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Pathogens and antimicrobial susceptibility profiles in critically ill patients with bloodstream infections: a
Rachel D Savage1, Robert A Fowler1, Asgar H Rishu1
1Dalla Lana School of Public Health (Savage), University of Toronto; Sunnybrook Health Sciences Centre (Savage, Fowler, Rishu, Daneman), Toronto, Ont.; Division of Critical Care Medicine (Fowler), Department of Medicine; Institute of Health Policy, Management and Evaluation (Fowler, Daneman), University of Toronto, Toronto, Ont.; Division of Critical Care Medicine (Bagshaw), Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alta.; Departments of Medicine and Clinical Epidemiology & Biostatistics (Cook), McMaster University, Hamilton, Ont.; Division of Critical Care Medicine (Dodek, Reynolds), Department of Medicine, University of British Columbia; Center for Health Evaluation and Outcome Sciences (Dodek), St. Paul's Hospital, Vancouver, BC; Department of Critical Care Medicine (Hall), Faculty of Medicine, Dalhousie University; Nova Scotia Health Authority (Hall), Halifax, NS; Section of Critical Care Medicine (Kumar), Department of Medicine; Departments of Medical Microbiology and of Pharmacology and Therapeutics (Kumar), University of Manitoba, Winnipeg, Man.; Centre de recherche du Centre hospitalier universitaire de Sherbrooke (Lamontagne), Sherbrooke, Que.; Service de médecine interne (Lamontagne), Département de médecine, Université de Sherbrooke, Sherbrooke, Que.; Axe Santé des populations et pratiques optimales en santé (Lauzier), Centre de recherche du Centre hospitalier universitaire de Québec-Université Laval, Québec, Que.; Départements de medicine et d'anesthésiologie et de soins intensifs (Lauzier), Université Laval, Québec, Que.; St. Michael's Hospital (Marshall), Toronto, Ont.; Department of Surgery (Marshall), University of Toronto, Toronto, Ont.; Department of Medicine (Martin), Western University; Critical Care Medicine (Martin), Schulich School of Medicine & Dentistry, London Health Sciences Centre, London, Ont.; Division of Critical Care (McIntyre), Department of Medicine, The Ottawa Hospital, Ottawa, Ont.; Department of Medicine (Muscedere), Queen's University, Kingston, Ont.; Department of Critical Care Medicine (Muscedere), Kingston General Hospital, Kingston, Ont.; Department of Critical Care Medicine (Stelfox), University of Calgary, Calgary, Alta.; Division of Infectious Diseases (Daneman), Department of Medicine, University of Toronto; Institute for Clinical Evaluative Sciences (Daneman), Toronto, Ont.
Background:
Surveillance of antimicrobial resistance is vital to guiding empirical treatment of infections. Collating and reporting routine data on clinical isolate testing may offer more timely information about resistance patterns than traditional surveillance network methods.
Methods:
Using routine microbiology testing data collected from the Bacteremia Antibiotic Length Actually Needed for Clinical Effectiveness retrospective cohort study, we conducted a descriptive secondary analysis among critically ill patients in whom bloodstream infections had been diagnosed in 14 intensive care units (ICUs) in Canada. The participating sites were located within tertiary care teaching hospitals and represented 6 provinces and 10 cities. More than 80% of the study population was accrued from 2011-2013. We assessed the epidemiologic features of the infections and corresponding antimicrobial susceptibility profiles. Susceptibility testing was done according to Clinical Laboratory Standards Institute guidelines at accredited laboratories.
Results:
A total of 1416 pathogens were isolated from 1202 patients. The most common organisms were Escherichia coli (217 isolates [15.3%]), Staphylococcus aureus (175 [12.4%]), coagulase-negative staphylococci (117 [8.3%]), Klebsiella pneumoniae (86 [6.1%]) and Streptococcus pneumoniae (85 [6.0%]). The contribution of individual pathogens varied by site. For 13 ICUs, gram-negative susceptibility rates were high for carbapenems (95.4%), tobramycin (91.2%) and piperacillin-tazobactam (90.0%); however, the proportion of specimens susceptible to these agents ranged from 75.0%-100%, 66.7%-100% and 75.0%-100%, respectively, across sites. Fewer gram-negative bacteria were susceptible to fluoroquinolones (84.5% [range 64.1%-97.2%]). A total of 145 patients (12.1%) had infections caused by highly resistant microorganisms, with significant intersite variation (range 2.6%-24.0%, χ2 = 57.50, p < 0.001).
Interpretation:
We assessed the epidemiologic features of bloodstream infections in a geographically diverse cohort of critically ill Canadian patients using routine pathogen and susceptibility data extracted from readily available microbiology testing databases. Expanding data sharing across more ICUs, with serial measurement and prompt reporting, could provide much-needed guidance for empiric treatment for patients as well as system-wide prevention methods to limit antimicrobial resistance.
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