How do you detect Bacillus cereus?
How do you detect Bacillus cereus?
The traditional method of B. cereus detection is based on the bacterial culturing onto selective agars and cells enumeration. In addition, molecular and chemical methods are proposed for toxin gene profiling, toxin quantification and strain screening for defined virulence factors.
What is Cereulide toxin?
Cereulide is a toxin produced by some strains of Bacillus cereus. It is a potent cytotoxin that destroys mitochondria. It also causes nausea and vomiting.
What other tests can be used to isolate differentiate and enumerate Bacillus cereus from food samples?
Various selective solid media such as MYP (mannitol-egg yolk-phenol red-polymyxin-agar) and PEMBA (polymyxin-pyruvate-egg yolk-mannitol-bromthymol blue-agar) were used for the isolation and detection of B. cereus from food.
How common is B. cereus in rice?
Bacillus cereus is a toxin-producing bacteria that is one of the most common causes of food poisoning, also called “fried rice syndrome.” An estimated 63,000 cases of food poisoning caused by B.
How do you identify Bacillus?
Bacillus species are rod-shaped, endospore-forming aerobic or facultatively anaerobic, Gram-positive bacteria; in some species cultures may turn Gram-negative with age. The many species of the genus exhibit a wide range of physiologic abilities that allow them to live in every natural environment.
How does Cereulide cause damage?
Cereulide is a cyclic dodecadepsipeptide, and a putative potassium ionophore. It causes mitochondrial swelling and consequently cell death [4,5].
Is Cereulide an enterotoxin?
The diarrheal form of B. cereus FI is similar to that caused by C. perfringens. The toxin, unlike the emetic type, is an enterotoxin released in the intestine and is heat labile.
What agar is used for Bacillus cereus?
The MYP agar has been the standard media for plating B. cereus, but it has little selectivity so background flora is not inhibited and can mask the presence of B. cereus.
What temperature does Bacillus cereus grow?
10 to 50 °C
cereus grows in a range of 10 to 50 °C, with a temperature optimum between 30 and 40 °C. However, individual cold-tolerant strains can also multiply at temperatures of 4 to 6 °C, though with considerably longer generation times.
What is the incubation period for Bacillus cereus?
Incubation period: In general, 2-3 hours (range 0.5-6hr) for the emetic form and 8-12 hours (range 6-24) for the diarrhoeal form. Period of communicability: B. cereus is not a contagious pathogen.
How do you detect toxic cereulide?
Current detection methods are time consuming and do not necessarily detect toxic cereulide. Here, we developed a rapid protocol using Matrix Assisted Laser Desorption/Ionization-Time of Flight (MALDI-TOF) mass spectrometry that detects the toxin originating from a colony smear of B. cereus.
Is cereulide toxic to humans?
The presence of cereulide in foodstuff containing toxic B. cereus presents a serious safety concerns for the consumer. While several methods currently exist to detect bacterial contamination in food products, these cannot ascertain the presence of cereulide toxin.
How do you detect cereulide ionophore?
Cereulide can be detected by MALDI-TOF as [M + Na] + and [M + K] + adduct ions at m/z 1,175 and m/z 1,191, respectively. This ionophore binds in vivo to the negatively charged cell-membrane phospholipids and induces pore formation and cytotoxicity via leakage of K + into the mitochondria.
How is the cereulide extracted from the food matrix?
The cereulide is extracted from the food matrix with acetonitrile. Labeled cereulide is used as the internal standard. Cereulide is detected with UHPLC/ESI-MS/MS in positive mode.
