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

Improving gonorrhoea molecular diagnostics: Genome mining-based identification of identical multi-repeat sequences (IMRS) in Neisseria gonorrhoeae

Background

Curable sexually transmitted infections (STIs), such as Neisseria gonorrhoeae (N. gonorrhoeae), are a major cause of poor pregnancy outcomes. The infection is often asymptomatic in pregnant women, and a syndrome-based approach of testing leads to a missed diagnosis. Culture followed by microscopy is inadequate and time-consuming. The gold standard nucleic acid amplification tests require advanced infrastructure settings, whereas point-of-care tests are limited to immunoassays with sensitivities and specificities insufficient to accurately diagnose asymptomatic cases. This necessitates the development and validation of assays that are fit for purpose.

Methods

We identified new diagnostic target biomarker regions for N. gonorrhoeae using an algorithm for genome mining of identical multi-repeat sequences (IMRS). These were then developed as DNA amplification primers to design better diagnostic assays. To test the primer pair, genomic DNA was 10-fold serially diluted (100 pg/μL to 1 × 10-3 pg/μL) and used as DNA template for PCR reactions. The gold standard PCR using 16S rRNA primers was also run as a comparative test, and both assay products were resolved on 1% agarose gel.

Results

Our newly developed N. gonorrhoeae IMRS-PCR assay had an analytical sensitivity of 6 fg/μL representing better sensitivity than the 16S rRNA PCR assay with an analytical sensitivity of 4.3096 pg/μL. The assay was also successfully validated using clinical urethral swab samples. We further advanced this technique by developing an isothermal IMRS, which was both reliable and sensitive for detecting cultured N. gonorrhoeae isolates at a concentration of 38 ng/μL. Combining isothermal IMRS with a low-cost lateral flow assay, we were able to detect N. gonorrhoeae amplicons at a starting concentration of 100 pg/μL.

Conclusion

Therefore, there is a potential to implement this concept within miniaturized, isothermal, microfluidic platforms, and laboratory-on-a-chip diagnostic devices for highly reliable point-of-care testing.

Detection of urogenital pathogens in sterile pyuria samples by polymerase chain reaction

Background

Patients with sterile pyuria may be infected with sexually transmitted diseases or have renal tuberculosis. This study investigated the possibility of detecting sexually transmitted diseases and Mycobacterialtuberculosis in sterile pyuria samples with polymerase chain reaction.

Methods

Forty-four day-3 negative urine culture samples were investigated for the presence of sexually transmitted diseases and Mycobacterialtuberculosis.

Results

Among the 44 samples, 61.4% were positive by polymerase chain reaction (PCR) for bacterial DNA (either sexually transmitted diseases or Mycobacteria). Among the 27 positive samples, 37% were positive for Ureaplasmaurealyticum, 26% were positive for Chlamydiatrachomatis, 14.8% were positive for Neisseriagonorrhoeae, 11.1% were positive for Mycoplasmagenitalium, 7.4% were positive for Mycoplasmahominis, and only one sample (3.7%) was positive for Mycobacterialtuberculosis. No significant associations were found between PCR-positive urine samples and patient characteristics.

Conclusions

It was concluded that Ureaplasmaurealyticum was predominant in sterile pyuria followed by Chlamydiatrachomatis. There were no significant associations between PCR-positive samples and sex, symptomatic patients, or antibiotic use. PCR is an instant diagnostic tool for sexually transmitted diseases in sterile pyuria; hence, it is advised to be performed on negative culture samples as a routine laboratory screening test whenever possible.

Visual and Rapid Diagnosis of Neisseria gonorrhoeae Using Loop-Mediated Isothermal Amplification Combined With a Polymer Nanoparticle-Based Biosensor in Clinical Application

Neisseria gonorrhoeae is a host-adapted human pathogen that causes sexually transmitted gonorrhea and remains to be a serious global public health challenge, especially in low- and middle-income regions. It is vital to devise a reliable, simple, cost-saving, and easy-to-use assay for detecting the N. gonorrhoeae agent. In the current study, we firstly report a novel approach, loop-mediated isothermal amplification linked with a polymer nanoparticle-based biosensor (LAMP-PNB), that was used for identifying N. gonorrhoeae in clinical samples. The results showed that the LAMP primers based on the orf1 gene were valid for development of the N. gonorrhoeae-LAMP-PNB assay. The detection system with optimal conditions could be performed at a fixed temperature of 64°C for 40 min. The whole process, including genomic DNA preparation (approximately 10 min), LAMP reaction (40 min), and PNB reporting (approximately 2 min), could be accomplished within 60 min. The limit of detection (LoD) of the N. gonorrhoeae-LAMP-PNB assay was 50 copies per test. The specificity of the current assay was 100%, and no cross-reactions to non-N. gonorrhoeae isolates were observed. These results confirmed that the N. gonorrhoeae-LAMP-PNB technique is a reliable, specific, sensitive, rapid, low-cost, and easy-to-use method for detecting gonococci isolates. More importantly, this assay has great potential to develop a point-of-care (POC) testing method in clinical practice, especially in resource-constrained regions.

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

Background & objectives:

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

Methods:

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

Results:

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

Interpretation & conclusions:

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

[Prevalence and phylogenetic analysis of Chlamydia trachomatis in a population of women in Posadas, Misiones]

OBJECTIVE

Chlamydia trachomatis is the most prevalent bacteria causing sexually transmitted infections. In women, this infection can cause cervicitis and urethritis, although it's usually asymptomatic. The aim of this study was to investigate the prevalence of C. trachomatis in women attending the lab Instituto de Previsión Social and detect the genotypes.

METHODS

Endocervical samples from 505 symptomatic and asymptomatic women were assayed. It was determined the presence of C. trachomatis by PCR through amplification of a fragment of the cryptic plasmid. Positive samples were genotyped by the partial amplification of the ompA gene and analyzed phylogenetically.

RESULTS

Forty-three positive samples were detected to infection with C. trachomatis, obtaining a prevalence of 8.5% (IC 95%: 6.4-11.3%). The prevalence of C. trachomatis was higher in women with vaginal symptoms [11.3% (30/265) vs. 5.4% (13/240)] (p = 0.018), as well as in women under 26 year-old [11.5% (28/244) vs. 6.2% (15/246)] (p = 0.021). Based on phylogenetic analysis, it was observed that 62% of the samples were genotype E, 15% genotype J, 15% genotype D, and 8% genotype F.

CONCLUSIONS

This work is the first contribution on the molecular epidemiology of C. trachomatis in the Misiones province, Argentina, which shows the rate of prevalence of this bacterium and offers information on circulating genotypes.

Microbiological comparison of blood culture and amplification of 16S rDNA methods in combination with DGGE for detection of neonatal sepsis in blood samples

It is estimated that 15% of all newborns admitted to the neonatal intensive care unit (NICU) for suspected sepsis receive multiple broad-spectrum antibiotics without pathogen identification. The gold standard for bacterial sepsis detection is blood culture, but the sensitivity of this method is very low. Recently, amplification and analysis of the 16S ribosomal DNA (rDNA) bacterial gene in combination with denaturing gradient gel electrophoresis (DGGE) has proven to be a useful approach for identifying bacteria that are difficult to isolate by standard culture methods. The main goal of this study was to compare two methods used to identify bacteria associated with neonatal sepsis: blood culture and broad range 16S rDNA-DGGE. Twenty-two blood samples were obtained from newborns with (n = 15) or without (n = 7) signs and symptoms of sepsis. Blood samples were screened to identify pathogenic bacteria with two different methods: (1) bacteriological culture and (2) amplification of the variable V3 region of 16S rDNA-DGGE. Blood culture analysis was positive in 40%, whereas 16S rDNA-DGGE was positive in 87% of neonatal sepsis cases. All 16S rDNA-DGGE positive samples were associated with some other signs of neonatal sepsis.

CONCLUSION

Our study shows that the molecular approach with 16S rDNA-DGGE identifies twofold more pathogenic bacteria than bacteriological culture, including complex bacterial communities associated with the development of bacterial sepsis in neonates. What is Known: • Neonatal sepsis affects 2.3% of birth in the NICU with a high mortality risk. • Evidence supports the use of molecular methods as an alternative to blood culture for identification of bacterial associated neonatal sepsis. What is New: • The DGGE gel is a good methodological approach for the identification of bacterial in neonatal blood samples. • This study describes the pattern of electrophoretic mobility obtained by DGGE gels and allows to determine the type of bacteria associated in the development of neonatal sepsis.

Detection of genital chlamydial and gonococcal infection using urine samples: A community-based study from India

Sexually transmitted infections (STI) have a major impact on the reproductive health of women. Among the different etiological agents of STIs, Chlamydia trachomatis and Neisseria gonorrhoeae are the main bacterial pathogens that cause sexually transmitted infections in women. The aim of the study was to estimate the prevalence of genital chlamydial and gonococcal infection among women in the age group of 18-65 years from a community-based setting. A community-based cross-sectional study was performed using the archived urine samples (n=811) of women in the age group of 18-65 years for C. trachomatis and N. gonorrhoeae using a multiplex conventional Polymerase Chain Reaction (PCR). Out of 811 samples tested in the present study, 2 (0.24%) were tested positive for C. trachomatis and none were positive for N. gonorrhoeae. The study demonstrates the very low prevalence of C. trachomatis and N. gonorrhoeae infection in a rural community. For large population-based screening, urine samples were observed to be more socially acceptable and cost-effective.

Deriving and validating a risk estimation tool for screening asymptomatic chlamydia and gonorrhea

BACKGROUND

There has been considerable interest in the development of innovative service delivery modules for prioritizing resources in sexual health delivery in response to dwindling fiscal resources and rising infection rates.

METHODS

This study aims to derive and validate a risk scoring algorithm to accurately identify asymptomatic patients at increased risk for chlamydia and/or gonorrhea infection. We examined the electronic records of patient visits at sexual health clinics in Vancouver, Canada. We derived risk scores from regression coefficients of multivariable logistic regression model using visits between 2000 and 2006. We evaluated the model's discrimination, calibration, and screening performance. Temporal validation was assessed in visits from 2007 to 2012.

RESULTS

The prevalence of infection was 1.8% (n = 10,437) and 2.1% (n = 14,956) in the derivation and validation data sets, respectively. The final model included younger age, nonwhite ethnicity, multiple sexual partners, and previous infection and showed reasonable performance in the derivation (area under the receiver operating characteristic curve = 0.74; Hosmer-Lemeshow P = 0.91) and validation (area under the receiver operating characteristic curve = 0.64; Hosmer-Lemeshow P = 0.36) data sets. A risk score cutoff point of at least 6 detected 91% and 83% of cases by screening 68% and 68% of the derivation and validation populations, respectively.

CONCLUSIONS

These findings support the use of the algorithm for individualized risk assessment and have important implications for reducing unnecessary screening and saving costs. Specifically, we anticipate that the algorithm has potential uses in alternative settings such as Internet-based testing contexts by facilitating personalized test recommendations, stimulating health care-seeking behavior, and aiding risk communication by increasing sexually transmitted infection risk perception through the creation of tailored risk messages to different groups.

The presence of Chlamydia is associated with increased leukocyte counts and pain severity in men with chronic pelvic pain syndrome

OBJECTIVE

To examine the role of urinary chlamydial infection in patients with chronic prostatitis and/or chronic pelvic pain syndrome (CP-CPPS).

METHODS

We recruited men aged 18-55 years over 4 years. We excluded patients with acute urethritis and any acute genitourinary infections. The participants evaluated their CP-CPPS-like symptoms with the Korean version National Institutes of Health-Chronic Prostatitis Symptom Index questionnaires. We measured white blood cell (WBC) counts in expressed prostatic secretion (EPS). In-house nucleic acid amplification test for Chlamydia trachomatis and Neisseria gonorrhoeae detection and WBC counts were performed from the patient's first-voided urine.

RESULTS

A total of 765 eligible men were classified into 3 groups: 196 in non-CP-CPPS, 410 in noninflammatory CP-CPPS, and 159 in inflammatory CP-CPPS groups. The chlamydia-infected men showed higher pain, poor quality of life (QOL), and total scores in National Institutes of Health-Chronic Prostatitis Symptom Index questionnaires than the negative men (P = .041 for pain; P = .043 for QOL, and P = .027 for total). Multivariate analysis found that urinary chlamydial infection increased the risk of WBC count ≥16 in EPS (adjusted odds ratio [OR], 2.189; 95% confidence interval [CI], 1.021-4.690; P = .044) and WBC count between 2 and 4 in urine (OR, 5.227; 95% CI, 2.503-10.918; P = .001). In addition, chlamydial infection also increased the risk of inflammatory CP-CPPS than the non-CP-CPPS group (OR, 2.448; 95% CI, 1.010-5.932; P = .044), whereas the patients with noninflammatory CP-CPPS were not affected (OR, 1.6557; 95% CI, 0.738-3.717; P = .221).

CONCLUSION

Urinary chlamydial infection increased the pain scores and WBC counts in EPS and worsens the QOL in the patients with CP-CPPS.

Prevalence of Mycoplasma genitalium and Mycoplasma hominis in urogenital tract of Brazilian women

BACKGROUND

The role of Mycoplasma hominis and M. genitalium in urogenital tract infections remains unknown. Furthermore these mollicutes present a complex relationship with the host immune response. The role of inflammatory cytokines in infections also makes them good candidates to investigate bacterial vaginosis and mycoplasma genital infections. Therefore, the aim of this study was to detect the above-mentioned mollicutes by quantitative Polymerase Chain Reaction (qPCR) methodologies in vaginal swabs and dosage of cytokines.

METHODS

Vaginal swabs and peripheral blood were collected from 302 women, including healthy individuals. The molecular findings were correlated with some individual behavioral variables, clinical and demographic characteristics, presence of other important microorganisms in vaginal swabs, and levels of interleukin (IL)-1β and IL-6.

RESULTS

M. hominis and M. genitalium were detected in 31.8% and 28.1% of samples, respectively. The qPCR results were associated with clinical signs and symptoms of the infections studied. The frequency of Trichomonas vaginalis, Gardnerella vaginalis, Neisseria gonorrhoeae and Chlamydia trachomatis was 3.0%, 21.5%, 42.4%, and 1.7% respectively. Increased levels of IL-1β were associated with the presence of M. hominis and signs and/or symptoms of the genital infection of women studied.

CONCLUSION

IL-1β production was associated with the detection of M. hominis by qPCR. The sexual behavior of women studied was associated with the detection of mycoplasma and other agents of genital infections.

A multiplex PCR assay for the simultaneous detection of Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis

INTRODUCTION

For developing countries, sexually transmitted infections (STIs) and their complications are ranked in the top 5 disease categories for which adults seek medical treatment. Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), and Trichomonas vaginalis (TV) are the three most common STIs worldwide, with TV accounting for over half of the cases. In developing countries, traditional methods for diagnosing STIs are laborious, often not very sensitive, and have a long turnaround time with most recent commercially available diagnostic tests targeting one or, at most, two of these STIs at a time. Here, we describe the development of a highly sensitive, rapid and affordable sample-to-answer multiplex PCR-based assay for the simultaneous detection of Trichomonas vaginalis, Neisseria gonorrhoeae, and Chlamydia trachomatis.

MATERIALS AND METHODS

We designed a multiplex PCR assay for the detection of 4 targets (CT, TV, NG, and process/PCR control) using melt curve analysis. To establish the limit of detection (LOD) for each pathogen, we used previously extracted and quantified TV, NG, and CT genomic DNA (Vircell, Spain). For each target, the LOD was determined by lowering its copy number while increasing the other two STI loads in a stepwise fashion. The process/PCR control remained constant in the optimized assay and was spiked into each sample before extraction. For a concordance study, we tested urine, vaginal and rectal swab specimens from 26 patients positive for one or more of the tested STIs. In addition, 56 liquid cytology specimens (Thinprep) were used to assess specificity.

RESULTS

This assay has a turnaround time of less than 2h and has a limit of detection as low as 7-31 copies for each STI in the presence of the other 2 targets. Our assay also demonstrated 100% concordance with 26 known clinical samples from urine, vaginal and rectal swab specimens. TV, NG, CT, and our process/PCR control were consistently identified at 78°C, 82.3°C, 85.7°C, and ~92°C, respectively. When applied to DNA extracted from residual Thinprep specimens, the assay was negative in 54/56 samples. Two samples were found to be co-infected with CT.

CONCLUSIONS

Our multiplex assay combines a rapid and cost-effective approach to molecular diagnostics with the versatility required for use within a variety of laboratory settings. These performance characteristics make this multiplex STI assay highly suitable for use in a clinical laboratory.

Evaluation of an opa gene-based nucleic acid amplification test for detection of Neisseria gonorrhoeae in urogenital samples in North India

Due to the poor positive predictive value of nucleic acid amplification tests (NAATs) for gonorrhoea when applied to a low-prevalence setting, current guidelines recommend the use of supplementary polymerase chain reaction (PCR) targeting a different gene for confirmation of true positives in urogenital specimens. This study sought to standardize and evaluate performance of an in-house opa gene-based PCR assay for gonorrhoea compared to assays targeting the porA pseudogene and 16S rRNA gene. Four hundred samples (300 endocervical, 100 urethral swabs) from patients attending STD clinics in New Delhi, India were used. The sensitivity, specificity, positive predictive value and negative predictive value of the opa-based PCR were 100%, 97·9%, 89·5% and 100%, respectively. In females, the use of NAATs provided enhanced diagnosis of gonorrhoea.

Human papillomavirus infection in urine samples from male renal transplant patients

Renal allograft recipients have a well-documented increased incidence of human papillomavirus (HPV)-related malignancies and preventive strategies should be specifically implemented. While in females the use of the Papanicolau test and HPV detection assay are used currently as a screening test for cervical cancer, no diagnostic procedures have been implemented to monitor HPV infection in males. The aim of this study was to test for HPV infection and to determine the spectrum of viral genotypes in urine samples of men with renal transplants. The study included 88 patients who underwent kidney transplantation between 1999 and 2005. HPV sequences were detected by nested PCR, using the broad-spectrum consensus-primer pairs MY09/MY11 and the new MGP system, and characterized by nucleotide sequence analysis. Overall, 43 (48.9%) samples were found positive for HPV sequences and the most common genotypes were HPV 16 (53.5%) and HPV 54 (9.3%) followed by HPV 6, 53, 56, 58, 66, 11, 12, 20, 45, 62, and 71, in descending order of prevalence. The majority of HPV 16 isolates were classified as European and only one as African-1 variant on the basis of nucleotide signature present within the MGP L1 region. The high prevalence of HPV 16 among renal allograft recipients suggests that an HPV-16-based preventive or therapeutic vaccine may be effective for prevention or treatment of HPV-related neoplasia in this group of immune compromised patients.

Prevalence of Chlamydia infection among women visiting a gynaecology outpatient department: evaluation of an in-house PCR assay for detection of Chlamydia trachomatis

Background

Screening women for Chlamydia trachomatis infection in developing countries is highly desirable because of asymptomatic infection. The existing diagnostic methods in developing countries are not effective and their sensitivity fall below 45.0% which leads to further spread of infection. There is an urgent need for improved and cost effective diagnostic tests that will reduce the burden of sexually transmitted infections in the developing world.

Methods

Prevalence of C. trachomatis infection among women visiting gynaecology department of Hindu Rao hospital in Delhi, India was determined using Roche Amplicor Multi Well Plate kit (MWP) as well as using in-house PCR assay. We used 593 endocervical swabs for clinical evaluation of the in-house developed assay against Direct Fluorescence Assay (DFA; Group I n = 274) and Roche Amplicor MWP kit (Group II, n = 319 samples) and determined the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) of the in-house developed assay.

Results

We detected 23.0% positive cases and there was a higher representation of women aged 18-33 in this group. An in-house PCR assay was developed and evaluated by targeting unique sequence within the gyrA gene of C. trachomatis. Specificity of the reaction was confirmed by using genomic DNA of human and other STI related microorganisms as template. Assay is highly sensitive and can detect as low as 10 fg of C. trachomatis DNA. The resolved sensitivity of in-house PCR was 94.5% compared with 88.0% of DFA assay. The high specificity (98.4%) and sensitivity (97.1%) of the in-house assay against Roche kit and availability of test results within 3 hours allowed for immediate treatment and reduced the risk of potential onward transmission.

Conclusions

The in-house PCR method is cost effective (~ 20.0% of Roche assay) and hence could be a better alternative for routine diagnosis of genital infection by C. trachomatis to facilitate improved screening and treatment management.

Differentiation of Chlamydia trachomatis lymphogranuloma venereum-related serovars from other serovars using multiplex allele-specific polymerase chain reaction and high-resolution melting analysis

Lymphogranuloma venereum (LGV) is a sexually transmitted infection caused by Chlamydia trachomatis serovars L1, L2 and L3. Consequently, more specific and sensitive detection methods that are rapid and inexpensive are necessary to differentiate between C. trachomatis serovars. The purpose of this study was to identify and differentiate LGV-related C. trachomatis serovars from rectal swabs using high-resolution melting analysis (HRMA) and multiplex allele-specific polymerase chain reaction (MAS-PCR). Fifteen clinical samples from patients in Sydney were first screened and confirmed as C. trachomatis by using the COBAS®AMPLICOR PCR analyser. The same samples were assayed for C. trachomatis and LGV by HRMA and MAS-PCR of the polymorphic membrane protein H ( pmpH) gene. Both methods indicated that two of 15 samples were serovar L2 and the remainder (13/15) other C. trachomatis serovars. Both HRMA and MAS-PCR are inexpensive, rapid, easy methods that are useful tools for the identification of LGV in clinical and research laboratories.

Chlamydia in colposcopy clinics: to screen or not to screen?

The objective of the study was to assess the prevalence of Chlamydia trachomatis in our colposcopy clinic. A total of 337 consecutive patients newly referred to the colposcopy clinic between May and November 2003 were screened for chlamydia trachomatis. All our patients were referred by their GPs and none of the patients had had a recent chlamydia test performed. Four patients screened positive, overall giving a prevalence of 1.2% [95% CI 0.04-2.36%]. Three of those with positive results were in the 21 - 30 year age group (139 in the group, which equals 2.2% prevalence [95% CI 0 - 4.6%]). The fourth positive result was in the group over the age of 60. None of those screened in the other age groups was positive (< or =20, 31 - 40, 41 - 50, 51 - 60 years). Numbers screened in each of those groups were: 14, 115, 53 and 12, consecutively. Our study, though small in sample size, supports the view that the prevalence of chlamydia is not high in all colposcopy clinic attenders. Women younger than 30 years old are more likely to be infected than older women; hence opportunistic screening should target this age group. The prevalence rate may be low due to the enzyme linked immunosorbent assay giving a poor detection rate for chlamydia screening.

Underreporting and underestimation of gonorrhea cases in the Taiwan National Gonorrhea Notifiable Disease System in the Tainan region: evaluation by a pilot physician-based sentinel surveillance on Neisseria gonorrhoeae infection

OBJECTIVES

We established a pilot sentinel surveillance system for Neisseria gonorrhoeae infection in Tainan to evaluate underreporting in the National Gonorrhea Notifiable Disease System (NGNDS), and also conducted a survey to understand physicians' specific reasons for underreporting in the Tainan region.

METHODS

A sentinel surveillance network consisting of six specialty clinics was created in Tainan City. Three hundred seventeen patients who were clinically diagnosed with urethritis, cervicitis, or gonorrhea were enrolled. N. gonorrhoeae infection was detected by urine-based PCR. A questionnaire was mailed to healthcare providers who potentially see patients with gonorrhea in the Tainan region.

RESULTS

Forty-eight N. gonorrhoeae-positive subjects were identified from the sentinel surveillance, and none of these gonorrhea cases were notified to the NGNDS by their healthcare providers. During the study period, there were 67 notified cases in the NGNDS, depicting an underestimation of at least 42% for this epidemic. Of the 16 healthcare providers who had seen cases in the past 3 months, only seven (43.8%) reported that they notified the authorities and only 23 (32%) of 71 cases were reported. 'Not collecting a specimen' and 'afraid of the invasion of patient privacy by the authorities' were the main reasons for the lack of notification.

CONCLUSIONS

The underreporting of gonorrhea identified in this pilot is substantial. An overhaul of Taiwan's NGNDS that streamlines the reporting procedures and the requirement for laboratory confirmation, along with a continuing medical education program is warranted.

A fast real-time polymerase chain reaction method for sensitive and specific detection of the Neisseria gonorrhoeae porA pseudogene

Ever since the advent of molecular methods, the diagnostics of Neisseria gonorrhoeae has been troubled by false negative and false positive results compared with culture. Commensal Neisseria species and Neisseria meningitidis are closely related to N. gonorrhoeae and may cross-react when using molecular tests comprising too-low specificity. We have devised a real-time polymerase chain reaction (PCR), including an internal amplification control, that targets the N. gonorrhoeae porA pseudogene. DNA was automatically isolated on a BioRobot M48. Our subsequent PCR method amplified all of the different N. gonorrhoeae international reference strains (n = 34) and N. gonorrhoeae clinical isolates (n = 176) but not isolates of the 13 different nongonococcal Neisseria species (n = 68) that we tested. Furthermore, a panel of gram-negative bacterial (n = 18), gram-positive bacterial (n = 23), fungal (n = 1), and viral (n = 4) as well as human DNA did not amplify. The limit of detection was determined to be less than 7.5 genome equivalents/PCR reaction. In conclusion, the N. gonorrhoeae porA pseudogene real-time PCR developed in the present study is highly sensitive, specific, robust, rapid and reproducible, making it suitable for diagnosis of N. gonorrhoeae infection.

Use of PCR and reverse line blot hybridization assay for rapid simultaneous detection and serovar identification of Chlamydia trachomatis

The aim of this study was to develop and evaluate multiplex and nested PCR-reverse line blot (RLB) hybridization assays for detection and serovar identification of Chlamydia trachomatis. Two sets of primers targeting the VD2 region of the omp1 gene and one set targeting the cryptic plasmid were designed for use in multiplex (both targets) and nested PCR (omp1 only). For the RLB assay, labeled omp1 amplicons were hybridized to a membrane containing probes specific for 15 C. trachomatis serovars. The assays were used to test 429 clinical specimens, which had been previously tested for C. trachomatis using the COBAS AMPLICOR system. Specimens were tested without knowledge of the COBAS AMPLICOR result. Of 205 specimens that were positive by COBAS AMPLICOR, 201 (98%) were positive by multiplex PCR-RLB and 188 (92%) were also positive by omp1 nested PCR-RLB. In addition, three of 224 COBAS AMPLICOR-negative specimens were positive by omp1 nested PCR-RLB. One hundred sixty-six of 191 (87%) specimens in which C. trachomatis serovars were identified contained only one serovar and 25 (13%) contained two or three serovars. Serovars D, E, and F were found in 31 (16%), 83 (43%), and 51 (27%) specimens, respectively. Serovar E (41%) was the most commonly identified single serovar. Serovars J and K were found alone uncommonly (<2% each), but 18 of 25 (72%) specimens with multiple C. trachomatis serovars contained one or both (10 specimens) of these serovars. The nested (ompI) PCR-RLB is a specific and sensitive method for simultaneous detection and serovar identification of C. trachomatis, which can reliably identify mixed C. trachomatis serovars. It is suitable for use in epidemiological studies.

OmpA genotyping of Chlamydia trachomatis from Korean female sex workers

OBJECTIVES

To determine ompA genotypes of Chlamydia trachomatis in female commercial sex workers (FCSW) in Korea.

MATERIALS AND METHODS

To accomplish this, 40 endo-cervical chlamydial PCR positive samples from FCSWs in one city of Korea were collected from April 2004 to August 2004. OmpA gene of C. trachomatis from the extracted genomic DNA was amplified and read whole variable domains and some constant domains sequences.

RESULTS

The deduced serovars found, in descending order of prevalence, were E (45%), F (20%), G (15%), D (5%), H (5%), J (2.5%), and mixed type (7.5%). While we found various serovars in limited FCSWs, only one genotype was found in each E, F, G, D, H, and J type.

CONCLUSIONS

The serotype E was the most prevalent type in commercial sex workers and ompA DNA polymorphism in each serovar was not a typical finding in FCSWs. Interestingly, the prevalence of serovar G, KS_G1 in our study, was higher in Pacific cities of U.S.A. than that in European studies or other cities in U.S.A. It may suggest that the high prevalence of KS_G1 in Korea has a relation with the high incidence of serovar G in Pacific cities in U.S.A.

Optimization of PCR based detection of human papillomavirus DNA from urine specimens

BACKGROUND

Human papillomavirus (HPV) causes cervical cancer. Current screening requires a yearly pelvic exam and Pap smear. However, these procedures are impractical for screening all women at risk for disease. Urine sampling has been successfully utilized to screen for Chlamydia trachomatis (CT) and Neisseria gonorrhoreae (NG) infections and has been considered for HPV DNA detection by several investigators. However, no study to date has been performed to specifically optimize HPV detection in urine.

OBJECTIVES

To compare handling and extraction techniques in order to optimize the HPV specific PCR system in urine specimens.

STUDY DESIGN

Examination of 10 characteristics that may contribute to PCR inhibition in urine was performed utilizing 10SG mulitstixs. Five different DNA extraction methods were compared in spiked specimens and in 10 clinical specimens. After the optimal extraction technique was identified, concentration of the sample with and without prior dilution was compared to the original protocol. Lastly, specimen handling was compared between immediate processing, refrigerating overnight, or freezing overnight.

RESULTS AND CONCLUSIONS

the presence of protein in urine enhanced amplification while nitrites decreased amplification. Of the extraction methods tested, the QIAamp DNA Mini Kit demonstrated the best amplification from urine samples spiked with HPV DNA and clinical specimens. The addition of a dilution step and a concentration step before applying the Qiagen protocol further increased amplification of beta-globin (from 50 to 63%) and the HPV L1 gene (from 13 to 33%). Lastly, refrigerating the specimens at 4 degrees C overnight appears to produce better amplification (62% beta-globin and 17% HPV positive) than either immediate processing (46% beta-globin and 13% HPV+) or freezing the specimen for 24h prior to processing (46% beta-globin and 10% HPV+). In these studies, amplification was low despite optimization. Additional improvements are required prior to clinical application of a urine-based HPV DNA detection system.

Developments in the screening for Chlamydia trachomatis: a review

Many studies have evaluated selective screening criteria for women in various settings. Most have concluded and all guidelines recommend that all women aged < 25 be screened yearly for C. trachomatis infection. Behavioral criteria, such as the number of sex partners, new or more than one sex partners, and previous infection, also can serve as criteria for screening women aged > 25. Because re-infection rates are high and occur within a few months, complications may be reduced further if partners are treated and women rescreened 4 to 6 months after initial infection. Revised recommendations for C. trachomatis screening programs have stated that more frequent screening may be considered among women < 20 and those with recent infection. Screening in nontraditional settings and careful evaluation of local prevalence and risk factor information should be encouraged. Private providers and emergency room providers should discuss screening recommendations and adopt a C. trachomatis screening policy for the population they serve. The HEDIS measure should serve to encourage at least annual screening of 15- to 25-year-old sexually active females through providers linked to managed care organizations. In general, high yields (ie, percentage of tests that are positive) in nontraditional settings and enhanced feasibility and acceptability of urine-based tests may encourage further innovative approaches to reach and screen populations at risk. Several issues remain to be addressed to increase the effectiveness of screening efforts. If more sensitive amplification tests are used widely, more infected persons will be identified and treated, and transmission patterns may change, particularly if partner treatment also occurs. Current screening criteria should continue to be re-evaluated. An important issue that affects testing methods includes the possible need for confirmation testing when using NAATs if the prevalence of C. trachomatis is less than 2%. If the sensitivity of an NAAT is 85% and specificity is 99%, in a hypothetical population of 10,000 with a prevalence of 2%, the positive predictive value is 170/268 (63%). A second important issue affecting testing methods and feasibility of using NAATs for screening large numbers of individuals is the pooling of urine specimens, which has been evaluated in several studies and found to be very effective for reducing costs. A research issue for pooling is the determination of the most cost-effective prevalence levels for pooling. An additional research question is in which populations should a NAAT be used for detection of C. trachomatis and N. gonorrhoeae. There are no recommendations for the routine screening of men because of the paucity of data showing that this strategy can reduce sequelae. The CDC is conducting a multisite study to examine the feasibility, acceptability, and usefulness of screening of asymptomatic men. There are a few studies have determining cost-effective prevalence threshold levels, particularly with NAATs. A recently developed decision analysis model by CDC designed to maximize the effectiveness of screening strategies for C. trachomatis infections may be useful for decision makers. It is intended to serve as an easy and flexible tool to determine cost effectiveness at a local level and takes into account positivity rates and test performance characteristics (SOCRATES). It is unclear if recurrent infection is caused by true re-infection by the same or a different partner or recurrence of initial infection. Recurrence may be caused by persistence of C. trachomatis or antibiotic resistance. This distinction is of scientific interest because the appropriate intervention differs (eg, identification of risk factors for the former and microbiologic investigations for the latter). Effective partner management and retesting are critical to reducing sequelae of C. trachomatis infection. Screening for C. trachomatis infection remains an essential component of C. trachomatis control. It is cost effective, most infections are asymptomatic, and symptom-based health care seeking and testing identify few of those infected. The likelihood that opportunities for screening are missed is high particularly in non-STD clinic settings. Local studies using NAATs to determine C. trachomatis prevalence and risk factors are helpful to health care providers so they can make evidence-based decisions on who to screen. The use of nontraditional, non-clinic-based test settings should be explored further. We have focused on summarizing the medical evidence regarding recommendations for screening for C. trachomatis. High-risk populations for C. trachomatis infection may overlap with populations for other STDs, and comprehensive STD prevention programs that involve a range of STD service providers are needed to successfully reduce the STD-related health burden in the population.

Male infertility and genital chlamydial infection: victim or perpetrator?

The role of Chlamydia trachomatis in the cause of male infertility is under discussion. This paper attempts to summarize data from the literature, which support the role of C. trachomatis in male infertility or oppose this suggestion. The following observations are based on a survey of the literature: 1) Chlamydia trachomatis is a frequent pathogen in male genital inflammation, the micro-organisms are rarely present in healthy men. 2) Without doubt, C. trachomatis causes inflammations of the male urethra and the epididymis. Prostatitis and glandulitis vesicalis are discussed controversially. 3) Chlamydia trachomatis antigen or DNA is not demonstrable in secretions of the male accessory glands including the semen with sufficient reproducibility. However, it is easily demonstrable in urethral swabs and the urine. 4) Determination of chlamydial antibodies in serum or semen does not conclusively indicate a current infection with C. trachomatis. 5) There are no conclusive studies showing that men infected with C. trachomatis are less fertile than uninfected men. 6) The male genital chlamydial infection is a threat to the female genital organs, because C. trachomatis infection of the female genital organs may be deleterious to female fertility.

High prevalence of Neisseria gonorrhoeae and multiple sexually transmitted diseases among rural women in the Eastern Highlands Province of Papua New Guinea, detected by polymerase chain reaction

BACKGROUND

In a previous community-based study among rural women in the Eastern Highlands Province (EHP) of Papua New Guinea we determined that the prevalences of Trichomonas vaginalis infection, Chlamydia trachomatis infection, and syphilis were 46%, 26%, and 4%, respectively. Surprisingly, however, the prevalence of Neisseria gonorrhoeae infection was only 1%, which we considered low in consideration of the high prevalence of other sexually transmitted diseases (STDs). The aim of the current study was to reexamine samples that were collected in that survey and retest them with use of polymerase chain reaction (PCR).

STUDY DESIGN

Using a cluster-sampling method, we surveyed 201 women aged 15 to 45 years in a population of approximately 19,000 people. In addition, 243 other women living in the same area who wished to be screened for STDs were included in the study.

METHODS

Endocervical samples that were stored frozen at -80 degrees C were retested with multiplex PCR (M-PCR) for the detection of both N gonorrhoeae and C trachomatis and with a separate PCR for the detection of T vaginalis.

RESULTS

A total of 373 samples that were still available were analyzed. The prevalences of T vaginalis, C trachomatis, and N gonorrhoeae infections were 42.6%, 26.5%, and 18.2%, respectively; 59.8% of the women had at least one STD, while 21.7% had mixed infections, 5.9% of them with all three pathogens.

CONCLUSIONS

STDs are very common among rural women in the EHP of Papua New Guinea and often present as multiple infections.

Detection of Chlamydia trachomatis by isothermal ramification amplification method: a feasibility study

Chlamydia trachomatis is the leading cause of sexually transmitted disease in the United States. Effective screening for this agent can facilitate prompt treatment and prevent its sequelae. The recent introduction of liquid-based cytology has made possible the simultaneous screening of cervical intraepithelial lesions and detection of C. trachomatis in a single collection vial. In this study we determined whether cytological fluid could support DNA-based amplification for the detection of C. trachomatis. Three methods were compared, including ramification amplification (RAM), real-time PCR with molecular beacon, and Abbott's ligase chain reaction (LCx). RAM is a novel, recently introduced, isothermal DNA amplification technique that utilizes a circular probe for target detection and achieves exponential amplification through the mechanism of primer extension, strand displacement, and ramification. Our results show that RAM can detect as few as 10 C. trachomatis elementary bodies in less than 2 h, comparable to results with real-time PCR. Thirty clinical specimens collected in PreservCyt solution were tested by LCx, real-time PCR, and RAM. Among 30 specimens, 15 were positive by PCR and LCx and 14 were positive by RAM. One specimen missed by RAM had an inadequate amount of residual cellular material. Our results show that nucleic acid amplification methods can serve to detect C. trachomatis and presumably other sexually transmitted agents in cytological fluid and that the RAM assay can be an alternative to PCR and LCx because of its simplicity and isothermal amplification.

Detection of cervical infections in colposcopy clinic patients

The purpose of this study was to determine if Neisseria gonorrhoeae; Chlamydia trachomatis; herpes simplex virus; cytomegalovirus; Epstein-Barr virus; human herpesviruses 6, 7, and 8; or adeno-associated virus influenced the production of cervical intraepithelial neoplasia. Two hundred thirty-one cervical smear samples were tested for the presence of the organisms by PCR. In addition, human papillomavirus types in the samples were determined by PCR and classified into cancer risk types of high, moderate, and low. There was no link with cervical intraepithelial neoplasia status and detection of herpes simplex virus, cytomegalovirus, Epstein-Barr virus, human herpesviruses 6 and 8, gonorrhea, or chlamydia. However, high-grade cervical intraepithelial neoplasia was found more frequently with mixed infection by moderate-risk human papillomavirus types and human herpesvirus 7 than with these papillomavirus types alone. The presence of human herpesvirus 7 may increase the oncogenic potential of moderate-risk human papillomavirus types.

Evaluation of the NucliSens Basic Kit for detection of Chlamydia trachomatis and Neisseria gonorrhoeae in genital tract specimens using nucleic acid sequence-based amplification of 16S rRNA

We evaluated a new RNA amplification and detection kit, the NucliSens Basic Kit (Organon Teknika), for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae in genitourinary specimens. The Basic Kit provides an open platform for RNA amplification and detection and contains isolation reagents for nucleic acid extraction, nucleic acid sequence-based amplification (NASBA) reagents (enzymes and buffers), and a generic ruthenium-labeled probe for electrochemiluminescent (ECL) detection of amplified product. Using freshly purified and titrated stocks of C. trachomatis and N. gonorrhoeae and in vitro-generated RNA transcripts for sensitivity determinations, the Basic Kit detected 1 inclusion-forming unit of C. trachomatis, 1 CFU of N. gonorrhoeae, and 100 RNA molecules of 16S rRNA for both bacteria. The clinical performance of the Basic Kit was evaluated by testing a total of 250 specimens for N. gonorrhoeae by culture and NASBA and a total of 96 specimens for C. trachomatis by PCR and NASBA. The Basic Kit detected 139 of 142 N. gonorrhoeae culture-positive specimens and gave a negative result for 73 of 74 culture-negative specimens, for a sensitivity and specificity of 97.9 and 98.7%, respectively. For C. trachomatis, the Basic Kit detected 24 of 24 PCR-positive specimens and gave a negative result for 71 of 72 PCR-negative specimens, for a sensitivity and specificity of 100 and 98.6%, respectively. The Basic Kit also detected specimens containing both N. gonorrhoeae and C. trachomatis, using a multiplex NASBA assay using primers for both bacteria. The NucliSens Basic Kit offers a versatile platform for the development of sensitive RNA detection assays for sexually transmitted diseases.

Multiplex PCR: optimization and application in diagnostic virology

PCR has revolutionized the field of infectious disease diagnosis. To overcome the inherent disadvantage of cost and to improve the diagnostic capacity of the test, multiplex PCR, a variant of the test in which more than one target sequence is amplified using more than one pair of primers, has been developed. Multiplex PCRs to detect viral, bacterial, and/or other infectious agents in one reaction tube have been described. Early studies highlighted the obstacles that can jeopardize the production of sensitive and specific multiplex assays, but more recent studies have provided systematic protocols and technical improvements for simple test design. The most useful of these are the empirical choice of oligonucleotide primers and the use of hot start-based PCR methodology. These advances along with others to enhance sensitivity and specificity and to facilitate automation have resulted in the appearance of numerous publications regarding the application of multiplex PCR in the diagnosis of infectious agents, especially those which target viral nucleic acids. This article reviews the principles, optimization, and application of multiplex PCR for the detection of viruses of clinical and epidemiological importance.

Diagnostic performance of the Roche AMPLICOR PCR in detecting Neisseria gonorrhoeae in genitourinary specimens from female sex workers in Cotonou, Benin

The objective of this study was to evaluate the diagnostic performance of the Roche multiplex AMPLICOR Chlamydia trachomatis/Neisseria gonorrhoeae PCR test for the detection of Neisseria gonorrhoeae infection in female urine specimens and wet and dry endocervical swabs. Endocervical swabs and urine specimens were collected from 342 female sex workers from Cotonou, Benin, and were tested using the AMPLICOR C. trachomatis/N. gonorrhoeae test (Roche Diagnostic Systems, Inc., Branchburg, N.J.) with internal control detection. Endocervical swabs were also cultured on Thayer-Martin medium. A series of alternate standards that included a combination of all the tests but not the test being evaluated was used to assess the performance of the test with each type of specimen. The sensitivity, specificity, and positive and negative predictive values for the urine were 53.8, 98.9, 93.5, and 87.5%, respectively. Corresponding figures for the wet swab were 91.5, 100, 100, and 97.4%, respectively. Those for the dry swab were 96.3, 96.2, 88.5, and 98.8%, respectively. Based on this study, the AMPLICOR PCR assay showed a low sensitivity for detection of N. gonorrhoeae infection in urine specimens, whereas the test was found to be highly sensitive and specific with endocervical specimens.

Multiplex PCR: optimization and application in diagnostic virology

PCR has revolutionized the field of infectious disease diagnosis. To overcome the inherent disadvantage of cost and to improve the diagnostic capacity of the test, multiplex PCR, a variant of the test in which more than one target sequence is amplified using more than one pair of primers, has been developed. Multiplex PCRs to detect viral, bacterial, and/or other infectious agents in one reaction tube have been described. Early studies highlighted the obstacles that can jeopardize the production of sensitive and specific multiplex assays, but more recent studies have provided systematic protocols and technical improvements for simple test design. The most useful of these are the empirical choice of oligonucleotide primers and the use of hot start-based PCR methodology. These advances along with others to enhance sensitivity and specificity and to facilitate automation have resulted in the appearance of numerous publications regarding the application of multiplex PCR in the diagnosis of infectious agents, especially those which target viral nucleic acids. This article reviews the principles, optimization, and application of multiplex PCR for the detection of viruses of clinical and epidemiological importance.

Improvement of clinical algorithms for the diagnosis of Neisseria gonorrhoeae and Chlamydia trachomatis by the use of Gram-stained smears among female sex workers in Accra, Ghana

BACKGROUND

Screening for cervical infection is difficult in developing countries. Screening strategies must be improved for high-risk women, such as female sex workers.

GOAL

To evaluate the sensitivity and specificity of screening algorithms for cervical infection pathogens among female sex workers in Accra, Ghana.

STUDY DESIGN

A cross-sectional study among female sex workers was conducted. Each woman underwent an interview and a clinical examination. Biologic samples were obtained for the diagnosis of HIV, syphilis, bacterial vaginosis, yeast infection, Trichomonas vaginalis, Neisseria gonorrhoeae, and Chlamydia trachomatis infection. Signs and symptoms associated with cervicitis agents were identified. Algorithms for the diagnosis of cervical infection were tested by computer simulations.

RESULTS

The following prevalences were observed: HIV, 76.6%; N. gonorrhoeae, 33.7%; C. trachomatis, 10.1%; candidiasis, 24.4%; T. vaginalis, 31.4%; bacterial vaginosis, 2.3%; serologic syphilis, 4.6%; and genital ulcers on clinical examination, 10.6%. The best performance of algorithms were reached when using a combination of clinical signs and a search for gram-negative diplococci on cervical smears (sensitivity, 64.4%; specificity, 80.0%).

CONCLUSIONS

In the algorithms, examination of Gram-stained genital smears in female sex workers without clinical signs of cervicitis improved sensitivity without altering specificity for the diagnosis of cervical infection.

Prevalence of Chlamydia trachomatis, Neisseria gonorrhoeae, and HIV infection among drug users attending an STD/HIV prevention and needle-exchange program in Quebec City, Canada

OBJECTIVES

To determine the prevalence of Chlamydia trachomatis, Neisseria gonorrhoeae, and human immunodeficiency virus (HIV) infection among injection and noninjection drug users in Quebec City and to identify associated risk factors.

STUDY DESIGN

Cross-sectional study of 738 drug users attending a sexually transmitted disease/HIV prevention and needle-exchange program in Quebec City, Canada.

RESULTS

The prevalences of N. gonorrhoeae and C. trachomatis were, respectively, 0.4% (95% CI: 0.08%-1.2%) and 3.4% (95% Cl: 2.2%-5.0%). Through multivariate analysis, risk factors associated with sexually transmitted diseases were: among women, being aged between 20 and 24 years and having unprotected sex with commercial partners; in noninjection drug users; cocaine use and first intercourse before 13 years of age; in male noninjection drug users, having regular sexual partners in the previous 6 months. No case of HIV was found in participants who have never injected drugs, but the prevalence was 5.5% (6/110) among the exinjectors and 10.1% (35/347) in current injectors.

CONCLUSION

Moderate sexually transmitted disease and HIV prevalences were found, although a high proportion of drug users reported risky behaviors. Needle-exchange program sites may offer a good opportunity to provide sexually transmitted disease/HIV prevention and medical services to drug users.

Multiplex PCR for typing and subtyping influenza and respiratory syncytial viruses

A multiplex reverse transcription (RT)-PCR method that has been developed is capable of detecting and subtyping influenza A (H1N1 and H3N2) and B viruses as well as respiratory syncytial virus (RSV) types A and B in respiratory clinical samples taken as part of a national community-based surveillance program of influenza-like illness in England and Wales. The detection of each different pathogen depended on distinguishing five amplification products of different sizes on agarose gels following RT-PCR with multiple primer sets. The multiplex RT-PCR was tested with 65 nasopharyngeal apirates from which RSV had been isolated and 237 combined nose and throat swabs from which influenza A (H1N1 and H3N2) or B virus had been detected by virus isolation, as well as 40 respiratory samples from which other viruses including cytomegalovirus, herpes simplex virus, enteroviruses, and parainfluenza viruses had been grown. For the typing and subtyping of influenza A and B viruses and RSV types A and B, the multiplex RT-PCR gave an excellent (100%) correlation with the results of conventional typing and subtyping with specific antisera. Multiplex RT-PCR can also be used to accurately detect more than one viral template in the same reaction mixture, allowing viral coinfections to be identified with the same respiratory specimen.

Managing sexually transmitted diseases in adolescents

Control of sexually transmitted diseases (STDs) in adolescents is a primary responsibility of health care providers. Using the tools of history and physical examination, and drawing on the awareness of different stages of adolescent development, health care providers can define at-risk for STDs. This article discusses screening practices, disease control through reporting and preventive counseling, and treatment guidelines for common STD syndromes.

The pediatrician and the sexually active adolescent. A primer for sexually transmitted diseases

Sexual activity is a common practice among young adolescents, placing them at high risk for STDs, many of which have long-term consequences. Early diagnosis and treatment are essential to limit both the consequences and the spread of these infections. The clinician has a responsibility to the adolescent patient to recognize and treat these diseases. Using history and physical examination, the clinician should be able to determine an adolescent's risk for an STD, and, based on this risk, undertake the appropriate evaluations. Patient treatment, follow-up, and management of sex partners are then guided by the results of either presumptive or definitive diagnostic tests.

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.

Multiplex polymerase chain reaction for simultaneous detection of Lawsonia intracellularis, Serpulina hyodysenteriae, and salmonellae in porcine intestinal specimens

Proliferative enteritis, swine dysentery, and porcine salmonellosis are the most common enteric bacterial diseases affecting pigs in the growing and finishing stages of production. Currently, diagnoses of these diseases by standard cultural techniques of intestinal specimens can be laborious, time consuming, and expensive (swine dysentery, porcine salmonellosis) or impossible (proliferative enteritis). Amplification by polymerase chain reaction (PCR) of DNA sequences specific for each bacterial agent is a highly sensitive and specific method that overcomes the limitations associated with standard detection methods. A multiplex PCR (M-PCR) assay was developed for simultaneous detection and identification of the etiologic agents associated with proliferative enteritis, swine dysentery, and porcine salmonellosis in a single reaction using total DNA obtained directly from intestinal specimens. Purified DNA obtained from pure cultures of each bacterial agent alone or mixed in different combinations and concentrations and total DNA from intestinal specimens were amplified using the Lawsonia intracellularis-, Serpulina hyodysenteriae-, and salmonellae-specific M-PCR assay. Intestinal specimens consisted of feces and mucosal scrapings obtained from field cases of each disease alone or in combinations and feces obtained from pigs challenged with S. hyodysenteriae. The banding pattern of the amplified PCR products, after agarose gel electrophoresis and staining, indicated the presence of individual or combinations of etiologic agents in each specimen. Results from this study indicated that simultaneous amplification of L. intracellularis-, S. hyodysenteriae-, and salmonellae-specific DNA sequences by M-PCR can be used for specific detection and identification of three major enteric bacterial pathogens associated with proliferative enteritis, swine dysentery, and porcine salmonellosis occurring alone or in combinations. Also, the M-PCR assay can be done using DNA obtained directly from intestinal specimens submitted for diagnostic investigation.

Urinary diagnosis of gonorrhoea and Chlamydia in men in remote aboriginal communities

AIMS

(1) To evaluate the acceptability and validity of an intervention based on urine tests for diagnosis and treatment of gonorrhoea and chlamydia in men in remote Aboriginal communities. (2) To provide a prevalence estimate of these infections in the male population in the surveyed communities.

METHODS

First-void urine samples from 460 men in remote communities and 33 men in the Alice Springs Gaol were tested for gonorrhoea and chlamydia with at least one of polymerase chain reaction (PCR), enzyme immunoassay (EIA) and culture (gonorrhoea only).

RESULTS

One hundred and three men (20.9%) were infected with gonorrhoea or chlamydia. The prevalence of infection for gonorrhoea only was 11.7%, for chlamydia only 4.1% and for dual infection 5.1%. Eighty-eight infected men and 45 of their sexual partners were recorded as having been treated within two months of testing. PCR tests detected the largest number of infections and were the easiest to use.

CONCLUSIONS

The prevalence of these infections was higher than anticipated. Urine PCR tests were acceptable to men and are well suited to the remote-community setting. As an effective alternative to urethral swabs, they permit a range of community-based strategies to address high rates of infection with gonorrhoea and chlamydia.

Detection of Chlamydia psittaci DNA in avian clinical samples by polymerase chain reaction

A polymerase chain reaction (PCR) assay was developed to detect. Chlamydia psittaci DNA in faeces and tissue samples from avian species. Primers were designed to amplify a 264 bp product derived from part of the 5' non-translated region and part of the coding region of the ompA gene which encodes the major outer membrane protein. Amplified sequences were confirmed by Southern hybridization using an internal probe. The sensitivity of the combined assay was found to be between 60 to 600 fg of chlamydial DNA (approximately 6 to 60 genome copies). The specificity of the assay was confirmed since PCR product was not obtained from samples containing several serotypes of C. trachomatis, strains of C. pneumoniae, the type strain of C. pecorum, nor from samples containing microorganisms commonly found in the avian gut flora. In this study, 404 avian faeces and 141 avian tissue samples received by the Central Veterinary Laboratory over a 6 month period were analysed by PCR, antigen detection ELISA and where possible, cell culture isolation. PCR performed favourably compared with ELISA and cell culture, or with ELISA alone. The PCR assay was especially suited to the detection of C. psittaci DNA in avian faeces samples. The test was also useful when applied to tissue samples from small contact birds associated with a case of human psittacosis where ELISA results were negative and chlamydial isolation was a less favourable method due to the need for rapid diagnosis.

Comparison of ligase chain reaction and culture for detection of Neisseria gonorrhoeae in genital and extragenital specimens

In addition to the urogenital tract, Neisseria gonorrhoeae infects extragenital sites such as the pharynx and anorectal canal. Culture and a ligase chain reaction (LCR)-based assay were compared for their performance for the diagnosis of N. gonorrhoeae infection with specimens from various urogenital and extragenital sites of 200 men and 125 women. The sensitivity and specificity of the LCR assay with male urethral swabs were both 100%, compared to values of 95.9 and 100%, respectively, for culture of urethral swabs or 98.0 and 100%, respectively, for LCR with first-void urine (FVU). For women, LCR with FVU showed the highest sensitivity (94.7%), and culture of urethral samples showed the lowest sensitivity (63.2%) (P < 0.05). In a selected subgroup of 47 men and 22 women at increased risk, the rates of pharyngeal infection were 15 and 18%, respectively, and those of anorectal infection were 13 and 45%, respectively. The sensitivity of LCR was greater than that of culture for both pharyngeal and anorectal specimens. Thus, the overall performance of LCR testing with swabs or FVU was better than that of culture for the diagnosis of genital or extragenital gonorrhea.