Clinical evaluation of the molecular-based BD SARS-CoV-2/Flu for the BD MAX™ system.

BACKGROUND: COVID-19 and influenza (flu) share similar clinical symptoms. Therefore, differential detection of these viruses during the respiratory virus season will be an important component for proper patient triage, management, and treatment. OBJECTIVES: Establish the diagnostic performance related to SARS-CoV-2 and Flu A/B detection for the BD SARS-CoV-2/Flu for BD MAX™ System ("MAX SARS-CoV-2/Flu") multiplex assay. MATERIALS AND METHODS: Two hundred and thirty-five (235) retrospective nasopharyngeal specimens were obtained from external vendors. The BD BioGx SARS-CoV-2 Reagents for BD MAX™ System ("BioGx SARS-CoV-2″) and the Cepheid Xpert® Xpress Flu/RSV ("Xpert Flu/RSV") were utilized as reference methods. RESULTS: By reference methods, 52 specimens were SARS-CoV-2-positive, 59 were Flu A-positive, and 60 were Flu B-positive. MAX SARS-CoV-2/Flu had positive percent agreement (PPA) and negative percent agreement (NPA) values for SARS-CoV-2 detection of 96.2% ([95%CI]:87.0-98.9) and 100% [95%CI:88.7-100], respectively; PPA values for Flu A and Flu B of 100% [95%CI:93.9-100] and 98.3% [95%CI:91.1-99.7], respectively, and NPA values for Flu A and Flu B of 98.9% [95%CI:94.0-99.8] and 100% [95%CI:95.9-100], respectively. CONCLUSIONS: The MAX SARS-CoV-2/Flu assay met FDA-EUA performance criteria for SARS-CoV-2 (≥95% for PPA and NPA) and FDA clearance criteria for Flu A/B (PPA ≥90%; lower bound of the 95%CI ≥80% and NPA ≥95%; lower bound of the 95%CI ≥90%).

Multicenter Study of the Accuracy of the BD MAX Multidrug-resistant Tuberculosis Assay for Detection of Mycobacterium tuberculosis Complex and Mutations Associated With Resistance to Rifampin and Isoniazid.

BACKGROUND: Tuberculosis (TB) control is hindered by absence of rapid tests to identify Mycobacterium tuberculosis (MTB) and detect isoniazid (INH) and rifampin (RIF) resistance. We evaluated the accuracy of the BD MAX multidrug-resistant (MDR)-TB assay (BD MAX) in South Africa, Uganda, India, and Peru. METHODS: Outpatient adults with signs/symptoms of pulmonary TB were prospectively enrolled. Sputum smear microscopy and BD MAX were performed on a single raw sputum, which was then processed for culture and phenotypic drug susceptibility testing (DST), BD MAX, and Xpert MTB/RIF (Xpert). RESULTS: 1053 participants with presumptive TB were enrolled (47% female; 32% with human immunodeficiency virus). In patients with confirmed TB, BD MAX sensitivity was 93% (262/282 [95% CI, 89-95%]); specificity was 97% (593/610 [96-98%]) among participants with negative cultures on raw sputa. BD MAX sensitivity was 100% (175/175 [98-100%]) for smear-positive samples (fluorescence microscopy), and 81% (87/107 [73-88%]) in smear-negative samples. Among participants with both BD MAX and Xpert, sensitivity was 91% (249/274 [87-94%]) for BD MAX and 90% (246/274 [86-93%]) for Xpert on processed sputa. Sensitivity and specificity for RIF resistance compared with phenotypic DST were 90% (9/10 [60-98%]) and 95% (211/222 [91-97%]), respectively. Sensitivity and specificity for detection of INH resistance were 82% (22/27 [63-92%]) and 100% (205/205 [98-100%]), respectively. CONCLUSIONS: The BD MAX MDR-TB assay had high sensitivity and specificity for detection of MTB and RIF and INH drug resistance and may be an important tool for rapid detection of TB and MDR-TB globally.

Molecular-based Testing for Sexually Transmitted Infections Using Samples Previously Collected for Vaginitis Diagnosis.

Background: Vaginal symptoms are a leading cause of primary care visits for women. Individuals exhibiting symptoms often receive laboratory testing based on clinic-specific standards of care. Thus, women seen at a family practice clinic might only receive a vaginitis workup, whereas those seen at a sexually transmitted diseases clinic could be more likely to receive only sexually transmitted infection (STI) testing. Methods: The likelihood of STIs was assessed in women from whom samples were tested for vaginitis using a molecular diagnostic assay. Positivity rates for Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis DNA, detected using the BD MAX CT/GC/TV assay, were calculated. Concordance between the BD MAX Vaginal Panel and the BD MAX CT/GC/TV assay for detection of T. vaginalis was determined. Results: Women with bacterial vaginosis alone or with concurrent Candida spp infections had high rates of coinfection with sexually transmitted infections (24.4%-25.7%); samples from women who were negative for vaginitis had significantly lower positivity rates (7.9%; P < .001). Trichomonas vaginalis results were concordant between the BD MAX Vaginal Panel and the BD MAX CT/GC/TV assay in 559 of 560 samples tested. Conclusions: These data suggest, as have other studies, that women with vaginitis symptoms may be at risk for an STI. Molecular testing could provide broad diagnostic coverage for symptomatic women and improve patient management, regardless of the type of clinic in which patients are treated.

Diagnostic Performance of a Molecular Test versus Clinician Assessment of Vaginitis.

Vaginitis is a common complaint, diagnosed either empirically or using Amsel's criteria and wet mount microscopy. This study sought to determine characteristics of an investigational test (a molecular test for vaginitis), compared to reference, for detection of bacterial vaginosis, Candida spp., and Trichomonas vaginalis Vaginal specimens from a cross-sectional study were obtained from 1,740 women (≥18 years old), with vaginitis symptoms, during routine clinic visits (across 10 sites in the United States). Specimens were analyzed using a commercial PCR/fluorogenic probe-based investigational test that detects bacterial vaginosis, Candida spp., and Trichomonas vaginalis Clinician diagnosis and in-clinic testing (Amsel's test, potassium hydroxide preparation, and wet mount) were also employed to detect the three vaginitis causes. All testing methods were compared to the respective reference methods (Nugent Gram stain for bacterial vaginosis, detection of the Candida gene its2, and Trichomonas vaginalis culture). The investigational test, clinician diagnosis, and in-clinic testing were compared to reference methods for bacterial vaginosis, Candida spp., and Trichomonas vaginalis The investigational test resulted in significantly higher sensitivity and negative predictive value than clinician diagnosis or in-clinic testing. In addition, the investigational test showed a statistically higher overall percent agreement with each of the three reference methods than did clinician diagnosis or in-clinic testing. The investigational test showed significantly higher sensitivity for detecting vaginitis, involving more than one cause, than did clinician diagnosis. Taken together, these results suggest that a molecular investigational test can facilitate accurate detection of vaginitis.

Clinical Validation of a Test for the Diagnosis of Vaginitis.

OBJECTIVE: Vaginitis may be diagnosed as bacterial vaginosis, vulvovaginal candidiasis, trichomoniasis, or coinfection. A new molecular test assays the vaginal microbiome and organisms that cause three common infections. The objective of the trial was to evaluate the clinical accuracy of the investigational test for vaginal swabs collected by patients (self) or clinicians. The primary and secondary outcomes were to compare the investigational test with reference methods for the three most common causes of vaginitis and compare clinician-collected with self-collected swabs. METHODS: We conducted a cross-sectional study in which women with symptoms of vaginitis were recruited at ten clinical centers and consented to the investigation between May and September 2015. The woman collected a vaginal swab, sheathed, and then handed it to the clinician. These swabs were to evaluate how self-collected swabs compared with clinician-collected swabs. The clinician collected an investigational test swab and reference test swabs. From 1,740 symptomatic patients, clinician-collected and self-collected vaginal swabs were evaluated by the molecular test and six tests. The reference methods for bacterial vaginosis were Nugent's score and Amsel's criteria for intermediate Nugent results. The reference methods for Candida infection were isolation of any potential Candida microorganisms from inoculation of two culture media: chromogenic and Sabouraud agar and sequencing. The reference methods for trichomoniasis were wet mount and culture. RESULTS: For clinician-collected swabs, by reference methods, bacterial vaginosis was diagnosed in 56.5%, vaginal candidiasis in 32.8%, trichomoniasis in 8%, and none of the three infections in 24% with a coinfection rate of 20%. The investigational test sensitivity was 90.5% (95% confidence interval [CI] 88.3-92.2%) and specificity was 85.8% (95% CI 83.0-88.3%) for bacterial vaginosis. The investigational test sensitivity was 90.9% (95% CI 88.1-93.1%) and specificity was 94.1% (95% CI 92.6-95.4%) for the Candida group. Sensitivity for Candida glabrata was 75.9% (95% CI 57.9-87.8%) and specificity was 99.7% (95% CI 99.3-99.9%). Investigational test sensitivity was 93.1% (95% CI 87.4-96.3%) and specificity was 99.3% (95% CI 98.7-99.6%) for trichomoniasis. Results from self-collected swabs were similar to clinician-collected swabs. CONCLUSION: A molecular-based test using vaginal swabs collected by clinicians or patients can accurately diagnose most common bacterial, fungal, and protozoan causes of vaginitis. Women and their clinicians seeking accurate diagnosis and appropriate selection of efficacious treatment for symptoms of vaginitis might benefit from this molecular test.

Analytical comparison of nine PCR primer sets designed to detect the presence of Escherichia coli/Shigella in water samples.

The analytical performance of 9 different PCR primer sets designed to detect Escherichia coli and Shigella in water has been evaluated in terms of ubiquity, specificity, and analytical detection limit. Of the 9 PCR primer sets tested, only 3 of the 5 primer sets targeting uidA gene and the primer set targeting tuf gene amplified DNA from all E. coli strains tested. However, of those 4 primer sets, only the primer set targeting the tuf gene also amplified DNA from all Shigella strains tested. For the specificity, only the primer sets targeting the uidA gene were 100% specific although the primer sets targeting 16S rRNA, phoE, and tuf genes only amplified Escherichia fergusonii as non-specific target. Finally, the primer set targeting the 16S-ITS-23S gene region, was not specific as it amplified DNA from many other Enterobacteriaceae species. In summary, only the assay targeting the tuf gene detected all E. coli/Shigella strains tested in this study. However, if it becomes important to discriminate between E. coli and E. fergusonii, assays targeting the uidA gene would represent a good choice although none of them were totally ubiquitous to detect of the presence of Shigella strains.

Phylogeny of the Enterobacteriaceae based on genes encoding elongation factor Tu and F-ATPase beta-subunit.

The phylogeny of enterobacterial species commonly found in clinical samples was analysed by comparing partial sequences of their elongation factor Tu gene (tuf) and of their F-ATPase beta-subunit gene (atpD). An 884 bp fragment for tuf and an 884 or 871 bp fragment for atpD were sequenced for 96 strains representing 78 species from 31 enterobacterial genera. The atpD sequence analysis exhibited an indel specific to Pantoea and Tatumella species, showing, for the first time, a tight phylogenetic affiliation between these two genera. Comprehensive tuf and atpD phylogenetic trees were constructed and are in agreement with each other. Monophyletic genera are Cedecea, Edwardsiella, Proteus, Providencia, Salmonella, Serratia, Raoultella and Yersinia. Analogous trees based on 16S rRNA gene sequences available from databases were also reconstructed. The tuf and atpD phylogenies are in agreement with the 16S rRNA gene sequence analysis, and distance comparisons revealed that the tuf and atpD genes provide better discrimination for pairs of species belonging to the family Enterobacteriaceae. In conclusion, phylogeny based on tuf and atpD conserved genes allows discrimination between species of the Enterobacteriaceae.