To assess the prevalence, antimicrobial susceptibilities and molecular characteristics of ESBL-producing Escherichia coli and Klebsiella pneumoniae infecting patients receiving care in Canadian ...hospitals from January 2007 to December 2016.
Clinical isolates of E. coli (n = 8387) and K. pneumoniae (n = 2623) submitted to CANWARD, an ongoing Canadian national surveillance study, were tested using the CLSI reference broth microdilution method to determine their susceptibility to 15 antimicrobial agents. ESBL-producing E. coli and K. pneumoniae confirmed by the CLSI phenotypic method and putative AmpC-producing E. coli underwent PCR testing and DNA sequencing to identify resistance genes. Annual proportions of isolates harbouring ESBL and AmpC genes were assessed by the Cochran-Armitage test of trend.
The annual proportion of isolates of E. coli that were ESBL producing increased from 3.4% in 2007 to 11.1% in 2016 (P < 0.0001); >95% of ESBL-producing E. coli were susceptible to amikacin, colistin, ertapenem, meropenem and tigecycline. The proportion of isolates of K. pneumoniae that were ESBL producing increased from 1.3% in 2007 to 9.7% in 2016 (P < 0.0001); >95% of ESBL-producing K. pneumoniae were susceptible to amikacin and meropenem. CTX-M-15 was the predominant genotype in both ESBL-producing E. coli (64.2% of isolates) and ESBL-producing K. pneumoniae (51.0%). The annual proportion of isolates of E. coli that were AmpC producing annual proportion mean 1.9% (range 0.3%-3.1%) was unchanged from 2007 to 2016 (P > 0.5).
The prevalence of both ESBL-producing E. coli and K. pneumoniae increased significantly in Canada during the study period while the prevalence of AmpC-producing E. coli remained low and stable.
Understanding the epidemiology of invasive Candida infections is essential to patient management decisions and antifungal stewardship practices. This study characterized the species distribution and ...antifungal susceptibilities of prospectively collected isolates of Candida species causing bloodstream infections (BSIs) in patients admitted to tertiary care hospitals located in 14 cities across 8 of the 10 Canadian provinces between 2011 and 2016.
Antifungal susceptibility testing was performed by broth microdilution using CLSI methods, breakpoints and epidemiological cut-off values. DNA sequencing of fks loci was performed on all echinocandin-non-susceptible isolates.
Candida albicans (49.6%), Candida glabrata (20.8%) and Candida parapsilosis complex (12.0%) were the most common species out of 1882 isolates associated with BSIs. Candida tropicalis (5.2%), Candida krusei (4.3%), Candida dubliniensis (4.1%), Candida lusitaniae (1.4%) and Candida guilliermondii (1.1%) were less frequently isolated. Between 2011 and 2016, the proportion of C. albicans significantly decreased from 60.9% to 42.1% (P < 0.0001) while that of C. glabrata significantly increased from 16.4% to 22.4% (P = 0.023). C. albicans (n = 934), C. glabrata (n = 392) and C. parapsilosis complex (n = 225) exhibited 0.6%, 1.0% and 4.9% resistance to fluconazole and 0.1%, 2.5% and 0% resistance to micafungin, respectively. Mutations in fks hot-spot regions were confirmed in all nine micafungin non-susceptible C. glabrata.
Antifungal resistance in contemporary isolates of Candida causing BSIs in Canada is uncommon. However, the proportion of C. glabrata isolates has increased and echinocandin resistance in this species has emerged. Ongoing surveillance of local hospital epidemiology and appropriate antifungal stewardship practices are necessary to preserve the utility of available antifungal agents.
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.
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.
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).
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.
To compare the epidemiology and antimicrobial susceptibility patterns of Streptococcus pneumoniae collected from respiratory and blood culture samples in Canada between 2007 and 2016.
S. pneumoniae ...strains were obtained from Canadian hospitals as part of the ongoing national surveillance study, CANWARD. Isolates were serotyped using the Quellung method. Antimicrobial susceptibility testing was performed using the CLSI broth microdilution method. MDR and XDR were defined as resistance to three or more and five or more classes of antimicrobials, respectively.
Of the 2581 S. pneumoniae isolates collected, 1685 (65.3%) and 896 (34.7%) were obtained from respiratory and blood samples, respectively. Respiratory isolates demonstrated lower rates of antimicrobial susceptibility than blood isolates to penicillin, ceftriaxone, clarithromycin, clindamycin, doxycycline and trimethoprim/sulfamethoxazole (P ≤ 0.03). From 2007 to 2016, invasive isolates demonstrated trends towards increasing penicillin susceptibility and decreasing clarithromycin susceptibility. MDR was significantly higher in respiratory S. pneumoniae compared with blood (9.1% versus 4.5%, P < 0.0001). Serotypes 11A, 16F, 19F, 23A/B/F, 34, 35B and non-typeable strains were more commonly isolated from respiratory specimens, while 4, 5, 7F, 8, 12F, 14 and 19A were more commonly invasive serotypes. Numerous serotypes, including 3 and 22F, were isolated frequently from both specimen sources.
S. pneumoniae from respiratory samples demonstrated lower antimicrobial susceptibilities and higher MDR in a greater diversity of serotypes than isolates obtained from blood. Many serotypes were associated with one specific specimen source, while others were associated with both; genetic characterization is necessary to elucidate the specific factors influencing the ability of these serotypes to commonly cause both invasive and non-invasive disease.
The CANWARD surveillance study was established in 2007 to annually assess the in vitro susceptibilities of a variety of antimicrobial agents against bacterial pathogens isolated from patients ...receiving care in Canadian hospitals.
42 936 pathogens were received and CLSI broth microdilution testing was performed on 37 355 bacterial isolates. Limited patient demographic data submitted with each isolate were collated and analysed.
Of the isolates tested, 43.5%, 33.1%, 13.2% and 10.2% were from blood, respiratory, urine and wound specimens, respectively; 29.9%, 24.8%, 19.0%, 18.1% and 8.2% of isolates were from patients in medical wards, emergency rooms, ICUs, hospital clinics and surgical wards. Patient demographics associated with the isolates were: 54.6% male/45.4% female; 13.1% patients aged ≤17 years, 44.3% 18-64 years and 42.7% ≥65 years. The three most common pathogens were Staphylococcus aureus (21.2%, both methicillin-susceptible and MRSA), Escherichia coli (19.6%) and Pseudomonas aeruginosa (9.0%). E. coli were most susceptible to meropenem and tigecycline (99.9%), ertapenem and colistin (99.8%), amikacin (99.7%) and ceftolozane/tazobactam and plazomicin (99.6%). Twenty-three percent of S. aureus were MRSA. MRSA were most susceptible to ceftobiprole, linezolid and telavancin (100%), daptomycin (99.9%), vancomycin (99.8%) and tigecycline (99.2%). P. aeruginosa were most susceptible to ceftolozane/tazobactam (98.3%) and colistin (95.0%).
The CANWARD surveillance study has provided 10 years of reference antimicrobial susceptibility testing data on pathogens commonly causing infections in patients attending Canadian hospitals.
Carbapenem-resistant Pseudomonas aeruginosa are emerging worldwide with increasing reports of carbapenemase-producing isolates. Carbapenem-resistant isolates may also be XDR. This study characterized ...carbapenem-resistant and XDR P. aeruginosa isolated from patients receiving care at Canadian hospitals from 2007 to 2016.
Antimicrobial susceptibility testing was performed using CLSI broth microdilution methods. PCR was used to detect carbapenemases (GES, KPC, NDM, IMP, VIM, OXA-48) and other resistance markers; specific carbapenemase gene variants were identified by DNA sequencing. Genetic relatedness was assessed by MLST and PFGE.
From 2007 to 2016, 3864 isolates of P. aeruginosa were collected; 466 (12.1%) isolates were carbapenem resistant. The prevalence of carbapenem-resistant P. aeruginosa reached a peak of 17.3% in 2014. Colistin (94% susceptible) and ceftolozane/tazobactam (92.5%) were the most active agents against carbapenem-resistant P. aeruginosa. XDR P. aeruginosa comprised 4.5% of isolates; they were found to be genetically diverse and remained susceptible to colistin and ceftolozane/tazobactam. Only 4.3% (n = 20) of carbapenem-resistant P. aeruginosa harboured a carbapenemase; most were blaGES-5 (35%, n = 7). Wide genetic diversity was observed among carbapenem-resistant P. aeruginosa with >200 different sequence types identified.
Although the prevalence of carbapenem-resistant P. aeruginosa in Canada spiked in 2014 and 2015, carbapenemase-producing P. aeruginosa remain rare with only 20 (4.3%) isolates identified over a 10 year period. Broad genetic diversity was observed among both carbapenem-resistant and XDR phenotypes of P. aeruginosa. Pan-drug-resistant P. aeruginosa have not yet been identified in Canada.
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.
...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.
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.
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.
A systematic review and meta-analysis were conducted to determine the efficacy of selective dry-cow antimicrobial therapy compared to blanket therapy (all quarters/all cows). Controlled trials were ...eligible if any of the following were assessed: incidence of clinical mastitis during the first 30 DIM, frequency of intramammary infection (IMI) at calving, or frequency of IMI during the first 30 DIM. From 3480 identified records, nine trials were data extracted for IMI at calving. There was an insufficient number of trials to conduct meta-analysis for the other outcomes. Risk of IMI at calving in selectively treated cows was higher than blanket therapy (RR = 1.34, 95% CI = 1.13, 1.16), but substantial heterogeneity was present (I2 = 58%). Subgroup analysis showed that, for trials using internal teat sealants, there was no difference in IMI risk at calving between groups, and no heterogeneity was present. For trials not using internal teat sealants, there was an increased risk in cows assigned to a selective dry-cow therapy protocol, compared to blanket treatment, with substantial heterogeneity in this subgroup. However, the small number of trials and heterogeneity in the subgroup without internal teat sealants suggests that the relative risk between treatments may differ from the determined point estimates based on other unmeasured factors.
A systematic review and network meta-analysis were conducted to assess the relative efficacy of internal or external teat sealants given at dry-off in dairy cattle. Controlled trials were eligible if ...they assessed the use of internal or external teat sealants, with or without concurrent antimicrobial therapy, compared to no treatment or an alternative treatment, and measured one or more of the following outcomes: incidence of intramammary infection (IMI) at calving, IMI during the first 30 days in milk (DIM), or clinical mastitis during the first 30 DIM. Risk of bias was based on the Cochrane Risk of Bias 2.0 tool with modified signaling questions. From 2280 initially identified records, 32 trials had data extracted for one or more outcomes. Network meta-analysis was conducted for IMI at calving. Use of an internal teat sealant (bismuth subnitrate) significantly reduced the risk of new IMI at calving compared to non-treated controls (RR = 0.36, 95% CI 0.25-0.72). For comparisons between antimicrobial and teat sealant groups, concerns regarding precision were seen. Synthesis of the primary research identified important challenges related to the comparability of outcomes, replication and connection of interventions, and quality of reporting of study conduct.
Ten years of the CANWARD Study (2007-16) Zhanel, George G; Adam, Heather J
Journal of antimicrobial chemotherapy,
08/2019, Volume:
74, Issue:
Suppl 4
Journal Article
PDF