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An internal investigation was performed following notification from a customer in germany they obtained misidentifications for two isolates collected from environmental monitoring in association with the vitek® ms (ref 410895, serial (b)(4).As the two isolates were collected from environmental monitoring samples, there is no patient involved.Investigation: device history record and complaint analysis review of the complaint database and device history record did not reveal this to be any systemic quality problem.Fine tuning status good at the time of acquisition.Spot preparation quality the customer¿s spot preparation quality was not optimal.The calibrator and sample ¿all peaks¿ values were heterogeneous.Knowledge base review the expected identification is unknown because no reference method was used to confirm the identification.Sample data analysis: sample 22s00545 ,the misidentification as bacillus cereus mentioned in this case was not observed.The no identification results were obtained from spectra having a correct amount of peaks (between 53 to 83).Analysis of mzml sample files show that number of all peaks are heterogeneous during the issue (53 and 83).This could be explained by a non-optimal spot preparation of the sample strain (culture, spot, different operator¿)."no identification" results are not a product malfunction.The system did not provide any misidentification and informed the customer that the strain could not be identified.Where a no identification result is obtained, customer has to follow the process described in the vitek workflow user manual 161150-127-c: ¿repeat the acquisition for the same deposit.If the message is displayed again, redo the deposit and then the acquisition.If the message is displayed again, repeat the identification using another method (such as vitek® 2, api strip, other biochemical or molecular methods).¿ by reprocessing the customer data with vitek ms kb v3.2, the result continue to be 'no identification.' reprocessing the customer data with vitek ms kb v3.3 (under development), spectra led to staphylococcus petrasii which is not present in the vitek ms kb v3.1.The issue is due to a system limitation with the vitek ms kb v3.1 (species not present in the knowledge base library).The following system limitation is mentioned in the vitek ms v3.1 knowledge base user manual ref.161150-564-a: ¿* testing of species not found in the database may result in an unidentified result or a misidentification.* interpretation of results and use of the vitek ms system require a competent laboratorian who should judiciously make use of experience, specimen information, and other pertinent procedures before reporting the identification of test organisms.Additional information known to the user, such as gram stain reaction, colonial and cellular morphology, and growth aerobically or in co2 should be considered when accepting vitek ms results.¿ sample 22s00525 the results were obtained from spectra having a low number of peaks (between 31 to 34) and a low identification score (between -0.15 to -0.37) which is near the acceptable limit for giving an ¿identification¿ result or a ¿no identification¿ result.When the number of peaks is just over 30, the risk to get ¿doubtful¿ results is high due to a lack of information (missing peaks, not enough peaks to eliminate candidate identification).In this case, as the fine tuning status was good, this could be explained by a non-optimal spot preparation of the sample strain.Reprocessing the customer data with vitek ms kb v3.2 yields the same result.Reprocessing the customer data with vitek ms kb v3.3 (under development), 2 spectra led to no identification and 1 spectra led to a single choice to corynebacterium afermentans ssp afermentans with a low score (-0.35).Based on these findings, it could also be a species outside of the vitek ms kb.The identification of the strain has to be confirmed by a reference method.*expected identification after investigation -sample 22s00545 : the most probable identification is staphylococcus petrasii (to be confirmed by reference method) -sample 22s00525 : it could be corynebacterium afermentans ssp afermentans (it has to be confirmed by reference method) conclusion per the investigation, the issue appears to be due to a combination of non-optimal spot preparation as well as a known system limitation where the organism in questions is not part of the knowledge base.
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Intended use: vitek® ms is a mass spectrometry system using matrix-assisted laser desorption/ionization time of flight mass spectrometry (maldi-tof ms) for the identification of microorganisms cultured from human specimens.The vitek® ms system is a qualitative in vitro diagnostic device indicated for use in conjunction with other clinical and laboratory findings to aid in the diagnosis of bacterial, yeast and mold infections.Description: a customer in germany notified biomérieux of obtaining misidentifications for two isolates collected from environmental monitoring in association with the vitek® ms (ref 410895, serial (b)(4).For one isolate (22s00545), three spots were prepared and the customer reported obtaining a result of bacillus cereus group (gram-positive rods) while the microscopic identification showed micrococci.The misidentification was obtained only for one of the three spots."no identification" was obtained for the other two spots.The culture plate showed no signs of mixed culture.For a second isolate (22s00525), three spots were prepared and the customer reported obtaining an identification of corynebacterium afermentans for two spots while an identification of clostridium cadaveris was obtained for one spot.The customer reported that the result of clostridium cadaveris is a misidentification as c.Cadaveris is an obligate anaerobe and the cultures were prepared aerobically.The culture plate showed no signs of mixed culture.As the two isolates were collected from environmental monitoring samples, there is no patient involved.A biomérieux internal investigation was performed.
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