Draft Genome Sequences of 25 Listeria monocytogenes Isolates Associated with Human Clinical Listeriosis in Ireland

Listeria monocytogenes is a Gram-positive opportunistic pathogen that is the causative agent of listeriosis. Here, we report the draft genome sequences of 25 L. monocytogenes strains isolated from patients with clinical listeriosis in the Republic of Ireland between 2013 and 2015. Listeria monocytogenes is a Gram-positive, intracellular foodborne pathogen that causes listeriosis. Contaminated foods, in particular, ready-to-eat foods, are the primary vehicle of transmission to humans. Infections can result in mild gastroenteritis in otherwise healthy individuals. However, more common presentations of the disease are invasive infections such as bloodstream infection, meningitis, and meningoencephalitis. These conditions are typically associated with pregnancy, the new-born, the elderly, and those that are otherwise immunocompromised (1, 2). Although disease incidence is uncommon, mortality is as high as 30% (1). Given the severity of the disease, epidemiological surveillance and control of L. monocytogenes is important to ensure early detection of linked cases allowing timely intervention to protect public health and ensure the safety of the food chain. Whole-genome sequencing of L. monocytogenes is emerging as the primary means of molecular typing of isolates and allows epidemiological surveillance of strains from food sources and from clinical disease, thus facilitating detection of previously undetected links. This underpins the investigation of mechanisms that may influence disease pathogenesis (1, 3). To aid in the molecular epidemiological surveillance of the pathogen, the draft genome sequences of 25 L. monocytogenes isolates have been determined. The isolates were obtained from clinical cases of disease in Ireland between 2013 and 2015 and were submitted to the National Salmonella, Shigella and Listeria (human health) Reference Laboratory service at Galway University Hospital. Whole-genomic DNA was extracted using the GenElute bacterial genomic DNA kit (Sigma Aldrich) per the manufacturer’s instructions. Library preparation and 250-bp paired-end sequencing was performed using the Illumina HiSeq 2500 platform (Microbes NG, University of Birmingham, UK). Raw reads were mapped to a reference genome using BWA-mem and de novo assembly was performed using SPAdes genome assembler. Contigs were reordered using Mauve aligner (v2.4.0). Prediction of putative open reading frames (ORFs) was performed using PRODIGAL prediction software (http://prodigal.ornl.gov/) and supported by BLASTx (4) alignments. Results of Prodigal/ BLASTx were combined manually and a preliminary identification of ORFs was performed on the basis of BLASTp (4) analysis against a nonredundant protein database Received 19 February 2017 Accepted 16 March 2017 Published 11 May 2017 Citation O’Callaghan A, Hilliard A, Morgan CA, Culligan EP, Leong D, DeLappe N, Hill C, Jordan K, Cormican M, Gahan CGM. 2017. Draft genome sequences of 25 Listeria monocytogenes isolates associated with human clinical listeriosis in Ireland. Genome Announc 5:e00184-17. https://doi.org/10.1128/genomeA . 00184-17. Copyright © 2017 O’Callaghan et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license. Address correspondence to Cormac G. M. Gahan, c.gahan@ucc.ie. * Present address: Eamonn P. Culligan, Department of Biological Sciences, Cork Institute of Technology, Bishopstown, Cork, Ireland. A.O. and A.H. contributed equally to this work. PROKARYOTES