A customer in (b)(6) notified biomérieux of obtaining discrepant ceftolozane/tazobactam results for enterobacter cloacae between the vitek® 2 ast-xn13 test kit and the etest® cxa/tazo/con-4 c/t ww s30 (ref 414447, lot 1007622890).The customer was performing a validation of their new vitek® 2 ast-xn13 cards and reported that the ast-xn13 cards obtained false resistant results compared to the etest® cxa/tazo/con-4 c/t ww s30.An internal biomérieux investigation was performed and determined that the expected ceftolozane/tazobactam result is actually resistant.Broth microdilution (bmd) testing was performed on the customer's isolate as bmd is the reference method used for the development of the ceftolozane/tazobactam (ct01n) on the ast-xn13 card.The bmd results obtained during the investigation were mic = 32 mg/l (resistant) customer testing: vitek® 2 ast-xn13: mic = 32 mg/l (resistant) etest®: mic = 2 mg/l (susceptible) investigational testing: bmd: mic = 32 mg/l (resistant) there is no indication or report from the customer that this event led to any adverse event related to the patient's state of health.A biomérieux internal investigation related to the etest discrepancies has been initiated.Note: etest® cxa/tazo/con-4 c/t ww s30 (ref 414447) is not registered for use in the united states.The product list tool shows the pr registration status as "onhold".However a similar product, etest® ceftolozane/tazo c/t us s30 (ref 414445), is registered for use in the united states (k170670).
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Supplement 1: an investigation was initiated in response to a customer complaint of obtaining discrepant ceftolozane/tazobactam results for enterobacter cloacae between the vitek® 2 ast-xn13 test kit and the etest® cxa/tazo/con-4 c/t ww s30 (ref (b)(4), lot 1007622890).The customer was performing a validation of their new vitek® 2 ast-xn13 cards and reported that the ast-xn13 cards obtained false resistant results compared to the etest® cxa/tazo/con-4 c/t ww s30.As previously reported, the initial investigation into the discrepant results determined that the expected result for this enterobacter cloacae strain should be ceftolozane/tazobactam resistant.However, after observing broth microdilution (bmd) result discrepancies between biomérieux site laboratories performing the investigational testing, further testing was completed and ultimately determined that the strain should be ceftolozane/tazobactam susceptible.Investigation complaint trend analysis: a complaint trend analysis was performed for etest c/t lot 1007622890.No other complaint was reported on this lot of etest c/t.Quality control strains: retained samples for etest c/t, reference (b)(4) - lot number 1007622890 were tested in parallel with etest c/t, lot number 1008570550, used as reference.For the 5 qc strains tested, all the results complied with specifications for the both etest lots tested.Customer strain testing: the identification of the provided strain was confirmed to be enterobacter cloacae complex with vitek 2 gn test kit (ref (b)(4)).The customer's strain was tested using retain samples of etest c/t from the customer's lot (1007622890) and a random lot (1008390040), and compared to results obtained from broth microdilution (bmd) since this is the reference method used for the development of etest c/t.All etest results were mic = 2 g/ml (s) with both lots.These results are within essential agreement compared to the bmd mic = 2 g/ml (s) without any category error.Regarding the associated vitek 2 ast-xn13 test kit discrepancy, additional investigational testing was conducted.Vitek 2 ast-xn13 and vitek 2 ast-xn12 cards, using the same drug composition (ctn01) for ceftolozane/tazobactam were tested in parallel with the reference method (bmd).For all vitek 2 cards tested, a resistant c/t mic = 8 g/ml was obtained while the bmd results were mic = 2 g/ml (s).Complaint trending was completed and did not identify this issue as a trend for the vitek 2 ast- xn13.In accordance with section 2.15 of the fda guidance "medical device reporting for manufacturers, issued november 8, 2016", biomérieux has determined the vitek 2 ast-xn13 discrepancy to be "not reportable".The mdr guidance, section 2.15, establishes that once a malfunction has caused or contributed to a death or serious injury, a presumption that the malfunction is likely to cause or contribute to a death or serious injury has been established.Based upon our mdr review and analysis of the vitek 2 mdr submissions for product code lon (vitek 2 ast gram-positive, gram-negative and streptococcus test kits), there have been no death or serious injury events reported for the organism/antibiotic combination(s) associated with this complaint for greater than two years; therefore, based upon section 2.15 of the fda guidance, establishing that they are not "likely to cause or contribute to death or serious injury" if there is recurrence.Conclusion the investigation concluded that the etest c/t is performing as intended and the susceptible results obtained by the customer align with the expected result for this strain compared to the reference method (bmd).
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