outer membrane protein (MOMP) primer-based PCR. Discrepancies were resolved by using the direct immunofluorescence test (DIF) with the centrifuged sediment of the FVU specimens. Samples positive for N. gonorrhoeae were retested by chromosomal primer-based PCR and verified by a 16S RNA PCR. Of the samples tested, 1.8% were considered inhibitory by using the internal amplification control. Of 81 samples positive for C. trachomatis, 74 samples were positive by both plasmid- and MOMP-based PCRs, 6 samples were positive by plasmid-based PCR and DIF, and one sample was positive by both MOMP-based PCR and DIF. Nine samples (0.3%) were positive for N. gonorrhoeae by the chromosomal primer-based PCR; however, none of the results could be confirmed. The test offers the unique ability to identify inhibition of amplification with the optional internal control.

Lowering the cut off value of an automated chlamydia enzyme immunoassay and confirmation by PCR and direct immunofluorescent antibody test

AIMS

To increase the sensitivity of an automated chlamydia enzyme immunoassay by significantly lowering its cut off value, and to maintain specificity by confirmation with polymerase chain reaction (PCR) and direct immunofluorescent antibody test (DFA).

METHODS

Over five months, the cut off value of the enzyme immunoassay used to screen urogenital samples for chlamydia antigen was reduced from 80 to 10. Samples with a test value of 10 or above were further tested with a commercial PCR assay. All samples during the first three months and discrepant samples during the last two months of the study were also tested with the DFA.

RESULTS

3250 urogenital swabs (1246 urethral, 1335 endocervical, 669 pooled urethral/endocervical) from 1246 males and 2004 females were processed. Using the manufacturer's recommended cut off of 80, the enzyme immunoassay identified chlamydia antigen in 134 samples (4.1%). Using the lower cut off value of 10 and either PCR or DFA as the confirmatory test, Chlamydia trachomatis was identified in 178 samples (5.5%). Thus, 45 additional positive samples were identified and the confirmed detection rate was increased by 33.8% (45/133). Excluding equivocal PCR results, the concordance between DFA and PCR was 91.8%. This strategy increased the detection rate by 2.1% in men and 0.9% in women (significant only in men). In female patients, pooled urethral/endocervical swabs as a specimen gave a significantly higher yield than endocervical swabs regardless of whether the lower cut off strategy was used.

CONCLUSIONS

This strategy of significantly lowering the cut off test value with confirmation on the same specimen by either PCR or DFA is feasible and cost effective. The use of pooled urethral/ endocervical specimens in females should be considered routinely as detection rate was significantly improved.

Ability of commercial ligase chain reaction and PCR assays to diagnose Chlamydia trachomatis infections in men by testing first-void urine

A total of 287 men (37.6% with symptoms of urethritis) attending a hospital-based sexually transmitted disease clinic had urethral swabs tested by culture and by direct fluorescent-antibody assay. First-void urine (FVU) was tested for Chlamydia trachomatis by commercially available ligase chain reaction (LCR) and PCR assays. By using an expanded reference standard, 35 men (12.2%) were found to be positive. By performing LCR and PCR, the infection prevalence was found to be approximately twice (11.5 and 12.2%, respectively) that determined swab testing. The sensitivity values were 94.3% for LCR and 100% for PCR. One of the two positive specimens missed by LCR contained inhibitors. PCR produced five false-positive results and LCR produced one.

Chlamydial antibodies in semen: search for "silent" chlamydial infections in asymptomatic andrological patients

The importance of a serological diagnostic workup in male genitourinary infections with Chlamydia trachomatis and its relevance for male infertility is still under debate. In a prospective study, antichlamydial serum and seminal plasma antibodies of 131 consecutive patients (mean age 31: 20-57) without evidence of acute urethritis and with negative urethral chlamydial culture were investigated. The antibody determination was carried out with a genus specific rELISA. In patients with positive seminal plasma IgA, chlamydial genome was evaluated by polymerase chain reaction (PCR). The results were associated with standard semen parameters according to evaluated WHO guidelines. Specific serum IgG antibodies were found in 51 patients (38.9%), IgA in 39 (29.7%); both antibodies were present in 25 patients (19%). Seminal plasma IgG was demonstrable in seven patients (5.3%), IgA in 26 (19.9%), and five patients were positive for both antibody classes (3.8%). Of the 26 men positive for specific seminal plasma IgA antibodies 12 did not demonstrate a serum antibody reaction. Only two patients with positive IgA titers in their seminal plasma showed a positive chlamydial genome reaction in PCR (8%). Men with antichlamydial seminal plasma IgA and/or IgG did not differ significantly in any of the standard semen sperm parameters from men testing negative for antibodies, with the exception of peroxidase positive leukocytes (p < 0.01), nor was there an association between any of the ejaculate parameters and any of the antibody titers. The data of about 40% antichlamydial serum antibody findings without a significant association with seminal plasma antibodies and no clinical signs of infection seem to reflect a history of urogenital infection. The unique presence of seminal plasma IgA in 12 of 26 cases may be caused by a local antibody response due to a "silent" infection. Thus, seminal plasma IgA was associated with signs of inflammation, whereas, there was no association with genome or pathogen demonstration. Therefore, it appears to be necessary to reevaluate genus-specific seminal plasma IgA antibodies with a species-specific microimmunofluorescence test and to compare these results with a genome screening using PCR or in situ hybridization.

Comparison of an automated enzyme immunoassay with a direct fluorescent antibody test and polymerase chain reaction for the detection of Chlamydia trachomatis in diagnostic specimens from male patients

Endourethral swabs and first-pass urine (FPU) samples from 148 male patients were tested for Chlamydia trachomatis by an automated enzyme immunoassay (EIA) (Vidas; bioMérieux, France), a direct fluorescent antibody (DFA) test (MicroTrak; Syva, USA) and two polymerase chain reaction (PCR) methods. Chlamydia trachomatis was considered present if a specimen was positive by at least two methods. This expanded criterion identified 27 patients (18%) as truly infected. One of the PCR methods was most sensitive for both types of specimen. When the recommended cut-off value of Vidas was reduced by 50%, its sensitivity on endourethral swabs was comparable to that of the DFA test, but the DFA test performed better with FPU. In general, FPU was suitable only for PCR.

Detection of Chlamydia trachomatis in genitourinary tract specimens using an automated enzyme-linked fluorescent immunoassay

BACKGROUND AND GOAL

The VIDAS Enzyme Linked Fluorescent Assay is a fully automated assay for the detection of Chlamydia trachomatis in clinical specimens. Because there is an increasing demand for automated assays for large volume laboratories and there is little performance data available, the authors evaluated the performance of the VIDAS enzyme linked fluorescent assay by comparing it with Chlamydiazyme and polymerase chain reaction.

STUDY DESIGN

Endocervical swabs from 330 women attending a hospital based obstetrics/gynecology clinic and 100 first void urine specimens from males attending a sexually transmitted disease clinic were tested by enzyme linked fluorescent assay, Chlamydiazyme, and polymerase chain reaction.

RESULTS

Fourteen of 330 endocervical specimens and 14 of 100 first void urine specimens were positive by Chlamydiazyme. Enzyme linked fluorescent assay detected 12 of 14 endocervical and 11 of 14 first void urine specimens. Compared with Chlamydiazyme, enzyme linked fluorescent assay had a sensitivity of 85.7% (12 of 14) for endocervical swabs and 76.9% (11 of 14) for first void urine specimens. Polymerase chain reaction detected an additional five endocervical and two first void urine specimens that had negative results by both enzyme linked fluorescent assay and Chlamydiazyme. All 7 were confirmed positive by polymerase chain reaction using a second primer set. Using an expanded gold standard of blocked Chlamydiazyme and confirmed polymerase chain reaction, enzyme linked fluorescent assay had a sensitivity of 63.2% (12 of 19) for endocervical swabs and 68.8% (11 of 16) for first void urine specimens compared with 73.7% (14 of 19) and 87.5% (14 of 16) for Chlamydiazyme. Polymerase chain reaction had a sensitivity of 100% (19 of 19) and 93.8% (15 of 16) for endocervical swabs and first void urine specimens, respectively. The specificity of enzyme linked fluorescent assay and Chlamydiazyme was 100%.

CONCLUSIONS

The VIDAS enzyme linked fluorescent assay for the detection of Chlamydia trachomatis in genitourinary specimens is highly specific but is not sufficiently sensitive for use as a routine diagnostic test.

Analytic performance and contamination control methods of a ligase chain reaction DNA amplification assay for detection of Chlamydia trachomatis in urogenital specimens

A ligase chain reaction (LCR) DNA amplification assay that targeted the cryptic plasmid of Chlamydia trachomatis was developed to detect C. trachomatis urogenital tract infection. The objectives of this study were to determine the cutoff and analytic performance of the LCR assay and to characterize the effectiveness of its postdetection contamination control method. The assay's cutoff was determined after receiver-operator characteristic (ROC) analysis of 4660 clinical data points. The assay detected one infectious unit per reaction of each of the 15 C. trachomatis serovars and did not cross-react with 13 Chlamydia pneumoniae strains, 13 Chlamydia psittaci strains, and 87 other bacteria, fungi, parasites, or viruses. In addition, the assay did not detect 77 processed urine specimens collected from patients with urinary tract infections caused by yeast or bacteria other than C. trachomatis. The assay was sufficiently precise to detect consistently two infectious units of C. trachomatis per reaction. False-positive assay results attributable to contamination with amplified product were minimized by the use of standard procedures as well as by a postdetection chemical inactivation method that could reduce the amount of amplified LCR product by a factor of > or = 10(7).

Sensitivities of PCR, MicroTrak, ChlamydiaEIA, IDEIA, and PACE 2 for purified Chlamydia trachomatis elementary bodies in urine, peripheral blood, peripheral blood leukocytes, and synovial fluid

Routine microbiological diagnosis of Chlamydia-induced reactive arthritis is based mainly on the detection of Chlamydia trachomatis with urogenital swabs or in urine. Because chlamydial antigen, rRNA, and DNA are present in low quantities in the inflamed joint, highly sensitive assays are needed to detect C. trachomatis not only at the primary site of infection but also in peripheral blood and peripheral blood leukocytes, which are suspected carriers for dissemination, and in synovial fluid. To evaluate possible tools for this purpose, the sensitivities of PCR, MicroTrak, Chlamydia EIA, IDEIA, and PACE 2 for the detection of defined numbers of purified C. trachomatis elementary bodies (EB) in urine, peripheral blood, peripheral blood leukocytes, and synovial fluid were determined. In urine, PCR detected 2, MicroTrak and ChlamydiaEIA detected 2 x 10(3), and PACE 2 and IDEIA detected 2 x 10(4) EB per ml. In peripheral blood, only PCR and MicroTrak detected C. trachomatis, with detection limits of 100 and 2 x 10(7) EB per ml, respectively. For peripheral blood leukocytes, the detection limits were 2 EB per ml for PCR and 2 x 10(4) EB per ml for MicroTrak, ChlamydiaEIA, IDEIA, and PACE 2. In synovial fluid, PCR detected 200, MicroTrak and IDEIA detected 2 x 10(5), and PACE 2 detected 10(6) EB per ml. ChlamydiaEIA was unable to detect 2 x 10(6) EB per ml in synovial fluid. In summary, PCR was found to be the most sensitive method. The sensitivities of the other methods tested were at least 1,000 times lower than that of PCR. PCR should therefore be considered a most promising tool for routine diagnosis of Chlamydia-induced arthritis.

Multiplex PCR for detection of Chlamydia trachomatis and Neisseria gonorrhoeae in Genitourinary specimens

We developed a multiplex PCR (M-PCR) assay for the simultaneous detection of Chlamydia trachomatis and Neisseria gonorrhoeae. M-PCR employed C. trachomatis-specific primers KL1-KL2 and N. gonorrhoeae-specific primers HO1-HO3 and produced products of 241 and 390 bp, respectively. PCR products were easily detected by agarose gel electrophoresis and confirmed by Southern hybridization using labelled oligonucleotide probes. M-PCR had a sensitivity of 10 fg of C. trachomatis and N. gonorrhoeae DNA (equivalent to 1 to 2 genome copies). M-PCR detected the presence of C. trachomatis and N. gonorrhoeae DNA in 15 male urethral and 12 female endocervical specimens, 3 of which were positive for C. trachomatis, 18 of which were positive for N. gonorrhoeae and 6 of which were positive for both organisms. M-PCR was evaluated further by testing 200 male first void urine (FVU) specimens, of which 18 were positive by C. trachomatis PCR and Chlamydiazyme and 4 were positive by C. trachomatis PCR but negative by Chlamydiazyme. All 22 FVU specimens were positive by a confirmatory PCR using a second plasmid target and were positive by M-PCR. Ten of 11 men with cultures that were positive for N. gonorrhoeae had FVU specimens that were positive by both N. gonorrhoeae PCR and M-PCR. Two other men with negative N. gonorrhoeae urethral cultures had FVU specimens that were positive by N. gonorrhoeae PCR, by two confirmatory N. gonorrhoeae PCR assays using 165 rRNA and cytosine methyltransferase primers, and by M-PCR. The sensitivity of M-PCR for detecting C. trachomatis was 100% (22 of 22 specimens), compared with 81.8% (18 of 22 specimens) for enzyme immunoassay. Sensitivity of M-PCR for N. gonorrhoeae was 92.3% (12 of 13 specimens) compared with 84.6% (11 of 13 specimens) for urethral culture. The specificity of M-PCR was 100% for both C. trachomatis (178 of 13 specimens) and N. gonorrhoeae (187 of 187 specimens). M-PCR testing of FVU specimens provided a sensitive and noninvasive method for detecting C. trachomatis and N. gonorrhoeae infection in men.

Evaluation of a commercial polymerase chain reaction assay for Chlamydia trachomatis and suggestions for improving sensitivity

A commercial polymerase chain reaction (PCR) assay (Amplicor, Roche) for Chlamydia trachomatis was compared with a direct fluorescent antibody (DFA) test using urethral and cervical samples, many of which on the basis of prior testing by DFA contained small rather than large numbers of elementary bodies. Urine samples were collected from patients in a sequential unselected manner. Of 244 clinical specimens (138 male urethral and cervical; 106 male and female urine), 66 were positive by both DFA and PCR and 141 were negative by both tests. Nine samples were DFA negative and PCR positive, and 28 samples were DFA positive and PCR negative. However, 24 (86%) of the latter samples contained fewer than ten elementary bodies. When serial dilutions of laboratory stock strains (serovars E and H) were tested, the DFA test detected Chlamydia trachomatis at a dilution tenfold greater than the PCR. Furthermore, of five DFA-positive clinical samples, three that were PCR negative when tested according to the manufacturer's instructions were positive when they were diluted less. A modification of the PCR assay along these lines might improve sensitivity.

Amplification of plasmid and chromosome Chlamydia DNA in synovial fluid of patients with reactive arthritis and undifferentiated seronegative oligoarthropathies

OBJECTIVE

To investigate the hypothesis that whole bacteria might be found in the joints of patients with Chlamydia-associated reactive arthritis.

METHODS

The presence of 2 plasmid- and 2 chromosome-specific sequences of Chlamydia DNA was investigated by amplification with the polymerase chain reaction, in synovial fluid (SF) samples from 71 patients with various arthropathies.

RESULTS

Chlamydia DNA was found in SF samples from 22 patients.

CONCLUSION

Whole chlamydiae are likely present in the SF of patients with Chlamydia-associated reactive arthritis.

Detection of Chlamydia trachomatis in urine specimens from women by ligase chain reaction

The performance of a plasmid-based ligase chain reaction (LCR) with urine specimens was compared with those of cell culture of cervical swabs and enzyme immunoassay with urine specimens for the detection of Chlamydia trachomatis infection in women who had attended a family planning clinic. The prevalence of chlamydial infection determined by LCR was 3.1%. Discrepant results among the three assays were resolved by testing urine by a second LCR assay based on the C. trachomatis chromosomal gene encoding the major outer membrane protein. Sensitivity, specificity, and positive and negative predictive values for the cell cultures were 56.3, 100, 100, and 98.4%, respectively, whereas those for the enzyme immunoassay were 18.8, 100, 100, and 97.1%, respectively, and those for LCR were 87.5, 100, 100, and 99.5%, respectively. LCR thus provides a highly sensitive and specific noninvasive screening method for detecting genital chlamydial infections in women.

Infrequent detection of Chlamydia trachomatis in a longitudinal study of women with treated cervical infection

OBJECTIVE

To determine how often Chlamydia trachomatis cervical infections are detected in women following completion of a currently recommended treatment regimen and the reason for recurrence.

METHODS

A longitudinal follow-up study of 43 initially C trachomatis-positive women for periods of up to two years.

RESULTS

C trachomatis was detected in three women, 19, 16 and about four months, respectively after completion of treatment. All specimens from the other 40 women which were taken during visits two to seven, that is periods of three to 700 days after treatment, were chlamydia-negative.

CONCLUSION

Although C trachomatis is usually eradicated from the genital tract by conventional treatment, occasionally it may be found again. It is difficult to determine whether detection after treatment is due to persistence or reinfection and further studies are required.

Influence of volume of sample processed on detection of Chlamydia trachomatis in urogenital samples by PCR

In the present study, it was demonstrated that the sensitivity of the PCR for the detection of Chlamydia trachomatis is influenced by the volume of the clinical sample which is processed in the PCR. An adequate sensitivity for PCR was established by processing at least 4%, i.e., 80 microliters, of the clinical sample volume per PCR. By using this preparation procedure, 1,110 clinical samples were evaluated by PCR and by cell culture, and results were compared. After discordant analysis, cell culture resulted in a sensitivity of 79.1% and PCR resulted in a sensitivity of 92.7%. Furthermore, it was shown that treatment with antibiotics immediately resulted in negative cell culture results but that PCR could give positive results up to 2 weeks posttreatment.

Mycoplasma genitalium in the joints of two patients with arthritis

Mycoplasma genitalium was sought in synovial fluids from 13 patients, of whom five had Reiter's syndrome, four had rheumatoid arthritis, and one each had systemic lupus erythematosus, psoriatic arthritis, rheumatic fever and undefined arthritis. The mycoplasma was detected by a PCR assay in the knee joint of a 25-year-old man with Reiter's syndrome, from whom urethral ureaplasmas were isolated and whose synovial fluid mononuclear cells responded to ureaplasmal antigens in a proliferation assay. Mycoplasma genitalium was also detected in the knee joint during an exacerbation of arthritis in a 58-year-old man who had had seronegative juvenile polyarthritis that had evolved to seronegative rheumatoid arthritis.

Diagnosis of Chlamydia trachomatis infections in men and women by testing first-void urine by ligase chain reaction

From April to September 1993, 305 men and 447 women in Hamilton, Canada, consented to the collection of a urethral or cervical swab, respectively, for culture and 20 ml of first-void urine (FVU) for testing by the enzyme immunoassay Chlamydiazyme and by ligase chain reaction (LCR) in the form of a kit from Abbott Laboratories called LCx Chlamydia trachomatis. Evaluation of test performance with each specimen was calculated on the basis of an expanded "gold standard" of a patient found to be positive by culture or by a confirmed nonculture test. By using this expanded standard, the prevalence of infection was determined to be 6% (27/447) for the women and 18.4% (56/305) for the men. LCR testing of FVU in both studies was the most sensitive approach (96%). The performance of Chlamydiazyme was as follows: cervical swab, 78.3% sensitivity; female FVU, 37% sensitivity; and male FVU, 67.9% sensitivity. Culture was the least sensitive approach to diagnosis: female cervix, 55.6%; and male urethra, 37.5%. LCR testing of FVU from men or women diagnosed the greatest number of genitourinary tract infections with no false positives.

Role of confirmatory PCRs in determining performance of Chlamydia Amplicor PCR with endocervical specimens from women with a low prevalence of infection

The role of confirmatory PCR assays for determining the performance of Chlamydia Amplicor PCR for endocervical specimens from women with a low prevalence of infection was evaluated. An endocervical swab was collected from 770 women and tested by culture or direct fluorescent antibody (DFA) staining. A second swab was tested by Chlamydia Amplicor PCR (Roche Molecular Systems, Branchburg, N.J.). Discordant results were resolved by three confirmatory PCRs: one targeting the plasmid by using different primers and two directed to the major outer membrane protein (MOMP) gene. Of the 30 swabs that were positive by culture or DFA (3.9%), 27 were positive by Amplicor PCR. An additional five swabs were positive by Amplicor PCR but negative by culture or DFA. Both plasmid and MOMP confirmatory PCRs identified the five culture-DFA negatives and the three Amplicor negatives as true positives. The three specimens originally classified as negative by Amplicor PCR were positive on repeat Amplicor testing. After resolution of the discordant results by confirmatory PCR testing, the sensitivity of the initial Amplicor PCR was 91.4% (32 of 35 specimens), changing to 100% after storage and repeat testing. The specificity of Amplicor PCR was 100% (735 of 735 specimens). Our results demonstrated that plasmid and MOMP confirmatory PCRs worked equally well in resolving false-positive and false-negative Amplicor PCR results. Some specimens may contain inhibitors of Amplicor PCR which may disappear with time.

Simultaneous detection of three common sexually transmitted agents by polymerase chain reaction

OBJECTIVE

Human papillomaviruses, herpes simplex viruses, and Chlamydia trachomatis are very common infections of the genital tract. The purpose of our study was to develop a polymerase chain reaction-based assay for the simultaneous detection of these organisms from a single genital swab.

STUDY DESIGN

To prove the technical feasibility of a simultaneous polymerase chain reaction assay for these organisms, a mixture of deoxyribonucleic acids extracted from cells infected by these three agents was amplified in the same tube with three different sets of primers corresponding to specific regions of the human papillomavirus genome, the herpes simplex virus 1 and 2 genomes, and the Chlamydia trachomatis plasmid, respectively. Then genital swabs from patients with suspected infection by one or more of these agents were assayed by polymerase chain reaction for the presence of herpes simplex virus, human papillomavirus, and Chlamydia trachomatis independently and simultaneously. Most of the samples were analyzed in parallel by other methods: herpes simplex virus by culture., Chlamydia trachomatis by culture and antigen staining, and human papillomavirus by the filter in situ hybridization method.

RESULTS

Analysis of the polymerase chain reaction products amplified from the deoxyribonucleic acid mixture revealed three bands corresponding to the respective amplified region of each microorganism. A total of 391 genital swabs were assayed independently by polymerase chain reaction for the presence of herpes simplex virus (113 samples), human papillomavirus (200 samples), and Chlamydia trachomatis (78 genital swabs and four urethral swabs). Forty-nine were herpes simplex virus positive (47 by culture), 45 were human papillomavirus positive (43 by filter in situ hybridization), and one sample was positive for Chlamydia trachomatis, both by polymerase chain reaction and by culture. Ninety-two of the 391 samples were analyzed simultaneously by polymerase chain reaction for the presence of the three agents. The correlation between the results obtained independently and simultaneously was of the order of 100%: 29 were positive for herpes simplex virus, 16 were positive for human papillomavirus, and one was positive for Chlamydia trachomatis, in one sample we could detect both human papillomavirus and herpes simplex virus.

CONCLUSIONS

The polymerase chain reaction simultaneous assay is a quick and efficient way of detecting herpes simplex virus, human papillomavirus, and Chlamydia trachomatis from a single genital swab. This method can greatly simplify the diagnostic procedures in the laboratory.

Unsatisfactory performance of the leukocyte esterase test of first voided urine for rapid diagnosis of urethritis

BACKGROUND AND OBJECTIVES

The objective of this study was to determine the performance characteristics of a dipstick test for leukocyte esterase (LE), (Chemstrip 2LN, Boehringer Mannheim) in predicting the presence of urethritis and urethral pathogens in men presenting to a busy sexually transmitted disease clinic and to street outreach facilities.

METHODS

Urethral swabs for polymorphonuclear (pmn) cell count, gonorrhoea culture and chlamydia enzyme immunoassay (EIA) as well as 15 ml of first voided urine (FVU) were collected from 737 symptomatic and 726 asymptomatic men. Gonorrhoea cultures and pmn counts were processed according to standard methods. Either Abbott Chlamydiazyme EIA (confirmed) or Syva Microtrak EIA (confirmed) test was employed to detect C trachomatis. The LE test was immediately dipped in FVU, read after 60-120 seconds by the clinician and considered positive if trace, 1+ or 2+.

RESULTS

Microscopic evidence of urethritis (> or = = 4 pmn cells per 1000 x field) was found on urethral smear of 782 (53.5%) patients. Chlamydia, gonorrhoea or both were present in 104 (7.1%) patients. Performance characteristics of the LE test were as follows: (table below)

CONCLUSION

The LE test did not have adequate sensitivity to be considered a reliable rapid diagnostic test for urethritis or urethral pathogens, particularly in the asymptomatic portion of this STD clinic population.

Chlamydia trachomatis in women: the more you look, the more you find

OBJECTIVE

To determine the extent to which testing of multiple sites and samples is required to define whether a woman is Chlamydia trachomatis-positive.

DESIGN

One-hundred and fifty women attending the Genitourinary Medicine clinic at St Mary's Hospital were enrolled; they had not received antichlamydial antibiotics in the previous three months, were not in a high-risk group for HIV infection, or pregnant, or using an intrauterine contraceptive device. Thirty-two women were re-examined three months after recruitment.

METHODS

An urethral specimen was Gram stained (smear) and cultured for gonococci. Another urethral specimen was taken to detect C trachomatis elementary bodies (EBs) by the MicroTrak direct fluorescent antibody (DFA) test (Syva). An endocervical swab specimen was Gram stained (smear) and cultured for gonococci. One of two other endocervical swabs was used for the DFA test and was then placed in medium which was centrifuged in a MicroCentaur at 13,000 rpm for 10 min; the deposit was examined by using the DFA test. The first 15-20 ml of voided urine (first pass urine; FPU) was also centrifuged and the deposit tested similarly.

RESULTS

Of 182 cervical smears and/or deposits tested for C trachomatis, 38 were positive; more cervical deposits (37) than smears (26) were positive and, of these, one-fifth of the deposits and one-third of the smears contained fewer than 10 elementary bodies. Of 162 paired urethral smears and FPU deposits available, one or other specimen of 36 pairs was chlamydia-positive, that is 31 smears and 32 deposits; of these, two-fifths of the smears and half of the deposits contained fewer than 10 EBs. Of 150 sets of cervical and urinary tract samples tested, 31 were chlamydia-positive at both sites, six in the cervix alone and four in the urinary tract alone. Of 139 women for whom there were valid first visit sample results, 36 (26%) were chlamydia-positive in the cervix, 34 (25%) in the urinary tract and 41 (29%) had at least one sample from either site positive. Overall, DFA tests of deposits from centrifuged cervical specimens achieved the highest sensitivity (88%) and those of cervical smears the lowest (70%).

CONCLUSIONS

Deposits from centrifuged cervical specimens were C trachomatis-positive more often than were cervical smears. Testing deposits from centrifuged urines was as successful as testing urethral smears. One-fifth (cervical deposits) to one-half (urine deposits) of specimens contained fewer than 10 EBs. The urinary tract was chlamydia-positive almost as frequently as the cervix but both sites needed to be tested to define whether a woman was chlamydia-positive.

Interlaboratory agreement study of a double set of PCR plasmid primers for detection of Chlamydia trachomatis in a variety of genitourinary specimens

We conducted a tricenter interlaboratory agreement study to assess the agreement of PCR results obtained for detection of Chlamydia trachomatis in genitourinary specimens. A total of 120 specimens (49 positive and 71 negative), including 20 first-void urine samples, 50 endocervical and 50 urethral swabs (40 males), were coded and sent from a reference laboratory (laboratory A) to two other laboratories. Laboratories B and C were provided with a standardized protocol and reagent package including two sets of plasmid PCR primers (KL1-KL2 and T1-T2) and were asked to test each specimen with the first set of primers (KL1-KL2) and to confirm positives with the second set of primers (T1-T2). Laboratory B identified 47 of 49 positives and 69 of 70 negatives (one specimen dried up on shipping) following the initial PCR, for an accuracy of 97.5% (116 of 119), and 47 of 49 positives and 70 of 70 negatives after confirmatory testing of the positives, for an accuracy of 98.3% (117 of 119). Laboratory C identified 42 of 49 positives and 70 of 70 negatives for the initial PCR, for an accuracy of 94.1% (112 of 119), and 39 of 42 positives and 70 of 70 negatives for the confirmatory PCR, for an accuracy of 91.6% (109 of 119). The overall accuracy of PCR testing was 96.6% (345 of 357). The kappa agreement statistics for agreement between pairs of laboratories after confirmation of positives were 0.97 for laboratories A and B, 0.83 for laboratories B and C, and 0.83 for laboratories A and C. Use of the confirmatory PCR improved the specificity and overall accuracy of results for individual laboratories but reduced slightly the results obtained for agreement between laboratories. These results demonstrate that when standardized reagents and protocols are used, PCR results are highly reproducible and excellent agreement between laboratories is obtainable.

Evaluation of an enzyme immunoassay for detection of Chlamydia trachomatis in urine of asymptomatic men

In a study of 1,486 men attending two sexually transmitted disease clinics, of whom 891 had no symptoms of urethritis, we compared an enzyme immunoassay (EIA) (Baxter-Bartels, formerly Northumbria AntigEnz) of urine sediment to urethral culture for the detection of Chlamydia trachomatis. C. trachomatis prevalence by culture alone was 7.7% in asymptomatic men and 10.9% in symptomatic men. Discrepant results between EIA of urine and urethral culture were evaluated by direct fluorescent-antibody staining (DFA) for elementary bodies in urine sediment or in culture transport media. When chlamydial infection was defined as either a positive urethral culture or positive EIA confirmed by DFA, chlamydia prevalence increased to 8.9% in asymptomatic men and 11.6% in symptomatic men. The urine EIA sensitivity, specificity, and positive and negative predictive values for chlamydia detection in asymptomatic men were 84.8, 99.3, 91.8, and 98.5%, respectively, with nearly identical results for symptomatic men. The sensitivities of urethral culture alone compared with the combination of urethral culture and urine EIA (with DFA confirmation) were 87.3 and 94.3% for asymptomatic and symptomatic men, respectively. The present EIA of urine sediment is both highly sensitive and specific for the detection of C. trachomatis in asymptomatic men, thus providing a noninvasive screening method for chlamydia infection in asymptomatic men attending sexually transmitted disease clinics.

Diagnosis of Chlamydia trachomatis endocervical infections by a commercial polymerase chain reaction assay

We evaluated a prototype polymerase chain reaction (PCR)-based assay for Chlamydia trachomatis developed by Roche Molecular Systems to detect endocervical infection in women. Of 587 endocervical samples obtained from women attending the Harborview Medical Center sexually transmitted diseases clinic, 58 (10%) were positive for C. trachomatis by cell culture. Compared with culture, the PCR method had a sensitivity of 88% (51 of 58) and a specificity of 99.2% (525 of 529). The positive and negative predictive values were 92.7% (51 of 55) and 98.7% (525 of 532), respectively. After resolution of discrepant results whereby true positives were considered to be either culture-positive patients (58 patients) or culture-negative patients positive upon PCR analysis using both plasmid- and major outer membrane protein-based primers (4 patients), the resolved sensitivities of the PCR and culture were 89 and 93%, respectively. We subsequently performed a second analysis of 362 women, comparing the proposed commercial PCR assay from Roche Molecular Systems with chlamydia cultures. Thirty (8%) women were infected with C. trachomatis. Compared with culture, the assay had a sensitivity of 60% (18 of 30) and a specificity of 99% (328 of 332). Repeat PCR assay done 2 to 5 days later subsequently yielded positive results for 7 of 11 PCR-negative samples from culture-positive women. We conclude that the Roche Molecular Systems PCR assay provides highly specific results compared with culture in a high-risk population of women. Further study is needed, however, to more clearly define the sensitivity of the PCR assay in detecting endocervical C. trachomatis infection in women and to identify factors that may compromise sensitivity.

Diagnosis of Chlamydia trachomatis urethritis in men by polymerase chain reaction assay of first-catch urine

To determine the accuracy of a recently developed polymerase chain reaction (PCR) urine assay to detect Chlamydia trachomatis urethral infection in men, we obtained urethral swabs and first-catch urine from 365 men attending a sexually transmitted diseases clinic. Thirty-three (9%) of the 365 men were infected with C. trachomatis as defined by urethral culture. Thirty-two of the 33 men with culture-positive urethral swabs also had PCR-positive urine assays. Of 332 patients with culture-negative urethral swabs, 325 had PCR-negative urine. Compared with chlamydia culture of urethral specimens, PCR assay of urine samples thus had a sensitivity of 97% and a specificity of 98%. The positive predictive value of the urine PCR assay was 82%, and the negative predictive value was 99%. Analysis of discrepant results indicated that six of seven PCR-positive, urethral culture-negative patients probably had chlamydial urethritis. All six patients had symptoms of urethritis and had either a positive urethral swab PCR or a positive urine PCR with a different amplification target. After resolution of discrepant results, (defining true positives as the 33 culture-positive patients and the 6 PCR-positive, culture-negative patients just described), the sensitivity and specificity of culture were 85% (33 of 39) and 100% (326 of 326), respectively. The revised sensitivity and specificity of PCR were 97% (38 of 39) and 99.7% (325 of 326), respectively. We conclude that this urine PCR assay provides a highly sensitive, noninvasive alternative method for the detection of C. trachomatis urethral infection in high-risk men attending a sexually transmitted diseases clinic. This assay could greatly facilitate the testing of larger numbers of male patients for chlamydial infection and should be studied in other settings.

Evaluation of sensitivity of 10 diagnostic assays for Chlamydia trachomatis by use of a simple laboratory procedure

AIMS

To determine the sensitivity of commercially available diagnostic assays for Chlamydia trachomatis using a simple method.

METHODS

Nine commercial assays and an "in-house" polymerase chain reaction (PCR) were evaluated using serial dilutions of a laboratory grown H serovar--four of them using a laboratory grown E serovar. Seven of the assays were further tested using dilutions of several cervical samples known to contain chlamydiae.

RESULTS

The most sensitive assays were the MicroTrak direct fluorescent antibody (DFA) test (Syva) and the PCR which detected C trachomatis at a 10(-8) dilution of the H serovar, while the two least sensitive, Clearview (Unipath) and TestPack (Abbott), were positive only at 10(-4) and 10(-3) dilutions, respectively. A range of enzyme immunoassays (EIAs) and a nucleic acid hybridisation test were of intermediate sensitivity. The results with serovar E were consistent with these. When clinical samples were examined, the DFA test detected C trachomatis in dilutions at least 10-fold greater than any other assay.

CONCLUSIONS

The range of sensitivity of diagnostic assays determined by the laboratory dilution procedure is very wide. Sensitivity assessed in this way, however, reflects the ability of the assays to detect C trachomatis in large scale clinical trials. The dilution procedure, which is simple to undertake, could therefore be applied by any laboratory before a new diagnostic method is considered for routine use.

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.