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Note: reference 412324 is not registered in the united states.The u.S.Similar device is product reference 412323.A customer in (b)(6) notified biomerieux of obtaining false susceptible daptomycin results in association with the etest® daptomycin cpc 256 ww s30 test strips (ref.412324, lot 1007847460) when testing sixteen (16) randomly selected enterococcus faecalis isolates from frozen storage.The customer obtained the false susceptible results when performing a comparison study with the vitek® 2 ast-p643 test kit (ref.418671, lot 7431337103).The customer noted all sixteen (16) isolates obtained susceptible mic results ranging from 0.19 to 0.75 when tested with etest® daptomycin cpc 256 ww s30 test strips and resistant mic results when tested on the vitek® 2.The customer submitted four (4) strains to biomérieux for investigation.The isolates were confirmed to be e.Faecalis by vitek® ms.Broth microdilution testing determined all four (4) of the submitted strains were either in agreement or in essential agreement (within two doubling dilutions) with the vitek 2 results.As the false susceptible daptomycin etest® results obtained with lot 1007847460 occurred during a study and not for clinical testing, there is no adverse impact to any patient¿s state of health.Further internal investigation will occur regarding the false susceptible daptomycin etest® results.
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A customer in australia notified biomérieux of obtaining false susceptible daptomycin results in association with the etest® daptomycin cpc 256 ww s30 test strips (ref.412324, lot 1007847460) when testing sixteen (16) randomly selected enterococcus faecalis isolates from frozen storage.The following strains were provided by the customer for the investigation : -390036696 jh20m434112; -395211494 jh20m430349; -388184217 jh20m436300; and -391540369 jh20m431781.Historical review: the qc results obtained prior to product release of etest lot 1007847460 are within the expected range.The mic values obtained are the following : - e.Faecalis atcc® 29212¿ : mic values between 1 and 1.5 g/ml (expected range : 1 ¿ 4 g/ml).- s.Aureus atcc® 29213¿ : mic values between 0.25 and 0.38 g/ml (expected range : 0.25 ¿ 1 g/ml).- s.Pneumoniae atcc® 49619¿ : mic values between 0.094 and 0.125 g/ml (expected range : 0.064 ¿ 0.5 g/ml).Review of historical complaint records identified no other complaints were registered for the customer¿s lot number for this type of issue.Investigation: the identification of the four submitted strains were confirmed via vitek® 2 as e.Faecalis.Retained samples for the impacted etest lot number (1007847460) were tested in parallel with one internal etest lot number used as a reference lot (reference 412324, lot 1008193720, expiry date on 24-july-2022).The tests were performed using the quality control (qc) strains enterococcus faecalis atcc® 29212¿, staphylococcus aureus atcc® 29213¿ and streptococcus pneumoniae atcc® 49619¿ according to the qc protocol used for the release of each etest lot.Three (3) etest daptomycin strips were tested per strain for each lot number.The reference method, broth microdilution (bmd), was performed to determine the expected daptomycin (dap) mic.Note that daptomycin clsi 2021 breakpoints are [s = 2 - i 4 - r = 8].The following results were obtained with bmd: - s1 (395211494 jh2om430349) dap mic = 2 g/ml = s; - s2 (391540369 jh2om431781) dap mic = 1 g/ml = s; - s3 (390036696 jh2om434112) dap mic = 4 g/ml = i; and - s4 (388184217 jh2om436300) dap mic = 2 g/ml = s.Strains s1, s3 and s4 are borderline strains; their mics are on the breakpoint therefore the interpretation can shift from susceptible to intermediate for s1 and s4, and from intermediate to susceptible or resistant for s3 within one doubling dilution.The four submitted strains were tested with etest daptomycin (dpc) 256 (ref 412324, lot# 1007847460, exp.29 january 2022) in parallel with a reference lot 1008193720 (exp.24 july 2022).The following results were obtained with etest: - s1 etest dpc mics = 0.5 ¿g/ml = s on both lots.- s2, s3 and s4 etest dpc mics = 1 g/ml = s on both lots.For strain s1, the etest mics (0.5 g/ml = s) are essential agreement errors compared to the reference method mic (2 g/ml = s) with no category error.For strain s2, the etest mics (1 g/ml = s) are within essential agreement compared to the reference mic (1 ¿g/ml = s) with no category error.For strain s3, the etest mics (1 g/ml = s) are essential agreement errors compared to the reference mic (4 g/ml = i) that leads to minor category errors (susceptible for intermediate).For strain s4, the etest mics (1 g/ml = s) are within essential agreement compared to the reference mic (2 g/ml = s) with no category error.Susceptible results obtained by the customer were also obtained internally for the four strains tested.The etest results are within category agreement compared to the bmd reference method with a minor category error for s3.However, the results are indeed 1 to 2 dilutions lower than the reference method.The mics are on the breakpoint, therefore the interpretation can shift from susceptible to intermediate for s1 and s4, and from intermediate to susceptible or resistant for s3 within one doubling dilution.Etest results are within category agreement compared to the bmd reference method with a minor category error for s3.Conclusion: the results of the quality control tests obtained during our investigation on the impacted etest® daptomycin (dpc 256) lot complied with specifications for all the strains tested.Testing on the customer strains reproduced the issue reported.Results obtained with bmd, show that strains s1, s3 and s4 are borderline strains because their mics are on the breakpoint; therefore the interpretation can shift from susceptible to intermediate for s1 and s4, and from intermediate to susceptible or resistant for s3 within one doubling dilution.Etest results are within category agreement compared to the bmd reference method with a minor category error for s3.
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