Nationwide antibiogram analysis using NCCLS M39-A guidelines

Abstract

Lack of standardization in antibiogram (ABGM) preparation (the overall profile of antimicrobial susceptibility results of a microbial species to a battery of antimicrobial agents) has not been addressed until recently. The objective of this study was to analyze current antibiograms using the recently published NCCLS M39-A guidelines for preparation of antibiograms to identify areas for improvement in the reporting of antibiogram susceptibility data. Antibiograms from across the United States were obtained by various methods, including direct mailings, Internet searches, and professional contacts. Each ABGM collected was analyzed using prospectively defined elements from the M39-A guidelines. Additionally, seven quality indicators were also evaluated to look for the reporting of any atypical or inappropriate susceptibility data. The 209 antibiograms collected from 149 institutions showed at least 85% compliance to 5 of the 10 M39-A elements analyzed. Clinically relevant elements not met included annual analysis, duplicate isolate notation, and the exclusion of organisms with fewer than 10 isolates. As for the quality indicators evaluated, unexpected results included the 7% of antibiograms that reported <100% vancomycin susceptibility for Staphylococcus aureus, 24% that had inconsistent beta-lactam susceptibility for Staphylococcus aureus, 20% that reported <100% imipenem susceptibility for Escherichia coli, and 37% that reported >0% ampicillin susceptibility for Klebsiella pneumoniae. These findings suggest that antibiograms should be reviewed thoroughly by infectious disease specialists (physicians and pharmacists), clinical microbiologists, and infection control personnel for identification of abnormal findings prior to distribution.