Characterization of Healthcare-Associated and Community-Associated Clostridioides difficile Infections among Adults, Canada, 2015-2019.

We investigated epidemiologic and molecular characteristics of healthcare-associated (HA) and community-associated (CA) Clostridioides difficile infection (CDI) among adult patients in Canadian Nosocomial Infection Surveillance Program hospitals during 2015-2019. The study encompassed 18,455 CDI cases, 13,735 (74.4%) HA and 4,720 (25.6%) CA. During 2015-2019, HA CDI rates decreased by 23.8%, whereas CA decreased by 18.8%. HA CDI was significantly associated with increased 30-day all-cause mortality as compared with CA CDI (p<0.01). Of 2,506 isolates analyzed, the most common ribotypes (RTs) were RT027, RT106, RT014, and RT020. RT027 was more often associated with CDI-attributable death than was non-RT027, regardless of acquisition type. Overall resistance C. difficile rates were similar for all drugs tested except moxifloxacin. Adult HA and CA CDI rates have declined, coinciding with changes in prevalence of RT027 and RT106. Infection prevention and control and continued national surveillance are integral to clarifying CDI epidemiology, investigation, and control.

A Clostridioides difficile surveillance study of Canadian retail meat samples from 2016-2018.

In this study, we isolated and molecularly characterized 10 (1.6%) C. difficile isolates from 644 commercially available raw meat samples. Molecular typing by PFGE and ribotyping revealed NAP and ribotypes commonly associated with human clinical cases, suggesting retail meat could be a possible source of transmission warranting further investigation.

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.

Emergence of pstS-Null Vancomycin-Resistant Enterococcus faecium Clone ST1478, Canada, 2013-2018.

Rates of vancomycin-resistant enterococci bloodstream infections have remained relatively low in Canada. We recently observed an increase of 113% in these infections rates, which coincided with emergence of Enterococcus faecium pstS-null sequence type 1478. The proportion of this sequence type increased from 2.7% to 38.7% for all tested isolates from 2013-2018.

Antimicrobial susceptibility of Clostridioides difficile isolated from diarrhoeal stool specimens of Canadian patients: summary of results from the Canadian Clostridioides difficile (CAN-DIFF) surveillance study from 2013 to 2017.

OBJECTIVES: To summarize data generated by the Canadian Clostridioides difficile (CAN-DIFF) surveillance study from 2013 to 2017. METHODS: Isolates of C. difficile (n = 2158) were cultured from toxin-positive diarrhoeal stool specimens submitted by eight hospital laboratories to a coordinating laboratory. Antimicrobial susceptibility testing was performed according to the CLSI agar dilution method (M11, 2018). Isolate ribotypes were determined using an international, standardized, high-resolution capillary gel-based electrophoresis protocol. RESULTS: Of the 2158 isolates of C. difficile, 2133 (98.8%) had vancomycin MICs ≤2 mg/L [i.e. were vancomycin susceptible (EUCAST breakpoint tables, v 9.0, 2019) or WT (CLSI M100, 29th edition, 2019)]. Fidaxomicin MICs were lower than those of all other agents tested (MIC90, 0.5 mg/L); however, one isolate with a fidaxomicin MIC of >8 mg/L was identified. Metronidazole MICs ranged from 0.12 to 4 mg/L; all isolates were metronidazole susceptible by the CLSI breakpoint (≤8 mg/L) compared with 96.8% susceptible by the EUCAST breakpoint (≤2 mg/L). In total, 182 different ribotypes were identified from 2013 to 2017. The most common ribotypes identified were 027 (19.3% of isolates) and 106 (8.2%). Ribotype 027 isolates were frequently moxifloxacin resistant (87.3% of isolates) and MDR (48.6%), associated with vancomycin (10/25, 40.0%) and metronidazole (58/69, 84.1%) resistance and from patients aged ≥80 years. The prevalence of ribotype 027 decreased significantly (P < 0.0001) from 2013 (27.5%) to 2017 (9.0%) and was replaced by increases in ribotype 106 (P = 0.0003) and multiple less common ribotypes. CONCLUSIONS: Periodic surveillance is required to monitor clinical isolates of C. difficile for changes to in vitro susceptibility testing profiles and ribotype evolution.

Characterization of MRSA in Canada from 2007 to 2016.

OBJECTIVES: This study assessed the demographic and molecular characteristics of community-associated (CA) and healthcare-associated (HA) MRSA genotypes in Canadian hospitals between 2007 and 2016. METHODS: A total of 1963 MRSA were identified among 9103 Staphylococcus aureus isolates collected from inpatients and outpatients presenting to tertiary-care medical centres across Canada. Antimicrobial susceptibility testing was performed by broth microdilution in accordance with CLSI standards (M7 11th edition, 2018). PCR was performed to detect the Panton-Valentine leucocidin (PVL) genes and molecular analysis was performed by spa typing. RESULTS: Between 2007 and 2016, the annual proportion of S. aureus that were MRSA decreased from 26.1% to 16.9% (P < 0.0001). The proportion of CA-MRSA genotypes increased significantly from 20.8% in 2007 to 56.3% in 2016 (P < 0.0001) while HA-MRSA genotypes decreased from 79.2% to 43.8% throughout the study period (P < 0.0001). Predominant genotypes included HA genotype CMRSA2 (USA100/800) (53.6%) and CA genotype CMRSA10 (USA300) (24.9%). PVL was present in 30.1% of all MRSA isolates, including 78.4% of CA-MRSA and 1.7% of HA-MRSA genotypes. Resistance to clarithromycin, clindamycin, trimethoprim/sulfamethoxazole and fluoroquinolones decreased significantly over time (P < 0.0001). CONCLUSIONS: The proportion of MRSA in Canada declined between 2007 and 2016. In contrast, the proportion of CA-MRSA strain types, particularly CMRSA10 (USA300), continues to increase. In 2016, CA-MRSA genotypes surpassed HA-MRSA as the most common cause of MRSA infections in Canadian hospitals.

Trends in antimicrobial resistance over 10 years among key bacterial pathogens from Canadian hospitals: results of the CANWARD study 2007-16.

OBJECTIVES: We sought to analyse 10 years of longitudinal surveillance data (2007-16) from the CANWARD study and describe emerging trends in antimicrobial resistance for key bacterial pathogens across Canada. METHODS: Longitudinal data from CANWARD study sites that contributed isolates every year from 2007 to 2016 were analysed to identify trends in antimicrobial resistance over time using univariate tests of trend and multivariate regression models to account for the effects of patient demographics. RESULTS: Statistically significant increases occurred in the proportion of Escherichia coli isolates resistant to extended-spectrum cephalosporins, amoxicillin/clavulanate, trimethoprim/sulfamethoxazole and ciprofloxacin. Similarly, the proportion of Klebsiella pneumoniae isolates resistant to extended-spectrum cephalosporins, amoxicillin/clavulanate, trimethoprim/sulfamethoxazole, ciprofloxacin and carbapenems increased during the study. The proportion of Enterobacter cloacae isolates resistant to ceftazidime and trimethoprim/sulfamethoxazole increased. The proportion of both ESBL-positive E. coli and K. pneumoniae (including bloodstream isolates) increased significantly between 2007 and 2016. A reduction in the proportion of Pseudomonas aeruginosa that were ciprofloxacin, cefepime, colistin, amikacin and gentamicin resistant and an increase in the proportion of P. aeruginosa isolates non-susceptible to meropenem were observed. The proportion of isolates of Staphylococcus aureus non-susceptible to clarithromycin, clindamycin and trimethoprim/sulfamethoxazole decreased over time while an increase in the proportion of isolates of Streptococcus pneumoniae non-susceptible to clarithromycin, clindamycin and doxycycline was observed. CONCLUSIONS: Increases in Enterobacteriaceae resistance to multiple classes of antimicrobials, increases in ESBL-positive E. coli and K. pneumoniae, and the small but significant increase in carbapenem-resistant K. pneumoniae were the most remarkable changes in antimicrobial resistance observed from 2007 to 2016 in Canada.

Pediatric oncology and stem cell transplant patients with healthcare-associated Clostridium difficile infection were already colonized on admission.

Clostridium difficile is the leading cause of healthcare-associated infections worldwide. The diagnosis of C. difficile infection (CDI) in pediatric oncology patients is complex as diarrhea is common, and there is a high rate of colonization in infants and young children. This study was conducted to assess the accuracy of the surveillance definitions of healthcare-associated CDI (HA-CDI) and to determine the prevalence of toxigenic C. difficile colonization among pediatric oncology and stem cell transplant patients. METHODS: A prospective cohort study was conducted over a three-year period in an inpatient pediatric oncology and stem cell transplant setting. Baseline stool samples were collected within three days of admission and were genotypically compared with clinically indicated samples submitted after three days of admission. RESULTS: A total of 175 patients were recruited with a total of 536 admissions. The adjusted prevalence of baseline toxigenic C. difficile colonization among admissions was 32.8%. Seventy-eight percent of positive admissions did not have history of CDI. Colonization with a toxigenic strain on admission was predictive of CDI (OR = 28.6; 95% CI, 6.58-124.39; P < 0.001). Nearly all clinical isolates (8/9) shared identical pulsed-field gel electrophoresis patterns with baseline isolates or were closely related (1/9). Only one of the 11 cases that were considered HA-CDI was potentially nosocomially acquired. CONCLUSION: The prevalence of colonization with toxigenic C. difficile in our cohort is high. Unfortunately, the current CDI surveillance definitions overestimate the incidence of HA-CDI in pediatric oncology and stem cell transplantation settings.

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.

Severe MRSA Enterocolitis Caused by a Strain Harboring Enterotoxins D, G, and I.

We describe a case of methicillin-resistant Staphylococcus aureus (MRSA) enterocolitis in a healthy adult with previous antibiotic exposure. Colonoscopy revealed diffuse colitis and mild ileitis without ulceration. Stool cultures demonstrated abundant growth of MRSA and absent normal flora. Oral vancomycin treatment was effective and seems to be the consensus choice for therapy.

A Whole-Genome Sequencing Approach To Study Cefoxitin-Resistant Salmonella enterica Serovar Heidelberg Isolates from Various Sources.

This study characterized cefoxitin-resistant and -susceptible Salmonella enterica serovar Heidelberg strains from humans, abattoir poultry, and retail poultry to assess the molecular relationships of isolates from these sources in Québec in 2012. Isolates were collected as part of the Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS). All isolates were subjected to antimicrobial susceptibility testing, PCR for CMY-2, pulsed-field gel electrophoresis (PFGE), and whole-genome sequencing (WGS). A total of 113 S Heidelberg isolates from humans (n = 51), abattoir poultry (n = 18), and retail poultry (n = 44) were studied. All cefoxitin-resistant isolates (n = 65) were also resistant to amoxicillin-clavulanic acid, ampicillin, ceftiofur, and ceftriaxone, and all contained the CMY-2 gene. PFGE analysis showed that 111/113 (98.2%) isolates clustered together with ≥90% similarity. Core genome analysis using WGS identified 13 small clusters of isolates with 0 to 4 single nucleotide variations (SNVs), consisting of cefoxitin-resistant and -susceptible human, abattoir poultry, and retail poultry isolates. CMY-2 plasmids from cefoxitin-resistant isolates all belonged to incompatibility group I1. Analysis of IncI1 plasmid sequences revealed high identity (95 to 99%) to a previously described plasmid (pCVM29188_101) found in Salmonella Kentucky. When compared to pCVM29188_101, all sequenced cefoxitin-resistant isolates were found to carry 1 of 10 possible variant plasmids. Transmission of S Heidelberg may be occurring between human, abattoir poultry, and retail poultry sources, and transmission of a common CMY-2 plasmid may be occurring among S Heidelberg strains with variable genetic backgrounds.

Molecular Epidemiology of a Vancomycin-Intermediate Heteroresistant Staphylococcus epidermidis Outbreak in a Neonatal Intensive Care Unit.

Coagulase-negative staphylococci (CoNS) have become the leading cause of bloodstream infections (BSIs) in intensive care units (ICUs), particularly in premature neonates. Vancomycin-intermediate heteroresistant CoNS (hVICoNS) have been identified as sources of BSIs worldwide, and their potential to emerge as significant pathogens in the neonatal ICU (NICU) remains uncertain. This study describes the molecular epidemiology of an outbreak of vancomycin-heteroresistant (hV) Staphylococcus epidermidis central-line-associated BSI (CLABSI) in a single tertiary care NICU and compares it to a second tertiary care NICU that had not been associated with an outbreak. Between November 2009 and April 2014, 119 S. epidermidis CLABSIs were identified in two tertiary care NICUs in Quebec, Canada. Decreased vancomycin susceptibility was identified in about 88% of all collected strains using Etest methods. However, discrepancies were found according to the Etest and population analysis profiling-area under the concentration-time curve (PAP-AUC) methods used. All strains were susceptible to linezolid, and a few isolates were nonsusceptible to daptomycin. Great genetic diversity was observed within the collection, with 31 pulsed-field gel electrophoresis (PFGE) patterns identified. The outbreak strains were all determined to be heteroresistant to vancomycin and were polyclonal. The study identified two major clones, PFGE patterns E and G, which were found in both NICUs across the 5-year study period. This suggests the persistence of highly successful clones that are well adapted to the hospital environment. hV S. epidermidis seems more common than currently realized in the NICU, and certain hV S. epidermidis clones can become endemic to the NICU. The reservoirs for these clones remain unknown at this time, and identification of the reservoirs is needed to better understand the impact of hV S. epidermidis in the NICU and to inform infection prevention strategies. In addition, there is a need to investigate and validate hV determination protocols for different species of CoNS.

A cross sectional study of animal and human colonization with Methicillin-Resistant Staphylococcus aureus (MRSA) in an Aboriginal community.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) infections are common among humans in Aboriginal communities in Canada, for unknown reasons. METHODS: Cross sectional study of humans and dogs in an Aboriginal community of approximately 1200 persons. Our objectives were to measure community-based prevalence of nasal MRSA colonization among humans, use multivariable logistic regression to analyze risk factors for MRSA colonization, and perform molecular typing of Staphylococci isolated to investigate interspecies transmission. RESULTS: 461 humans were approached for consent and 442 provided complete data. 109/442 (24.7 %, 95 % C.I. = 20.7-28.7 %) of humans were colonized with MRSA. 169/442 (38.2 %) of humans had received antibiotics in the last 12 months. Only number of rooms in the house (OR 0.86, p = 0.023) and recreational dog use (OR 7.7, p = 0.002) were significant risk factors for MRSA colonization. 95/109 (87.1 %) of MRSA strains from humans were of the same spa type (CMRSA10/USA300). 8/157 (5.1 %, 95 % C.I. = 1.7-8.5 %) of dogs were colonized with methicillin-susceptible S. aureus, and no dogs were colonized with MRSA. CONCLUSIONS: Human MRSA colonization in this community is very common, and a single clone is predominant, suggesting local transmission. Antibiotic use is also very common. Crowding may partially explain high colonization, but most considered risk factors including animal exposure were not predictive. Very few dogs carried human Staphylococcal strains.

Characterization of Clostridium difficile Strains in British Columbia, Canada: A Shift from NAP1 Majority (2008) to Novel Strain Types (2013) in One Region.

Background. Clostridium difficile is a major cause of gastrointestinal illness. Epidemic NAP1 strains contain toxins A and B, a deletion in repressor tcdC, and a binary toxin. Objectives. To determine the molecular epidemiology of C. difficile in British Columbia and compare between two time points in one region. Methods. C. difficile isolates from hospital and community laboratories (2008) and one Island Health hospital laboratory (2013) were characterized by pulsed-field gel electrophoresis, PCR-ribotyping, toxin possession, tcdC genotype, and antimicrobial susceptibility. Results. In 2008, 42.7% of isolates had NAP1 designation. Hospital-collected isolates were associated with older patients and more NAP1 types. Unlike other isolates, most NAP1 isolates possessed binary toxin and a 19 bp loss in tcdC. All isolates were susceptible to metronidazole and vancomycin. A 2013 follow-up revealed a 28.9% decrease in NAP1 isolates and 20.0% increase in isolates without NAP designation in one region. Then, community-associated cases were seen in younger patients, while NAP types were evenly distributed. Isolates without NAP designation did not cluster with a PFGE pattern or ribotype. Conclusions. Evaluation of C. difficile infections within British Columbia revealed demographic associations, epidemiological shifts, and characteristics of strain types. Continuous surveillance of C. difficile will enable detection of emerging strains.

Staphylococcus aureus isolates colonizing and infecting cirrhotic and liver-transplantation patients: comparison of molecular typing and virulence factors.

BACKGROUND: S. aureus is an important agent of colonization and infection in liver transplant patients. It harbors several virulence factors that can increase its pathogenicity. However, studies of virulence and molecular typing of MRSA in cirrhotic and liver transplantation patients are scarce. RESULTS: Here we use SCCmec, PFGE, spa typing, MLST and virulence factors to characterize MRSA isolates in pre and post liver transplantation patients. Sixteen (13%) of 126 cirrhotic and 15 of the 64 liver-transplanted patients (23%) were colonized by MRSA (p=0.091). SCCmec types I, II and III that are generally associated with nosocomial infections were identified in 91% of the isolates. None of the isolates carried PVL, adhesion factors and fib gene. Only three MRSA colonized isolates carried tst gene and were characterized as SCCmec type I and t149. Ten spa types and five STs were identified; t002 and ST105 were the most frequent profiles. Spa types and ST1510 never described in Brazil and a new spa type t14789 were identified. Nineteen PFGE subtypes were found and grouped into nine types. There was a predominant cluster, which was related to the New York/Japanese epidemic clone and harboured SCCmec type II identified in both cirrhotic and post-transplantation patients. Based on SCCmec and virulence factors the MRSA isolates belonged to NY/Jpn clone seen be more similar to the USA100 MRSA isolates. CONCLUSIONS: Although without significance, liver-transplantation was more frequently colonized by MRSA than cirrhotic patients. The most frequent SCCmec was type II, and the predominant cluster was related to the New York/Japanese clone. A new spa t14789, and ST1510 never reported in Brazil were identified.

Emergence of new CMRSA7/USA400 methicillin-resistant Staphylococcus aureus spa types in Alberta, Canada, from 2005 to 2012.

Methicillin-resistant Staphylococcus aureus (MRSA) has become one of the most significant pathogens affecting global public health and health care systems. In Canada and the United States, the spread of MRSA is primarily attributed to a single dominant epidemic clone: CMRSA10/USA300. Despite this, the CMRSA7/USA400 epidemic clone has been reported to be the predominate epidemic clone in several Canadian provinces and some parts of the United States. This study examined the epidemiology of CMRSA7/USA400 MRSA in Alberta, Canada, from June 2005 to December 2012. Molecular characterization of CMRSA7/USA400 isolates was done using spa, SCCmec, PVL, and PFGE typing and identified two predominant spa types in Alberta: t128 and t1787. Although closely related, these spa types have distinct geographic distributions. From 2010 to 2012, the number of t128 infections has remained stable while there has been a nearly 3-fold increase in the number of provincial t1787 infections, accompanied by 10-fold increases in t1787 infection rates in some communities. Most t128 and t1787 patients were First Nations or Inuit people, and isolates were usually from skin and soft tissue infections in outpatients. t128 patients were significantly older than t1787 patients. Antimicrobial susceptibility testing showed higher mupirocin resistance in t1787 than in t128 MRSA. Improved strategies to reduce or stabilize t1787 infections in Alberta are needed.

Changing epidemiology of methicillin-resistant Staphylococcus aureus in Canada.

OBJECTIVES: To compare the demographics, antimicrobial susceptibilities and molecular epidemiology of community-associated (CA) and healthcare-associated (HA) methicillin-resistant Staphylococcus aureus (MRSA) in Canada. METHODS: Between 2007 and 2011, 1266 MRSA were collected from inpatients and outpatients attending tertiary-care medical centres across Canada. Susceptibility testing was performed using broth microdilution and isolates were characterized by spa typing and PCR to detect the Panton-Valentine leucocidin (PVL) gene. Detection of heterogeneous vancomycin-intermediate S. aureus (hVISA) was performed using the Etest macromethod and confirmed by population analysis profiling. RESULTS: The annual proportion of S. aureus that were methicillin resistant decreased from 26.1% in 2007 to 19.3% in 2011 (P= 0.0002). Of 1266 MRSA isolated, 366 (28.9%) were CA-MRSA genotypes and 868 (68.6%) were HA-MRSA genotypes. The proportion of MRSA represented by CA-MRSA genotypes increased from 19.7% to 36.4% between 2007 and 2011 (P < 0.0001). CMRSA10 (USA300) was the predominant CA-MRSA genotype (22.1%); the most common HA-MRSA genotype was CMRSA2 (USA100/800) (58.1%). PVL was detected in 328/366 (89.6%) of CA-MRSA genotypes and 6/868 (0.7%) of HA-MRSA genotypes. The hVISA phenotype was detected in 7/27 (25.9%) of MRSA with a vancomycin MIC of 2 mg/L. CONCLUSIONS: The most frequent CA-MRSA genotype was CMRSA10 (USA300), while CMRSA2 (USA100/800) was the predominant HA-MRSA genotype. Despite a decrease in the numbers of MRSA, the proportion of CMRSA10 (USA300) CA-MRSA has risen significantly between 2007 and 2011 in Canada.

Vancomycin-resistant Enterococcus sequence type 1478 spread across hospitals participating in the Canadian Nosocomial Infection Surveillance Program from 2013 to 2018.

OBJECTIVE: To analyze the spread of a novel sequence type (ST1478) of vancomycin-resistant Enterococcus faecium across Canadian hospitals. DESIGN: Retrospective chart review of patients identified as having ST1478 VRE bloodstream infection. SETTING: Canadian hospitals that participate in the Canadian Nosocomial Infection Surveillance Program (CNISP). METHODS: From 2013 to 2018, VRE bloodstream isolates collected from participating CNISP hospitals were sent to the National Microbiology Laboratory (NML). ST1478 isolates were identified using multilocus sequence typing, and whole-genome sequencing was performed. Patient characteristics and location data were collected for patients with ST1478 bloodstream infection (BSI). The sequence and patient location information were used to generate clusters of infections and assess for intrahospital and interhospital spread. RESULTS: ST1478 VRE BSI occurred predominantly in a small number of hospitals in central and western Canada. Within these hospitals, infections were clustered on certain wards, and isolates often had <20 single-nucleotide variants (SNV) differences from one another, suggesting a large component of intrahospital spread. Furthermore, some patients with bloodstream infections were identified as moving from one hospital to another, potentially having led to interhospital spread. Genomic analysis of all isolates revealed close relatedness between isolates at multiple different hospitals (<20 SNV) not predicted from our epidemiologic data. CONCLUSIONS: Both intrahospital and regional interhospital spread have contributed to the emergence of VRE ST1478 infections across Canada. Whole-genome sequencing provides evidence of spread that might be missed with epidemiologic investigation alone.

Epidemiology of Primary and Recurrent Healthcare-Associated and Community-Associated Pediatric Clostridioides difficile Infection in Canada, 2015-2020.

Clostridioides difficile infection (CDI) among children remains a concerning cause of morbidity in hospital settings. We present epidemiological and molecular trends in healthcare- and community-associated CDI among children in Canadian inpatient and outpatient settings, including those who experienced recurrent infections.