Establishing quality control ranges for temocillin following CLSI-M23-A3 guideline

Abstract

Objectives:

This study aimed to establish acceptable quality control ranges for temocillin disk diffusion tests and Etest^® minimal inhibitory concentrations.

Methods:

According to Clinical and Laboratory Standards Institute (CLSI) guideline, a Tier 2 quality control study was performed and involves seven laboratories. Each of them tested 10 replicates of two quality control strains (Escherichia coli ATCC 25922 and E. coli ATCC 35218) on three different media lots and, for disk diffusion, two disk lots.

Results:

Proposed zone diameter quality control ranges were 12–25 mm for E. coli ATCC 25922 and 19–28 mm for E. coli ATCC 35218. Proposed Etest quality control ranges were 3–24 mg/l for E. coli ATCC 25922 and 2–6 mg/l E. coli ATCC 35218.

Conclusion:

Based on our results, we would advise the use of E. coli ATCC 35218 as QC strain for temocillin susceptibility testing and Etest because ranges obtained are narrower than with E. coli ATCC 25922 and do not overlap temocillin breakpoint.

Keywords:

• Temocillin
• Quality control
• Susceptibility testing
• Etest