catherine ludden

Catherine Ludden was born in Galway and grew up in a small village called Sylane in North West Galway. I developed an interest in Science at an early age and persued this interest by studying Biology at a higher level at the secondary school Presentation College Currylea Tuam. 
In 2009, I received a BSc in Medical science specialising in medical microbiology and clinical chemistry from Galway Mayo Institute of Technology. While completing my Medical Science Degree I completed laboratory placements in each of the 6 main hospital laboratory disciplines (Microbiology including virology, Biochemistry, Histology, Blood Transfusion, Immunology, Haematology) which allowed me to gain an in-depth knowledge of hospital laboratory systems. 
In my 3rd year of my Medical Science Degree I submitted a method report on: “The comparative study of Chromogenic Candida Agar, Auxacolor 2 and VITEK 2 for the identification of Candida  species from nail clippings.” 
My interest in antimicrobial resistance particulary arose when completing my final year project: "The investigation of the fluoroquinolone-modifying acetyltransferase gene aac(6’)-Ib-cr in environmental and clinical Escherichia coli isolates". This work was accepted as an oral presentation at the 3^rd symposium of antimicrobial resistance in animals and the environment. (1^st – 3^rd June, Tours, France. ARAE, 2009).  

From 2009 to 2010, I worked as a Microbiologist in Complete Laboratory Soultions, Ros Muc, Galway.

I started a PhD Bacteriology with the Antimicrobial Resistance and Microbial Ecology Group in 2010 specialising in antimicrobial resistance in the hospital and the community setting. I aim to graduate from my PhD by 2014.

PhD project

My PhD project is titled: 

The dissemination of antimicrobial resistance in the hospital and community setting.

My research is focused specifically on analysing the genetic basis for antimicrobial resistance in E. coli isolated from clinical specimens from hospitals, nursing homes and the community in Ireland. Further to this, I am also investigating a variety of antimicrobial resistance mechanisms in Staphylococcus aureus, Klebsiella species and Enterococcus species.

The objectives of my current research are: 
My current research project is based on assessing the role of nursing homes in the dissemination of antimicrobial resistance bacteria, particularly extended spectrum beta lactamase-producing Enterobacteriaceae (ESBL-PE). 
Firstly, my research involves performing an epidemiological investigation into the spread of ESBL E. coli O25b:ST131 clonal group in nursing homes, hospitals and the community using PCR, PFGE and whole genomic sequencing to identify changes in the ESBL E. coli O25b:ST131 clonal group over a period of time. This allows for an in-depth study into antimicrobial-resistance patterns, mechanisms of antimicrobial-resistance and an investigation into the relatedness of strains of E.coli O25b:ST131. This will aim to determine the evolution of the E. coli O25b-ST131 clonal group in Ireland, thus is this ’pandemic’ clonal group disseminating from nursing homes to the hospitals or vice versa or whether this clonal group is circulating within the community and being introduced into the health care setting. 
Secondly, I am carrying out a longitudinal study to assess the role of nursing homes in the dissemination of meticillin-resistant Staphylococcus aureus, extended spectrum beta lactamase-producing Enterobacteriaceae, Vancomycin Resistant Enterococci and Carbapenemase Producing Enterobacteriaceae. This study involves the collection of specimens from nursing home residents over a 1 year period and determining the time to environmental contamination in their nursing home environment.

Experimental strategies performed to date to complete the aims of my project include:

• Phenotypic testing including antimicrobial susceptibility testing to acquire an antibiogram of all resistant antimicrobials. Subsequently, this information can be used to assess a link between the resistance patterns to determine a resistance mechanism.
• Molecular methods are essential to determine resistance genes, corresponding variant of these genes, plasmids which harbour the genes and the epidemiology of the resistance patterns. Molecular analysis performed to date include: Polymerase Chain Reaction (PCR), Pulsed Field Gel Electrophoresis (PFGE) and Whole Genomic Sequencing (WGS).

Presentations/Publications

Publications

• Ludden C, Morris D, Boyle F, Hanahoe B, Kanagaratnam B, Cormican M. 2013. ESBL E. coli associated with Nursing Homes show limited diversity compared with isolates from hospitals. Submitted to Antimicrob Agents Chemother for review.

• Ludden C, Cormican M, Austin B, Morris D. 2013. Rapid environmental contamination of a new nursing home with antimicrobial-resistant organisms preceding occupation by residents. J. Hosp. Infect. 83:327-329.

• Morris, D., F. Boyle, C. Ludden, I. Condon, J. Hale, N. O'Connell, L. Power, T. W. Boo, H. Dhanji, C. Lavallee, N. Woodford, and M. Cormican. 2011. Production of KPC-2 carbapenemase by an Escherichia coli clinical isolate belonging to the international ST131 clone. Antimicrob Agents Chemother. 55:4935-6.

• Morris D, McGarry E, Cotter M, Passet V, Lynch M, Ludden C, Hannan MM, Brisse S, Cormican M. 2012. Detection of OXA-48 Carbapenemase in the Pandemic Clone Escherichia coli O25b:H4-ST131 in the Course of Investigation of an Outbreak of OXA-48-Producing Klebsiella pneumoniae. Antimicrob. Agents Chemother. 56:4030-4031.

Presentations