Integration of hospital with congregate care homes in response to the COVID-19 pandemic.

Background: The coronavirus disease 2019 (COVID-19) pandemic has highlighted the need to improve the safety of the environments where we care for older adults in Canada. After providing assistance during the first wave, many Ontario hospitals formally partnered with local congregate care homes in a "hub and spoke" model during second pandemic wave onward. The objective of this article is to describe the implementation and longitudinal outcomes of residents in one hub and spoke model composed of a hospital partnered with 18 congregate care homes including four long-term care and 14 retirement or other congregate care homes. Intervention: Homes were provided continuous seven-day per week access to hospital support, including infection prevention and control (IPAC), testing, vaccine delivery and clinical support as needed. Any COVID-19 exposure or transmission triggered a same-day meeting to implement initial control measures. A minimum of weekly on-site visits occurred for long-term care homes and biweekly for other congregate care homes, with up to daily on-site presence during outbreaks. Outcomes: Case detection among residents increased following implementation in context of increased testing, then decreased post-immunization until the Omicron wave when it peaked. After adjusting for the correlation within homes, COVID-related mortality decreased following implementation (OR=0.51, 95% CI, 0.30-0.88; p=0.01). In secondary analysis, homes without pre-existing IPAC programs had higher baseline COVID-related mortality rate (OR=19.19, 95% CI, 4.66-79.02; p<0.001) and saw a larger overall decrease during implementation (3.76% to 0.37%-0.98%) as compared to homes with pre-existing IPAC programs (0.21% to 0.57%-0.90%). Conclusion: The outcomes for older adults residing in congregate care homes improved steadily throughout the COVID-19 pandemic. While this finding is multifactorial, integration with a local hospital partner supported key interventions known to protect residents.

Evaluating the impact of a virtual outpatient care programme in preventing hospitalizations, emergency department visits and mortality for patients with COVID-19: a matched cohort study.

OBJECTIVES: To evaluate the impact of virtual care in preventing unnecessary healthcare visits for patients with SARS-CoV-2. METHODS: We conducted a retrospective matched cohort study, evaluating the COVID-19 Expansion to Outpatients (COVIDEO) programme involving virtual assessments for all positive patients in the Sunnybrook assessment centre from January 2020 to June 2021, followed by risk-stratified routine follow-up, couriering of oxygen saturation devices, and 24 hour/day direct-to-physician pager for urgent questions. We linked COVIDEO data to province-wide datasets, matching each eligible COVIDEO patient to ≤10 other Ontario SARS-CoV-2 patients on age, sex, neighbourhood, and date. The primary outcome was emergency department (ED) visit, hospitalization or death within 30 days. Multivariable regression accounted for comorbidities, vaccination, and pre-pandemic healthcare utilization. RESULTS: Among 6508 eligible COVIDEO patients, 4763 (73.1%) were matched to ≥1 non-COVIDEO patient. COVIDEO care was protective against the primary composite outcome (adjusted odds ratio [aOR] 0.91, 95% CI, 0.82-1.02), with a reduction in ED visits (7.8% vs. 9.6%; aOR 0.79, 95% CI, 0.70-0.89), but increase in hospitalizations (3.8% vs. 2.7%, aOR 1.37, 95% CI, 1.14-1.63) reflecting more direct-to-ward admissions (1.3% vs. 0.2%, p < 0.0001). Results were similar when matched comparators were limited to patients who had not received virtual care elsewhere with a decrease in ED visits (7.8 vs. 8.6%, aOR 0.86, 95% CI, 0.75-0.99) and an increase in hospitalizations (3.7 vs. 2.4%, aOR 1.45, 95% CI, 1.17-1.80). DISCUSSION: An intensive remote care programme can prevent unnecessary ED visits and facilitate direct-to-ward hospitalizations and thereby mitigate the impact of COVID-19 on the healthcare system.

Infective endocarditis of a native aortic valve due to Pseudomonas aeruginosa complicated by progressive multi-drug resistance.

BACKGROUND: Treatment of infective endocarditis secondary to Pseudomonas aeruginosa can be challenging because of this organism's ability to acquire antimicrobial resistance over time. METHODS: We describe a patient with native aortic valve infective endocarditis due to P. aeruginosa who developed progressive multi-drug resistance while on therapy. The resistance mechanisms were characterized using whole-genome sequencing. RESULTS: We identified two mutations in subsequent isolates (dacB and OprD) that conferred resistance to anti-pseudomonal penicillins, cephalosporins, and carbapenems. The patient was treated with combination high-dose continuous infusion meropenem and ciprofloxacin therapy, in addition to bioprosthetic aortic valve replacement and repair of ventricular septal wall defect. Antibiotics were continued for 6 weeks post-cardiac surgery and the patient remains infection free 18 months post-completion of antibiotic therapy. CONCLUSION: Clinicians should be aware of the ability of P. aeruginosa to acquire resistance mechanisms in response to selective antibiotic pressures in high-inoculum infections such as infective endocarditis. The mutations identified in this case report correlated well with the evolving antimicrobial resistance profile observed.

HISTORIQUE: Il peut être difficile de traiter une endocardite infectieuse causée par un Pseudomonas aeruginosa en raison de la capacité de cet organisme à acquérir une résistance aux antimicrobiens. MÉTHODOLOGIE: Les chercheurs décrivent un patient atteint d'une endocardite infectieuse de la valve aortique d'origine, attribuable à un P. aeruginosa, qui a acquis une multirésistance progressive pendant son traitement. Le mécanisme de résistance était caractérisé par le séquençage du génome entier. RÉSULTATS: Les auteurs ont dépisté deux mutations dans les isolats subséquents (dacB et OprD ), responsables d'une résistance aux pénicillines, aux céphalosporines et aux carbapénèmes antipseudomonaux. Le patient a reçu une polythérapie de perfusion continue de méropénem à forte dose et de ciprofloxacine, en plus du remplacement d'une valve aortique bioprothétique et de la réparation d'une communication interventriculaire. L'antibiothérapie s'est poursuivie six semaines après l'opération, et le patient n'avait pas d'infection 18 mois après la fin de l'antibiothérapie. CONCLUSION: Les cliniciens devraient savoir que le P. aeruginosa peut acquérir des mécanismes de résistance en réponse aux pressions antibiotiques sélectives en cas d'infections comportant un titre élevé d'inoculum comme une endocardite infectieuse. Les mutations constatées dans le présent rapport de cas étaient bien corrélées avec l'évolution du profil de résistance antimicrobienne observé.

Diagnostic accuracy of subjective dyspnoea in detecting hypoxaemia among outpatients with COVID-19: a retrospective cohort study.

OBJECTIVES: The majority of patients with mild-to-moderate COVID-19 can be managed using virtual care. Dyspnoea is challenging to assess remotely, and the accuracy of subjective dyspnoea measures in capturing hypoxaemia have not been formally evaluated for COVID-19. We explored the accuracy of subjective dyspnoea in diagnosing hypoxaemia in COVID-19 patients. METHODS: This is a retrospective cohort study of consecutive outpatients with COVID-19 who met criteria for home oxygen saturation monitoring at a university-affiliated acute care hospital in Toronto, Canada from 3 April 2020 to 13 September 2020. Dyspnoea measures were treated as diagnostic tests, and we determined their sensitivity (SN), specificity (SP), negative/positive predictive value (NPV/PPV) and positive/negative likelihood ratios (+LR/-LR) for detecting hypoxaemia. In the primary analysis, hypoxaemia was defined by oxygen saturation <95%; the diagnostic accuracy of subjective dyspnoea was also assessed across a range of oxygen saturation cutoffs from 92% to 97%. RESULTS: During the study period, 89/501 (17.8%) of patients met criteria for home oxygen saturation monitoring, and of these 17/89 (19.1%) were diagnosed with hypoxaemia. The presence/absence of dyspnoea had limited accuracy for diagnosing hypoxaemia, with SN 47% (95% CI 24% to 72%), SP 80% (95% CI 68% to 88%), NPV 86% (95% CI 75% to 93%), PPV 36% (95% CI 18% to 59%), +LR 2.4 (95% CI 1.2 to 4.7) and -LR 0.7 (95% CI 0.4 to 1.1). The SN of dyspnoea was 50% (95% CI 19% to 81%) when a cut-off of <92% was used to define hypoxaemia. A modified Medical Research Council dyspnoea score >1 (SP 98%, 95% CI 88% to 100%), Roth maximal count <12 (SP 100%, 95% CI 75% to 100%) and Roth counting time <8 s (SP 93%, 95% CI 66% to 100%) had high SP that could be used to rule in hypoxaemia, but displayed low SN (≤50%). CONCLUSIONS: Subjective dyspnoea measures have inadequate accuracy for ruling out hypoxaemia in high-risk patients with COVID-19. Safe home management of patients with COVID-19 should incorporate home oxygenation saturation monitoring.

Household Transmission of Carbapenemase-producing Enterobacterales in Ontario, Canada.

BACKGROUND: Data on household transmission of carbapenemase-producing Enterobacterales (CPE) remain limited. We studied risk of CPE household co-colonization and transmission in Ontario, Canada. METHODS: We enrolled CPE index cases (identified via population-based surveillance from January 2015 to October 2018) and their household contacts. At months 0, 3, 6, 9, and 12, participants provided rectal and groin swabs. Swabs were cultured for CPE until September 2017, when direct polymerase chain reaction (PCR; with culture of specimens if a carbapenemase gene was detected) replaced culture. CPE risk factor data were collected by interview and combined with isolate whole-genome sequencing to determine likelihood of household transmission. Risk factors for household contact colonization were explored using a multivariable logistic regression model with generalized estimating equations. RESULTS: Ninety-five households with 177 household contacts participated. Sixteen (9%) household contacts in 16 (17%) households were CPE-colonized. Household transmission was confirmed in 3/177 (2%) cases, probable in 2/177 (1%), possible in 9/177 (5%), and unlikely in 2/177 (1%). Household contacts were more likely to be colonized if they were the index case's spouse (odds ratio [OR], 6.17; 95% confidence interval [CI], 1.05-36.35), if their index case remained CPE-colonized at household enrollment (OR, 7.00; 95% CI, 1.92-25.49), or if they had at least 1 set of specimens processed after direct PCR was introduced (OR, 6.46; 95% CI, 1.52-27.40). CONCLUSIONS: Nine percent of household contacts were CPE-colonized; 3% were a result of household transmission. Hospitals may consider admission screening for patients known to have CPE-colonized household contacts.

Genomic Epidemiology of Invasive Methicillin-Resistant Staphylococcus aureus Infections Among Hospitalized Individuals in Ontario, Canada.

BACKGROUND: Prevention and control of methicillin-resistant Staphylococcus aureus (MRSA) infections remain challenging. In-depth surveillance integrating patient and isolate data can provide evidence to better inform infection control and public health practice. METHODS: We analyzed MRSA cases diagnosed in 2010 (n = 212) and 2016 (n = 214) by hospitals in Ontario, Canada. Case-level clinical and demographic data were integrated with isolate characteristics, including antimicrobial resistance (AMR), classic genotyping, and whole-genome sequencing results. RESULTS: Community-associated MRSA (epidemiologically defined) increased significantly from 23.6% in 2010 to 43.0% in 2016 (P < .001). The MRSA population structure changed over time, with a 1.5× increase in clonal complex (CC)8 strains and a concomitant decrease in CC5. The clonal shift was reflected in AMR patterns, with a decrease in erythromycin (86.7% to 78.4%, P = .036) and clindamycin resistance (84.3% to 47.9%, P < .001) and a >2-fold increase in fusidic acid resistance (9.0% to 22.5%, P < .001). Isolates within both CC5 and CC8 were relatively genetically diverse. We identified 6 small genomic clusters-3 potentially related to transmission in healthcare settings. CONCLUSIONS: Community-associated MRSA is increasing among hospitalized individuals in Ontario. Clonal shifting from CC5 to CC8 has impacted AMR. We identified a relatively high genetic diversity and limited genomic clustering within these dominant CCs.

A virtual care program for outpatients diagnosed with COVID-19: a feasibility study.

BACKGROUND: In patients who are discharged home to self-isolate while coronavirus disease 2019 (COVID-19) test results are pending, there is no formal method for physician assessments or counselling to occur if the result returns positive. Our aim was to develop and test the feasibility of a virtual care program for self-isolating outpatients diagnosed with COVID-19. METHODS: In preparation for this gap in health care, the COVID-19 Expansion to Outpatients (COVIDEO) program was developed at the Sunnybrook Health Sciences Centre, Toronto, Ontario, to provide ongoing care for outpatients diagnosed with COVID-19. As part of a feasibility study, we describe our experiences with the first 50 patients managed using this program from its inception (Mar. 1, 2020) until Mar. 27, 2020. RESULTS: All 50 people who tested positive for COVID-19 at the Sunnybrook Health Sciences Centre and were discharged home to self-isolation during the study period were assessed through the COVIDEO program. Thirty-two patients (64%) were assessed via the Ontario Telemedicine Network virtual care platform, and the remainder by telephone. The median time from viral swab collection to first COVIDEO program assessment was 2 (interquartile range [IQR] 1-2) days. Among the 26 patients for whom further follow-up care through the COVIDEO program was discontinued by the end of March 2020, the median duration of virtual care was 12.5 (IQR 8.75-16) days. During the study period, 6 patients required transfer to hospital for assessment, of whom 4 required admission. INTERPRETATION: We have shown that a virtual care program can be used in the management of outpatients diagnosed with COVID-19. Further studies evaluating its sustainability and impact on health outcomes are underway.

Assessing the utilization and impact of a newly established outpatient parenteral antimicrobial therapy (OPAT) program.

Background: Outpatient parenteral antimicrobial therapy (OPAT) is a safe and effective alternative to hospitalization for many patients with infectious disease. The objective of this study was to describe the experience with a newly established formal OPAT program at a Canadian academic centre. Methods: We conducted a retrospective cohort study including all patients referred to the OPAT clinic between July 2016 and June 2017 and a contemporary cohort of patients who received home parenteral therapy without clinic referral. A quasi-experimental design was used to assess the impact of the clinic on patient outcomes compared with a pre-intervention cohort of patients from 2012 to 2013. Results: Between July 2016 and June 2017, 334 patients were referred to the OPAT clinic; 33% of the patients visited the emergency department (ED), and 21% required readmission within 60 days. Compared with the clinic patients, urinary tract infection diagnoses were more common among the 39 contemporary patients who were treated with home parenteral antibiotics without OPAT clinic referral (51% versus 4%, respectively; p < 0.001) and treatment durations were shorter (median 10 days versus 42 days; p < 0.001). Compared with a pre-intervention cohort, OPAT clinic implementation was associated with a trend toward decreased ED visits (33% versus 43%; p = 0.07). On multivariable analysis, this translated to an overall adjusted odds ratio of 0.64 (95% CI 0.40 to 1.04, p = 0.07) for readmission and ED visits. Conclusions: The OPAT clinic served a high volume of patients in its first year of operation and may be helpful in reducing unfavourable patient outcomes.

Historique: L'antibiothérapie parentérale ambulatoire (APA) remplace l'hospitalisation de manière sécuritaire et efficace pour bien des patients atteints d'une maladie infectieuse. La présente étude visait à décrire l'expérience d'un nouveau programme officiel d'APA dans un centre universitaire canadien. Méthodologie: Les auteurs ont procédé à une étude de cohorte rétrospective incluant tous les patients orientés vers une clinique d'APA entre juillet 2016 et juin 2017 et une cohorte de patients qui, pendant la même période, ont reçu un traitement parentéral à domicile sans être orientés en clinique. Ils ont utilisé une méthodologie quasi-expérimentale pour évaluer les répercussions du suivi en clinique sur les patients par rapport à une cohorte de patients avant l'intervention, entre 2012 et 2013. Résultats: Entre juillet 2016 et juin 2017, 334 patients ont été orientés vers la clinique d'APA; 33 % ont consulté à l'urgence et 21 % ont dû être réhospitalisés dans les 60 jours. Les diagnostics d'infection urinaire étaient plus courants chez les 39 patients recevant une antibiothérapie parentérale à domicile sans être dirigés vers une clinique d'APA que dans la cohorte suivie en clinique (51 % par rapport à 4 %, respectivement; p < 0,001) et la durée du traitement était plus courte (médiane de dix jours par rapport à 42 jours; p < 0,001). Par rapport à la cohorte observée avant l'intervention, le suivi en clinique d'APA était associé à une tendance vers une diminution des consultations à l'urgence (33 % par rapport à 43 %; p = 0,07). À l'analyse multivariable, ces résultats se traduisaient par un rapport de cotes rajusté global de 0,64 (IC à 95 %, 0,40 à 1,04, p = 0,07) pour la réhospitalisation et les consultations à l'urgence. Conclusions: La clinique d'APA a accueilli un fort volume de patients pendant sa première année de fonctionnement et peut contribuer à réduire les résultats cliniques défavorables chez les patients.

Influenza Vaccine Effectiveness in Preventing Hospitalizations in Older Patients With Chronic Obstructive Pulmonary Disease.

BACKGROUND: Annual influenza immunization is recommended for people with chronic obstructive pulmonary disease (COPD) by all major COPD clinical practice guidelines. We sought to determine the seasonal influenza vaccine effectiveness (VE) against laboratory-confirmed influenza-associated hospitalizations among older adults with COPD. METHODS: We conducted a test-negative study of influenza VE in community-dwelling older adults with COPD in Ontario, Canada using health administrative data and respiratory specimens collected from patients tested for influenza during the 2010-11 to 2015-16 influenza seasons. Influenza vaccination was ascertained from physician and pharmacist billing claims. Multivariable logistic regression was used to estimate the adjusted odds ratio of influenza vaccination in people with, compared to those without, laboratory-confirmed influenza. RESULTS: Receipt of seasonal influenza vaccine was associated with an adjusted 22% (95% confidence interval [CI], 15%-27%) reduction in laboratory-confirmed influenza-associated hospitalization. Adjustment for potential misclassification of vaccination status increased this to 43% (95% CI, 35%-52%). Vaccine effectiveness was not found to vary by patient- or influenza-related variables. CONCLUSIONS: During the studied influenza seasons, influenza vaccination was at least modestly effective in reducing laboratory-confirmed influenza-associated hospitalizations in people with COPD. The imperfect effectiveness emphasizes the need for better influenza vaccines and other preventive strategies.

External validation of clinical prediction rules for complications and mortality following Clostridioides difficile infection.

BACKGROUND: Several clinical prediction rules (CPRs) for complications and mortality of Clostridioides difficile infection (CDI) have been developed but only a few have gone through external validation, and none is widely recommended in clinical practice. METHODS: CPRs were identified through a systematic review. We included studies that predicted severe or complicated CDI (cCDI) and mortality, reported at least an internal validation step, and for which data were available with minimal modifications. Data from a multicenter prospective cohort of 1380 adults with confirmed CDI were used for external validation. In this cohort, cCDI occurred in 8% of the patients and 30-day all-cause mortality occurred in 12%. The performance of each tool was assessed using individual outcomes, with the same cut-offs and standard parameters. RESULTS: Seven CPRs were assessed. Three predictive scores for cCDI showed low sensitivity (25-61%) and positive predictive value (PPV; 9-31%), but moderate specificity (54-90%) and negative predictive value (NPV; 82-95%). One model [using age, white blood cell count (WBC), narcotic use, antacids use, and creatinine ratio > 1.5× the normal level as covariates] showed a probability of 25% of cCDI at the optimal cut-off point with 36% sensitivity and 84% specificity. Two scores for mortality had low sensitivity (4-55%) and PPV (25-31%), and moderate specificity (71-78%) and NPV (87-92%). One predictive model for 30-day all-cause mortality [Charlson comorbidity index, WBC, blood urea nitrogen (BUN), diagnosis in ICU, and delirium] showed an AUC-ROC of 0.74. All other CPRs showed lower AUC values (0.63-0.69). Errors in calibration ranged from 12%- 27%. CONCLUSIONS: Included CPRs showed moderate performance for clinical use in a large validation cohort with a majority of patients infected with ribotype 027 strains and a low rate of cCDI and mortality. These data show that better CPRs need to be developed and validated.

Multilocus Variable-Number Tandem-Repeat Analysis of Clostridioides difficile Clusters in Ribotype 027 Isolates and Lack of Association with Clinical Outcomes.

The epidemiology of Clostridioides difficile infection (CDI) has drastically changed since the emergence of the epidemic strain BI/NAP1/027, also known as ribotype 027 (R027). However, the relationship between the infecting C. difficile strain and clinical outcomes is still debated. We hypothesized that certain subpopulations of R027 isolates could be associated with unfavorable outcomes. We applied high-resolution multilocus variable-number tandem-repeat analysis (MLVA) to characterize C. difficile R027 isolates collected from confirmed CDI patients recruited across 10 Canadian hospitals from 2005 to 2008. PCR ribotyping was performed first to select R027 isolates that were then analyzed by MLVA (n = 450). Complicated CDI (cCDI) was defined by the occurrence of any of admission to an intensive care unit, colonic perforation, toxic megacolon, colectomy, and if CDI was the cause or contributed to death within 30 days after enrollment. Three major MLVA clusters were identified, MC-1, MC-3, and MC-10. MC-1 and MC-3 were exclusive to Quebec centers, while MC-10 was found only in Ontario. Fewer cases infected with MC-1 developed cCDI (4%) than those infected with MC-3 and MC-10 (15% and 16%, respectively), but a statistically significant difference was not reached. Our data did not identify a clear association between subpopulations of R027 and different clinical outcomes; however, the data confirmed the utility of MLVA's higher discrimination potential to better characterize CDI populations in an epidemiological analysis. For a patient with CDI, the progression toward an unfavorable outcome is a complex process that probably includes several interrelated strain and host characteristics.

Results from the Canadian Nosocomial Infection Surveillance Program for detection of carbapenemase-producing Acinetobacter spp. in Canadian hospitals, 2010-16.

Objectives: Globally there is an increased prevalence of carbapenem-resistant Acinetobacter spp. (CRAs) and carbapenemase-producing Acinetobacter spp. (CPAs) in the hospital setting. This increase prompted the Canadian Nosocomial Infection Surveillance Program (CNISP) to conduct surveillance of CRA colonizations and infections identified from patients in CNISP-participating hospitals between 2010 and 2016. Methods: Participating acute care facilities across Canada submitted CRAs from 1 January 2010 to 31 December 2016. Patient data were collected from medical records using a standardized questionnaire. WGS was conducted on all CRAs and data underwent single nucleotide variant analysis, resistance gene detection and MLST. Results: The 7 year incidence rate of CRA was 0.02 per 10 000 patient days and 0.015 per 1000 admissions, with no significant increase observed over the surveillance period (P > 0.73). Ninety-four CRA isolates were collected from 58 hospitals, of which 93 (98.9%) were CPA. Carbapenemase OXA-235 group (48.4%) was the most common due to two separate clusters, followed by the OXA-23 group (41.9%). Patients with a travel history were associated with 38.8% of CRA cases. The all-cause 30 day mortality rate for infected cases was 24.4 per 100 CRA cases. Colistin was the most active antimicrobial agent (95.8% susceptibility). Conclusions: CRA remains uncommon in Canadian hospitals and the incidence did not increase from 2010 to 2016. Almost half of the cases were from two clusters harbouring OXA-235-group enzymes. Previous medical treatment during travel outside of Canada was common.

Prevalence of antibiotic-resistant organisms in Canadian Hospitals. Comparison of point-prevalence survey results from 2010, 2012, and 2016.

OBJECTIVE: Point-prevalence surveys for infection or colonization with methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), extended-spectrum ß-lactamase (ESBL)-producing Enterobacteriaceae, carbapenem-resistant Enterobacteriaceae (CREs), and for Clostridium difficile infection (CDI) were conducted in Canadian hospitals in 2010 and 2012 to better understanding changes in the epidemiology of antimicrobial-resistant organisms (AROs), which is crucial for public health and care management. METHODS: A third survey of the same AROs in adult inpatients in Canadian hospitals with ≥50 beds was performed in February 2016. Data on participating hospitals and patient cases were obtained using standard criteria and case definitions. Associations between ARO prevalence and institutional characteristics were assessed using logistic regression models. RESULTS: In total, 160 hospitals from 9 of the 10 provinces with 35,018 adult inpatients participated in the survey. Median prevalence per 100 inpatients was 4.1 for MRSA, 0.8 for VRE, 1.1 for CDI, 0.8 for ESBLs, and 0 for CREs. No significant change occurred compared to 2012. CREs were reported from 24 hospitals (15%) in 2016 compared to 10 hospitals (7%) in 2012. Routine universal or targeted admission screening for VRE decreased from 94% in 2010 to 74% in 2016. Targeted screening for MRSA on admission was associated with a lower prevalence of MRSA infection. Large hospitals (>500 beds) had higher prevalences of CDI. CONCLUSION: This survey provides national prevalence rates for AROs in Canadian hospitals. Changes in infection control and prevention policies might lead to changes in the epidemiology of AROs and our capacity to detect them.

Nasal colonization with Streptococcus pneumoniae and Staphylococcus aureus among hospitalized patients with laboratory-confirmed influenza.

Nasopharyngeal swabs from 148 adult patients with influenza were analyzed by polymerase chain reaction for Staphylococcus aureus and or Streptococcus pneumoniae. We found that patients colonized with S. pneumoniae were younger, had lower oxygen saturations, and were more likely to require admission to critical care.

The evolving epidemiology of Clostridium difficile infection in Canadian hospitals during a postepidemic period (2009-2015).

BACKGROUND: The clinical and molecular epidemiology of health care-associated Clostridium difficile infection in nonepidemic settings across Canada has evolved since the first report of the virulent North American pulsed-field gel electrophoresis type 1 (NAP1) strain more than 15 years ago. The objective of this national, multicentre study was to describe the evolving epidemiology and molecular characteristics of health care-associated C. difficile infection in Canada during a post-NAP1-epidemic period, particularly patient outcomes associated with the NAP1 strain. METHODS: Adult inpatients with C. difficile infection were prospectively identified, using a standard definition, between 2009 and 2015 through the Canadian Nosocomial Infection Surveillance Program (CNISP), a network of 64 acute care hospitals. Patient demographic characteristics, severity of infection and outcomes were reviewed. Molecular testing was performed on isolates, and strain types were analyzed against outcomes and epidemiologic trends. RESULTS: Over a 7-year period, 20 623 adult patients admitted to hospital with health care-associated C. difficile infection were reported to CNISP, and microbiological data were available for 2690 patients. From 2009 to 2015, the national rate of health care-associated C. difficile infection decreased from 5.9 to 4.3 per 10 000 patient-days. NAP1 remained the dominant strain type, but infection with this strain has significantly decreased over time, followed by an increasing trend of infection with NAP4 and NAP11 strains. The NAP1 strain was significantly associated with a higher rate of death attributable to C. difficile infection compared with non-NAP1 strains (odds ratio 1.91, 95% confidence interval [CI] 1.29-2.82). Isolates were universally susceptible to metronidazole; one was nonsusceptible to vancomycin. The proportion of NAP1 strains within individual centres predicted their rates of health care-associated C. difficile infection; for every 10% increase in the proportion of NAP1 strains, the rate of health care-associated C. difficile infection increased by 3.3% (95% CI 1.7%-4.9%). INTERPRETATION: Rates of health care-associated C. difficile infection have decreased across Canada. In nonepidemic settings, NAP4 has emerged as a common strain type, but NAP1, although decreasing, continues to be the predominant circulating strain and remains significantly associated with higher attributable mortality.

Acquisition of methicillin-resistant Staphylococcus aureus (MRSA) in contacts of patients newly identified as colonized or infected with MRSA in the immediate postexposure and postdischarge periods.

The acquisition of methicillin-resistant Staphylococcus aureus (MRSA) after exposure to patients colonized or infected with MRSA was assessed. Among contacts with complete surveillance screening, the rate of acquisition was 5.7% and was lower in those identified postdischarge (17/683, 2.5%) compared with those tested in the immediate postexposure period (62/706, 8.8%).