Dr Jai Mehat

Lecturer (B) in Molecular Bacteriology
PhD, PGCert, BSc

Academic and research departments

Department of Microbial Sciences, School of Biosciences.


Areas of specialism

Molecular Microbiology; Bacteriology; Host/Pathogen Interactions

University roles and responsibilities

  • Member of the NASPA Committee


    Research interests


    Postgraduate research supervision

    Postgraduate research supervision



    Aurore C. Poirier, Ruben D. Riaño Moreno, Leona Takaindisa, Jessie Carpenter, Jai W. Mehat, Abi Haddon, Mohammed A. Rohaim, Craig Williams, Peter Burkhart, Chris Conlon, Matthew Wilson, Matthew McClumpha, Anna Stedman, Guido Cordoni, Manoharanehru Branavan, Mukunthan Tharmakulasingam, Nouman S. Chaudhry, Nicolas Locker, Anil Fernando, Wamadeva Balachandran, Mark Bullen, Nadine Collins, David Rimer, Daniel L. Horton, Muhammad Munir, Roberto M. La Ragione (2023)VIDIIA Hunter diagnostic platform: a low-cost, smartphone connected, artificial intelligence-assisted COVID-19 rapid diagnostics approved for medical use in the UK, In: Frontiers in molecular biosciences101144001 Frontiers Media S.A

    Introduction: Accurate and rapid diagnostics paired with effective tracking and tracing systems are key to halting the spread of infectious diseases, limiting the emergence of new variants and to monitor vaccine efficacy. The current gold standard test (RT-qPCR) for COVID-19 is highly accurate and sensitive, but is time-consuming, and requires expensive specialised, lab-based equipment. Methods: Herein, we report on the development of a SARS-CoV-2 (COVID-19) rapid and inexpensive diagnostic platform that relies on a reverse-transcription loop-mediated isothermal amplification (RT-LAMP) assay and a portable smart diagnostic device. Automated image acquisition and an Artificial Intelligence (AI) deep learning model embedded in the Virus Hunter 6 (VH6) device allow to remove any subjectivity in the interpretation of results. The VH6 device is also linked to a smartphone companion application that registers patients for swab collection and manages the entire process, thus ensuring tests are traced and data securely stored. Results: Our designed AI-implemented diagnostic platform recognises the nucleocapsid protein gene of SARS-CoV-2 with high analytical sensitivity and specificity. A total of 752 NHS patient samples, 367 confirmed positives for coronavirus disease (COVID-19) and 385 negatives, were used for the development and validation of the test and the AI-assisted platform. The smart diagnostic platform was then used to test 150 positive clinical samples covering a dynamic range of clinically meaningful viral loads and 250 negative samples. When compared to RT-qPCR, our AI-assisted diagnostics platform was shown to be reliable, highly specific (100%) and sensitive (98–100% depending on viral load) with a limit of detection of 1.4 copies of RNA per µL in 30 min. Using this data, our CE-IVD and MHRA approved test and associated diagnostic platform has been approved for medical use in the United Kingdom under the UK Health Security Agency’s Medical Devices (Coronavirus Test Device Approvals, CTDA) Regulations 2022. Laboratory and in-silico data presented here also indicates that the VIDIIA diagnostic platform is able to detect the main variants of concern in the United Kingdom (September 2023). Discussion: This system could provide an efficient, time and cost-effective platform to diagnose SARS-CoV-2 and other infectious diseases in resource-limited settings.

    Jai Mehat, James R. G. Adams, Roberto La Ragione, Shahriar Behboudi (2023)Preventing bacterial disease in poultry in the post-antibiotic era: a case for innate immunity modulation as an alternative to antibiotic use, In: Frontiers in immunology14

    The widespread use of antibiotics in the poultry industry has led to the emergence of antibiotic-resistant bacteria, which pose a significant health risk to humans and animals. These public health concerns, which have led to legislation limiting antibiotic use in animals, drive the need to find alternative strategies for controlling and treating bacterial infections. Modulation of the avian innate immune system using immunostimulatory compounds provides a promising solution to enhance poultry immune responses to a broad range of bacterial infections without the risk of generating antibiotic resistance. An array of immunomodulatory compounds have been investigated for their impact on poultry performance and immune responses. However, further research is required to identify compounds capable of controlling bacterial infections without detrimentally affecting bird performance. It is also crucial to determine the safety and effectiveness of these compounds in conjunction with poultry vaccines. This review provides an overview of the various immune modulators known to enhance innate immunity against avian bacterial pathogens in chickens, and describes the mechanisms involved.

    Khushboo Borah Slater, Muhammad Ahmad, Aurore Poirier, Ash Stott, Bianca S. Siedler, Matthew Brownsword, Jai Mehat, Joanna Urbaniec, Nicolas Locker, Yunlong Zhao, Roberto La Ragione, S. Ravi P. Silva, Johnjoe McFadden (2023)Development of a loop-mediated isothermal amplification (LAMP)-based electrochemical test for rapid detection of SARS-CoV-2, In: iScience

    Rapid, reliable, sensitive, portable, and accurate diagnostics are required to control disease outbreaks such as COVID-19 that pose an immense burden on human health and the global economy. Here we developed a loop-mediated isothermal amplification (LAMP)-based electrochemical test for the detection of SARS-CoV-2 that causes COVID-19. The test is based on the oxidation-reduction reaction between pyrophosphates (generated from positive LAMP reaction) and molybdate that is detected by cyclic voltammetry using inexpensive and disposable carbon screen printed electrodes. Our test showed higher sensitivity (detecting as low as 5.29 RNA copies/μL) compared to the conventional fluorescent reverse transcriptase (RT)-LAMP. We validated our tests using human serum and saliva spiked with SARS-CoV-2 RNA and clinical (saliva and nasal-pharyngeal) swab samples demonstrating 100% specificity and 93.33% sensitivity. Our assay provides a rapid, specific, and sensitive test with an electrochemical readout in less than 45 min that could be adapted for point-of-care settings.

    Aurore C. Poirier, Dai Kuang, Bianca S. Siedler, Khushboo Borah, Jai W. Mehat, Jialin Liu, Cui Tai, Xiaoli Wang, Arnoud H. M. van Vliet, Wei Ma, David R. Jenkins, John Clark, Roberto M. La Ragione, Jieming Qu, Johnjoe McFadden (2022)Development of Loop-Mediated Isothermal Amplification Rapid Diagnostic Assays for the Detection of Klebsiella pneumoniae and Carbapenemase Genes in Clinical Samples, In: Frontiers in molecular biosciences8794961 Frontiers Media Sa

    Klebsiella pneumoniae is an important pathogenic bacterium commonly associated with human healthcare and community-acquired infections. In recent years, K. pneumoniae has become a significant threat to global public and veterinary health, because of its high rates of antimicrobial resistance (AMR). Early diagnosis of K. pneumoniae infection and detection of any associated AMR would help to accelerate directed therapy and reduce the risk of the emergence of multidrug-resistant isolates. In this study, we identified three target genes (yhaI, epsL, and xcpW) common to K. pneumoniae isolates from both China and Europe and designed loop-mediated isothermal amplification (LAMP) assays for the detection of K. pneumoniae in clinical samples. We also designed LAMP assays for the detection of five AMR genes commonly associated with K. pneumoniae. The LAMP assays were validated on a total of 319 type reference strains and clinical isolates of diverse genetic backgrounds, in addition to 40 clinical human sputum samples, and were shown to be reliable, highly specific, and sensitive. For the K. pneumoniae-specific LAMP assay, the calculated sensitivity, specificity, and positive and negative predictive values (comparison with culture and matrix-assisted laser desorption/ionization-time of flight mass spectrometry) were all 100% on clinical isolates and, respectively, of 100%, 91%, and 90%, and 100% when tested on clinical sputum samples, while being significantly faster than the reference methods. For the bla(KPC) and other carbapenemases' LAMP assays, the concordance between the LAMP results and the references methods (susceptibility tests) was 100%, on both pure cultures (n = 125) and clinical samples (n = 18). In conclusion, we developed highly sensitive and specific LAMP assays for the clinical identification of K. pneumoniae and detection of carbapenem resistance.

    Arnoud HM van Vliet, Siddhartha Thakur, Joaquin M Prada, Jai W Mehat, Roberto La Ragione (2021)Genomic screening of antimicrobial resistance markers in UK and US Campylobacter isolates highlights stability of resistance over an 18 year period, In: bioRxiv Cold Spring Harbor Laboratory
    Jai W. Mehat, Simon F. Park, Arnoud H. M. van Vliet, Roberto M. La Ragione (2018)CapC, a novel autotransporter and virulence factor of Campylobacter jejuni, In: Applied and Environmental Microbiologypp. e01032-18 American Society for Microbiology

    Campylobacter jejuni is recognized as an important causative agent of bacterial gastroenteritis in the developed world. Despite the identification of several factors contributing to infection, characterization of the virulence strategies employed by C. jejuni remains a significant challenge. Bacterial autotransporter proteins are a major class of secretory proteins in Gram-negative bacteria and notably many autotransporter proteins contribute to bacterial virulence. The aim of this study was to characterise the C. jejuni 81116 C8J_1278 gene (capC), predicted to encode an autotransporter protein, and examine the contribution of this factor to virulence of Campylobacter jejuni. The predicted CapC protein has a number of features that are consistent with autotransporters including the N-terminal signal sequence and the C-terminal β-barrel domain and was determined to localise to the outer membrane. Inactivation of the capC gene in C. jejuni 81116 and C. jejuni M1 resulted in reduced insecticidal activity in Galleria mellonella larvae. Furthermore, C. jejuni capC mutants displayed significantly reduced adherence to and invasion of non-polarized, partially differentiated Caco-2 and T84 intestinal epithelial cells. Gentamicin treatment showed that the reduced invasion of the capC mutant is primarily caused by reduced adherence to intestinal epithelial cells, not by reduced invasion capability. C. jejuni capC mutants caused reduced IL-8 secretion from intestinal epithelial cells and elicited a significantly diminished immune reaction in Galleria larvae indicating that CapC functions as an immunogen. In conclusion, CapC is a new virulence determinant of C. jejuni that contributes to the integral infection process of adhesion to human intestinal epithelial cells.

    Michael Hornsey, Jonathan W. Betts, Jai W. Mehat, David W. Wareham, Arnoud H. M. van Vliet, Martin J. Woodward, Roberto M. La Ragione (2019)Characterization of a colistin-resistant Avian Pathogenic Escherichia coli ST69 isolate recovered from a broiler chicken in Germany, In: Journal of Medical Microbiology68(1)pp. 111-114 Microbiology Society

    In recent years, several plasmids harbouring genes encoding phosphoethanolamine transferases conferring colistin resistance have been described in multiple Enterobacteriaceae species. Avian Pathogenic E. coli (APEC) causes colibacillosis and is responsible for a considerable proportion of the disease burden in commercial poultry flocks, and may be linked to zoonotic infections in humans. Here, we describe the genotypic and phenotypic characteristics of a multidrug-resistant APEC ST69 isolate (APECA2), recovered in 2016 from a diseased broiler at post-mortem examination in Germany. The isolate was resistant to several antibiotics of human and veterinary importance, including colistin. The mcr-1 gene was detected on a mobile genetic element located on an IncHI2/ST4 plasmid, which was characterized using long-read Nanopore and short-read Illumina sequencing of purified plasmid. Isolate APECA2 displayed resistance to chicken serum and harbours numerous virulence genes. This study highlights the public health importance of enhanced antimicrobial resistance surveillance and strict antimicrobial stewardship in human and veterinary healthcare.

    Jai Mehat, Roberto M. La Ragione, Arnoud van Vliet (2020)Campylobacter jejuni and Campylobacter coli autotransporter genes exhibit lineageassociated distribution and decay, In: BMC Genomics21314 BMC

    Background: Campylobacter jejuni and Campylobacter coli are major global causes of bacterial gastroenteritis. Whilst several individual colonisation and virulence factors have been identified, our understanding of their role in the transmission, pathogenesis and ecology of Campylobacter has been hampered by the genotypic and phenotypic diversity within C. jejuni and C. coli. Autotransporter proteins are a family of outer membrane or secreted proteins in Gram-negative bacteria such as Campylobacter, which are associated with virulence functions. In this study we have examined the distribution and predicted functionality of the previously described capC and the newly identified, related capD autotransporter gene families in Campylobacter. Results: Two capC-like autotransporter families, designated capC and capD, were identified by homology searches of genomes of the genus Campylobacter. Each family contained four distinct orthologs of CapC and CapD. The distribution of these autotransporter genes was determined in 5829 C. jejuni and 1347 C. coli genomes. Autotransporter genes were found as intact, complete copies and inactive formats due to premature stop codons and frameshift mutations. Presence of inactive and intact autotransporter genes was associated with C. jejuni and C. coli multi-locus sequence types, but for capC, inactivation was independent from the length of homopolymeric tracts in the region upstream of the capC gene. Inactivation of capC or capD genes appears to represent lineagespecific gene decay of autotransporter genes. Intact capC genes were predominantly associated with the C. jejuni ST-45 and C. coli ST-828 generalist lineages. The capD3 gene was only found in the environmental C. coli Clade 3 lineage. These combined data support a scenario of inter-lineage and interspecies exchange of capC and subsets of capD autotransporters. Conclusions: In this study we have identified two novel, related autotransporter gene families in the genus Campylobacter, which are not uniformly present and exhibit lineage-specific associations and gene decay. The distribution and decay of the capC and capD genes exemplifies the erosion of species barriers between certain lineages of C. jejuni and C. coli, probably arising through co-habitation. This may have implications for the phenotypic variability of these two pathogens and provide opportunity for new, hybrid genotypes to emerge.

    Siddhartha Thakur, Joaquin M Prada, Jai W Mehat, Roberto M La Ragione, Arnoud Van Vliet (2022)Genomic Screening of Antimicrobial Resistance Markers in UK and US Campylobacter Isolates Highlights Stability of Resistance over an 18-Year Period, In: Antimicrobial agents and chemotherapy66(5)e0168721

    Campylobacter jejuni and Campylobacter coli are important bacterial causes of human foodborne illness. Despite several years of reduced antibiotics usage in livestock production in the United Kingdom (UK) and United States (US), a high prevalence of antimicrobial resistance (AMR) persists in . Both countries have instigated genome sequencing-based surveillance programs for , and in this study, we have identified AMR genes in 32,256 C. jejuni and 8,776 C. coli publicly available genome sequences to compare the prevalence and trends of AMR in isolated in the UK and US between 2001 and 2018. AMR markers were detected in 68% of C. coli and 53% of C. jejuni isolates, with 15% of C. coli isolates being multidrug resistant (MDR), compared to only 2% of C. jejuni isolates. The prevalence of aminoglycoside, macrolide, quinolone, and tetracycline resistance remained fairly stable from 2001 to 2018 in both C. jejuni and C. coli, but statistically significant differences were observed between the UK and US. There was a statistically significant higher prevalence of aminoglycoside and tetracycline resistance for US C. coli and C. jejuni isolates and macrolide resistance for US C. coli isolates. In contrast, UK C. coli and C. jejuni isolates showed a significantly higher prevalence of quinolone resistance. Specific multilocus sequence type (MLST) clonal complexes (e.g., ST-353/464) showed >95% quinolone resistance. This large-scale comparison of AMR prevalence has shown that the prevalence of AMR remains stable for in the UK and the US. This suggests that antimicrobial stewardship and restricted antibiotic usage may help contain further expansion of AMR prevalence in but are unlikely to reduce it in the short term.

    Jai W Mehat, Roberto M La Ragione, Arnoud Van Vliet (2021)The Avian Pathogenic Escherichia coli (APEC) pathotype is comprised of multiple distinct, independent genotypes, In: Avian Pathology50(5)pp. 402-416 Taylor and Francis

    Avian Pathogenic E. coli (APEC) is the causative agent of avian colibacillosis, resulting in economic losses to the poultry industry through morbidity, mortality and carcass condemnation, and impacts the welfare of poultry. Colibacillosis remains a complex disease to manage, hampered by diagnostic and classification strategies for E. coli that are inadequate for defining APEC. However, increased accessibility of whole genome sequencing (WGS) technology has enabled phylogenetic approaches to be applied to the classification of E. coli and genomic characterisation of the most common APEC serotypes associated with colibacillosis O1, O2 and O78. These approaches have demonstrated that that the O78 serotype is representative of two distinct APEC lineages, ST-23 in phylogroup C and ST-117 in phylogroup G. The O1, and O2 serotypes belong to a third lineage comprised of 3 sub-populations in phylogroup B2; ST-95, ST-140 and ST-428/ST-429. The frequency with which these genotypes are associated with colibacillosis implicates them as the predominant APEC populations and distinct from those causing incidental or opportunistic infections. The fact that these are disparate clusters from multiple phylogroups suggests that these lineages may have become adapted to the poultry niche independently. WGS studies have highlighted the limitations of traditional APEC classification and can now provide a path towards a robust and more meaningful definition of the APEC pathotype. Future studies should focus on characterising individual APEC populations in detail and use this information to develop improved diagnostics and interventions.

    Cristina Lagatolla, Jai W. Mehat, Roberto Marcello La Ragione, Roberto Luzzati, Stefano Di Bella (2022)In Vitro and In Vivo Studies of Oritavancin and Fosfomycin Synergism against Vancomycin-Resistant Enterococcus faecium, In: Antibiotics (Basel)11(10)1334 MDPI

    Therapeutic options for infections caused by vancomycin-resistant enterococci are currently suboptimal. Combination regimens where fosfomycin is used alongside existing treatments are emerging given the proven synergistic potential and PK/PD properties. In the studies presented here, we tested five vanA and five vanB clinical isolates of Enterococcus faecium using a combination of oritavancin + fosfomycin both in vitro (checkerboard, time killing) and in vivo ( Galleria mellonella ). The combination of oritavancin and fosfomycin increased drug susceptibility, showing a synergistic effect in 80% of isolates and an additive effect in the remaining isolates. The combination restored fosfomycin susceptibility in 85% of fosfomycin-resistant isolates. Time killing on four selected isolates demonstrated that the combination of oritavancin and fosfomycin provided a CFU/mL reduction > 2 log 10 compared with the most effective drug alone and prevented the bacterial regrowth seen after 8–24 h at sub-inhibitory drug concentrations. In addition, the combination was also tested in a biofilm assay with two isolates, and a strong synergistic effect was observed in one isolate and an additive effect in the other. Finally, we demonstrated in vivo ( Galleria mellonella ) a higher survival rate of the larvae treated with the combination therapy compared to monotherapy (fosfomycin or oritavancin alone). Our study provides preclinical evidence to support trials combining oritavancin and fosfomycin for VRE BSI in humans, even when biofilm is involved.