This report was initially submitted following notification that a customer in the united states reported the occurrence of out-of-range-low (oorl) qc results (eggerthella lenta atcc® 43055¿) in association with the etest® tlc256 foam packaging (ref.522658) batches 1004598840 and 1004910630.On the supplement insert, the range for this qc strain is 16-64 ¿g/ml.The results of the customer were 4-8 ¿g/ml.The qc strain atcc® 43055¿ is not a strain that is tested for discharge control.A different anaerobic qc strain (bacteroides thetaiotaomicron atcc® 29741¿) is indicated in the u.S.Supplement insert; test results for this qc strain are within specification at the customer site.This last qc strain is tested for discharge control.Biomérieux investigation was conducted.The following qc strains claimed in the u.S.Package insert were tested with etest® tlc256 foam packaging (ref.522658) batches 1004598840 and 1004910630 (customer batches) and 1004439730 (reference batch): atcc® 27853¿ (pseudomonas aeruginosa), atcc® 25922¿ (escherichia coli), atcc® 29212¿ (enterococcus faecalis), atcc® 35218¿ (escherichia coli), atcc® 29741¿ (bacteroides thetaiotaomicron).The results for each qc strain were in specification for each of the three batches tested.The qc strain eggerthella lenta atcc® 43055¿ gave an oorl mic with each of the three batches tested.The expected range for this strain is 16-64 ¿g/ml while the results obtained were 6 or 8 ¿g/ml.Therefore, the non-conformity observed by the customer was reproduced.The batches were also tested with an incubation of 72 hours rather than 48 hours as performed by the customer.The package insert (ref.15203) indicates to incubate the strain during 24h, 48h or 72h: batch 1004598840 : mic = 8¿g/ml with 48 hours and 72 hours of incubation: oorl.Batch 1004910630 => mic = 8¿g/ml with 48 hours of incubation : oorl, and 12¿g/ml with 72 hours of incubation: oorl.Batch 1004439730 : mic = 6¿g/ml with 48 hours and 72 hours of incubation: oorl.Etest® tlc is widely used for susceptibility testing of gram-negative and gram-positive anaerobic bacteria.Since the quality control strain eggerthella lenta atcc® 43055¿ is recurrently out of range low, potential false susceptible results (s instead of r) might be obtained with this organism, as well as with the other gram-positive anaerobes which are clostridium, peptostreptococcus and propionibacterium.Of note, the anaerobic gram-negative bacteria are not impacted since the representative qc strain bacteroides thetaiotaomicron atcc® 29741¿ remains in range.A health hazard assessment (hha) was performed.The hha concluded that the overall risk to patients is minor to irrelevant.The investigation concluded the customer can continue to used etest® tlc256, except for gram-positive anaerobes in the event of gram-positive qc failure.
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