Background: Antimicrobial resistance is a growing threat to the world’s ability to prevent and treat infections. Links between quantitative antibiotic use and the emergence of bacterial resistance are well documented. This study presents benchmark antimicrobial use (AMU) rates for inpatient adult populations in acute-care hospitals across Canada. Methods: In this retrospective surveillance study, acute-care adult hospitals participating in the Canadian Nosocomial Infection Surveillance Program (CNISP) submitted annual AMU data on all systemic antimicrobials from 2009 to 2016. Information specific to intensive care units (ICUs) and non-ICU wards were available for 2014–2016. Data were analyzed using defined daily doses (DDD) per 1000 patient days (DDD/1000pd). Results: Between 2009 and 2016, 16–18 CNISP adult hospitals participated each year and provided their AMU data (22 hospitals participated in ≥1 year of surveillance; 11 in all years). From 2009 to 2016, there was a significant reduction in use (12%) (from 654 to 573 DDD/1000pd, p = 0.03). Fluoroquinolones accounted for the majority of this decrease (47% reduction in combined oral and intravenous use, from 129 to 68 DDD/1000pd, p < 0.002). The top five antimicrobials used in 2016 were cefazolin (78 DDD/1000pd), piperacillin-tazobactam (53 DDD/1000pd), ceftriaxone (49 DDD/1000pd), vancomycin (combined oral and intravenous use was 44 DDD/1000pd; 7% of vancomycin use was oral), and ciprofloxacin (combined oral and intravenous use: 42 DDD/1000pd). Among the top 10 antimicrobials used in 2016, ciprofloxacin and metronidazole use decreased significantly between 2009 and 2016 by 46% (p = 0.002) and 26% (p = 0.002) respectively. Ceftriaxone (85% increase, p = 0.0008) and oral amoxicillin-clavulanate (140% increase, p < 0.0001) use increased significantly but contributed only a small component (8.6 and 5.0%, respectively) of overall use. Conclusions: This study represents the largest collection of dispensed antimicrobial use data among inpatients in Canada to date. Between 2009 and 2016, there was a significant 12% decrease in AMU, driven primarily by a 47% decrease in fluoroquinolone use. Modest absolute increases in parenteral ceftriaxone and oral amoxicillin-clavulanate use were noted but contributed a small amount of total AMU. Ongoing national surveillance is crucial for establishing benchmarks and antimicrobial stewardship guidelines.

Objectives: An antimicrobial stewardship intervention was implemented for pediatric medicine units using an in-person rounds-based approach to provide stewardship recommendations and education from an antimicrobial stewardship physician and antimicrobial stewardship pharmacist. Design, Setting, Participants, and Methods: In this exploratory qualitative study, purposeful sampling was used to recruit participants for individual interviews at a tertiary- and quaternary-care referral center. Pediatricians and residents who attended ≥1 stewardship round were included. A semistructured interview guide was created focusing on perceptions of antimicrobial stewardship, personal experiences at stewardship rounds, and perceived impacts on patient care. Using a constant comparative analysis approach, codes were developed and collapsed into themes. Results: Overall, 8 pediatricians and 10 residents completed interviews. Qualitative analysis yielded 3 themes: insights into clinical reasoning, opportunity for growth and learning, and establishing and exploring professional relationships. The handshake-rounds approach encouraged participants to critically evaluate antimicrobial choices and to engage in discussion with the antimicrobial stewardship team. Participants felt validated at stewardship rounds and gained confidence prescribing antimicrobials. Face-to-face interaction reduced reluctance for some participants to consult infectious disease (ID) service; however, others worried that physicians may avoid ID consultation because of stewardship rounds. Conclusions: Participants found stewardship rounds to be an effective strategy for education and development of clinical reasoning skills for optimal antimicrobial prescribing—choosing wisely or choosing rightly. The effects of stewardship rounds on timing and frequency of ID consultation are interesting. Further research into important patient outcomes and consultation practices are needed locally, but our experiences may help others to reflect on the power of conversation and relationships in antimicrobial stewardship.

Congenital syphilis is a re-emerging infectious threat in areas of North America. The purpose of this study was to quantitatively describe the rate of decline of nontreponemal (rapid plasma reagin, RPR) titers in pregnant persons with syphilis and their infants. In a retrospective review, we included 120 pregnant persons with 563 reactive RPR measurements (median 5, range 2 to 11 per person) and 35 infants with 81 RPR measurements (median 2, range 2 to 6 per infant). First-order decay, second-order decay, and a mathematical model representing functional FcRn-mediated antibody recycling were fitted to individual patient RPR trajectories. The RPR titers decreased with a median half-life of 39 days (IQR 28–59) and 27 days (IQR 17–41) in birthing parents and infants, respectively. The half-life varied with the initial RPR titer, suggesting that the kinetics of RPR decline was not first-order. A mathematical model accounting for saturable antibody recycling explained the longevity of RPR reactivity, predicted the observed non-linear kinetics, and fit the empiric data well. In summary, RPR titers decline with a half-life of roughly one month; however, the elimination does not follow first-order kinetics. Saturable antibody recycling may explain the prolonged and non-linear elimination of nontreponemal antibodies.

We identified minimal conserved epitopes on the M-protein (J8, P*17) and the anti-neutrophil chemoattractant virulence factor, SpyCEP (K4S2), of Streptococcus pyogenes (‘Strep A’) as targets of protective antibodies