|
On 08-jun-2021, a customer from (b)(6) reported to biomérieux that they observed discrepant results (false negative) when testing two patient serum samples with vidas® lyme igm 60 tests (ref 30319, batch 1008490740, expiry date 21-dec-2021) compared to other methods.The clinical context for both patients was not reported.The first line of screening was done on triturus analyser (lyme igm) and gave a high positive result (ratio 4.37 for one patient and >5.4 for the other).Then, a confirmation test was performed on (b)(6) 2021 using vidas lyme igm 60 tests (batch 1008490740 and the results were negative: - patient n°(b)(6): tv=0.06, - patient n° (b)(6): tv=0.13.These results were obtained after a valid calibration performed on (b)(6) 2021 : - s1 rfv results: 2429 - 2412 (acceptable range [1172-2538), - c1 rfv= 1829, tv= 0.75 (positive), - c2 rfv= -2 rfv, tv= 0.00 (negative).The s1 results were within the acceptable range but close to the upper limit.The customer did not use a vortex in the calibration steps but instead homogenization by numerous manual reversals.Since the values on triturus analyzer were high, western blot was performed and was positive for both patients showing presence of antibodies against ospc antigens.Igg test with elisa technique was negative for both patients.At the time of reporting, there is no indication or report from the laboratory that the discrepant result led to any adverse event related to the patient's state of health.A biomérieux internal investigation has been initiated.Note ref.30319 is not registered in the united state; the similar device is ref.416436.
|
|
A customer from belgium notified biomérieux that they obtained discrepant results (false negative) when testing two patient serum samples with vidas lyme igm 60 tests (ref 30319, batch 1008490740, expiry date 21-dec-2021) compared to other methods.Investigation: first, the investigator reviewed the production records for the customer¿s lot (ref.30319; 1008490740).The review did not highlight any issue during manufacturing process.There were no capas nor non conformities on vidas lyme igm ref 30319 linked to customer's complaint.The complaints laboratory performed a control chart analysis using 4 internal samples (one negative and three positive), including one close to the positive cut off targeted at 0.39 tv, on 6 different batches of vidas lyme igm including lot 1008490740.The analysis of the control charts showed that all results are within specifications; results from the customer's lot is consistent with the other lots.Investigative tests were performed on internal samples available at the complaints laboratory and the customer's samples mentioned above.Three internal samples, including one negative and two positive, with one close to the positive cut off (targeted at 0.34) were tested on lyme igm ref 30319 lot 1008490740(retain kit).All the results were within specifications and similar to the results obtained before the batch released.The investigator requested samples of the isolates in question and received the following from the customer at 2-8 ° c: samples id (b)(6) , id (b)(6) and id (b)(6).The 3 patient samples were tested with two vidas lyme igm batches 1008490740 and 1008694220 and vidas lyme igg 1008628420.All the results were negative and similar to those obtained by the customer with vidas lyme igm.All the results were also negative with vidas lyme igg (ref 30320) and similar to the results obtained by the customer with elisa novatec igg.The patient sample n ° (b)(6) has been send to an external laboratory to perform a third method, igg and igm lia-liaison- diasorin method [igg <5 ua / ml (<10 negative cut off); igm 39 ua / ml (> 21 positive cut off)].The results obtained with lia-liasion were igm positive and igg negative.In a clinical point of view, according to the package insert recommendation, in the chapter performance of the vidas® lyme igm and vidas® lyme igg assays on serum, sensitivity: ¿for each stage of the disease, the sensitivity of the vidas® lyme igm and vidas® lyme igg assays, as well as the sensitivity resulting from the combination of these two tests, were expressed with a 95% confidence interval.- in a clinical context of erythema migrans: the sensitivity were between 47.3%.61.2% and - in a clinical context of neuroborreliosis: the sensitivity were between and 35.7%.58.3% - in a clinical context of arthritid / acrodermatitis: the sensitivity were between and 37.3%.40%.¿ also in the package insert: ¿notice to readers recommendations for test performance and interpretation from the second national conference on serologic diagnosis of lyme disease¿: ¿a positive igm test result alone is not recommended for use in determining active disease in persons with illness greater than 1 month's duration because the likelihood of a false-positive test result for a current infection is high for these persons.It was recommended that an igm immunoblot be considered positive if two of the following three bands are present: 24 kda (ospc) *, 39 kda (bmpa), and 41 kda (fla) (1).It was further recommended that an that igg immunoblot be considered positive if five of the following 10 bands are present: 18 kda, 21 kda (ospc) *, 28 kda, 30 kda, 39 kda (bmpa), 41 kda (fla), 45 kda, 58 kda (not groel), 66 kda, and 93 kda (2).¿ conclusion: biomérieux reproduced the negative results with two different batches of vidas lyme igm ref 30319.The negative results observed with vidas lyme igm are not linked to a specific batch.All the results obtained in lyme igg were negative whatever the method used: vidas, lia liaison diasorin or elisa novatec.The results are discrepant only for lyme igm detection.However, the clinical contexts for the samples id (b)(6) , id (b)(6) are not in favor of a primary infection and for the sample id (b)(6) we cannot be sure at 100% of the infection as there was no clinical evidence of borreliosis.In the package insert, chapter limitations of the method: antibody detection methods do not provide definitive results for establishing or ruling out diagnosis of lyme borreliosis.Negative results with the vidas® lyme igm and vidas® lyme igg assays does not rule out the possibility of b.Burgdorferi infection in a patient.Patients in the early stages of infection or who have undergone antibiotic therapy, may not produce measurable igm and igg.Patients with clinical history and / or symptoms suggestive of lyme borreliosis, but with negative test results, should be reported as "no detectable antibodies to b.Burgdorferi.A second specimen should be collected 4-6 weeks later.Note: it is estimated that in 50% of subjects in the primary stage of disease, antibody levels remain below the detectable threshold.¿ to explain the lyme igm discrepant results between vidas and the other methods, the samples may have a specific profile that reacts differently depending on the method (design) used.According to the information mentioned above there is no reconsideration of performance for lyme igm batch 1008490740.
|
