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Thomas Tran

Publications and source records attributed to Thomas Tran.

2 recordsLinked to original sources
PubMed2026

CRISPR-Cas-based diagnostics for point-of-care detection of sexually transmitted infections: a laboratory development and evaluation study.

BACKGROUND: Timely, point-of-care diagnosis of sexually transmitted infections (STIs) is crucial for enabling prompt treatment and reducing transmission. We aimed to develop a portable, multiplexed, CRISPR-based assay panel for the detection of Neisseria gonorrhoeae (including the ciprofloxacin resistance marker gyrA S91F), Chlamydia trachomatis, Treponema pallidum, and herpes simplex virus (HSV). METHODS: In this laboratory development and evaluation study, we developed and optimised four multiplexed, CRISPR-based, diagnostic STI assays for point-of-care use. The complete assay panel comprised a CRISPR TP-HSV (cTP-HSV) panel for the detection of T pallidum and pan-HSV, with reflex testing to distinguish HSV-1 from HSV-2, and a CRISPR NG-CT (cNG-CT) panel for the detection of N gonorrhoeae and C trachomatis, with reflex testing to detect N gonorrhoeae using two additional genome regions and to identify the gyrA S91F mutation. Each pathogen was targeted at two independent genomic regions by isothermal amplification and CRISPR-Cas reaction using Cas12a and Cas13a, each with distinct fluorescent reporters. Analytical specificity and limits of detection (LODs) were determined, and a retrospective, masked concordance study was conducted on genomic DNA from 900 clinical samples (400 for cTP-HSV and reflex testing and 500 for cNG-CT and reflex testing), using quantitative PCR as the reference standard. The diagnostic accuracy of the test was assessed by analysis of receiver operating characteristic curves. FINDINGS: The overall sensitivity of the TP-HSV CRISPR assay was 82·5% (95% CI 74·0-88·7) for T pallidum and 94·4% (90·2-97·0) for pan-HSV; LODs were 6·2 copies per μL for T pallidum and 7·8 copies per μL for HSV. Reflex testing gave sensitivities of 97·0% (91·1-99·3) for HSV-1 and 96·0% (89·7-98·7) for HSV-2. The NG-CT CRISPR assay had an overall sensitivity of 80·0% (74·0-84·9) for N gonorrhoeae and 73·0% (65·5-79·3) for C trachomatis, with a LOD of 3·9 copies per μL for both pathogens. Reflex testing for the detection of the gyrA S91F mutation in N gonorrhoeae showed an overall sensitivity of 63·1% (55·1-70·4); however, this was dependent on sample type, with a sensitivity of 85·7% (46·7-99·5) in genital samples and 61·2% (52·8-68·9) in extragenital samples. For all pathogens, assay sensitivity was positively correlated with pathogen load. Area under the curve (AUC) values were 0·90 for T pallidum and 0·99 for pan-HSV in the TP-HSV assay, with values of 0·99 for HSV-1 and 0·97 for HSV-2 obtained in the reflex HSV-1-HSV-2 assay. For the cNG-CT assay, AUC values were 0·90 for N gonorrhoeae and 0·85 for C trachomatis, with a value of 0·72 obtained for gyrA S91F in the reflex cNG-gyrA assay. INTERPRETATION: Our multiplexed, CRISPR-based, point-of-care platform achieved performance consistent with WHO target product profiles for N gonorrhoeae and T pallidum. Proof-of-concept detection of the gyrA S91F resistance marker highlights its potential for resistance-guided therapy. Although optimisation is required before large-scale deployment, this suite offers a promising approach for rapid, decentralised, and resistance-informed STI diagnosis, particularly in resource-limited settings. FUNDING: Victorian Government Department of Health, Australian Government Department of Health, Disability and Ageing and Aged Care, and Australian Research Council.

Humans↗
PubMed2026

Characterisation of Bordetella pertussis virulence and macrolide resistance in Australia by targeted culture-independent sequencing: a genomic epidemiology study.

BACKGROUND: Bordetella pertussis continues to circulate globally despite widespread vaccination, with a notable epidemic in 2024. Its resurgence is confounded by the emergence of pertactin-deficient, macrolide-resistant B pertussis strains in Asia and Europe, which are under-recognised by conventional diagnostics. We aimed to apply targeted culture-independent next-generation sequencing (tNGS) of respiratory specimens to improve global B pertussis diagnostic capability and genomic surveillance. METHODS: We did a nationwide genomic epidemiology study of B pertussis RT-PCR-positive respiratory specimens that were retrospectively and prospectively collected by diagnostic and public health laboratories in six of seven states and territories of Australia. Specimens underwent tNGS and macrolide-resistant B pertussis-specific PCR, and an opportunistic subset from New South Wales and Queensland were cultured for confirmatory susceptibility testing and whole-genome sequencing. Sequencing data were analysed for genome recovery, virulence profiles, and macrolide resistance mutations, and were compared with international macrolide-resistant B pertussis genomes and ancestral Australian genomes. The performance of the tNGS approach was assessed with logistic regression relative to RT-PCR cycle threshold values, and sensitivity and specificity values were calculated. FINDINGS: 255 respiratory specimens positive for B pertussis were included in the study. 64 (25%) were retrospectively collected between Jan 12, 2012, and Dec 31, 2023, and 191 (75%) were prospectively collected between Jan 1 and Oct 28, 2024. Of these 255 specimens, 148 (58%) yielded near-complete B pertussis genomes through tNGS. Seven co-circulating lineages of B pertussis were documented, including two associated with macrolide-resistance. Eight epidemiologically unrelated and geographically dispersed cases of macrolide-resistant B pertussis with a 23S rRNA 2037A→G mutation were identified by tNGS and confirmed by whole-genome sequencing. Three of these were further validated by phenotypic testing. The estimated prevalence of macrolide resistance among Australian cases positive for B pertussis was 4% (eight of 188). INTERPRETATION: tNGS can recover near-complete B pertussis genomes directly from clinical specimens, enabling identification of macrolide resistance mutations and high-resolution phylogenetic analysis. These findings show that tNGS complements PCR-based surveillance by providing genome-wide assessment of resistance, virulence, and genomic diversity in a single workflow. FUNDING: NSW Health Prevention Research Support Program.

Macrolides↗