A biomérieux internal investigation was performed to examine this issue.The customer¿s strain was requested but not submitted for the investigation.The production records for the lot in question were reviewed, and no anomalies were noted.The quality controls for lot number 1008219170, reference 43841, conformed with specifications.The three retained chromid® mrsa agar samples of the impacted lot number 1008219170 were tested in parallel with one internal lot number used as reference (one retained sample only coming from lot 1008233970, expiry date on 04-nov-2020).Results obtained with routine qc strains remain conform with specification and were equivalent between both lots tested during the investigation.In parallel, the internal collection strain staphylococcus hominis atcc® 700236 was tested according to the qc protocol on the three retained kits of the impacted lot number and on the retained kit of the lot number used as reference.A good growth of the strain was observed after 24h incubation at 33-37°c with white colonies.Although the instructions for use of this reference product recommend that culture should be examined after 24h incubation only, we extended the incubation to 48h to observe the behavior of the strain.Indeed, some colonies of this strain of staphylococcus hominis turned to pale green.In summary, testing carried out with staphylococcus hominis atcc® 700236 showed good growth with colorless colonies after 24h incubation and pale green colonies after 48h incubation on both lots tested.During the development of chromid® (b)(6) agar, it was noted that some coagulase negative staphylococci, including staphylococcus hominis, may develop on the agar after 24h.For this reason a limitation has been added to the instructions for use: ¿the following (b)(6) organisms may grow on chromid® (b)(6) but do not produce green pigmented colonies at 24 hours: acinetobacter baumannii, citrobacter freundi (carbapenemase-producing ndm), corynebacterium jeikeium, enterobacter cloacae, pseudomonas aeruginosa, pseudomonas putida, staphylococcus capitis, staphylococcus hominis ((b)(6)), staphylococcus sciuri (oxacillin susceptible), staphylococcus warneri ((b)(6)), stenotrophomonas maltophilia, and micrococcus spp.¿ the performance of the lot is within specifications, and the investigation did not identify a product performance issue.
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