A customer from the united states notified biomérieux of discrepant meropenem susceptible results when testing klebsiella pneumonia strains isolated from a patient's sample using etest® method (ref.513848, lot 1007583220).The customer stated they inoculated the suspension of the microorganism isolated from the patient's sample into biomérieux mhe agar and applied the meropenem etest strip lot 1007583220; after incubation the customer obtained a meropenem mic value of 0.25 g/ml, categorizing the strain to be susceptible to this antimicrobial agent.The customer mentioned that a suspension of the same microorganism isolated for the same patient's was tested for antibiotic susceptibility test using vitek® 2 ast-gn79 test kit (ref.413436) and a mic >16 g/ml was obtained that categorized the strain to be resistant to meropenem.The customer also performed carbanp test for carbapenemase detection and a positive result was obtained; this is not consistent with the susceptible result to meropenem.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.
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This report was initially submitted following notification from a customer in the united states regarding discrepant meropenem susceptible results when testing klebsiella pneumonia strains isolated from a patient's sample using etest® method (ref.513848, lot 1007583220).The investigation included testing multiple quality control (qc) strains using the retain samples of this impacted lot 1007583220 as well as two other lots, 1007735480 and 1008195550.The qc results obtained for the strains tested were in accordance with the expected specifications and equivalent between the three lots of etest mp 32.No product performance issues were observed during the quality control investigation.The customer¿s strain was returned to biomerieux for testing.Analysis of the strain confirmed the strain was klebsiella pneumoniae ssp pneumoniae.Whole genome sequencing (wgs) was performed, and it confirmed the presence of a carbapenemase-producing strain (presence of the gene kpc-3).The customer¿s susceptible results obtained with etest® mp 32 lot number 1007583220 was reproduced internally on the strain provided.The strain was tested with the agar dilution (ad) methodology as it was the reference method used for the etest® meropenem (mp 32) development and with etest® mp 32 strips (lot numbers 1007583220,1007735480, and 1008062280).The etest® mp 32 mics (0.5 g/ml, 0.5 g/ml, and 0.25 g/ml, respectively) were within essential agreement compared to the reference mic (agar dilution 0.25 g/ml, susceptible) without any category error.The device performed as expected.This phenomenon with some strains characterized as ¿carbapenemase-producing bacteria ¿ and having a low susceptibility to carbapenems, is known.See section h10.
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