ERP Micro December 2019

Table 2017.09F. Summary of results for the confirmation of Cronobacter: Inclusivity

Correctly confirmed

Incorrectly confirmed

Total

Selective media no growth

Organism

MALDI Biotyper Reference

MALDI Biotyper

Reference

MALDI Biotyper Reference

C. condimenti QL 17031.1 a C. dublinensis QL 17031.2 C. dublinensis CCUG 58094 b C. malonaticus QL 123015.1A C. malonaticus CCUG 28859 C. muytjensii ATCC 51329 c C. sakazakii CCUG 21205 C. sakazakii CCUG 28857 C. sakazakii CCUG 28867 C. sakazakii CCUG 28870 C. sakazakii FSL F6-023 d

41 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42

14 14 14 12 14 13 14 14 13 12 11 14 14 14 13 14

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 2 0 1 0 0 1 2 3 0 0 0 1 0

1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

41 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42

14 14 14 14 14 14 14 14 14 14 14 14 14 14 14 14

C. sakazakii FSL F6-032 C. sakazakii FSL F6-038 C. sakazakii FSL F6-041 C. sakazakii FSL F6-046 C. sakazakii FSL F6-051

 Total isolates

671

214

10

1 e

671 f

224 g

a  QL = Q Laboratories Collection (Cincinnati, OH, USA). b  CCUG = Culture Collection University Gothenburg (Gothenburg, Sweden). c  ATCC = American Type Culture Collection biological materials resource (Manassas, VA, USA). d  FSL = Collection of the Food Safety Laboratory, Cornell University (Ithaca, NY, USA). e  No growth on CCI only. f  Total numbers represent isolates analyzed on the three recommended culture media: TSA, CCI, and ESIA. g  Reference method performed from TSA agar only.

agars; Cronobacter species: ESIA, CCI, or any nonselective agars; Campylobacter species: CBA, mCCDA, RCA, CCA, CFA, or any nonselective agars). Organisms for testing must be subcultured as necessary to ensure purity. Testing should be conducted on a culture that has been grown for 24–48 h in appropriate temperature conditions. Use only a single isolated colony (or colonies to get sufficient biological material) when performing identification on the MALDI Biotyper System. Note : Unknown cultures cannot be refrigerated prior to identification, and spotted target overlaid with HCCA Matrix must be analyzed withing 24 h. ( b ) Preparation of BTS.— Add 50 µL standard solvent to BTS tube. Dissolve by gently pipetting up and down 20 times; avoid generating bubbles. Let stand at room temperature (20–25°C) for 5 min. Repeat pipetting 20 times. Centrifuge for 2 min at maximum speed (15 871 to 21 130 g, equivalent to 13 000 to 15 000 rpm for Eppendorf tube centrifuged with a 5424R rotor). Aliquot 5 µL into microcentrifuge tubes (screw caps recommended) and store at –20°C or below for up to 5 months; do not refreeze once thawed. ( c ) Preparation of 70% formic acid.— Transfer 70 µL formic acid to 30 µL HPLC grade water. ( d ) Preparation of HCCAMatrix.— Add 250 µL standard solvent. Vortex for 1 min or until dissolved. Once reconstituted, store in the dark at room temperature (20–25°C) up to 1 week. Check for crystal formation on bottom of tube each day before use, and vortex for a minimum of 1 min if needed or until dissolved.

D. Cleaning Target Plate (Reusable Polished Stainless Steel Target Plates Only) When using reusable polished stainless steel target plates, two procedures can be followed to guarantee an appropriate and efficient cleaning of the reusable polished stainless steel target plates, one using trifluoroacetic acid and one using GdnHCl. ( a ) Trifluoroacetic acid procedure (conduct in a chemical fume hood).— Before each run, ensure that the target plate has been cleaned properly. Prepare the solutions required for cleaning targets as follows: ( 1 )  Preparation of 70% aqueous ethanol.— ( a ) To prepare 100 mL solution, measure 30 mL HPLC grade water with a graduated cylinder. ( b ) Transfer the water into a beaker. ( c ) Measure 70 mL absolute ethanol and mix with the water in a beaker. ( d ) Generate a homogeneous mixture by transferring the mixture from the beaker into the graduated cylinder and back again. ( e ) Repeat step ( d ) five times. ( 2 )  Preparation of 80% aqueous trifluoroacetic acid (conduct in a fume cabinet).— ( a ) Transfer 50 μL HPLC grade water into a 1.5 mL microcentrifuge tube. ( b ) Carefully add 200 μL trifluoroacetic acid. ( c ) Close the tube tightly. ( d ) Mix by inverting tube five times.

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