Shiloh
Editor, Senior Moderator
Source: http://www.cidrap.umn.edu/news-perspective/2019/12/stewardship-resistance-scan-dec-13-2019
Stewardship / Resistance Scan for Dec 13, 2019
Whole-genome sequencing for surveillance; Asymptomatic C diff carriers
Filed Under:
Antimicrobial Stewardship; Clostridium difficile; Diagnostics
[h=3]UK study supports whole-genome sequencing for resistance surveillance[/h] New research by a team of scientists from the United Kingdom suggests that whole-genome sequencing (WGS) should be considered as an alternative to traditional phenotypic testing for national surveillance of antibiotic resistance.
In a study published yesterday in Eurosurveillance, researchers from the UK's Animal and Plant Health Agency and the University of East Anglia performed WGS on a collection of 515 Escherichia coli isolates collected from pigs on 57 UK farms. They also tested their susceptibility to a panel of nine antibiotics, using the minimal inhibitory concentration (MIC) to determine phenotypic resistance or susceptibility. The aim of the study was to determine whether the presence of antibiotic resistance genes and mutations in the E coli isolates could accurately predict their resistance to antibiotics of human clinical and veterinary importance.
Overall, correlation of WGS results with susceptibility to the nine antibiotics was 98.9% for test specificity, and 97.5% for the positive predictive value of a test. The overall kappa score (k = 0.914) indicated the presence of antibiotic resistance genes was highly predictive of reduced susceptibility and showed excellent correlation with the phenotypic MIC data from the isolates. However, there was variation for each antibiotic; five showed "almost perfect" agreement, three showed strong agreement, and one showed moderate agreement. Suggested epidemiologic cutoff adjustments increased concordance between genotypic data and kappa values for the four strong-to-moderate agreement antibiotics.
The authors of the study say WGS provides the additional benefit of being able to detect genes that confer resistance to antibiotics that aren't routinely tested in MIC panels, and can identify other elements of bacterial strains—such as multilocus sequence types and plasmids—that are important for assessing their ability to transmit antibiotic resistance.
Dec 12 Eurosurveill study
[h=3]Asymptomatic C diff carriage found in nearly 10% of hospital patients[/h] A study conducted at a New York hospital has found that asymptomatic carriage of Clostridioides difficile is prevalent among admitted patients and confers a significant risk of developing into C difficile infection (CDI), researchers reported this week in Infection Control and Hospital Epidemiology.
In the study, conducted from March 2017 to July 2018, researchers at Montefiore Medical Center created a pilot screening program to test patients being admitted to the hospital without diarrhea for C difficile. Eligible subjects, including adult patients from the community and nursing facility residents, underwent swabbing of their perirectal area. The swabs were tested by polymerase chain reaction within 24 hours of admission, and the patients were then observed for 6 months. Development of clinical CDI was compared among the C difficile carriers and non-carriers.
Of the 220 patients tested, 21 (9.6%) were asymptomatic C difficile carriers, with 17 of 168 nursing facility residents (10.2%) and 4 of 52 community residents (7.7%) testing positive. Among the 21 C difficile carriers, 8 (38.1%) progressed to clinical CDI within 6 months, compared with 4 of 199 (2.0%) non-carriers. In the time-to-event analysis, C difficile carriers had significantly increased risk of developing clinical CDI compared with non-carriers (hazard ratio, 23.9; 95% confidence interval, 7.2 to 79.6; P < .001).
The authors of the study say that identifying asymptomatic carriers is important because, even without diarrhea, they still shed spores that can contaminate hospital surfaces, and could represent a significant reservoir for C difficile transmission.
"Therefore, identification of asymptomatic carriers could reduce the spread of C. difficile," they write. "Specific environmental, isolation, and stewardship strategies to prevent spread of C. difficile from carriers to uninfected patients as well as prevent progression to symptomatic CDI warrant further study."
Dec 11 Infect Control Hosp Epidemiol abstract
Stewardship / Resistance Scan for Dec 13, 2019
Whole-genome sequencing for surveillance; Asymptomatic C diff carriers
Filed Under:
Antimicrobial Stewardship; Clostridium difficile; Diagnostics
[h=3]UK study supports whole-genome sequencing for resistance surveillance[/h] New research by a team of scientists from the United Kingdom suggests that whole-genome sequencing (WGS) should be considered as an alternative to traditional phenotypic testing for national surveillance of antibiotic resistance.
In a study published yesterday in Eurosurveillance, researchers from the UK's Animal and Plant Health Agency and the University of East Anglia performed WGS on a collection of 515 Escherichia coli isolates collected from pigs on 57 UK farms. They also tested their susceptibility to a panel of nine antibiotics, using the minimal inhibitory concentration (MIC) to determine phenotypic resistance or susceptibility. The aim of the study was to determine whether the presence of antibiotic resistance genes and mutations in the E coli isolates could accurately predict their resistance to antibiotics of human clinical and veterinary importance.
Overall, correlation of WGS results with susceptibility to the nine antibiotics was 98.9% for test specificity, and 97.5% for the positive predictive value of a test. The overall kappa score (k = 0.914) indicated the presence of antibiotic resistance genes was highly predictive of reduced susceptibility and showed excellent correlation with the phenotypic MIC data from the isolates. However, there was variation for each antibiotic; five showed "almost perfect" agreement, three showed strong agreement, and one showed moderate agreement. Suggested epidemiologic cutoff adjustments increased concordance between genotypic data and kappa values for the four strong-to-moderate agreement antibiotics.
The authors of the study say WGS provides the additional benefit of being able to detect genes that confer resistance to antibiotics that aren't routinely tested in MIC panels, and can identify other elements of bacterial strains—such as multilocus sequence types and plasmids—that are important for assessing their ability to transmit antibiotic resistance.
Dec 12 Eurosurveill study
[h=3]Asymptomatic C diff carriage found in nearly 10% of hospital patients[/h] A study conducted at a New York hospital has found that asymptomatic carriage of Clostridioides difficile is prevalent among admitted patients and confers a significant risk of developing into C difficile infection (CDI), researchers reported this week in Infection Control and Hospital Epidemiology.
In the study, conducted from March 2017 to July 2018, researchers at Montefiore Medical Center created a pilot screening program to test patients being admitted to the hospital without diarrhea for C difficile. Eligible subjects, including adult patients from the community and nursing facility residents, underwent swabbing of their perirectal area. The swabs were tested by polymerase chain reaction within 24 hours of admission, and the patients were then observed for 6 months. Development of clinical CDI was compared among the C difficile carriers and non-carriers.
Of the 220 patients tested, 21 (9.6%) were asymptomatic C difficile carriers, with 17 of 168 nursing facility residents (10.2%) and 4 of 52 community residents (7.7%) testing positive. Among the 21 C difficile carriers, 8 (38.1%) progressed to clinical CDI within 6 months, compared with 4 of 199 (2.0%) non-carriers. In the time-to-event analysis, C difficile carriers had significantly increased risk of developing clinical CDI compared with non-carriers (hazard ratio, 23.9; 95% confidence interval, 7.2 to 79.6; P < .001).
The authors of the study say that identifying asymptomatic carriers is important because, even without diarrhea, they still shed spores that can contaminate hospital surfaces, and could represent a significant reservoir for C difficile transmission.
"Therefore, identification of asymptomatic carriers could reduce the spread of C. difficile," they write. "Specific environmental, isolation, and stewardship strategies to prevent spread of C. difficile from carriers to uninfected patients as well as prevent progression to symptomatic CDI warrant further study."
Dec 11 Infect Control Hosp Epidemiol abstract