ERP Micro December 2019

1608  B astin et al . : J ournal of AOAC I nternational V ol . 102, N o . 5, 2019

Table 2017.09R. Comparative results for the confirmation of Gram-negative organisms ( Cronobacter exclusivity)

Candidate Chromogenic Cronobacter Isolation Agar

Candidate Tryptic Soy Agar

Candidate Enterobacter sakazakii Isolation Agar

Ref. Tryptic Soy Agar

X  a

N  b

Percent PA c

Target

Collaborator

Percent PA

Percent PA

Percent PA

X N

X N

X N

Gram-negative organisms

1 2 3 4 5 6 7 8 9

8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8

100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0

8 8 8 8 8 8 7 7 d 8 8 8 8 8 8 8 8 7 8 8 8 8 8 5 5 e 5 5 e 6 6 f

100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 88.0

8 8 8 8 8 8 8 8 8 8 8 8 7 7 d 8 8 8 8 8 8 8 8 8 8 7 7 d 6 6 f

100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0

8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8

100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0

10 11 12 13 14

a X = Number of correct identifications. b N = Total number of isolates tested. c  PA = Positive agreement.

d  No growth observed on agar for one isolate. e  No growth observed on agar for three isolates. f   No growth observed on agar for two isolates.

( q )  BGA, standard formulation. ( r )  RSA . ( s )  ASAP . ( t )  BSA . ( u )  ESIA, standard formulation. ( v )  CCI, standard formulation. ( w )  CBA, standard formulation. ( x )  mCCDA, standard formulation. ( y )  CCA, standard formulation. ( z )  RCA . ( aa )  CFA . ( bb )  Vortex mixer.

( a )  Microflex LT/SH MALDI-MS System (Cat. No. 8269956) or MALDI Biotyper Smart System (Cat. No. 1853665). ( b )  MBT Compass Library (version with 6903 MSPs or higher) .—Cat. No. 1829023. ( c )  MBT Compass software .—Cat. No. 1843241. ( d )  MBT Explorer module .—Cat. No. 1828476. ( e )  Barcode scanner (Cat. No. 8268821). —Optional. ( f )  Holder for barcode scanner (Cat. No. 8276754). — Optional. ( g )  MSP 96 target polished steel BC (Cat. No. 8280800), MSP 48 target polished steel BC (Cat. No. 8281817), or MBT Biotarget 96 (Cat. No. 1840375) with the MSP adapter MALDI Biotarget (Cat. No. 8267615). ( h )  α-Cyano-4 hydroxycinnamic acid (HCCA) matrix, portioned (Cat. No. 8255344), or MBT Galaxy ™ HCCA Matrix GPR (Cat. No. 1823405). ( i )  Internal positive E. coli DNA .—Bacterial test standard (BTS, Cat. No. 8255343). Additional items required: ( j )  Incubators .—Capable of maintaining temperatures of 34–38°C. ( k )  Pipets .—Adjustable, variable volume, capable of sampling and delivering 1–1000 μL. ( l )  Micropipet tips .—Aerosol-resistant. ( m )  Refrigerator .—Capable of maintaining 2–8°C. ( n )  Freezer .—Capable of maintaining –20°C.

( cc )  Bench-top microcentrifuge .—Eppendorf centrifuge, Model No. 5424R or equivalent, capable of 15871–21130 × g . ( dd )  Standard solvent .—Acetonitrile 50%, water 47.5%, and trifluoroacetic acid 2.5%. ( ee )  HPLC grade water. ( ff )  Formic acid. ( gg )  McFarland standards. ( hh )  Absolute ethanol. ( ii )  Guanidine hydrochloride (GdnHCl, 8 M). — Commercially available. ( jj )  Trifluoroacetic acid.

( kk )  Colony transfer device. ( ll )  Sterile inoculation loops. ( mm )  Microcentrifuge tubes. —1.5 mL.

( nn )  Fiber-free cloth .—For the cleaning of MSP 96 target polished steel BC (Cat. No. 82808000) or MSP 48 target polished steel BC (Cat. No. 8281817).

( o )  TSA, standard formulation. ( p )  XLD, standard formulation.