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About Sickkids
About SickKids

Valerie Waters, MD, MSc

The Hospital for Sick Children
Staff Physician
Infectious Diseases

Research Institute
Associate Scientist
Translational Medicine

University of Toronto
Assistant Professor
Department of Paediatrics

Phone: 416-813-7654 ext. 4541
Fax: 416-813-8404
Email: valerie.waters@sickkids.ca

Research Interests

Respiratory tract infections are the most common and potentially most severe of infections treated by health care practitioners. Both nosocomial and community-acquired pneumonias are increasingly caused by newer bacterial pathogens, especially multidrug resistant strains. My research goal is to develop a program that studies the host and pathogen factors involved in the diagnosis, treatment and prevention of emerging respiratory infections in high-risk populations, notably cystic fibrosis (CF) patients.

Stenotrophomonas maltophilia is an emerging, multi-drug resistant pathogen that has been isolated with increasing frequency from the sputum of CF patients. In order to determine its role in CF lung disease, we are developing an enzyme linked immunosorbent assay (ELISA) to detect antibodies to S. maltophilia in patients with chronic S. maltophilia infection. This ELISA will be used to follow these patients longitudinally to determine if it can be used to predict worsening clinical status.

Respiratory bacterial infections in CF patients are particularly difficult to treat as organisms such as Pseudomonas aeruginosa are known to grow as a biofilm, or slime layer, in the CF lung. Antibiotics to treat respiratory bacterial infections in CF patients are currently selected from conventional antimicrobial susceptibility results based on planktonic or "free-floating" growth of bacteria. New technology has been developed to determine antimicrobial susceptibility results based on biofilm growth of bacteria. In collaboration with the company which developed the technology., we will be conducting a randomized controlled trial to determine if antibiotics chosen based on a biofilm antimicrobial susceptibility assay are more effective than those chosen based on a conventional antimicrobial susceptibility assay. Results from this study have the potential to alter the management of pulmonary exacerbations in CF patients worldwide.

Finally, methicillin-resistant Staphylococcus aureus (MRSA) infections have been noted increasingly in the community as well as hospitalized patients, especially CF patients. We are currently studying the risk factors and the clinical impact of MRSA in both the adult and paediatric CF population. In addition, we are investigating novel mechanisms of resistance in CF strains of MRSA that may have significant clinical impact both in terms of treatment and outcomes. In collaboration with the Department of Pathology at the University of Toronto and the Department of Biochemistry at Queens University, we are also developing new antimicrobial compounds for the treatment of MRSA infections. This translational approach will hopefully lead to further understanding of this pathogen both in the CF and the general population.

External Funding

Innovotech Inc. and National Research Council - Industrial Research Assistance Program (NRC-IRAP)
Time period: 2008-2011
Title of project: Randomized double blind controlled trial of the use of a biofilm antimicrobial susceptibility assay to guide antibiotic therapy in chronic Pseudomonas aeruginosa infected cystic fibrosis patients (The Hospital for Sick Children and St Michael’s Hospital)
Investigator status: Principal investigator

Bickell Foundation
Time period: 2007-2008
Title of project: Defining the role of Stenotrophomonas maltophilia in CF patients
Investigator status: Principal investigator


Corral DM, Coates AL, Yau YC, Tellier R, Glass M, Jones SM, Waters VJ: Burkholderia pseudomallei infection in a cystic fibrosis patient from the Caribbean: a case report. Can Respir J 2008; 15(5):237-9.

Waters V, Ratjen F. Combination antimicrobial susceptibility testing for acute exacerbations in chronic infection of Pseudomonas aeruginosa in cystic fibrosis. Cochrane Database Syst Rev. 2008 Jul 16;(3):CD00696.

Lam W, Tjon J, Seto W, Dekker A, Wong C, Atenafu E, Bitnun A, Waters V, Yau Y, Solomon M, Ratjen F. Pharmacokinetic modelling of a once-daily dosing regimen for intravenous tobramycin in paediatric cystic fibrosis patients. J Antimicrob Chemother. 2007 Jun;59(6):1135-40.

Waters V, Peterson KS, Larussa P. Live viral vaccines in a DiGeorge syndrome patient. Arch Dis Child 2007 Jun;92(6):519-20.

Waters VJ, Gomez MI, Soong G, Amin S, Ernst R, Prince A. Immunostimulatory properties of the emerging pathogen Stenotrophomonas maltophilia. Infect Immun. 2007 Apr; 75(4): 1698-703.

Waters V, Ratjen F. Multidrug-resistant organisms in cystic fibrosis: management and infection-control issues. Expert Rev Anti Infect Ther. 2006 Oct; 4(5): 807-19.

Barton M, Hawkes M, Moore D, Conly J, Nicolle L, Allen U, Boyd N, Embree J, Van Horne L, LeSaux N, Richardson S, Moore A, Tran D, Waters V, Vearncombe M, Katz K, Weese JS, Embil J, Ofner-Agostini M, Ford-Jones EL. Guidelines for the prevention and management of community-associated methicillin-resistant Staphylococcus aureus: a perspective for Canadian health care practitioners. Can J Infect Dis Med Microbiol 2006 Oct; 17S: 4-24.

Waters V, Sokol S, Reddy B, Soong G, Chun J, Prince A. The effect of cyclosporin A on airway cell proinflammatory signaling and pneumonia. Am J Respir Cell Mol Biol 2005; 33: 138-44.

Waters V, Larson E, Wu F, San Gabriel P, Haas J, Cimiotti J, Della-Latta P, Saiman L: Molecular epidemiology of gram-negative bacilli from infected neonates and healthcare workers' hands in neonatal intensive care units. Clin Infect Dis 2004; 38:1682-7.