Medical device manufacturer, BioMerieux, has issued a field safety notice (FSN) concerning its ETEST COLISTIN CO256 WW. The affected product reference numbers are 537300 and 537308.

Based on the first results of investigations due to a potential underestimation of the minimum inhibitory concentrations (MIC) values for Enterobacteriaceae and Acinetobacter, a FSN stating that ETEST COLISTIN CO256 WW can only be used for diagnostic purposes with MH-E (Mueller Hinton-E agar from the manufacturer's Ref.: 413822-413823-413824-413825) agar for Enterobacteriaceae strains was issued on 25 July 2016. Since then, further investigations were performed and the potential hazards have been identified:

• For Salmonella strains that have not the mcr-1 gene, in 20% of the cases, there is a potential of Very Major Error (VME): Resistant gives Susceptible (R → S) on ETEST COLISTIN CO256 compared to the Broth Micro-dilution (BMD) method. According to the manufacturer, there is no risk of VME for Salmonella strains that have the mcr1 gene in case of epidemiological use.
• For P.aeruginosa strains, there is a potential of VME Resistant gives Susceptible (R → S) for P.aeruginosa strains on ETEST COLISTIN CO256 compared to broth-micro dilution (BMD) method. This potential issue was already corrected by the past FSN.
• There is a potential under-estimation of the MIC values for Susceptible Enterobacteriaceae strains.

For diagnostic purposes, users can continue to use the affected product, only if it is used with MH-E agar (Mueller Hinton-E agar from the manufacturer's Ref.: 413822-413823-413824-413825) for Enterobacteriaceae (except for Salmonella strains) with the following recommendations:

• Categorization (Susceptible or Resistant) results need to be reported based on the EUCAST (S ≤2 mg/L et >2 mg/L R) critical concentrations.
• Due to the under-estimation of the MIC for Enterobacteriaceae Susceptible Strains, to verify the MIC of susceptible strains as needed with the BMD method of reference before reporting results.

If users do not use Mueller Hinton-E agar, or if users test other strains, the manufacturer recommends users to restrict its use to epidemiological surveys. In case of epidemiological use with other agars than MH-E supplied by the manufacturer, the manufacturer recommends users to validate the agar before use.

Among tests previously performed, the manufacturer is asking users to identify any possible false susceptible results, analyze the related risks and determine appropriate actions if relevant.

According to the local supplier, the affected products are distributed in Hong Kong.

If you are in possession of the products, please contact your supplier for necessary actions.

Posted on 16 December 2016