Andrew Hardick

Mycoplasma genitalium as a Contributor to the Multiple Etiologies of Cervicitis in Women Attending Sexually Transmitted Disease Clinics

Objectives: The purpose of this study was to investigate the prevalence of Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis, and Mycoplasma genitalium, in women attending a sexually transmitted disease (STD) clinic, as well as the frequency of coinfections, and relationship of each organism to cervicitis. Methods: In this cross-sectional study of 324 women attending Baltimore City STD Clinics, C. trachomatis, N. gonorrhoeae, T. vaginalis, and M. genitalium were detected using nucleic acid amplification tests. Demographic characteristics and risk factors were ascertained. Results: Overall prevalence of infection with C. trachomatis, N. gonorrhoeae, T. vaginalis, and M. genitalium was found to be 11.1%, 4.6%, 15.3%, and 19.2%, respectively. Prevalence in women with cervicitis was 15.8%, 6%, 18.9%, and 28.6% for C. trachomatis, N. gonorrhoeae, T. vaginalis, and M. genitalium, respectively. Percentages of coinfections were high. C. trachomatis and M. genitalium were significantly associated with cervicitis in univariate analysis, but only M. genitalium was significantly associated with cervicitis (AOR: 2.5) in multiple logistic regression models. Conclusion: Knowledge of the statistical association of M. genitalium with cervicitis in this study increases the need for further confirmation of the etiologic significance of this organism with cervicitis in more diverse populations. The high prevalence merits more study and may have implications for diagnosis and treatment of cervicitis.

Rapid PCR-based diagnosis of septic arthritis by early Gram-type classification and pathogen identification.

ABSTRACT Septic arthritis (SA) is a rheumatologic emergency associated with significant morbidity and mortality. Delayed or inadequate treatment of SA can lead to irreversible joint destruction and disability. Current methods of diagnosing SA rely on synovial fluid analysis and culture which are known to be imprecise and time-consuming. We report a novel adaptation of a probe-based real-time PCR assay targeting the 16S rRNA gene for early and accurate diagnosis of bacterial SA. The assay algorithm consists of initial broad-range eubacterial detection, followed by Gram typing and species characterization of the pathogen. The platform demonstrated a high analytical sensitivity with a limit of detection of 101 CFU/ml with a panel of SA-related organisms. Gram typing and pathogen-specific probes correctly identified their respective targets in a mock test panel of 36 common clinically relevant pathogens. One hundred twenty-one clinical synovial fluid samples from patients presenting with suspected acute SA were tested. The sensitivity and specificity of the assay were 95% and 97%, respectively, versus synovial fluid culture results. Gram-typing probes correctly identified 100% of eubacterial positive samples as to gram-positive or gram-negative status, and pathogen-specific probes correctly identified the etiologic agent in 16/20 eubacterial positive samples. The total assay time from sample collection to result is 3 h. We have demonstrated that a real-time broad-based PCR assay has high analytical and clinical performance with an improved time to detection versus culture for SA. This assay may be a useful diagnostic adjunct for clinicians, particularly those practicing in the acute care setting where rapid pathogen detection and identification would assist in disposition and treatment decisions.

Comparison between the Gen-Probe Transcription-Mediated Amplification Trichomonas vaginalis Research Assay and Real-Time PCR for Trichomonas vaginalis Detection Using a Roche LightCycler Instrument with Female Self-Obtained Vaginal Swab Samples and Male Urine Samples

ABSTRACT This study compared two assays for Trichomonas vaginalis detection, Gen-Probes transcription-mediated amplification (TMA) assay for Trichomonas vaginalis and BTUB FRET PCR, using self-obtained clinical samples from 611 patients. Infection status was defined as two positive results by two different tests. The initial TMA assay sensitivity was 96.7%; specificity was 97.5%. The TMA assay was comparable to BTUB FRET PCR.

Rapid Identification of Biothreat and Other Clinically Relevant Bacterial Species by Use of Universal PCR Coupled with High-Resolution Melting Analysis

ABSTRACT A rapid assay for eubacterial species identification is described using high-resolution melt analysis to characterize PCR products. Unique melt profiles generated from multiple hypervariable regions of the 16S rRNA gene for 100 clinically relevant bacterial pathogens, including category A and B biothreat agents and their surrogates, allowed highly specific species identification.

Performance of the Gen-Probe Transmission-Mediated Amplification Research Assay Compared to That of a Multitarget Real-Time PCR for Mycoplasma genitalium Detection

ABSTRACT Mycoplasma genitalium (MG) can cause nongonococcal urethritis and is potentially associated with urethritis, endometritis, and cervicitis. Several assays have been developed to detect MG. Molecular amplification assays for organism detection can be problematic due to the potential for false-positive and false-negative results. Confirmatory testing is often required in these situations, requiring additional time and resources. Use of multigene targets could integrate both detection and verification at lower cost. Utilizing two targets, the MgPa adhesion gene and the 16S rRNA gene, a multitarget real-time (MTRT) PCR for the detection of MG was developed. Samples from patients attending sexually transmitted disease clinics were collected in duplicate. Urine samples from males (n = 286) and self-collected vaginal swabs from females (n = 321) were analyzed by MTRT PCR for MG and the Gen-Probe transmission-mediated amplification (TMA) assay, which targets MG rRNA for detection (TMA-MG research use only). Utilizing the criteria of any two targets being positively amplified, the MTRT PCR had a sensitivity and specificity of 91.8% (101 positive samples/110 samples tested) and 99.5% (495/497), respectively, with a positive predictive value (PPV) of 98.1% (101/103) and a negative predictive value (NPV) of 98.2% (495/504). The Gen-Probe TMA-MG assay had a sensitivity, specificity, PPV, and NPV of 98.1% (108/110), 98.1% (488/497), 92.3% (108/117), and 99.5% (488/490), respectively. Comparison between the MTRT PCR and TMA-MG assay by kappa statistic analysis indicated that an overall kappa value was 0.941 (95% confidence interval, 0.907 and 0.976). Both assays demonstrated accuracy in the detection of MG from urine samples from male patients and self-collected vaginal swabs from female patients.

Evaluation of multiplex real-time PCR for detection of Haemophilus ducreyi, Treponema pallidum, herpes simplex virus type 1 and 2 in the diagnosis of genital ulcer disease in the Rakai District, Uganda

Objective: To develop a real-time PCR assay that reliably and accurately detects the predominant sexually transmitted aetiological agents of genital ulcer disease (GUD) (Haemophilus ducreyi, Treponema pallidum and herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2)) and to assess the use of real-time PCR diagnostic testing in a rural African field site. Methods: Two multiplex real-time PCR reactions were used to detect H ducreyi/and HSV-1/HSV-2 in ulcer swabs from 100 people with symptomatic genital ulcers in rural Rakai, Uganda. Results were compared with syphilis, HSV-1 and HSV-2 serology. Results: Of 100 GUD samples analysed from 43 HIV positive and 57 HIV negative individuals, 71% were positive for one or more sexually transmitted infection (STI) pathogens by real-time PCR (61% for HSV-2, 5% for T pallidum, 3% for HSV-1, 1% for H ducreyi and 1% for dual H ducreyi/HSV-2). The frequency of HSV in genital ulcers was 56% (32/57) in HIV negative individuals and 77% (33/43) in HIV positive individuals (p = 0.037). Assay reproducibility was evaluated by repeat PCR testing in the USA with 96% agreement (κ = 0.85). Conclusions: STI pathogens were detected in the majority of GUD swab samples from symptomatic patients in Rakai, Uganda, by real-time PCR. HSV-2 was the predominant cause of genital ulcers. Real-time PCR technology can provide sensitive, rapid and reproducible evaluation of GUD aetiology in a resource-limited setting.

Mycoplasma genitalium compared to chlamydia, gonorrhoea and trichomonas as an aetiological agent of urethritis in men attending STD clinics.

Objectives: To investigate prevalence of Mycoplasma genitalium, Chlamydia trachomatis, Neisseria gonorrhoeae and Trichomonas vaginalis in men, frequency of co-infections, and association of organisms with urethritis in men. Methods: This was a cross-sectional study of 290 men (age range 19–34 years) attending Baltimore City STD clinics. M genitalium, C trachomatis, N gonorrhoeae and T vaginalis, during 2004 were detected using nucleic acid amplification tests (NAATs) (153 with urethritis and 137 without urethritis). Demographic characteristics and risk factors were ascertained. Results: The overall prevalences of infection with C trachomatis, N gonorrhoeae, T vaginalis and M genitalium were 20.3%, 12.8%, 3.4% and 15.2%, respectively. Prevalences in men with urethritis were 32.7%, 24.2%, 5.2% and 22.2% for C trachomatis, N gonorrhoeae, T vaginalis and M genitalium, respectively. Percentages of co-infections were high. All men with N gonorrhoeae had urethritis. C trachomatis and M genitalium were found to be significantly associated with urethritis in univariate analysis and in multiple logistic regression analysis. Conclusion: The association of M genitalium with urethritis in this study provides confirmation of the importance of screening men for M genitalium as a cause of non-gonococcal urethritis and supports treatment considerations for urethritis for agents other than gonococci and chlamydia.

Prevalence of rectal Trichomonas vaginalis and Mycoplasma genitalium in male patients at the San Francisco STD clinic, 2005-2006.

Sexually transmitted infections (STI), such as Chlamydia trachomatis, Neisseria gonorrhoeae, Herpes Simplex Virus (HSV), and Treponema pallidum, are common causes of proctitis among gay men and other men who have sex with men (MSM) [1, 2]. Inflammatory proctitis caused by an STI may increase the susceptibility and infectivity of HIV[3, 4]. In many cases of proctitis, however, no etiological organism is detected[1]. The advent of nucleic acid amplification techniques (NAATs) presents an opportunity to detect organisms previously difficult to isolate from the rectum. Two such organisms, Trichomonas vaginalis and Mycoplasma genitalium, have been implicated in male urethritis, female cervicitis and endometrial infection[5-11].

Cost-effectiveness of screening strategies for chlamydia trachomatis using cervical swabs, urine, and self-obtained vaginal swabs in a sexually transmitted disease clinic setting

Background: We evaluated the cost-effectiveness of Chlamydia screening strategies that use different methods of specimen collection: cervical swabs, urines, and self-obtained vaginal swabs. Methods: A decision analysis was modeled for a hypothetical cohort of 10,000 per year of women attending sexually transmitted disease (STD) clinics. Incremental cost-effectiveness of 4 screening strategies were compared: 1) Endocervical DNA probe test (PACE2, Gen-Probe), 2) Endocervical AC2 (Aptima Combo 2, Gen-Probe), 3) Self-Obtained Vaginal AC2, and 4) Urine AC2. Sensitivities of the vaginal, urine, and cervical AC2 tests were derived from 324 women attending STD clinics. The primary outcome was cases of pelvic inflammatory disease prevented. The model incorporated programmatic screening and treatment costs and medical cost savings from sequelae prevented. Results: Chlamydia prevalence in the sampled population was 11.1%. Sensitivities of vaginal, urine, and cervical AC2 were 97.2%, 91.7%, and 91.7%, respectively. The sensitivity of the DNA probe was derived from the literature and estimated at 68.8%. The self-obtained vaginal AC2 strategy was the least expensive and the most cost-effective, preventing 17 more cases of pelvic inflammatory disease than the next least expensive strategy. Conclusions: Use of a vaginal swab to detect Chlamydia in this STD clinic population was cost-saving and cost-effective.

Use of Quantitative Broad-based Polymerase Chain Reaction for Detection and Identification of Common Bacterial Pathogens in Cerebrospinal Fluid

BACKGROUND Conventional laboratory diagnosis of bacterial meningitis based on microscopy followed by culture is time-consuming and has only moderate sensitivity. OBJECTIVES The objective was to define the limit of detection (LOD), analytic specificity, and performance characteristics of a broad-based quantitative multiprobe polymerase chain reaction (PCR) assay for rapid bacterial detection and simultaneous pathogen-specific identification in patients with suspected meningitis. METHODS A PCR algorithm consisting of initial broad-based detection of Eubacteriales by a universal probe, followed by pathogen identification using either pathogen-specific probes or Gram-typing probes, was employed to detect pathogens. The 16S rRNA gene, which contains both conserved and variable regions, was chosen as the target. Pathogen-specific probes were designed for Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae, Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli, and Listeria monocytogenes. Gram-positive and -negative typing probes were designed based on conserved regions across all eubacteria. The LOD and time to detection were assessed by dilutional mocked-up samples. A total of 108 convenience cerebrospinal fluid (CSF) clinical samples obtained from the Johns Hopkins Hospital (JHH) microbiology laboratory were tested, and results were compared with hospital microbiologic culture reports. RESULTS The LOD of the assay ranged from 10(1) to 10(2) colony-forming units (CFU)/mL. Pathogen-specific probes showed no cross-reactivity with other organisms. Time to detection was 3 hours. In clinical specimens, the universal probe correctly detected 16 of 22 culture-positive clinical specimens (sensitivity = 72.7%; 95% confidence interval [CI] = 49.8% to 89.3%), which were all correctly characterized by either pathogen-specific or Gram-typing probes. Adjusted sensitivity after removing probable microbiologic laboratory contaminants was 88.9% (95% CI = 65.3% to 98.6%). The universal probe was negative for 86 of 86 culture-negative specimens. CONCLUSIONS A broad-based multiprobe PCR assay demonstrated strong analytic performance characteristics. Findings from a pilot clinical study showed promise in translation to human subjects, supporting potential utility of the assay as an adjunct to traditional diagnostics for early identification of bacterial meningitis.