After the boss's surname recognized "melamine", the boss's surname recognized a new term-β-lactamase. β-lactamase is a kind of bacteria-specific enzyme that breaks down antibiotics. It is possible that β-lactamase is detected in milk by the cow itself, or it may be produced by milk infected with some bacteria during processing . Another possibility is that β-lactamase is added artificially during the processing because it can decompose the β-lactam antibiotics left in the milk and cover the antibiotics. Detection method of β-lactamase-cup and saucer method 1 Principle This method uses a standard strain that is absolutely sensitive to penicillin drugs, uses sulbactam to specifically inhibit the activity of β-lactamase, and adds penicillin as a control, adding β-lactamase inhibitors and not adding inhibitors by comparison The size of the inhibition circle generated by the sample is used to indirectly determine whether the sample contains β-lactamase drugs. 2 Equipment and materials In addition to the conventional sterilization and cultivation equipment in the microbiology laboratory, other equipment and materials are as follows: 2.1 β-lactamase detector 2.2 Constant temperature incubator: 36 ℃ ± 1 ℃. 2.3 Autoclave. 2.4 Sterile Petri Dish: A glass dish with an inner diameter of 90 mm, a flat and smooth bottom, and a ceramic tile cover. 2.5 Sterile Oxford cup: outer diameter (8.0 ± 0.1) mm, inner diameter (6.0 ± 0.1) mm, height (10.0 ± 0.1) mm. 2.6 McNeil Turbidimeter or standard turbidimetric tube. 2.7 pH meter. 2.8 Sterile pipette: 1mL (0.01mL scale value), 10mL (0.1mL scale value). 2.9 Sampler: 5μL ～ 20μL, 20μL-200μL and matching tips. 3. Operation steps 3.1 Preparation of bacterial suspension Inoculate Micrococcus luteus on the inclined surface of nutrient agar, incubate at 36 ± 1 ℃ for 18h-24h, wash the moss with physiological saline to obtain the bacterial suspension, and determine the concentration of the bacterial suspension. The final concentration should be greater than 1 × 1010 CFU / mL, stored at 4 ℃, storage period is 2 weeks. 3.2 Sample preparation Mix the sample to be tested thoroughly, take 1 mL of the sample to be tested in a 1.5 mL centrifuge tube, a total of 4 tubes, labeled as: A, B, C, D, each sample in three parallel, a total of 12 tubes, each time For the test, 1 mL of pure water should be added to a 1.5 mL centrifuge tube as a control. If the sample is milk powder, dilute the milk powder at a ratio of 1:10. If the sample is an acidic dairy product, the pH should be adjusted to 6-7. 3.3 Preparation of test plates Take a 90mm sterilized glass petri dish, add 10 mL of sterilized antibiotic detection medium II to the bottom layer, and after solidification, add 5 mL of antibiotic detection medium II containing 1 × 108 CFU / mL Micrococcus luteus to solidify Back up. 3.4 Determination of samples Add the penicillin standard solution, β-lactamase standard solution, and sulbactam standard solution to the sample and pure water in the following order: A 5 μL of penicillin. B Sulbactam 25 μL, Penicillin 5 μL. 25 μL of C β-lactamase and 5 μL of penicillin G. D β-lactamase 25 μL, sulbactam 25 μL, penicillin 5 μL. After mixing, add 200 μL of each of the above A to D samples to 4 sterile Oxford cups placed on the test plate, incubate at 36 ± 1 ℃ for 18 to 22 hours, and measure the diameter of the zone of inhibition. For each sample, take the average of three parallel tests. 3.5 Results report The results of the pure water sample should be: (A), (B), (D) should produce a zone of inhibition; the difference between the zone of inhibition of (A) and the zone of inhibition of (B) is within 3 mm (including 3 mm), and the repeatability is good; the inhibition zone of (C) is smaller than that of (D), the difference is more than 3 mm (including 3 mm), and the repeatability is good. If this is the result, the system is established and the sample results can be determined as follows. 4 If (B), and (D) produce antibacterial circles in the sample results, and the difference between (C) and (D) antibacterial circles is more than 3 mm (including 3 mm), you can press 7.1.1, 7.1. 2 Judgment result. 4.1 The difference between the inhibition zone of (A) and the inhibition zone of (B) is more than 3 mm (including 3 mm), and the repeatability is good. It should be determined that the sample is added with β-lactamase and report β-lactam Enzyme drugs test results were positive. 4.2 The difference between the zone of inhibition of (A) and the zone of inhibition of (B) is less than 3 mm, and the repeatability is good. It should be determined that the sample is not added with β-lactamase, and the test results of β-lactamase drugs should be reported. Negative. 4.3 If neither (A) or (B) produces a zone of inhibition, the sample should be diluted before testing. Xunshu sulbactam sensitive β-lactamase tester is a new product launched by Xunshu in 12 years. This instrument is a new type of instrument developed for the detection of β-lactamase in milk. It can accurately determine whether the verification of pure water is true. It can be easily combined with the accurate measurement of multiple bacteriostatic circles on the plate. It can be combined with the new standard of the Ministry of Health that reports "positive or negative test results of β-lactamase drugs". Realize the automated analysis of the presence of sulbactam sensitive β-lactamases. Xunshu sulbactam sensitive β-lactamase tester 1. Imaging system 1. Image sensor: 10 million pixel CMOS, true color 2. Optical lens: 8mm F / 1.4, distortion <1% 3. Image shooting environment: fully enclosed, no sunlight interference, automatic centering, dark box shooting 4. Built-in light source: three-color LED mixed soft light, suspended dark field shooting system (Xunshu patent) 2. Multi-mode measurement technology of Szone bacteriostatic zone 1. Automatic detection: Accurate edge detection based on the contour of the bacteriostatic circle, suitable for clear edges, standard circular bacteriostatic circle 2. Quasi-circle approximation: circular fitting approximation based on the contour of the bacteriostatic circle, suitable for edge rupture, non-standard circular bacteriostatic circle 3. Manual detection: click three points on the edge of the bacteriostatic circle to form a circle, suitable for the bacteriostatic circle with blurred edges 3. Sulbactam sensitive β-lactamase test 1. Verification of pure water: According to (A), (B), (D), the bacteriostatic zone is generated, DC ≧ 3, BA ≦ 3, the judgment system is established 2. Automatic detection of (A), (B), (C), (D) inhibition zone of three parallel samples, and data import 3. Automatically calculate the average value of the parallel test, intelligently identify the positive and negative results 4. Invalid report automatic warning 4. Instrument detection accuracy 1. Repeatability self-test: relative error ≤0.01% 2. Uniformity self-check: relative error ≤0.05% Five, database management 1. Data storage / inquiry: the inspection images can be saved to the database; and the previous inspection images can be searched and queried by date, number and name 2. Data security: double password protection, operator use authority, administrator data modification authority. Milk Storage Bag,Breast Milk Cooler Bag,Breast Milk Storage,Breast milk Bag Zhejiang Carebao Co., Ltd , https://www.carebao.com