11:00-12:00 – Molecular Diagnostics
Chair: Fidelma Hernon, Senior Medical Scientist, Blackrock Clinic
11:00-11:30 Whole Genome Sequencing: Diagnostic Friend or Foe?
Dr Peter Flanagan, Ph.D, Clinical Scientist – Irish Mycobacterium Reference Laboratory, Visiting Fellow – Trinity College Dublin, Clinical Microbiology, School of Medicine
Dr. Flanagan has over 10 years of experience working in the higher education sector and diagnostic laboratories in the UK and Ireland as a Research Assistant, Postgraduate Research Fellow and Clinical Scientist. Upon graduating from NUI Maynooth with a B.Sc. in Biological Sciences, Dr. Flanagan was offered a Research Assistant position at The University of Oxford, Nuffield Dept. of Clinical & Experimental Medicine. Here, he spent 2 years working as part of a multidisciplinary team on the SPARTAC trial where he was responsible for longitudinal target sequencing of samples from patients acutely infected with HIV. Following this, Dr. Flanagan completed his Masters in Virology at Imperial College London which focused on molecular biology and pathology of viruses. Shortly later, Dr. Flanagan successfully secured a place to complete a Ph.D. in molecular microbiology of the fungal pathogen Candida albicans at the Dublin Dental University Hospital, Trinity College Dublin. After his education, Dr. Flanagan was later appointed to Postdoctoral Fellow and pioneered the implementation of 3rd generation sequencing to the molecular microbiology group within the Dublin Dental Hospital using Oxford Nanopore Technology and the use of their portable MinION sequencer. He also developed the bioinformatic pipeline within his immediate research group and beyond in order to analysis sequences. Abstract Currently, Dr. Flanagan is undertaking work in the Irish Mycobacteria Reference Laboratory to develop and deploy a WGS pipeline for the rapid identification of Mycobacterium tuberculosis recovered from patient samples and determining drug resistance. His role sees him collaborating with the National MRSA Reference Laboratory and Interim Gonococcal Reference laboratory as they develop WGS as a diagnostic tool. To date, hospitals are facing a larger incidence of difficult to treat infections due to increasing drug resistance and newly derived infectious agents such as SARS-CoV-2. Strain identification, as well as virulence and drug resistance profiling can be a timely task. Moreover, current phenotypic tests are limited in the information that they provide. Until recently, whole genome sequencing (WGS) has been a tool utilised by research institutes the world over. However, in recent years more evidence is mounting, suggesting that WGS can be of substantial benefit in a clinical diagnostic setting. In particular, WGS can provide enhanced information on drug resistance, bacterial fitness factors, horizontal gene transfer, multi-locus sequence typing but also, provide an understanding of transmission. Furthermore, genomic analysis can provide vital information into the relatedness of samples during an outbreak regionally, nationally and globally, allowing epidemiological connections as well as contact tracing.
11:30-12:00 Microarray-based Epigenetic Classifier for Brain Tumours
Teresa Loftus, Senior Medical Scientist, Beaumont Hospital
I am a Specialist Medical Scientist in the Molecular Laboratory in Beaumont Hospital. Having completed an MSc in Molecular Medicine from Trinity College Dublin, I became a Fellow of the Academy of Clinical Science and Laboratory Medicine (ACSLM), and sit on the advisory board for Molecular Diagnostics for the ACSLM. I am a quality assessor for the Central Nervous System Cytogenomic External Quality Assurance Scheme (CEQAS). Recently Beaumont Hospital embarked on a laboratory modernisation project which included upgrading the molecular facility. This involved overseeing the move of all instrumentation to the newly located laboratory and the revalidation of all instrumentation and assays to the ISO15189 international standard. Beaumont Hospital is the national referral centre for all Paediatric and Adult molecular neurooncology. We perform an array of assays, including techniques such as real time PCR, pyrosequencing, array comparative genomic hybridization and Next Generation Sequencing. In 2019 we set about introducing DNA methylation profiling within the department.
DNA methylation profiling of brain tumours has proven to be very useful in the medical setting in recent years. It has important diagnostic, prognostic and treatment implications. It was set up in the Molecular lab in Beaumont Hospital in 2019 to facilitate the needs of paediatic and adult neurooncology patients. Using this technology, the data generated is analysed to determine a tumour classification, copy number profile and MGMT methylation result.
13:00-13:30 – Transfusion and Transplantation Science
Chair: Fergus Guilfoyle, Chief Medical Scientist, Coombe Women and Infants University Hospital.
The identification and management of Anti-Jk3 in pregnancy
Cait Geaney, Senior Medical Scientist, Red Cell Immunohaematology Laboratory, Irish Blood Transfusion Service, James’s St. Dublin 8
Since graduating from D.I.T in 2009, Cáit worked in Crumlin Transfusion and Haematology Laboratory’s for 3 years and worked in a Medical and Pharmaceutical Laboratory’s in Melbourne, Australia for 4 years. Since returning from Australia she has worked in the Irish Blood Transfusion Service. She completed an MSc in Biomedical Science (2018) which focused on antenatal testing in the Red Cell Immunohaematology Laboratory. Cáit is a Senior Medical Scientist in charge of antenatal testing in the RCI laboratory and rare reference cell co-ordinator. Today she will present a recent case where anti-Jk3 was detected in a pregnant patient.
The Kidd-null phenotype Jk(a-b-) occurs in individuals who do not express the JK glycoprotein. The Kidd blood group system contains three antigens: Jka, Jkb and Jk3. Anti-Jk3 is a high incidence antigen present in more than 99.9% of populations. Jk(a-b) individuals can make an antibody against the Jk3 antigen. Jk(a-b-) is the rare null phenotype commonly found in Polynesians. Kidd antibodies may cause acute and delayed haemolytic reactions as well as haemolytic disease of the fetus and newborn (HDFN). We present a case of a pregnant 45 year old female where anti-Jk3 was identified. The process of antibody identification, antibody titration throughout her pregnancy will be discussed. In addition the complexity of trying to source blood for this patient; targeted screening of the Irish donor population and importation of blood from the European Union to cover delivery.
On initial workup the patient grouped as ORhD positive a historical red cell phenotype was available C+ E- c- e+ M+ S- s+ K- Fy(a+b-) Jk(a-b-). Pan reactivity was observed by the indirect antiglobulin test (IAT) and by enzyme-IAT technique. Using rare Jk (a-b-) cells from the RCI repertoire of rare reference cells negative reactions were obtained. To ensure there were no other clinically significant antibodies detectable adsorption techniques were performed. Throughout her pregnancy antibody titrations were performed. Titrations are performed using the Kidd phenotypes: Jk(a-b+), Jk(a+b-) and Jk(a+b+) to indicate the requirement for Fetal Medicine Specialist unit referral.
The provision of blood for these patients does require importation of units if suitable blood cannot be sourced in the country. Jk3- negative people are most likely to be found in Polynesians, South East Asians and Finns. Liquid donations and frozen units from the bank were sought to cover delivery. Siblings of patients with anti-Jk3 should be tested for compatibility and the patient also and patients are urged to donate blood for cryogenic storage.
15.00-16.00 – Presidents Prize. Chair: Academy President, Bernadette Jackson
James Harte, CIT/UCC
Biographical detail: James Harte is a graduate of the BSc (Honours) in Biomedical Science from CIT/UCC. James achieved a first-class honours ranking at third-level, consistently scoring highest in his class and was recognised as the ’Best Honours Degree Student’ in BSc (Honours) in Biomedical Science and ’Best Honours Degree Student’ in the School of Science and Informatics at Cork Institute of Technology. During his time as an undergraduate, this recognition was documented by several nominal honours including successive ‘College Scholar’ titles for achieving first-class honours, successive ‘Faculty Scholar’ titles for ranking first-in-class, and three, highly prestigious ‘Quercus College Scholarships’ for exceptional examination results. In 2017, James was awarded the highly competitive ‘Quercus University Scholarship’ for consistent academic excellence, a distinction bestowed on a single student each year. His curiosity for scientific endeavour has also driven an extraordinary engagement with academic research, including experience as a research assistant in the Centre for Research in Advanced Therapeutic Engineering at CIT; one-of-eight APC Microbiome Institute Summer Studentships, conducting an independent metagenomic project; a research survey into antimicrobial resistance in Ireland, which is currently in preparation for publication, and one-of-twenty distinguished Europe-wide Amgen Scholarships, which supported intensive research at the University of Cambridge. His final year project, under the supervision of Dr. Justin McCarthy at University College Cork, characterised the sequential proteolysis of a novel gamma-secretase substrate. Subsequently, he was retained as a research intern to continue aspects of the characterisation, and his experimental data will form part of a forthcoming publication. In addition to his avidity for science, James has a keen interest in teaching and learning. He has been a tutor at first-, second-, and third-level for many years, fastening his abiding love for science with community engagement. As a tutor, James takes pride and pleasure in distilling complex concepts into their most basic components, and has taught several undergraduates fundamental and advanced laboratory skills during his time as a research intern at University College Cork. James also engaged in a variety of recognised student activities, including standing as the academic representative for his year group, writing articles for the UCC Express in Irish and in English, partaking in societal offices, and speaking at student-focused events. His engagement with the profession of medical science has been pivotal in hammering and forging James’ personality. He holds three axiomatic principles close to his heart: the pursuit of personal development and identity; the pursuit of professional development and higher education; and the pursuit of life-long happiness. As he embarks on the next stage of his journey, he hopes to continue to challenge himself at every possible level, to advance his own knowledge and understanding of medical science, and hopefully, to contribute to the ever-expanding field of medical research in a way which is beneficial to the greater population as a whole.
ANGIOTENSIN-CONVERTING ENZYME 2 (ACE2) IS A NOVEL SUBSTRATE FOR γSECRETASE-DEPENDENT INTRAMEMBRANE PROTEOLYSIS. DISCIPLINE: Clinical chemistry
AUTHORS: Harte, J.V.1,2, McCarthy J.V.3 1 Department of Biological Sciences, Cork Institute of Technology, Rossa Avenue, Bishopstown, Cork, Ireland. 2 School of Biochemistry and Cell Biology, University College Cork, College Road, Cork, Ireland. 3 Signal Transduction Laboratory, School of Biochemistry and Cell Biology, ABCRF,
3.41 Western Gateway Building, Western Road, University College Cork, Cork, Ireland.
Introduction: The renin-angiotensin system (RAS) is a critical component of the response to hypovolaemia and hypotension; however, RAS dysfunction is an appreciable mechanism of disease1. The recently discovered angiotensin-converting enzyme 2 (ACE2) is known to counterregulate the potentially destructive effects of uncontrolled angiotensinergic activity2. Subversion of ACE2 by pathophysiological conditions, including infection by zoonotic coronaviruses, can contribute to inappropriate activation of the RAS and accentuate inflammatory and fibrotic disease. Although ACE2 is known to undergo ectodomain shedding, a feature shared by many substrates of γ-secretase-dependent regulated intramembrane proteolysis3, no studies have investigated the subsequent cleavage of the ACE2 carboxyl-terminal fragment (CTF). Materials and Methods:
The molecular mechanism of ACE2 cleavage following ectodomain shedding was investigated by Western blot analysis in cultured cells expressing exogenous or endogenous ACE2 using pharmacological inhibitors and genetic deficiency of presenilin. The subcellular localization of γ-secretase-dependent proteolysis was also investigated using inhibitors of clathrin-dependent endocytosis.
Results: In this study, we show that following ectodomain shedding, the membrane-bound ACE2 CTF is subsequently cleaved by γ-secretase, and that specific biochemical and genetic loss of γsecretase activity independently compromise sequential cleavage of ACE2. Pharmacological inhibition of proteasomal degradation also revealed a putative γ-secretase generated ACE2 intracellular domain (ICD). Moreover, we show that clathrin-mediated internalization of ACE2 is necessary for γ-secretase-dependent proteolysis.
Conclusions: These observations demonstrate that ACE2 is a novel γ-secretase substrate and the formation of a potentially biologically active intracellular domain may be partly responsible for the counter-regulation of the “classical” RAS. Internalization-dependent cleavage may also partly explain the uptake of zoonotic coronaviruses. Thus, the identification of ACE2 as a γ-secretase substrate may facilitate translational approaches for manipulating RAS activity in vivo, with potential biomedical significance in terms of health and disease.
REFERENCES: 1. Forrester S, Booz G, Sigmund C, Coffman T, Kawai T, Rizzo V, et al. Angiotensin II Signal Transduction: An Update on Mechanisms of Physiology and Pathophysiology. Physiological Reviews. 2018;98(3):1627-1738. 2. Paz Ocaranza, M, Riquelme, J, García, L, et al. Counter-regulatory renin–angiotensin system in cardiovascular disease. Nature Reviews Cardiology. 2020;17(2):116-129. 3. McCarthy, A, Coleman-Vaughan, C, and McCarthy, J. Regulated intramembrane proteolysis: emergent role in cell signalling pathways. Biochemical Society Transactions. 2017; 45(6); 1185– 1202.
Clodagh Lalor, GMIT
Biographical Detail: I successfully graduated with a BSc. in Medical Science from GMIT and completed my placement in University Hospital Limerick (UHL). Following this, I took a keen interest in Clinical Chemistry and worked in the Biochemistry Dept. as a student medical scientist and further completed a final year project in the laboratory. I majored in Clinical Chemistry and Medical Microbiology in 2019 after which I began working in the Biochemistry Laboratory, UHL and I am working there to this day.
Abstract: EVALUATION OF A FAECAL CALPROTECTIN ASSAY FOR INTRODUCTION INTO ROUTINE TESTING IN BIOCHEMISTRY LABORATORY, UHL
Discipline: Clinical Chemistry
Authors: (1) Lalor C, McGrath M, Conmy B. (1) Riversdale, North Circular Road, Limerick. Institution: Dept. of Biochemistry, University Hospital Limerick in collaboration with Dept. of Biopharmaceutical and Medical Science, Galway-Mayo Institute of Technology. Introduction: Faecal calprotectin (FC) is a routinely used, non-invasive biomarker for the diagnosis and monitoring of Inflammatory Bowel Disease (IBD) .
The primary aim of this study is to evaluate the Bühlmann fCAL faecal calprotectin turbo assay in order to bring FC testing into routine testing on site in University Hospital Limerick (UHL).
Material and Methods: The performance characteristics of fCAL turbo assay were verified on the Abbott Architect C16000 analyser. Precision was carried out by analysing two levels (low and high) of Internal Quality Control (IQC) in three replicates, daily for five days. Accuracy was measured by analysing nine EQA samples. Additionally, a comparison study was performed which involved the measurement of 20 patient samples on both the Abbott Architect C16000 and Phadia 250 instrument. Results: The precision study confirmed consistency with the manufacturer’s claims and revealed a total coefficient of variation (CV) of 1.53% and 3.8%, respectively. A high percentage inaccuracy of 21.83% and significant negative bias was observed for accuracy studies. A percentage bias of 88.9% and Passing-Bablok analysis revealed poor agreement between the two methods, further emphasised by a p value of 0.007 (α=0.05). The null hypothesis was thereby rejected.
Conclusion: The fCAL turbo assay performed in accordance with the manufacturer’s specifications of precision. However, accuracy and method comparison results were unsatisfactory for the verification of the assay. Further analysis is required before introduction of the assay into routine testing. Once the analytical performance is evaluated successfully, the assay will be implemented on site, drastically reducing turnaround times, decreasing referral costs and improving service to users.
References:  Seenan JP, Thomson F, Rankin K, Smith K, Gaya DR. Are we exposing patients with a mildly elevated FC to unnecessary investigations? Frontline Gastroenterology. 6th ed. 2015; 156-160.
Ciara Liptrot, GMIT
Biographical Detail: I studied Medical Science at the Galway Mayo Institute of Technology graduating in November 2019. In my final year of study I chose to specialise in Haematology, Blood Transfusion and Cellular Pathology. Throughout college blood transfusion and haematology were my favourite modules. I was fortunate to have had the opportunity to carry out my final year research project in the Red Cell Immunohaematology laboratory (RCI) at the Irish Blood Transfusion Services. Here I began my career as a medical scientist and got to see aspects of my research project validated and adopted into routine practice. Working in the RCI laboratory, I gained great Blood Transfusion knowledge and experience. I have recently begun working in the Coombe Women and Infants University Hospital Haematology and Transfusion laboratories where I hope to further develop my Haematology knowledge and Blood Transfusion expertise.
Abstract: Improving the Process of Mitigating Daratumumab Interference in Pre-transfusion Compatibility Testing Liptrot, C., Cregg, H., Scally, E. Galway-Mayo Institute of Technology, Old Dublin Rd, Galway
Irish Blood Transfusion Services, National Blood Centre, St. James’s Street, Dublin 8
Transfusion and Transplantation Science
Multiple myeloma (MM) is a malignant plasma cell disorder. Daratumumab (DARA), a monoclonal antibody directed against CD38, may be used for the treatment of MM as CD38 is over expressed on the malignant plasma cells¹. Treatment with DARA, however, interferes with pre-transfusion compatibility testing as DARA binds CD38 on reagent red cell. Several methods may be utilised in order to mitigate DARA interference including DTT treatment of reagent cells and masking CD38 present on reagent-cells. The aim of this research was to improve the current process of mitigating interference due to DARA in pre-transfusion compatibility testing. The utility of extending the shelf life of DTT-treated reagent red cells was assessed. Batch DTT-treated reagent red cells remained stable for up to 28 days post treatment. However, based on this study, due to haemolysis of cells and a decrease in reaction strength of some red cell antigens by day 28, the shelf-life of DTT-treated cells should be extended no longer than 14 days. The validity of a room temperature crossmatch for patients who have been administered DARA and have a negative antibody screen was also assessed. Using NaCl gel cards, 22 patient plasma samples containing DARA were crossmatched against group O Rh D negative donor cells with compatible reactions observed. The implementation of a room temperature crossmatch would eliminate the need to DTT-treat donor red cells for compatibility testing and thus reducing laboratory turnaround-times. The efficacy of DaraEx, an anti-CD38 neutralizing agent was evaluated. The ability of DaraEx to inhibit DARA interference was found to be dependent on the amount of DARA circulating in patient plasma and possibly the number of CD38 antigenic sites on reagent cells. An advantage of the use of DaraEx-treated reagent-cells, in comparison to the DTT based method of pre-transfusion compatibility testing for this patient group, is that DaraEx-treated cells may be used for the detection of anti-K.
1. Chapuy, C., Aguad, M., Nicholson, R., AuBuchon, J., Cohn, C., Delaney, M., Fung, M., Unger, M., Doshi, P., Murphy, M., Dumont, L. and Kaufman, R. (2016). International validation of a dithiothreitol (DTT)-based method to resolve the daratumumab interference with blood compatibility testing. Transfusion, 56(12), pp.2964-2972.
Áine O’Connor, TU Dublin
Biographical Detail: I achieved a first class degree honours in Biomedical Science (BSc) from TU Dublin- City Campus in 2019. I completed a translational research project in Karolinska Institutet Sweden for my undergraduate thesis, analysing the regenerative potential of human placental amnion epithelial cells. I am currently working in a fast paced clinical lab setting in Tallaght hospital.
Abstract: In Vitro Expansion of Human Placental Amnion Epithelial Cells. Aine K. O’ Connor. Transfusion and Transplantation Science Karolinska Institutet Flemingsberg Trevet Grange Dunshaughlin Co. Meath O’ Connor, AOC., Brankin, BB., Gramignoli, RG.
Liver failure represents a major public health concern worldwide. According to the World Health Organisation, the total deaths caused by cirrhosis and liver cancer have increased by 50 million/ year since 1990 (1). Until recently orthotopic liver transplantation (OLT) has remained the only established curative therapy for treating acute, chronic liver disease or metabolic defects in liver function. However, organ donor availability remains one of the main constraints on health services. Over the past 3 decades, cell-based therapies have been gaining importance since they can contribute to regeneration of failing organs or damaged tissues by either direct replacement of the lost cells or by facilitating the body’s natural regenerative processes. Hepatocyte transplants (HT) have been gaining recognition as an alternative therapeutic option, although it is limited by the need for strict immunosuppressive therapy in support of long-term engraftment. Furthermore, allograft rejection remains a primary issue that prevents the long-term sustained therapeutic benefits of HT (2)
The placenta, or specifically the amniotic epithelial (AE) cells are a promising non-controversial source of potential stem cells. Their constitutive ability to mature into different cell types and correct life threatening liver disease in preclinical models have highlighted them as a potential candidate for liver-based therapy. Ex vivo expansion of AE cells may be important to generate an adequate yield for transplantation, in addition to reducing the number of allogenic donor AE cells per recipient. We isolated AE cells from six gestational full term placentas which generated high amounts of cells (up to 240 million of AE cells per placenta) characterised by high viability (91.5 ± 3.4 %). Whilst preserving several of their native characteristic features, we successfully expanded AE cells in a xenobiotic-free culture medium (PneumaCult™) supplemented with human platelet lysate in comparison to the current gold standard medium formulation. Our results showed AE cells proliferated robustly in PneumaCult™. Gene expression analysis by qRT-PCR showed expanded AE cells maintained their native epithelial marker expression (CD326 and cytokeratin 18). Using albumin ELISA quantitation AE cells secreted albumin upon expansion, albeit at levels equal to half of what is observed in healthy hepatocytes. Focusing on the wider clinical application of AE cells, it could be envisaged from these results that AE cells may aid in expanding the donor hepatocyte pool, generating functionally improved hepatocytes without the need to increase hepatocyte donor source.
1. Murray, C. and Lopez, A. (2013). Measuring the Global Burden of Disease. New England Journal of Medicine, 369(5), pp.448-457.
2. Iansante, V., Mitry, R., Filippi, C., Fitzpatrick, E. and Dhawan, A. (2017). Human hepatocyte transplantation for liver disease: current status and future perspectives. Pediatric Research, 83(1-2), pp.232-240
Cliona O’Shea, CIT/UCC
Biographical Detail: My name is Clíona O’ Shea. In 2019 I graduated with a first class honours joint Biomedical Science degree from Cork Institute of Technology and University College Cork (CIT/UCC). I completed my 5th year clinical laboratory placement in the Mercy University Hospital (MUH) in Cork City. My laboratory research project, in the MUH microbiology laboratory, aims to establish whether the reporting of Uncertainty of Measurement estimates for antibiotic susceptibility testing using the disc diffusion method is a necessity in the clinical microbiology laboratory. I am an enthusiastic, diligent and reliable person who is self-motivated and who enjoys working with others. I love being part of the team in a clinical laboratory and wider hospital and I believe in and value our profession. To give a small example, I recently aimed to educate MUH laboratory staff at a multi-disciplinary journal club on continuous professional development (CPD) and reflective practice for medical scientists. I am excited to start my career as a medical scientist. I am privileged and honoured to be a part of the President’s Prize competition at Biomedica 2020. I will be presenting on my final year research project which is titled ‘Investigation of the ability of the bacteriocin nisin to inhibit coagulase negative Staphylococci’. I am currently working as a medical scientist in CHI at Crumlin.
Investigation of the ability of the bacteriocin nisin to inhibit coagulase negative Staphylococci O’ Shea, C.,Twomey, E., Field, D., Begley, M. Department of Biological Sciences, Cork Institute of Technology Introduction: Coagulase negative Staphylococci (CoNS) are ubiquitous colonizers of human skin (1). While previously seen as harmless commensals, CoNS are now viewed as opportunistic pathogens and are reported to be the leading cause of infections related to implanted medical devices (2). Of particular concern, is the increasing development of resistance to conventional antibiotics. Furthermore, CoNS can form biofilms that aid adherence to biotic or abiotic surfaces, and biofilms are inherently refractory to treatment with antibiotics (3). As the number of medical device implantation surgeries is projected to increase, owing to the ageing population and improving healthcare in developing countries, alternative approaches to control CoNS are therefore urgently required. The present study investigates the ability of the natural microbially-produced peptide bacteriocin nisin to inhibit CoNS.
Materials and Methods: A bank of commensal and clinical CoNS was assembled, and strains were characterized using a variety of standard microbiological and biochemical tests. The ability of the strains to form biofilm was examined using a standard plastic microtiter plate-based assay. Agar-based deferred antagonism assays were employed to assess whether CoNS were inhibited by a nisin producing bacterium. Nisin peptide was purified from the nisin producer by reversed-phase high performance liquid chromatography (RP-HPLC), and minimum inhibitory
concentration assays were carried out. The microtiter plate-based assay was employed again to assess how nisin affected biofilm formation on plastic surfaces. Subsequent experiments of this study focused on optimizing a method to examine biofilm formation by CoNS on a medical device substrate i.e. stainless steel.
Results: All of the CoNS strains in this study were shown to form biofilm, however the extent of biofilm formation varied between strains, as determined by final optical densities of crystal violet stained biofilms. It was observed using the agar-based deferred antagonism assays, that a nisin producing bacterium had the ability to inhibit the growth of all CoNS. The minimum inhibitory concentration of nisin against the tested CoNS strains was shown to be in the micromolar (μM) range. The addition of nisin during microtiter plate-based assays resulted in a significant reduction of biofilm formation. Furthermore, biofilm formation on stainless steel was also shown to be significantly reduced in the presence of nisin.
Conclusion: In summary, this study reports the ability of nisin to inhibit a bank of CoNS and their ability to form biofilms. Nisin may ultimately be used to develop novel coatings for medical devices, or be impregnated into them, with the aim of reducing the incidence of or preventing, medical device related infections caused by CoNS. References:
1. Otto, M. 2009. Staphylococcus epidermidis – the “accidental” pathogen. Nat. Rev. Microbiol. 7:555-67.
2. Campoccia D., Montanaro L., and Arciola C.R. The significance of infection related to orthopaedic devices and issues of antibiotic resistance. Biomaterials 27:2331-9.
3. McCann M., Gilmore B.F. and Gorman S.P. Staphylococcus epidermidis device-related infections: pathogenesis and clinical management. J. Pharm. Pharmacol. 60:1551-71.
Natalia Unrath, TU Dublin
Biographical Detail: I graduated from TU Dublin in 2019 with a BSc in Biomedical Science. I started my career in the microbiology department in Connolly Hospital. I am currently pursuing a PhD in the Centre for Food Safety, University College Dublin where I am specialising in the use of Whole Genome Sequencing to assess the virulence and persistence potential of Listeria monocytogenes under the principal supervision of Professor Séamus Fanning.
CHARACTERIZATION OF A LARGE GROUP OF LISTERIA MONOCYTOGENES USING WHOLE GENOME SEQUENCING: ASSESSING THEIR VIRULENCE POTENTIAL. Medical Microbiology.
UCD-Centre for Food Safety, School of Public Health, Physiotherapy and Sports Science, Science Centre South, University College Dublin, Belfield, Dublin D04 N2E5. Unrath, N., McCabe, E., Hurley, D., Herra, C., Fanning, S. Listeria monocytogenes is the etiological agent of listeriosis, a foodborne illness associated with high hospitalization and mortality rates.(1) L. monocytogenes may be classified as hypovirulent, intermediate and hypervirulent, based on the presence of Listeria pathogenicity islands (LIPIs).(2) This bacterium can exist in food associated environments for years with persistent strains being linked to outbreaks of foodborne disease.(3) This study aimed to improve food-borne subtyping and identification of virulent and persistent L. monocytogenes in food associated environments through the application of whole genome sequencing (WGS). WGS was applied to a collection of 143 L. monocytogenes from a longitudinal study of a large food production facility, collected between 2014 and 2017. Sequence data was analysed using bioinformatic tools. Virulence was assessed using the Virulence Factor Database (VFDB). Persistent strains were detected using multilocus sequence typing (MLST) in silico, single nucleotide polymorphism (SNP) analysis and the determination of biocide resistance using the BacMet database. The assessment of virulence profiles revealed that only one isolate was hypovirulent and two others were hypervirulent, with the majority (98%) being intermediate. In silico MLST and SNP analysis showed that 77% of the isolates are potential persisters and harbor resistance genes to biocides commonly used in food environments. These findings suggest that virulent L. monocytogenes are present and persisting within Irish food environments which can have adverse effects on both the food producer and public health. WGS can achieve more than just discrimination between unrelated isolates. An additional benefit of WGS is the opportunity to extract specific information, such as, the determination of virulence, antibiotic or biocide resistance status, as well as the assignment of serotypes. WGS is the ultimate tool for characterization of bacterial isolates as it provides the highest possible resolution in strain typing and represents a paradigm shift for outbreak investigation and contamination-source tracking.
• EFSA and ECDC. The European Union One Health 2018 Zoonoses Report. EFSA Journal. 2019;17(12): 5926.
• Maury MM, Tsai YH, Charlier C, Touchon M, Chenal-Francisque V, Leclercq A, Criscuolo A, Gaultier C, Roussel S, Brisabois A, Disson O, Rocha EPC, Brisse S, Lecuit M. Uncovering Listeria monocytogenes hypervirulence by harnessing its biodiversity. Nature Genetics. 2016;48(3): 308-313.
• Ferreira V, Wiedmann M, Teixeira P, Stasiewicz MJ. Listeria monocytogenes persistence in food-associated environments: epidemiology, strain characteristics, and implications for public health. Journal of Food Protection. 2014;77(1): 150-170.