ERP Micro December 2019

1604  B astin et al . : J ournal of AOAC I nternational V ol . 101, N o . 5, 2018

When testing is complete, all materials possibly containing pathogens should be decontaminated following current industry standards for the disposal of contaminated waste (i.e., autoclave for 30 min at 121°C). Consult the Safety Data Sheet for additional information and local regulations for disposal. To reduce the risks associated with environmental contamination, follow current local/regional/national standards for disposal of contaminated waste. D. General Preparation ( a )  Isolation of organisms for testing .—Organisms for testing must be isolated on one of the recommended media. Please refer to the MALDI Biotyper System Quick Guide for Food Testing (No. 1855438) for a list of recommended isolation media ( Salmonella species: XLD, BGSA, RSA, BSA, and ASAP, or any nonselective agars; Cronobacter species: ESIA, CCI, 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 (unknown cultures cannot be refrigerated prior to identification, and spotted target overlaid with HCCAMatrix must be analyzed within 24 h). ( b )  Preparation of Bacterial Test Standard (BTS) .—Add 50 μL of 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 (15871 to 21130 g, equivalent to 13000 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 .—Prepare 70% formic acid by transferring 70 μL of formic acid to 30 μL of HPLC grade water. ( d )  Preparation of matrix .—Add 250 μL of 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. E. Cleaning Target Plate: Reusable Polished Stainless Steel Targets Plates Only When using reusable polished stainless steel targets plates, two procedures can be followed to guarantee an appropriate and efficient cleaning of the reusable polished stainless steel target plates, one using trifluoracetic acid and one using guanidine hydrochloride (a) Trifluoracetic acid procedure (conducted in a fume cabinet). —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. General Instructions

Follow all instructions carefully. Failure to do so may lead to inaccurate results. Caution: Laser class. —The MALDI Biotyper System with a closed safety cover is a Class 1 Laser (exempt from all beam hazard control measures) product. With the safety cover opened, it becomes a Class 4 Laser (considered to be hazardous to the skin and eyes from direct and scattered radiation) product. It has been designed and tested in accordance with International Electrotechnical Commission Publication 1010-1 (Pollution Degree 2) Safety Requirements for Electrical Equipment for Measurement, Control, and Laboratory Use. Do not use the MALDI Biotyper System until it has been installed by a Bruker service representative and laboratory staff have been appropriately trained by a Bruker representative. Read the User Manual for the microflex LT/SH smart (No. 605415) or the microflex (No. 1831173) for operational and safety instructions before using the MALDI Biotyper System. Please refer to all User Manuals listed below for the complete safety precautions. ( a ) Instructions for Use MBT Galaxy HCCA Matrix GPR when using the Galaxy to support the sample preparation. The user should read, understand, and follow all safety information in the instructions for the Bruker method. Retain the safety instructions for future reference. To reduce the risks associated with exposure to chemicals and biohazards, perform microbiological testing in a properly equipped laboratory under the control of trained personnel. Always follow standard laboratory safety practices, including wearing appropriate protective apparel and eye protection while handling chemicals, reagents, and contaminated samples. Avoid contact with the isolates and reagents. Dispose of isolates, chemicals, and reagents according to current local/regional/national guidelines. The Bruker MALDI Biotyper can detect biosafety level 2/3 organisms. Biological samples have the potential to transmit infectious diseases. Follow all applicable local, state/provincial, and/or national regulations on disposal of biological wastes. Wear appropriate protective equipment, which includes but is not limited to protective eyewear, face shield, clothing/lab coat, and gloves. All work should be conducted in properly equipped facilities utilizing the appropriate safety equipment (e.g., physical containment devices). Individuals should be trained in accordance with applicable regulatory and company/ institution requirements before working with potentially infectious materials. The cleaning of the target plates should be conducted in a fume cabinet. When testing foodborne bacterial isolates, a risk assessment should be performed for any new tests to determine the safety of the protocols and whether this procedure should be performed in a biological safety cabinet. In addition, the use of chemicals and the need to perform certain steps in a fume hood should also be evaluated. ( b ) Instructions for Use MBT Biotarget 96. ( c ) Instructions for USE Bruker Matrix HCCA. ( d ) Instructions for Use Bruker BTS. ( e ) User Manual MBT Subtyping Module. ( f ) User Manual MBT Compass. ( g ) User Manual MBT Explorer Module. ( h ) User Manual microflex LT/SH Smart. ( i ) User Manual microflex.