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Evaluation of the PASCO strep plus broth microdilution antimicrobial susceptibility panels for testing Streptococcus
1Hospital Infections Program, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.
Abstract:
Antimicrobial resistance continues to increase worldwide among isolates of Streptococcus pneumoniae and other species of streptococci. Increasing rates of penicillin resistance, particularly in viridans group streptococci, and resistance to multiple classes of antimicrobial agents, including beta-lactams, macrolides, and fluoroquinolones, in pneumococci have increased the importance of having accurate antimicrobial susceptibility testing results for guiding therapy. One commercial method of assessing resistance in streptococci is the PASCO Strep Plus panel. This broth microdilution-based method has recently been expanded to include a variety of newer antimicrobial agents. Therefore, we compared the results of the new PASCO Strep Plus panels for 26 antimicrobial agents against the results generated using the National Committee for Clinical Laboratory Standards (NCCLS) broth microdilution reference method for 75 pneumococci and 68 other streptococcal isolates. Only 4 (0.2%) very major errors (all with pneumococci and each with a different antimicrobial agent) were observed. There were 5 (0.3%) major errors observed with pneumococci (each with a different antimicrobial agent), but only 1 major error with nonpneumococcal streptococci. All of the very major and major errors resolved on retesting. Of the 65 (3.9%) and 17 (1.6%) minor errors observed with pneumococci and other streptococci, respectively, all were within 1 dilution of the broth microdilution reference MIC result. Thus, the PASCO Strep Plus panel has comparable accuracy to the NCCLS broth microdilution reference method.
Insights
Accurate antimicrobial susceptibility testing is crucial for treating Streptococcus pneumoniae and other streptococci infections. The PASCO Strep Plus panel demonstrates comparable accuracy to the NCCLS reference method for identifying antimicrobial resistance in these bacteria.
Area of Science:
- Clinical microbiology
- Infectious diseases
- Antimicrobial resistance
Background:
- Antimicrobial resistance in Streptococcus pneumoniae and other streptococci is a growing global concern.
- Increasing resistance to beta-lactams, macrolides, and fluoroquinolones necessitates reliable susceptibility testing.
- Accurate results guide effective antimicrobial therapy for streptococcal infections.
Purpose of the Study:
- To evaluate the accuracy of the commercial PASCO Strep Plus panel.
- To compare its performance against the NCCLS broth microdilution reference method.
- To assess its utility for antimicrobial susceptibility testing of streptococci.
Main Methods:
- Broth microdilution method was used for testing.
- The PASCO Strep Plus panel was compared to the NCCLS reference method.
- Seventy-five pneumococcal and 68 non-pneumococcal streptococcal isolates were tested against 26 antimicrobial agents.
Main Results:
- Very few very major (0.2%) and major (0.3%) errors were observed, with all resolving upon retesting.
- Minor errors were within one dilution of the reference method's minimum inhibitory concentration (MIC).
- The PASCO Strep Plus panel showed comparable accuracy to the NCCLS reference method.
Conclusions:
- The PASCO Strep Plus panel is a reliable tool for antimicrobial susceptibility testing of streptococci.
- Its accuracy supports its use in clinical laboratories for guiding therapy.
- This method aids in managing infections caused by resistant streptococcal strains.