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Variability in Antimicrobial Use Among Hospitals Participating in the Canadian Nosocomial Infection Surveillance Program
- Wallis Rudnick, Linda Pelude, Michelle Science, Daniel J.G. Thirion, Jeannette Comeau, Bruce Dalton, Johan Delport, Rita Dhami, Joanne Embree, Yannick Émond, Gerald Evans, Charles Frenette, Susan Fryters, Greg German, Jennifer Grant, Jennifer Happe, Kevin Katz, Pamela Kibsey, Justin Kosar, Joanne Langley, Bonita E. Lee, Marie-Astrid Lefebvre, Jerome Leis, Susan McKenna, Allison McGeer, Heather Neville, Anada Silva, Andrew Simor, Kathryn Slayter, Kathryn Suh, Alena Tse-Chang, Karl Weiss, John Conly, CNISP PHAC
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- Journal:
- Infection Control & Hospital Epidemiology / Volume 41 / Issue S1 / October 2020
- Published online by Cambridge University Press:
- 02 November 2020, p. s509
- Print publication:
- October 2020
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Background: The association between antimicrobial use (AMU) and emergence of antimicrobial resistance is well documented. The Canadian Nosocomial Infection Surveillance Program (CNISP) has conducted sentinel surveillance of AMU at participating Canadian hospitals since 2009 resulting in the largest pan-Canadian hospital database of dispensed antimicrobials. Objectives: Describe interhospital variability of AMU across Canada. Methods: Hospitals submit annual AMU data based on patient days (PD). Antimicrobials were measured in defined daily doses (DDD) for adults using the WHO Anatomical Therapeutic Chemical (ATC) system. The AMU data among pediatric patients have been available since 2017 using days of therapy (DOT). Surveillance includes systemic antibacterial agents (J01 ATC codes), oral metronidazole, and oral vancomycin. AMU was assessed using quintiles, interquartile ranges (IQR), and relative IQRs (upper- and lower-quartile values divided by the median). Results: Between 2009 and 2018, 20–26 hospitals participated in adult surveillance each year (35 teaching hospitals and 3 nonteaching hospitals participated in ≥1 year). Over this period, overall AMU decreased by 13% at participating adult hospitals from 645 to 560 DDD per 1,000 PD. AMU varied substantially between hospitals, but this variability decreased over time (Fig. 1). In 2009, the IQRs for overall AMU spanned 309 DDD per 1,000 PD, and in 2018 it spanned only 103 DDD per 1,000 PD. This decrease in variability was due to large decreases in use among hospitals with high use in 2009–2010. Among hospitals in the highest use quintile in 2009–2010, AMU decreased, on average, 44 DDD per 1,000 PD each year. Among hospitals in the lowest use quintile in 2009–2010, AMU increased, on average, 6 DDD per 1,000 PD each year. In 2018, antibiotics with the largest absolute IQR variability were cefazolin (61–113 DDD per 1,000 PD), piperacillin-tazobactam (32–64 DDD per 1,000 PD), and vancomycin (24–49 DDD per 1,000 PD). Among antibiotics with ≥1 DDD per 1,000 PD, antibiotics with the largest relative IQR variability were tobramycin (0.3–6 DDD per 1,000 PD), cefadroxil (0.08–9 DDD per 1,000 PD), and linezolid (0.2–3 DDD per 1,000 PD). In 2018, the IQR for overall pediatric AMU (n = 7 teaching hospitals) was 426–581 DOT per 1,000 PD. Antibiotics with the largest IQRs were vancomycin (0.6–58 DOT per 1,000 PD), cefazolin (33–88 DOT per 1,000 PD), and tobramycin (3–57 DOT per 1,000 PD). Among antibiotics with ≥1 DOT per 1,000 PD in 2018, antibiotics with the largest relative IQRs were tobramycin (3–57 DOT per 1,000 PD), cefuroxime (1–6 DOT per 1,000 PD), and amoxicillin (8–42 DOT per 1,000 PD). Conclusions: There is wide variation in overall antibiotic use across hospitals. Variation between AMU at adult hospitals has decreased between 2009 and 2018; in 2018, antibiotics with the largest IQRs were cefazolin and piperacillin-tazobactam. Benchmarking AMU is crucial for informing antimicrobial stewardship efforts.
Funding: CNISP is funded by the Public Health Agency of Canada.
Disclosures: Allison McGeer reports funds to her institution from Pfizer and Merck for projects for which she is the principal investigator. She also reports consulting fees from Sanofi-Pasteur, Sunovion, GSK, Pfizer, and Cidara.
Motion of a capsule in a cylindrical tube: effect of membrane pre-stress
- YANNICK LEFEBVRE, DOMINIQUE BARTHÈS-BIESEL
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- Journal:
- Journal of Fluid Mechanics / Volume 589 / 25 October 2007
- Published online by Cambridge University Press:
- 08 October 2007, pp. 157-181
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We present a numerical model of the axisymmetric flow of an initially spherical capsule in a co-axial cylindrical tube. The capsule consists of a liquid droplet enclosed by a thin hyper-elastic membrane that is assumed to obey different membrane constitutive equations such as Mooney–Rivlin, Skalak et al. (1973) or Evans & Skalak (1980) laws. It is further assumed that the capsule may be subjected to some isotropic pre-stress due to initial swelling. We compute the steady flow of the capsule inside the tube as a function of the size ratio between the capsule and tube radii, the amount of pre-swelling and the membrane constitutive law. We thus determine the deformed profile geometry and specifically the onset of the curvature inversion at the back of the particle. We show that for a given size ratio, the critical flow rate at which the back curvature changes is strongly dependent on pre-inflation. The elastic tension level in the membrane as well as the additional pressure drop created by the presence of the particle are also computed. The numerical results are then compared to experimental observations of capsules with alginate membranes as they flow in small tubes (Risso. et al. 2006). It is found that the experimental capsules were probably pre-inflated by about 3% and that their membrane is best modelled by the Skalak et al. law.