Time-Motion Analysis of Four Automated Systems for the Detection of Chlamydia trachomatis and Neisseria gonorrhoeae by Nucleic Acid Amplification Testing

A profile of the FDA-approved and CE/IVD-marked Aptima Mycoplasma genitalium assay (Hologic) and key priorities in the management of M. genitalium infections

INTRODUCTION

Mycoplasma genitalium (MG) causes frequently asymptomatic STIs. MG prevalence figures are lacking and management is complicated by the lack of etiological diagnostics and high antimicrobial resistance in many countries. Appropriately validated, quality-assured, and FDA-approved MG diagnostic assays have been lacking.

AREAS COVERED

The clinical and analytical performance characteristics of the Aptima® MG assay, the first FDA-approved MG nucleic acid amplification test (NAAT), are summarized. Key priorities in the management and control of MG infections are also discussed.

EXPERT OPINION

Highly sensitive, specific, and quality-assured MG NAATs, e.g. the Aptima MG assay on the automated and flexible Panther® platform, are imperative to improve the management and control of MG infections internationally. This testing, combined with macrolide-resistance testing (not yet available on the Panther platform), offers a rapid, high-throughput, and appropriate diagnosis of MG. Macrolide resistance-guided sequential treatment needs to be implemented for MG infections. Dual antimicrobial therapy, novel antimicrobials and, ideally, a vaccine may become essential.

Comparison of Workflow, Maintenance, and Consumables in the GeneXpert Infinity 80 and Panther Instruments While Testing for Chlamydia trachomatis and Neisseria gonorrhoeae

BACKGROUND

The 2015 Sexually Transmitted Diseases Treatment Guidelines from the Centers for Disease Control and Prevention recommend testing for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) using nucleic acid amplification tests, and prompt treatment of infected persons on site under direct observation. Faster time to results may enable treatment and management outcomes.

METHODS

Workflow parameters for processing 1, 10, 48, 96, and 192 tests were determined in the GeneXpert Infinity 80 (Cepheid) and Panther (Hologic) instruments.

RESULTS

In an Xpert CT/NG cartridge, the time to first results on the Infinity 80 was 1 hour 30 minutes for single or multiple tests and final results for 10, 48, 96, and 192 tests were available at 1 hour 37 minutes, 1 hour 54 minutes, 3 hour 17 minutes, and 5 hour 7 minutes, respectively. With the Aptima CT/GC assay on the Panther, the respective times were 3 hr 45 min for the first test result, and 3 hour 51 minutes, 4 hour 38 minutes, 5 hour 26 minutes, and 7 hour 4 minutes to final results. The Panther required more time for maintenance and consumed a greater variety of plastics and reagents but required less hands-on time when testing larger numbers of specimens.

CONCLUSIONS

The Infinity 80 is a versatile instrument for continuous random access testing of small or large numbers of clinical specimens and may provide diagnostic results, in some settings, in time for treatment of CT and NG infections.

Comparison of cobas 4800, m2000, Viper XTR, and Infinity 80 Automated Instruments When Processing Urine Specimens for the Diagnosis of Chlamydia trachomatis and Neisseria gonorrhoeae

OBJECTIVES

North American and European advisory groups recommend testing for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) with nucleic acid amplification tests. Testing is often performed on automated instruments. The objectives of this study were to process urines for the diagnosis of CT and NG and to examine workflow procedures and outcomes.

METHODS

While processing 1, 24, 48, 96, and 192 urine specimens on 3 batch-mode systems which use 96-well plates: cobas 4800, m2000, and Viper XTR and the random access cartridge testing GeneXpert Infinity 80, we measured assay performance, hands-on time for processing and maintenance, reagents and plastics consumption, time required to obtain results, and testing accuracy.

RESULTS

The Infinity 80 required the least hands-on time for single specimens and smaller batches, whereas the Viper XTR and m2000 required the most hands-on time for all batch sizes. Cumulative daily, weekly, and monthly maintenance was highest for the Viper XTR and lowest for Infinity 80. All batch-mode instruments consumed large amounts of disposables. Time to results was shortest for the Infinity 80, and the Viper XTR provided the shortest time for the batch-mode instruments. All systems showed similar diagnostic accuracy.

CONCLUSIONS

Because detection performances were similar, issues of hands-on time, maintenance, time to results, and consumables are important operational factors for the diagnosis and treatment of CT/NG infections.

Profile of the triplex assay for detection of chlamydia, gonorrhea and trichomonas using the BD MAX™ System

INTRODUCTION

Chlamydia, gonorrhea and trichomonas are the most common curable STI. improved access to testing could reduce infection rates and prevent sequelae. nucleic acid amplification tests are the recommend class of diagnostic assay for these infections which are often asymptomatic. Areas covered: A description of the BD MAX™ System (MAX) and the BD MAX CT/GC/TV assay is provided along with data from a large US clinical trial. The capacity of the system for other tests and for lab developed assays is also described. Expert commentary: The CT/GC/TV assay on the MAX is a triplex PCR assay suitable for use with female urine and vaginal or endocervical swab samples. Male urine can be tested by ordering the CT/GC results but has not yet been evaluated for trichomonas. The assay performance characteristics are similar to those of assays run on high-throughput platforms with sensitivity ≥91.5% and specificity ≥98.6% for all analytes. Screening with the CT/GC/TV assay can be combined with testing for vaginitis which would provide a greater depth of coverage for common co-infections. The throughput is moderate (1-48 samples per 8-hour shift) but the menu includes assays beyond STI pathogens making this a suitable platform for moderate volume laboratories.

Type-specific detection of herpes simplex virus type 1 and type 2 using the cobas® HSV 1 and 2 test on the cobas® 4800 platform

INTRODUCTION

HSV-1 and HSV-2 are among the most common causes of sexually transmitted infections (stis) globally. these infections are strongly associated with increased risk of hiv acquisition and rare, but devastating, neonatal disease. available treatment options can reduce HSV transmission and improve quality of life. accurate diagnosis early in disease can improve patient management. Areas covered: This paper describes the clinical manifestations of HSV infection often used for clinical diagnostic purposes. The paper then describes the evolution of laboratory diagnostic assays. Serology, culture and molecular diagnostics are described since all are currently in use. The features and performance characteristics of the cobas 4800 HSV1 and HSV2 Test (cobas HSV) on the cobas 4800® system (cobas 4800) are described in detail. Expert commentary: Diagnosis of HSV has historically been unreliable or technically difficult, but the availability of molecular assays such as the cobas HSV test for detection and typing of herpes can improve our ability to correctly manage this disease. Utilization of tools such as the cobas HSV assay may help shorten the time to accurate diagnosis and treatment thus potentially reducing the risk of transmission and the global burden of HSV.

Comparison of time-motion analysis of conventional stool culture and the BD MAX™ Enteric Bacterial Panel (EBP)

Background

Conventional bacterial stool culture is one of the more time-consuming tests in a routine clinical microbiology laboratory. In addition, less than 5 % of stool cultures yield positive results. A molecular platform, the BD MAX™ System (BD Diagnostics, Sparks, MD) offers the potential for significantly more rapid results and less hands-on time. Time-motion analysis of the BD MAX Enteric Bacterial Panel (EBP) (BD Diagnostics, Quebec, Canada) on the BD MAX System was compared to conventional stool culture in the microbiology laboratory of a tertiary care pediatric hospital.

Methods

The process impact analysis of time-motion studies of conventional cultures were compared to those of EBP with 86 stool specimens. Sample flow, hands-on time, processing steps, and overall turnaround time were determined and analyzed. Data were obtained and analyzed from both standard operating procedures and direct observation. A regression analysis was performed to ensure consistency of measurements. Time and process measurements started when the specimens were logged into the accessioning area of the microbiology laboratory and were completed when actionable results were generated.

Results

With conventional culture, negative culture results were available from 41:14:27 (hours:minutes:seconds) to 54:17:19; with EBP, positive and negative results were available from 2:28:40 to 3:33:39.

Conclusions

This study supports the suggestion that use of the EBP to detect commonly encountered stool pathogens can result in significant time savings and a shorter time-to-result for patients with acute bacterial diarrhea.

Workflow and maintenance characteristics of five automated laboratory instruments for the diagnosis of sexually transmitted infections

The choice of a suitable automated system for a diagnostic laboratory depends on various factors. Comparative workflow studies provide quantifiable and objective metrics to determine hands-on time during specimen handling and processing, reagent preparation, return visits and maintenance, and test turnaround time and throughput. Using objective time study techniques, workflow characteristics for processing 96 and 192 tests were determined on m2000 RealTime (Abbott Molecular), Viper XTR (Becton Dickinson), cobas 4800 (Roche Molecular Diagnostics), Tigris (Hologic Gen-Probe), and Panther (Hologic Gen-Probe) platforms using second-generation assays for Chlamydia trachomatis and Neisseria gonorrhoeae. A combination of operational and maintenance steps requiring manual labor showed that Panther had the shortest overall hands-on times and Viper XTR the longest. Both Panther and Tigris showed greater efficiency whether 96 or 192 tests were processed. Viper XTR and Panther had the shortest times to results and m2000 RealTime the longest. Sample preparation and loading time was the shortest for Panther and longest for cobas 4800. Mandatory return visits were required only for m2000 RealTime and cobas 4800 when 96 tests were processed, and both required substantially more hands-on time than the other systems due to increased numbers of return visits when 192 tests were processed. These results show that there are substantial differences in the amount of labor required to operate each system. Assay performance, instrumentation, testing capacity, workflow, maintenance, and reagent costs should be considered in choosing a system.