Quality Infectious Disease Testing
Rapid Influenza Diagnostic Testing:
Impact of H1N1 on Rapid Influenza Diagnostic Testing (RIDT) Practices in Outpatient Medical Settings
RIDT is used to diagnose respiratory illness and facilitate effective administration of antiviral medications (within 48 hours of the initial flu-like symptoms). The sensitivity varies from 40 to 69% with reduced reliability when cases are infrequent. Reliability improves when influenza prevalence is elevated during influenza season, an epidemic, or a pandemic. Test reliability and accuracy depend on the type of influenza, the age of the patient, the specific test system used, the skills of the testing personnel, and the knowledge of the health care provider interpreting and applying the findings.
A survey assessing influenza rapid testing practices was distributed in 2008 to a representative sample of physician’s offices, emergency departments and community health centers in the U.S. CDC recommendations for influenza testing changed during the 2009 H1N1 pandemic and a subsequent survey in 2010 aimed to identify changes in testing practices. The findings indicated that RIDT practices and treatment decisions varied widely among outpatient facilities in 2008 and 2010 suggesting that development and implementation of training programs about the appropriate use of RIDT and best testing practices could improve patient outcomes. Emergency departments reported that RIDTs were performed in the central laboratories.
In the 2010 survey, 29.4% of respondents reported an increased use of RIDTs. Testing practices varied in the areas of quality assurance, clinical follow-up, therapeutic choices, and test results reporting to health departments. Reporting of RIDT results to state health departments increased after H1N1 as well as prescribing of antiviral medications particularly for high-risk patients (e.g., pregnant women, children <2 years of age). A positive RIDT was a primary indication for prescribing antiviral medications in 2010 for 67.2% of facilities within 48 hours of flu-like symptoms while 33.2% took this action with patients more than 48 hours after the appearance of symptoms.
Now Available: Strategies for Improving Rapid Influenza Testing in Ambulatory Settings (SIRAS), a free continuing education (CE) course designed for physicians, physician assistants and registered nurses who provide care in ambulatory settings, is now available online. SIRAS was developed under a cooperative agreement between the Centers for Disease Control and Prevention (CDC) and The Joint Commission.
Development of Pilot Program for Surveillance for β-Lactam Resistant Enterobacteriaceae Isolates
Third-generation cephalosporin resistance is rare in the U.S., but the true prevalence is unknown due to challenges for detection of resistance genotypes.
The Nebraska Public Health Laboratory collected 675 Enterobacteriaceae isolates from multiple state-wide clinical microbiology laboratories to determine both the true prevalence of third-generation cephalosporin and carbapenem resistance, as well as the sensitivity and specificity of the new 2010 CLSI resistance threshold classification “breakpoints.”1 Susceptibility testing was performed using the CLSI reference method to detect extended-spectrum β-lactamases, AmpC β-lactamases, and carbapenemases.
Microbiology reports were obtained from the laboratories for each isolate including: a) the first 25 isolates, regardless of susceptibility; and b) approximately 160 isolates each of Enterobacter, Citrobacter, Klebsiella, and Escherichia from patients with positive blood cultures. Isolates with resistance were characterized by iso-electric focusing and molecular methods. Results to date have been presented at meetings of the Association of Public Health Laboratories and published.2
1Clinical and Laboratory Standards Institute. Performance Standards for Antimicrobial Susceptibility Testing; Twenty-second Informational Supplement. CLSI document M100-S22. (ISBN 1-56234-785-5 [Print]; ISBN 1-56238-786-3 [Electronic]. Clinical and Laboratory Standards Institute, 950 West Valley Road, Suite 2500, Wayne, Pennsylvania 19087 USA, 2012
2Bryant KA, Van Schooneveld TC, Thapa I, et al. KPC-4 Is encoded within a truncated Tn4401 in an IncL/M plasmid, pNE1280, isolated from enterobacter cloacae and Serratia marcescens. Antimicrob Agents Chemother. 2013 Jan;57(1):37-41. doi:10.1128/AAC.01062-12. Epub 2012 Oct 15. PubMed PMID: 23070154; PubMed Central PMCID: PMC3535906.