Charm Blue Yellow II Test
for Antimicrobial Drugs in Milk
The Charm® Blue Yellow II Test is a microbial inhibition assay, which detects inhibitors,
such as antibiotics, in raw or ultra-pasteurized cow milk.
Antibiotics are the most
common inhibitors found in raw milk. The test consists of a single service well that
contains pre-measured bacterial sporesA, media, and a pH indicator. Reagents are unit
dosed and compartmentalized to ensure uniformity. This eliminates reagent transfer
steps and prevents inadvertent contamination and reagent loss.
The Charm Blue Yellow II test has superior sensitivity to beta-lactams, sulfonamides,
aminoglycosides, and especially tetracyclines. Breakthrough sensitivity to tetracyclines
makes it the first inhibition test to closely match EU MRL levels.
ABacillus stearothermophilus var. calidolactis
Simple Procedure
Blue Yellow II Test
Analyzes for a broad spectrum of antibiotics for the dairy industry
Detects beta-lactams and other antimicrobial drugs near regulatory limits
Features the most sensitive inhibition test for antimicrobial drugs in milk
Delivers one-step testing – just add milk sample
Provides large volume testing capabilities
Supports optional air or waterbath incubation
Allows for optional color scanner and software for numerical results
ILVOA approved
AILVO-T&V Melle, Belgium
Charm® Blue Yellow II Test for Beta-lactams and Other Antimicrobial Drugs in Milk
The Charm Blue Yellow II Test detects antibiotics in raw commingled, pasteurized, or ultra-pasteurized cow milk and milk powder. Bacteria, cultured in a vial with milk, generate acid and turn a pH indicator from purple to yellow. Milk samples that prevent a color change are considered positive for antibiotics.
Sensitivity and Selectivity
Selectivity - Antimicrobial drug-free samples should yield 90% negative results with 95% confidence.
Table 1. Sensitivity – Detected antimicrobial drugs in μg/kg or ppb (parts per billion) compared to EU
MRL (Maximum Residue Limit). Antimicrobial drugs listed are representative of their respective drug
families. Other drugs will be detected at different levels.
Antimicrobial Drug1
Concentration† (μg/kg or ppb*)
EU / CODEX MRL (μg/kg or ppb*)
Amoxicillin
2 to 3
4/4
Ampicillin
2 to 3
4
Cefacetrile
10 to 15
125
Cefalexin
60 to 100
100
Cefalonium
10 to 15
20
Cefazolin
6 to 10
20
Cefoperazone
20 to 30
50
Cefquinome
40 to 60
20
Ceftiofur & Metabolites§
50 to 100
100/100
Cefuroxime
20 to 25
None
Cephapirin
4 to 6
60
Cloxacillin
10 to 20
30
Dicloxacillin
10 to 20
30
Nafcillin
3 to 5
30
Oxacillin
8 to 10
30
Penicillin G
1 to 2
4/4
Chlortetracycline
150 to 200
100/100
Doxycycline
25 to 75
0
Oxytetracycline
75 to 100
100/100
Tetracycline
75 to 100
100/100
Gentamicin
75 to 100
100/200
Neomycin
75 to 150
1500 to 1500
Dapsone
1 to 2
0
Sulfadiazine
80 to 100
100
Sulfadimethoxine
50 to 75
100
Sulfamethazine (Sulfadimidine)
75 to 125
100 / 25
Sulfapyridine
75 to 125
100
Sulfathiazole
25 to 75
100
Trimethoprim
200 to 300
50
Erythromycin
100 to 150
40
Lincomycin
100 to 150
150/150
Pirlimycin
50 to 100
100/100
Spiramycin
400 to 500
200/200
Tilmicosin
25 to 35
50
Tylosin
20 to 30
50/100
† Positive 90% of the time with 95% confidence
§ Concentrations listed are total parent and metabolites. The concentration for positive for parent ceftiofur only is 10 – 20 ug/kg.
Interferences and Cross Reactivity
The Blue Yellow II Test is a broad-spectrum antibiotic screening test.
The following drugs, at 100 ppb, showed no interferences; amphenicols, fluoroquinolones, and nitrofurans,
or colistin, chlorothiazide, dexamethasone, dipyrone, flumequine, flunixin, furosemide, ivermectin,
novobiocin, oxytocin, phenylbutazone, and trichlormethiazide. Other antimicrobials are detected.
There are no interferences from somatic cells at 5 x 105 SCC/ml or bacteria at 3 x 105 cfu/ml.
The Charm Blue Yellow II Test detects antibiotics in raw commingled, pasteurized, or ultra-pasteurized cow milk and milk powder. Bacteria, cultured in a vial with milk, generate acid and turn a pH indicator from purple to yellow. Milk samples that prevent a color change are considered positive for antibiotics.