• What does the BL-RED detect ?
The BL-RED detects beta-lactamases with clear activity on 3GC typically belong to Amber's class A, B and C, with main representatives like ESBL, MBL and AmpC, respectively. Oxacillinase from Amber's class D display variable hydrolysis profiles.
• What is beta-lactamase activity detected from ?
Active beta-lactamases are detected from positive blood cultures or bacterial colonies.
• From which agar plates can beta-lactamase activity be detected ?
Blood Agar Plates, MacConkey Agar Plates, Mueller-Hinton Agar.
• Which blood agar plates can be used ?
Currently, the only data available are associated with the Columbia horse blood from Biorad and, since the composition of this medium is rather standard to all other marks, they could fit too but no raw data available.
• Which blood cultures can be used ?
Both anaerobic and aerobic blood cultures from Becton Dickinson & Biomérieux can be used.
• What do customers who use blood cultures/agar plates from other manufacturers use ?
The BL-RED kit must be carried out on freshly-grown biological material, according to good microbiological practice. This test is compatible with Mueller-Hinton, MacConkey and horse blood agar-type solid culture media (Biorad), as well as with aerobic and anaerobic Becton Dickinson® and Biomérieux® brand blood culture flasks. We recommend using media that have been validated because a threshold of positivity has been determined specifically with the Dropstat reader for each of these media. A concordance should be considered with the media of other manufacturers.
• How is beta-lactamase hydrolysis activity detected ?
The BL-RED test is based on the use of an electroactive substrate, comparable to a 3GC whose enzymatic hydrolysis releases a product capable of generating an anodic oxidation current measurable by voltammetry. The intensity of such a current can be measured using screen-printed electrodes and a suitable reader configured for this use. In the BL-RED test, the measurement of a current with a greater intensity than a threshold value is the reflection of a bacterial hydrolysis activity of 3GCs, responsible for a reduced sensitivity of bacteria to these antibiotics. The substrate used in this test is not hydrolysed by penicillinases, induced cephalosporinases, or oxacillinases that do not hydrolyse 3GCs.
• How many tests are included in a kit ?
• How should the BL-RED tests be stored ?
All kits, open and unopen, must be stored between +2°C to +8°C and may under no circumstance be frozen (-20°C).
• How do the BL-RED Kits have to be shipped ?
The BL-RED Kits must be shipped refrigerated as the BL reagent should not be warmed up.
• How does the agar composition influence the measurement result of the BL-RED ?
Agar compounds may interfere with the electrochemical measurement.
• Which common ATCC strains are required for quality control ?
NCTC 13439 (Klebsiella pneumoniae) - NCTC 13438 (Klebsiella pneumoniae) - NCTC 13443 (Klebsiella pneumoniae) - NCTC 13476 (Escherichia coli).
Source : https://www.phe-culturecollections.org.uk/products/bacteria/index.jsp
• How is the Reader Performance checked ?
With a 10^-4 mol 1-hydroxyethylferrocene solution.
• Which interlaboratory comparisons did the BL-RED take part ?
Validations are in progress and will be refered to you as soon as available.
• What volume is required for the Reader for analysis ?
20µL of the mixture incubated at 37°C for one hour is required for the final analysis.
• Can measurement results be stored on the reader ?
The last three measurements are displayed on the Reader by pressing the Reader button again. Up to 248 measurement results are stored on the reader, which can be read out electronically on a computer using the DropView Software supplied with the reader on a USB key.
• How long are the BL-RED kits durable ?
BL-RED kits are stable between +2°C to +8°C for 12 months after manufacturing. All kit must be used before the expiry date indicated on the packaging.