A customer from austria reported to biomérieux a false susceptible ertapenem result for an enterobacter cloacae complex, external quality control sample ((b)(4)), in association with etest® ertapenem etp 32 ww b30.The customer reported the etest® result was out of range low (mic 0.5 ug/ml) and the expected result was resistant (mic > = 2 ug/ml).The sample was tested with vitek® 2 and the result was mic 2 ug/ml.Testing with the disc method produced a result of 20 mm.As the issue occurred during external quality control testing, there was no patient involvement.A biomérieux internal investigation will be initiated.
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A customer from austria reported to biomérieux a false susceptible ertapenem result for an enterobacter cloacae complex, external quality control sample ((b)(4)), in association with etest® ertapenem etp 32 ww.An investigation was performed.The sample identification was confirmed as enterobacter cloacae with the vitek® 2 gn card.Susceptibility testing included the use of: clsi 2017 breakpoints enterobacteriaceae -ertapenem [ s = 0.5 - 1 - >/= 2 r ].Eucast 2017 breakpoints enterobacteriaceae -ertapenem [ s = 0.5 - > 1 r ].Reference method used for etest development: agar dilution (ad) : etp mic = 0.5 mg/l : s reference method recommended by neqas : broth microdilution (bmd) : etp mic = 1 mg/l : i mechanism of resistance detection: pcr imp, oxa48 like, kpc, ndm and vim negative (essay msast-465).A reproducibility study was performed with the etest customer lot and a reference lot, and the customer result (s) was reproduced.All qc strains (pseudomonas aeruginosa atcc 27853, escherichia coli atcc 25922, staphylococcus aureus atcc 29213, enterococcus faecalis atcc 29212, bacteroides fragilis atcc 25285, streptococcus pneumoniae atcc 49619, haemophilus influenzae atcc 49766) were conforming and the neqas strain gave mic equal to 0.5 mg/l s.The broth microdilution which is the method used by neqas, was also performed.It gave an etp mic equal to 1 mg/l i.This result is in the middle of the clsi breakpoints, so within 1 doubling dilution the category can be s or r.In conclusion , the customer's susceptible result with etest etp was duplicated.The etest etp (mic 0.5 ;g/ml s) is in essential agreement with the reference mic 0.5 mg/l, obtained with agar dilution (method used for the development of etest etp strip ) , without category error.The etest etp strip performed as intended, and no further action is required.
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