Validation of roche COBAS Amplicor assay for detection of Chlamydia trachomatis in rectal and pharyngeal specimens by an omp1 PCR assay

Diagnosis of Chlamydia trachomatis genital infections in the era of genomic medicine

PURPOSE

Chlamydial genital infections constitute significant sexually transmitted infections worldwide. The often asymptomatic status of C. trachomatis (CT) infections leads to an increased burden on human reproductive health, especially in middle- and low-income settings. Early detection and management of these infections could play a decisive role in controlling this public health burden. The objective of this review is to provide an insight into the evolution of diagnostic methods for CT infections through the development of new molecular technologies, emphasizing on -omics' technologies and their significance as diagnostic tools both for effective patient management and control of disease transmission.

METHODS

Narrative review of the diagnostic methodologies of CT infections and the impact of the introduction of -omics' technologies on their diagnosis by review of the literature.

RESULTS

Various methodologies are discussed with respect to working principles, required specifications, advantages, and disadvantages. Implementing the most accurate methods in diagnosis is highlighted as the cornerstone in managing CT infections.

CONCLUSION

Diagnostics based on -omics' technologies are considered to be the most pertinent modalities in CT testing when compared to other available methods. There is a need to modify these effective and accurate diagnostic tools in order to render them more available and feasible in all settings, especially aiming on turning them to rapid point-of-care tests for effective patient management and disease control.

Rectal chlamydial infection among men who have sex with men: Partner notification as a means of nucleic acid amplification test validation

Nucleic acid amplification tests for the diagnosis of rectal chlamydial infection are not yet licenced. However, the detection of urethral Chlamydia trachomatis in sexual contacts of men who have sex with men (MSM) with rectal chlamydiae might support the validity of such tests. This was a retrospective study of the outcome of partner notification among MSM with rectal chlamydia who consecutively attended a sexually transmitted diseases clinic. During the study period, 5213 MSM attended the Department as new or ‘return new’ patients. There were 243 (5%) episodes of rectal chlamydial infection. In 87 men, at least one sexual partner was identified and attended the clinic. Overall, 34 (39%) of the 87 evaluable sexual contacts had urethral chlamydial infection. The finding of urethral C. trachomatis infection in a sizeable proportion of sexual contacts of men with rectal chlamydiae lends further support to the validation of the test system for the diagnosis of rectal chlamydia.

Infectious Diseases Perspective of Anorectal Abscess and Fistula-in-ano Disease

BACKGROUND

Anorectal abscess and fistula-in-ano is a rare disease with an exemplary prognosis. Most patients are diagnosed with cryptoglandular disease but unusual infections raise difficult antimicrobial management challenges.

METHODS

All primary references identified in PubMed, EMBASE, the ISI Web of Knowledge database and the Cochrane Library, published between 1960 and 2015, using the keywords "anorectal abscess," "fistula-in-ano," "perianal abscess," or "perianal fistula" or all, were uploaded into a database. The databases were also interrogated using keywords specific for each infection type studied.

RESULTS

In all, 52 relevant primary medical publications were identified. There were also 4 relevant organizational standards guideline publications, 1 relevant review and 4 historical publications about the diagnosis and outcomes of anorectal abscess and fistula-in-ano with data derived primarily from prospective and retrospective trials as well as institutional case series to provide an evidence level opinion. The use of antimicrobial therapy in combination with surgical incision and drainage in the treatment of cryptoglandular disease has failed to improved healing times or reduce recurrences or both. Based on limited data, routine antimicrobial therapy may benefit patients with significant comorbid conditions, extensive cellulitis and systemic symptoms. For patients with unusual infecting pathogens (eg, Mycobacterium tuberculosis, Actinomyces species and Chlamydia species) outcomes are favorable with selected antimicrobial therapy agents of various durations.

CONCLUSION

Surgical incision and drainage is the main treatment for anorectal abscess and fistula-in-ano, but a select group of patients with unusual infections benefit from tailored prolonged antimicrobial therapy with the overall recurrence rate remaining low.

Lymphogranuloma venereum: diagnostic and treatment challenges

Lymphogranuloma venereum is a sexually transmitted disease caused by L1, L2, and L3 serovars of Chlamydia trachomatis. In the last 10 years outbreaks have appeared in North America, Europe, and Australia in the form of proctitis among men who have sex with men. Three stages of disease have been described. The disease in primary stage may go undetected when only a painless papule, pustule, or ulceration appears. The diagnosis is difficult to establish on clinical grounds alone and frequently relies upon either serologic testing, culture, or more recently, nucleic acid amplification testing of direct specimens. A proper treatment regimen cures the infection and prevents further damage to tissues. Lymphogranuloma venereum causes potentially severe infections with possibly irreversible sequels if adequate treatment is not begun promptly. Early and accurate diagnosis is essential. Doxycycline is the drug of choice. Pregnant and lactating women should be treated with erythromycin or azithromycin. Patient must be followed up during the treatment, until disease signs and symptoms have resolved. Repeated testing for syphilis, hepatitis B and C, and HIV to detect early infection should be performed.

Analysis of laboratory testing results collected in an enhanced chlamydia surveillance system in Australia, 2008-2010

BACKGROUND

Chlamydial infection is the most common notifiable disease in Australia, Europe and the US. Australian notifications of chlamydia rose four-fold from 20,274 cases in 2002 to 80,846 cases in 2011; the majority of cases were among young people aged less than 29 years. Along with test positivity rates, an understanding of the number of tests performed and the demographics of individuals being tested are key epidemiological indicators. The ACCESS Laboratory Network was established in 2008 to address this issue.

METHODS

The ACCESS Laboratory Network collected chlamydia testing data from 15 laboratories around Australia over a three-year period using data extraction software. All chlamydia testing data from participating laboratories were extracted from the laboratory information system; patient identifiers converted to a unique, non-reversible code and de-identified data sent to a single database. Analysis of data by anatomical site included all specimens, but in age and sex specific analysis, only one testing episode was counted.

RESULTS

From 2008 to 2010 a total of 628,295 chlamydia tests were referred to the 15 laboratories. Of the 592,626 individual episodes presenting for testing, 70% were from female and 30% from male patients. In female patients, chlamydia positivity rate was 6.4% overall; the highest rate in 14 year olds (14.3%). In male patients, the chlamydia positivity rate was 9.4% overall; the highest in 19 year olds (16.5%). The most common sample type was urine (57%). In 3.2% of testing episodes, multiple anatomical sites were sampled. Urethral swabs gave the highest positivity rate for all anatomical sites in both female (7.7%) and male patients (14%), followed by urine (7.6% and 9.4%, respectively) and eye (6.3% and 7.9%, respectively).

CONCLUSIONS

The ACCESS Laboratory Network data are unique in both number and scope and are representative of chlamydia testing in both general practice and high-risk clinics. The findings from these data highlight much lower levels of testing in young people aged 20 years or less; in particular female patients aged less than 16 years, despite being the group with the highest positivity rate. Strategies are needed to increase the uptake of testing in this high-risk group.

A cohort study of Chlamydia trachomatis treatment failure in women: a study protocol

BACKGROUND

Chlamydia trachomatis is the most commonly diagnosed bacterial sexually transmitted infection in the developed world and diagnosis rates have increased dramatically over the last decade. Repeat infections of chlamydia are very common and may represent re-infection from an untreated partner or treatment failure. The aim of this cohort study is to estimate the proportion of women infected with chlamydia who experience treatment failure after treatment with 1 gram azithromycin.

METHODS/DESIGN

This cohort study will follow women diagnosed with chlamydia for up to 56 days post treatment. Women will provide weekly genital specimens for further assay. The primary outcome is the proportion of women who are classified as having treatment failure 28, 42 or 56 days after recruitment. Comprehensive sexual behavior data collection and the detection of Y chromosome DNA and high discriminatory chlamydial genotyping will be used to differentiate between chlamydia re-infection and treatment failure. Azithromycin levels in high-vaginal specimens will be measured using a validated liquid chromatography-tandem mass spectrometry method to assess whether poor azithromycin absorption could be a cause of treatment failure. Chlamydia culture and minimal inhibitory concentrations will be performed to further characterize the chlamydia infections.

DISCUSSION

Distinguishing between treatment failure and re-infection is important in order to refine treatment recommendations and focus infection control mechanisms. If a large proportion of repeat chlamydia infections are due to antibiotic treatment failure, then international recommendations on chlamydia treatment may need to be re-evaluated. If most are re-infections, then strategies to expedite partner treatment are necessary.

Analytical evaluation of GeneXpert CT/NG, the first genetic point-of-care assay for simultaneous detection of Neisseria gonorrhoeae and Chlamydia trachomatis

GeneXpert CT/NG was evaluated with 372 characterized bacterial strains. Sensitivity of 10 genome copies/reaction was obtained for both agents. Four Neisseria mucosa and two Neisseria subflava isolates were positive for one of two gonococcal targets; however, the assay flagged all as negative. The assay was analytically highly sensitive and specific.

Self-collection of specimens for nucleic acid-based diagnosis of pharyngeal, cervicovaginal, urethral, and rectal Neisseria gonorrhoeae and Chlamydia trachomatis infections

Commercially available nucleic acid amplification tests (NAATs) for Neisseria gonorrhoeae and Chlamydia trachomatis detection allow for self-collection including home-based collection from multiple anatomic sites such as the urethra, cervicovagina, rectum, and pharynx. Verification studies need to be done prior to processing pharyngeal and rectal specimens. We review specimen collection and test characteristics of NAATs at different anatomical sites.

Differing Neisseria gonorrhoeae bacterial loads in the pharynx and rectum in men who have sex with men: implications for gonococcal detection, transmission, and control

The bacterial loads for gonococcal infections of the pharynx and rectum were determined among men with male sexual partners. The median bacterial load for rectal infections (18,960 copies/swab) was significantly higher than the load for pharyngeal infections (2,100 copies/swab; P = 0.001). Bacterial loads among men with symptomatic proctitis were strikingly high (median, 278,000 copies/swab).

Evaluation of an automated extraction method for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae by Cobas Amplicor PCR from different sample materials

A commercially available automated device (MagNA Pure LC) was adapted for nucleic acid extraction of urogenital specimen for subsequent PCR detection of Chlamydia trachomatis and Neisseria gonorrhoeae in a clinical laboratory. Results were compared to the standard manual extraction procedure and showed excellent correlation, with even slightly increased sensitivity.

Diagnosis, management and prevalence estimation of gonorrhoea: influences of Aptima Combo 2 assay with alternative target confirmation

Case-notes and laboratory data were retrospectively reviewed for influences of dual testing by Aptima Combo 2 (AC2) for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) on the diagnosis, management and prevalence estimation of gonorrhoea in the genitourinary (GU) medicine clinic and community. NG positives by AC2 were confirmed by Aptima Gonococcus assay. Unconfirmed positives were rare. Our study showed that in the GU medicine clinic, AC2 detected about 20% extra cases of NG beyond culture. For best standard of care, NG culture and microscopy are still required in some patients to ensure that treatment is rapid and appropriate. Compared to self-referral at the GU medicine clinic, community tests made a substantial contribution to the overall number of NG cases found (40 community versus 35 Macclesfield GU medicine clinic). The ratio of female to male NG cases found was significantly higher (P = 0.002) in the community (13 M, 27 F) than at the GU medicine clinic (25 M, 10 F). In the community, over 60% of NG infections occurred in chlamydia-negative patients. The overall prevalence of NG in the GU medicine clinic was 1.3%, the true prevalence being much lower at 0.9% on primary test. Prevalence in the community was 0.4%. Data from dual testing in the community can clarify NG prevalence beyond the existing KC60 (sexually transmitted infections) reports.

Multicenter study of nucleic acid amplification tests for detection of Chlamydia trachomatis and Neisseria gonorrhoeae in children being evaluated for sexual abuse

BACKGROUND

Diagnosis of sexually transmitted infections in children suspected of sexual abuse is challenging due to the medico-legal implications of test results. Currently, the forensic standard for diagnosis of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) infections is culture. In adults, nucleic acid amplification tests (NAATs) are superior to culture for CT, but these tests have been insufficiently evaluated in pediatric populations for forensic purposes.

METHODS

We evaluated the use of NAATs, using urine and genital swabs versus culture for diagnosis of CT and NG in children evaluated for sexual abuse in 4 US cities. Urine and a genital swab were collected for CT and NG NAATs along with routine cultures. NAAT positives were confirmed by PCR, using an alternate target.

RESULTS

Prevalence of infection among 485 female children were 2.7% for CT and 3.3% for NG by NAAT. The sensitivity of urine NAATs for CT and NG relative to vaginal culture was 100%. Eight participants with CT-positive and 4 with NG-positive NAATs had negative culture results (P = 0.018 for CT urine NAATs vs. culture). There were 24 of 485 (4.9%) female participants with a positive NAAT for CT or NG or both versus 16 of 485 (3.3%) with a positive culture for either, resulting in a 33% increase in children with a positive diagnosis.

CONCLUSIONS

These results suggest that NAATs on urine, with confirmation, are adequate for use as a new forensic standard for diagnosis of CT and NG in children suspected of sexual abuse. Urine NAATs offer a clear advantage over culture in sensitivity and are less invasive than swabs, reducing patient trauma and discomfort.

Asymptomatic sexually transmitted infections in HIV-infected men who have sex with men: prevalence, incidence, predictors, and screening strategies

Sexually transmitted infections (STIs) have increased among men who have sex with men (MSM) and are associated with unsafe sex practices, intrinsic morbidity, and enhanced genital shedding and transmission of HIV. Screening for asymptomatic STIs is recommended as part of the HIV prevention efforts, however, optimal screening strategies among HIV-infected MSM have not been well defined. In this study, conducted from April 2004 to September 2006, 212 HIV-infected MSM from two urban HIV clinics were screened for asymptomatic STIs. Testing for Neisseria gonorrhea and Chlamydia trachomatis from pharynx, rectum, and urine, as well as serologic testing for syphilis were performed initially, and then after 6 and 12 months. A self-administered questionnaire was used to assess possible predictors of incident asymptomatic STIs. A cost analysis was performed to assess different screening strategies for detecting incident STIs. The baseline prevalence of STIs was 14% (n = 29; 95% confidence interval [CI] 9%-19%) and the incidence of new infections was 20.8 cases per 100 person years (95% CI 14.8-28.4 cases per 100 person years). Younger age, higher CD4 cell count, and marijuana use were associated with increased risk of acquiring an asymptomatic STI. The laboratory cost to detect one positive STI did not significantly differ between once- and twice-yearly screening. However, almost half of all incident STIs were detected at the 6-month screening visit, potentially resulting in an increased duration of infectivity if these cases remained undiagnosed. In conclusion, prevalent and incident asymptomatic STIs are common among HIV-infected MSM. Our data support current Center for Disease Control and Prevention STI guidelines that recommend routine screening at increased frequency for HIV-infected MSM.

Confirming the Chlamydia trachomatis status of referred rectal specimens

OBJECTIVES

To assess the reliability of different laboratory methods for the detection of Chlamydia trachomatis in rectal specimens

METHODS

1782 rectal specimens confirmed as C trachomatis positive using a standard laboratory method, were forwarded to the Sexually Transmitted Bacteria Reference Laboratory (STBRL). All specimens were retested using a C trachomatis specific independent in-house real time polymerase chain reaction (PCR). If this test was negative, a second test (Artus Real-Art PCR Kit) was employed as a confirmation. A correlation between real time PCR results obtained at the reference centre (STBRL), and the method of C trachomatis detection used in the primary laboratory was undertaken.

RESULTS

The percentage of specimens that could be confirmed as positive, compared with primary method of detection was as follows: C trachomatis culture 87.5%, strand displacement assay (SDA: Becton Dickinson) 93.4%, Cobas Amplicor (Roche) 89.2%, Aptima Combo Two assay (Genprobe) 83.3%, and enzyme immunoassays (EIA) 35.4%.

CONCLUSIONS

High rates of confirmation can be achieved using an independent real time PCR assay to examine rectal specimens which had initially tested C trachomatis positive using nucleic acid amplification tests and chlamydia tissue culture. This is not possible for specimens that had been screened using EIA tests, which reflects the low specificity of this test when used for rectal specimens. Laboratories currently using EIA based assays to test rectal specimens should review this approach.

Diagnóstico de la infección por Chlamydia trachomatis en un centro de diagnóstico y prevención de infecciones de transmisión sexual: evaluación de los exudados cervicales, uretrales y rectales mediante técnica de PCR

INTRODUCTION

The aim of this study is to analyze the clinical and epidemiological characteristics of Chlamydia trachomatis infection in patients attended in a clinic for sexually transmitted disease in Seville (Spain). Microbiological diagnosis was performed in various types of samples.

MATERIAL AND METHODS

The study included 3854 patients (50.8% women and 49.2% men, mean age 30.1 years) seen from 2002 to 2004. Among the total, 50% belonged to groups engaging in high risk sexual practices: female commercial sex workers (CSWs) (47%), men who maintain sexual relationships with other men (MSM) (45%), users of prostitution (4%), promiscuous heterosexual men (4%), those with a risk partner (2.7%) and injection drug users (IDU) (2.2%). We analyzed a total of 5978 samples (2384 cervical exudates, 2645 urethral exudates and 949 rectal exudates), for the detection of C. trachomatis by PCR technique with the COBAS Amplicor CT System.

RESULTS

Prevalence of C. trachomatis infection was 6% (4.3% in women and 7.8% in men). Among the total in women, 51.2% of positive samples were from women with high-risk sex factors and 73.8% of the women were asymptomatic. In men, the proportions were 70.5% and 36.9%, respectively. Cervical, urethral and rectal exudates yielded positive results in 4%, 4.9% and 4.3%, respectively.

CONCLUSIONS

Systematic sampling for C. trachomatis detection is necessary in symptomatic and asymptomatic patients practicing high-risk sex; periodic follow-up studies are also needed for early detection of sexually transmitted infection. Rectal sample collection is important for detecting this infection in MSM and in patients whose sexual habits make it advisable.

Sexually transmitted proctitis

Sexually transmitted infections such as chlamydia, gonorrhoea, herpes simplex virus and syphilis commonly present with rectal symptoms. Recent outbreaks of lymphogranuloma venereum among homosexual men throughout Europe highlight the need to consider sexually transmitted infections in the differential diagnosis of proctitis. This article examines the causative organisms, clinical features, diagnosis and treatment of sexually transmitted proctitis.

Testing specimens for Chlamydia trachomatis

The introduction of NAATs has revolutionised chlamydial diagnostics and these tests are now the standard of care. However, as with all new technologies, they have also presented new challenges. This review attempts to answer some of the questions that have been raised, particularly by groups about to embark on implementing a screening programme. Laboratory tests are continually changing but it is hoped that the paper provides a useful update of the current situation.

Epidemiological correlates of asymptomatic gonorrhea

OBJECTIVES

To assess correlates of asymptomatic gonorrhea among patients attending Genitourinary Medicine Clinics participating in the Gonococcal Resistance to Antimicrobials Surveillance Programme (GRASP) in England for 2001-2003.

STUDY DESIGN

GRASP is a sentinel surveillance program that monitors antimicrobial resistance to Neisseria gonorrhoeae. Data collection occurs annually in June to August each year.

RESULTS

Women with previously diagnosed gonorrhea had decreased odds of asymptomatic gonococcal infection, as did women diagnosed with other sexually transmitted infections (all except chlamydia, syphilis, herpes, and warts). Heterosexual men, but not women, coinfected with chlamydia had significantly higher likelihood of being diagnosed with asymptomatic gonorrhea, as did homosexual men coinfected with syphilis and warts.

CONCLUSION

The heterogeneity in correlates of asymptomatic gonorrhea has implications for screening in clinical settings. Such findings also depend on the extent of testing on sexually transmitted infections from different sites of infection, which has particular relevance in homosexual men and would thus need to be investigated in other studies.

The superiority of polymerase chain reaction over an amplified enzyme immunoassay for the detection of genital chlamydial infections

BACKGROUND/OBJECTIVES

The polymer conjugate enhanced enzyme immunoassay (IDEIA) and Cobas Amplicor polymerase chain reaction Chlamydia trachomatis (CT) (Amplicor PCR) are two commonly used assays for the diagnosis of CT infection. The performance of these assays was compared for the diagnosis of genital CT infection among 1000 consecutive patients attending a genitourinary medicine (GUM) clinic. Confirmation of positive results and the clinical significance of the absence of cryptic plasmid in chlamydia on the diagnosis of infection by Amplicor PCR were also investigated.

METHODS

IDEIA, Amplicor PCR, and two nested in-house PCR assays targeting cryptic plasmid and omp1 gene were performed on all samples. DNA from Amplicor PCR negative samples was pooled for in-house PCR assays. Each pool contained DNA from seven Amplicor PCR negative samples.

RESULTS

Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and efficiency of IDEIA in the diagnosis of genital CT infection were 80%, 97%, 80%, 97%, and 95%, respectively. Sensitivity, specificity, PPV, NPV and efficiency of Amplicor PCR were 99%, 98%, 89%, 100%, and 98%, respectively. 16 (11%) of 144 Amplicor PCR positive results were identified as false positive by in-house PCR assays. No isolate of plasmid free CT was detected among the study population.

CONCLUSIONS

IDEIA should not be used for the diagnosis of CT infection because of its poor sensitivity. Although the analytic specificity of Amplicor PCR was 98%, because of the adverse medical, social, and psychological impact of false positive results for patients, confirmation of Amplicor PCR positive results by a different assay with comparable sensitivity is essential. Amplification assays targeting cryptic plasmid are appropriate for the diagnosis of genital CT infections.

Is screening for sexually transmitted infections in men who have sex with men who receive non-occupational HIV post-exposure prophylaxis worthwhile?

BACKGROUND/AIMS

Non-occupational HIV post-exposure prophylaxis (NPEP) is routinely prescribed after high risk sexual exposure. This provides an opportunity to screen and treat individuals at risk of concurrent sexually transmitted infections (STI). The aim of this study was to assess the efficacy of an STI screening programme in individuals receiving NPEP.

METHODS

STI screens were offered to all individuals receiving NPEP from March 2001 to May 2004. Screen results were compared to type of sexual exposure and baseline patient characteristics.

RESULTS

A total of 253 subjects were screened, representing 85% of the target population. All were men who have sex with men (MSM). Common exposure risks were receptive anal intercourse (RAI) in 61% and insertive anal intercourse (IAI) in 33%. 32 (13%) individuals had one or more STI. The most common STIs were rectal infections with Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) in 11 (4.5%) and six (2.5%) individuals, respectively. Subjects with rectal CT were significantly more likely to be co-infected with rectal NG (p<0.001). There was no association between the presence of a rectal STI and age or exposure risk. Only six (19%) individuals with an STI were symptomatic at screening.

CONCLUSION

In this cohort of MSM receiving NPEP, high rates of concomitant STIs are observed highlighting the importance of STI screening in this setting.

Genotyping of Chlamydia trachomatis from clinical specimens in Taiwan

This study was conducted to determine the prevalence and distribution of Chlamydia trachomatis genotypes in Taiwan. Urine and endocervical-swab samples were collected from two hospitals located in northern and southern Taiwan. The genotypes of a total of 145 samples positive for C. trachomatis were analysed by sequencing the omp1 gene and this was successful in 102 samples. Nine different C. trachomatis genotypes were identified. Genotype E was the most prevalent (22 %), followed by D and Da (19 %), F (16 %), J (15 %), K (11 %), G (11 %), H (6 %) and Ba (2 %). There was a geographical difference in the prevalence of genotype H (P < 0.018) between northern and southern Taiwan. Sequence mutation analysis by blast searching against GenBank reference sequences identified 12 genetic variants from a total of 102 omp1 gene sequences.

Diagnostic and Clinical Implications of Anorectal Lymphogranuloma Venereum in Men Who Have Sex with Men: A Retrospective Case-Control Study

BACKGROUND

Recently, outbreaks of anorectal lymphogranuloma venereum (LGV) have occurred among men who have sex with men (MSM). This study identifies risk factors and clinical predictors of LGV to determine the implications for clinical practice.

METHODS

The Chlamydia trachomatis serovars for all MSM who had anorectal chlamydia diagnosed at a sexually transmitted infection clinic in Amsterdam, The Netherlands, in 2002 and 2003 were retrospectively typed; 87 persons were infected with C. trachomatis serovar L2b and received a diagnosis of LGV. MSM infected with C. trachomatis serovars A-K and who thus had non-LGV anorectal chlamydia (n = 377) and MSM who reported having receptive anorectal intercourse but who did not have anorectal chlamydia (n = 2677) served as 2 separate control groups. Risk factors and clinical predictors were analyzed by multivariate logistic regression. Receiver operating characteristic curves were used to determine clinical relevance.

RESULTS

HIV seropositivity was the strongest risk factor for LGV (odds ratio for patients with LGV vs. those with non-LGV chlamydia, 5.7 [95% confidence interval, 2.6-12.8]; odds ratio for patients with LGV vs. control subjects without chlamydia, 9.3 [95% confidence interval, 4.4-20.0]). Proctoscopic findings and elevated white blood cell counts in anorectal smear specimens were the only clinically relevant predictors for LGV infection (area under the curve of the receiver operating characteristic curve, > 0.71). Use of these 2 parameters and HIV infection status provided the highest diagnostic accuracy (for MSM with anorectal chlamydia, the area under the curve was > 0.82; sensitivity and specificity were 89% and 50%, respectively).

CONCLUSIONS

LGV testing is recommended for MSM with anorectal chlamydia. If routine LGV serovar typing is unavailable, we propose administration of syndromic LGV treatment for MSM with anorectal chlamydia and either proctitis detected by proctoscopic examination, > 10 white blood cells/high-power field detected on an anorectal smear specimen, or HIV seropositivity.

Screening for chlamydia and gonorrhoea in men who have sex with men in clinical and non-clinical settings

Background: There are few published data on the rate of chlamydia and gonorrhoea infection in men who have sex with men (MSM). Our aim was to determine the rate of positive chlamydia and gonorrhoea tests in this population in the Australian Capital Territory (ACT). Methods: Results of all chlamydia and gonorrhoea tests generated by Canberra Sexual Health Centre between June 2001 and September 2003, including those from outreach clinics, were reviewed (audit one). Between September 2003 and April 2004, Canberra Sexual Health Centre outreach program staff and a general practitioner with a high caseload of MSM offered screening of the throat, urethra and rectum to all MSM, irrespective of their reported participation in unprotected anal intercourse. Chlamydia and gonorrhoea test results generated during this period were reviewed (audit two). Results: In the first audit, 1086 specimens from 314 individuals were tested and 30/314 (9.6%, 95% CI 6.6–13.4) men were positive for chlamydia in one or more anatomical site. A total of 306 specimens from 118 individuals were tested for gonorrhoea. Of these, eight (6.8%, 95% CI 3.0–12.9) individuals tested positive. In the second audit, 16 of 157 men (10.2%, 95% CI 9.5–16.0) tested positive for chlamydia and 4/155 (2.6%, 95% CI 0.7–6.5) tested positive for gonorrhoea. The rectum was the most commonly infected anatomical site for both infections. The overall proportions of positive chlamydia and gonorrhoea tests were 36/471 (7.6%, 95% CI 5.4–10.4) and 12/273 (4.4%, 95% CI 2.2–7.6) respectively. Conclusions: These data, collected in a range of settings, indicate high rates of chlamydia and gonorrhoea in MSM in the ACT and provide support for annual testing, particularly of the rectum, in this population.

Comparison of three in-house multiplex PCR assays for the detection of Neisseria gonorrhoeae and Chlamydia trachomatis using real-time and conventional detection methodologies

AIMS

To develop and evaluate multiplex PCR assays for Chlamydia trachomatis and Neisseria gonorrhoeae, using real-time and conventional PCR detection methodologies.

METHODS

Two real-time multiplex PCR assays, using nuclease (TaqMan-ABI7500) and hybridisation (LightCycler) probe formats, and a third assay using conventional PCR with solid-phase hybridisation and colour detection, were developed. The porA pseudogene was targeted for N. gonorrhoeae, and the major outer membrane protein gene for C. trachomatis. A total of 145 urogenital specimens were tested in all assays, and the results were compared with the Roche Cobas Amplicor assay.

RESULTS

There was little difference in clinical sensitivity and specificity, result discrimination and test cost for the three in-house assays. Our results showed that competitive inhibition of the PCR occurred in some samples that were positive for both organisms.

CONCLUSIONS

These results highlight the suitability and versatility of three multiplex PCR methods for the detection of C. trachomatis and N. gonorrhoeae.

Prevalence of rectal, urethral, and pharyngeal chlamydia and gonorrhea detected in 2 clinical settings among men who have sex with men: San Francisco, California, 2003

BACKGROUND

The Centers for Disease Control and Prevention developed screening and diagnostic testing guidelines for chlamydia and gonorrhea at urethral, rectal, and pharyngeal sites for men who have sex with men (MSM). However, in most clinical settings, rectal chlamydial testing is not performed for MSM, and primarily sexually transmitted disease (STD) clinics alone perform routine rectal and pharyngeal gonorrhea screening for asymptomatic men.

METHODS

We evaluated the prevalence of rectal, urethral, and pharyngeal chlamydial and gonococcal infections among MSM seen at the municipal STD clinic and the gay men's community health center. We also determined the proportion of asymptomatic rectal infections, described the patterns of single and multiple anatomic sites of infection, and evaluated the proportion of chlamydial infections that would be missed and not treated if MSM were not routinely tested for chlamydia. We tested specimens using previously validated nucleic acid amplification tests (NAATs).

RESULTS

The prevalence of infection varied by anatomic site (chlamydia: rectal, 7.9%; urethral, 5.2%; and pharyngeal, 1.4%; for gonorrhea, rectal, 6.9%; urethral, 6.0%; and pharyngeal, 9.2%). Approximately 85% of rectal infections were asymptomatic supporting the need for routine screening. Because 53% of chlamydial infections and 64% of gonococcal infections were at nonurethral sites, these infections would be missed and not treated if only urethral screening was performed. In addition, >70% of chlamydial infections would be missed and not treated if MSM were tested only for gonorrhea.

CONCLUSIONS

Because these infections enhance both HIV transmission and susceptibility, clinical settings serving MSM should evaluate the prevalence of chlamydial and gonococcal infections by anatomic site using validated NAATs.

Variability of the Chlamydia trachomatis omp1 gene detected in samples from men tested in male-only saunas in Melbourne, Australia

A recent screening program in Melbourne, Victoria, Australia, has shown that Chlamydia trachomatis is an important infection among men who frequent male-only saunas. To evaluate the C. trachomatis isolates circulating in local saunas, the C. trachomatis-positive samples collected during the program underwent amplification and sequencing of the omp1 gene, and the corresponding serovars were deduced. Forty-seven C. trachomatis-positive samples collected (from October 2001 to September 2002) from 39 men were evaluated. The deduced serovars found, in descending order of prevalence, were D, G, and J; and serovars B, E, F, and H were each found in single samples. The seven different serovars identified in the study sample indicate that local saunas are a reservoir of multiple C. trachomatis strains, possibly maintained by the introduction of new patrons or regular patrons who have been exposed to C. trachomatis elsewhere. No significant genetic variants were found, as most variable positions were silent and were detected only in single samples.

Genital Chlamydia trachomatis infection in Australia: epidemiology and clinical implications

Over the last decade, notification rates for genital Chlamydia trachomatis infection in Australia have been rising progressively. While chlamydia is common and possibly increasing in the general population, heterosexual adolescents, indigenous Australians in remote settings, and homosexually active men are at particular risk of infection. Few studies are available on the extent of morbidity from chlamydia-associated diseases. Australia urgently needs a national strategy to control chlamydia, with widespread, selective screening as a key component. As general practitioners have an important role to play, we proffer guidelines for selective testing in primary care.