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Antimicrobial Proficiency Testing of National Nosocomial Infections Surveillance System Hospital Laboratories

Published online by Cambridge University Press:  02 January 2015

Jeffrey C. Hageman*
Affiliation:
Division of Healthcare Quality Promotion, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia
Scott K. Fridkin
Affiliation:
Division of Healthcare Quality Promotion, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia
Jasmine M. Mohammed
Affiliation:
Division of Healthcare Quality Promotion, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia
Christine D. Steward
Affiliation:
Division of Healthcare Quality Promotion, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia
Robert P. Gaynes
Affiliation:
Division of Healthcare Quality Promotion, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia
Fred C. Tenover
Affiliation:
Division of Healthcare Quality Promotion, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia
*
Division of Healthcare Quality Promotion, MS A-35, Centers for Disease Control and Prevention, 1600 Clifton Rd., Atlanta, GA 30333

Abstract

Objective:

The National Nosocomial Infections Surveillance (NNIS) System personnel report trends in antimicrobial-resistant pathogens. To validate select antimicrobial susceptibility testing results and to identify test methods that tend to produce errors, we conducted proficiency testing among NNIS System hospital laboratories.

Setting:

NNIS System hospital laboratories in the United States.

Methods:

Each laboratory received five organisms (ie, an imipenem-resistant Serratia marcescens, an oxacillin-resistant Staphylococcus aureus, a vancomycin-resistant Enterococcus faecalis, a vancomycin-intermediate Staphylococcus epidermidis, and an extended-spectrum beta-lactamase (ESβL)-producing Klebsiella pneumoniae). Testing results were compared with reference testing results from the Centers for Disease Control and Prevention.

Results:

Of 138 laboratories testing imipenem against the Serratia marcescens strain, 110 (80%) correctly reported minimum inhibitory concentrations (MICs) or zone sizes in the resistant range. All 193 participating laboratories correctly reported the Staphylococcus aureus strain as oxacillin resistant. Of the 193 laboratories, 169 (88%) reported correct MICs or zone sizes for the vancomycin-resistant Enterococcus faecalis. One hundred sixty-two (84%) of 193 laboratories demonstrated the ability to detect a vancomycin-intermediate strain of Staphylococcus epidermidis; however, disk diffusion performed poorly when testing both staphylococci and enterococci with vancomycin. Although laboratory personnel correctly reported nonsusceptible extended-spectrum cephalosporins and aztreonam results for K. pneumoniae, only 98 (51%) of 193 correctly reported this organism as an ESβL producer.

Conclusion:

Overall, NNIS System hospital laboratory personnel detected most emerging resistance patterns. Disk diffusion continues to be unreliable for vancomycin testing of staphylococci and must be used cautiously for enterococci. Further education on the processing of ESβL-producing organisms is warranted.

Information

Type
Orginal Articles
Copyright
Copyright © The Society for Healthcare Epidemiology of America 2003

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