Marek Smieja, MD PhD FRCPC

Biography

Marek Smieja, MD PhD FRCPC

Marek Smieja is an Infectious Diseases physician, Medical Microbiologist, and Clinical Epidemiologist at McMaster University and St. Joseph's Hospital, Hamilton. He obtained his MD from the University of Western Ontario in London, Ontario, Canada, his internship from Dalhousie University in Halifax, Nova Scotia Canada, and his fellowship training in Internal Medicine, Infectious Diseases, and Medical Microbiology from McMaster University, Hamilton, Ontario, Canada. He is currently Associate Professor in the Department of Pathology and Molecular Medicine at McMaster, with associate appointments in the Department of Medicine and in the Department of Clinical Epidemiology and Biostatistics. He is an Infectious Diseases and HIV physician at St. Joseph's Hospital and the Hamilton Health Sciences. He teaching observational epidemiology and supervises graduate and post-graduate students in Infectious Diseases, Microbiology and Health Research Methodology. His primary research interests are in the role of infections in respiratory and cardiac diseases. He is a Canadian Institutes of Health Research New Investigator and leads the Canadian HIV Vascular Study, a multi-centre cohort study assessing the relationships between HIV medications, metabolic abnormalities, and vascular disease among HIV-positive subjects. He is a member of the Canadian Pandemic Influenza Laboratory Preparedness Network, co-chair of the Ontario Rapid Testing of Emerging Infectious Diseases (RT-EID) laboratory network, and is involved in the design and improvement of pre-analytic, analytic, and post-analytic aspects of respiratory virus testing.

Enhancing Culture, DFA and PCR Diagnosis of Respiratory Viruses in Adults and Children

Background

The timely diagnosis of viral respiratory infections improves appropriate treatment and infection control interventions, minimizes unnecessary diagnostic testing and treatment, and improves community surveillance. However, the proportion of specimens testing positive for respiratory viruses remains low, and improvements are needed in pre-analytical (swab type, collection, and transport) as well as analytical aspects of diagnosis.

Methods

In five studies, we sequentially assessed and attempted to improve on pre-analytic aspects of respiratory virus diagnosis. Study 1 examined flocked versus rayon nasal swabs (NS) and nasopharyngeal swabs (NPS) in 16 volunteers for respiratory epithelial cell yield. Study 2 examined the effect of flocked versus rayon NPS on antigen detection (by DFA) and respiratory cell yield in 61 symptomatic patients. Study 3 examined the effect of introducing flocked swabs and universal transport media (UTM) into routine diagnostic practice on the positivity rate for viral detection over 3 respiratory virus seasons. Study 4 compared viral detection by NS or NPS in 72 hospitalized adults, using DFA, culture or PCR. Study 5 examined two novel NS designs or NPS for respiratory epithelial cell yield in 52 volunteers, and the feasibility of self-collection.

Results

In Study 1, respiratory epithelial cell yield in volunteers was higher with flocked than rayon swabs, and with NPS versus NS. In Study 2, respiratory epithelial cell yield and the number of virus-infected cells was higher in patients infected with influenza or respiratory syncytial virus (RSV), who were swabbed with flocked versus rayon NPS. In Study 3, the detection of a viral etiology increased from 30 to 40%, on average, following the introduction of flocked swabs and universal transport medium (UTM) into regular laboratory diagnostics. In Study 4, viral detection by DFA, culture, or PCR was superior in NPS than NS. In Study 5, an improved NS design yielded similar respiratory cell yield to NPS. Self-collection of NS yielded fewer respiratory epithelial cells than staff-collection. Self-administration was easy (97%) and the majority (75%) preferred selfcollection or were neutral.

Conclusions

Our studies in volunteers and in patients demonstrate that a flocked swab is superior to rayon, NPS is superior to NS, and UTM improves antigen detection, culture, and molecular detection of respiratory viruses. For inpatient diagnosis, NPS with a flocked swab and UTM optimizes current viral diagnosis. For outpatients or for community surveillance, in where widespread use of NPS remains impractical, a new flocked NS design sampled as well as NPS with less discomfort, but clinical validation is needed.