Overall laboratory summary: in collaboration with cdc and four ar lab network public health laboratories, we evaluated the thermofisher sensititre gn7f panel.We followed the sensititre (b)(4) only instructions for use -cid: (b)(4).Based on previous issues with a ruo sensititre panel (gnx2f), we evaluated whether the gn7f panel had similar performance issues.The five labs in this study followed the same protocol to evaluate the different transfer inoculum volumes (standard [10 ul from 0.5 mcfarland equivalent to 11 ml camhb] and increased [30 ul from 0.5 mcfarland equivalent to 11 ml camhb]) (see pg 4 in ifu).In addition, we evaluated the performance of the specific inoculum instructions for the proteeae tribe organisms (1 ul from 0.5 mcfarland equivalent to 11 ml camhb).These various inoculum levels were tested from the same 0.5 mcfarland equivalent to be able to compare the effect of these inoculum methods.Methods were otherwise according to the ifu, with the exception of two labs who used a turbidity meter instead of a sensititre nephelometer.All labs manually read the gn7f panel.In one lab, in addition to the manual read, read the panels with the aris 2x.All labs tested the same 100 organisms from the cdc & fda ar isolate bank (40 enterobacterales, 30 p.Aeruginosa, and 30 a.Baumannii).The greatest effect of the 1 ul/10 ul standard inoculum methods was observed for enterobacterales.All laboratories saw that using the 1 ul with the proteeae tribe undercalled resistance, specifically in the beta-lactam agents.Amongst all laboratories, using the 1 ul for proteeae tribe and 10 ul for non-proteeae tribe, no lab could obtain essential agreement >90% for doripenem, ertapenem, imipenem, meropenem, cefepime, piperacillin-tazobactam.All labs observed at least 1 very major error (up to 5) for doripenem, ertapenem, meropenem, aztreonam, ceftolozane-tazobactam, and piperacillin-tazobactam.Increasing the transfer inoculum of all organisms to 30 ul or 50 ul (off-label) improved ea and very major error rates.Data can be provided upon request.Fda safety report id # (b)(4).
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