Product description: etest® is a manual, quantitative technique for the determination of antimicrobial susceptibility of non-fastidious gram-negative and gram-positive aerobic bacteria and fastidious bacteria.The system comprises a predefined antibiotic gradient which is used to determine the minimum inhibitory concentration (mic, in g/ml) of different antimicrobial agents against microorganisms tested on agar media after overnight incubation.Complaint description: a customer in the united states complained after having obtained incorrect antibiotic susceptibility test results when testing five patients' samples' using etest technique.The customer said that they had tested vancomycin-resistant enterococci (vre) isolated from 5 different patients' samples' using etest daptomycin dpc 256 us s30 - reference (b)(4) (lot#1010146860 - expiration date : 19/07/2025) in association with mueller hinton plates and that they had obtained daptomycin resistant results.The customer reported that they had noticed inconsistent results with daptomycin etest when using mueller hinton small plates compared with mueller hinton large plates.Lot information were not provided by the customer.The customer said that they had obtained the same discrepant resistant dapotomicyn results when testing the same strains using their second lot of etest daptomycin dpc 256 us s30 - reference (b)(4).This event has been recorded under cn-(b)(4).The customer mentioned that they had sent these strains to their reference laboratory (arup) for testing.The reference laboratory tested the strains using broth microdilution technique and had obtained susceptible results.The customer indicated that only the arup results were reported to the patient charts.Customer confirmed that no biased patient results were reported to a physician.At the time of the assessment, there is no indication or report from the customer that this event led to death, serious injury, or serious deterioration in the state of health for any patient.
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Following the false resistant daptomycin with vancomycin-resistant enterococci (vre) isolates reported by the customer when testing suspensions of microoganisms isolated from 5 different patients' samples' using etest daptomycin dpc 256 us s30 - reference 412323 (lot#1010146860 and 009977190) an investingation has been carried out at biomérieux manufcturing site.Retained samples analysis biomérieux retains samples of every lot number released to the market.The retained samples from the impacted lot numbers 1010146860 and 1009977190 were tested in parallel with an internal lot number used as a reference lot (reference 412323, lot 1009548780, expiry date 22 aug 2024).The tests were performed by using the quality control (qc) strains staphylococcus aureus atcc 29213, enterococcus faecalis atcc 29212 and streptococcus pneumoniae atcc 49619 according to the quality control protocol used for the release of each lot number.Compliant results were obtained for the three strains tested on all etest lot numbers.Strains return analysis four enterococcus faecium strains have been received from the customer for analysis.1) testing of patient sample using reference method the reference method broth micro dilution (bmd) was performed and the minimum inhibitory concentration (mic) values obtained were 4 g/ml for the four strains tested.Following the clsi breakpoints 2024 for enterococcus faecium / daptomycin [s = 4 ¿ r = 8], the strains are on the breakpoints so, within one doubling dilution, the category can be susceptible (s) or resistant (r).The four strains can be considered as borderline strains for daptomycin.2) testing of patient sample or reference material using manufacturer's device the four strains were tested in parallel on etest daptomycin (dpc 256) lot numbers 1009977190 (customer lot) ; 1010146860 (customer lot ) and on the lot number 1009548780 used as reference lot.Among the four strains tested, two strains showed resistant results on the three etest lots tested with mic values at 8 g/ml.These two strains are within essential agreement compared to the bmd method.The third strain showed resistant results (mic equal to 8 g/ml) for etest lot numbers 1009977190 (related to the complaint) and 1009548780 (reference lot) and showed susceptible results (mic equal to 4 g/ml) for the etest lot number 1010146860.This strain is also within essential agreement compared to the bmd method.Concerning the fourth strain, resistant results were obtained for the three etest lot numbers tested with mic values equal to 8 g/ml for the etest reference lot and equal to 16 g/ml for the two etest lot 1009977190 and lot 1010146860 for this strain, essential agreement error is observed for the two lot numbers related to the complaints while the etest reference lot is within essential agreement compared to the bmd method.Considering the global results obtained during the investigation, the etest daptomycin (dpc 256) performances are not questioned as the etest lots tested are within essential agreement compared to the bmd method for three strains tested.Complaint analysis the complaint analysis did not indicate any systematic quality issue for the product etest® daptomycin (dpc 256), reference (b)(4).Conclusion no product issue was observed on the lot numbers 1009977190 and 1010146860 during the tests performed on the retained samples with quality control strains.The etest lots tested are within essential agreement compared to the bmd method for three strains out of four.Following the clsi breakpoints 2024 for enterococcus faecium / daptomycin [s = 4 ¿ r = 8] and the results obtained with bmd, the four returned strains are on the breakpoints and can be considered as borderline strains.This explained the difference of category we can observed between bmd (s results) and etest dpc (r results) as, within one doubling dilution, the category can be susceptible (s) or resistant (r).The complaint trend analysis does not show any negative trend for the product etest® daptomycin (dpc 256), reference (b)(4).Based on these elements, the performance of the two complained etest lot numbers are not questioned.
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