Treatment of Bacillus Cereus Sample
Spores of gram positive aerobic bacteria belonging to the genus Bacillus are part of the normal flora of the dust, soil among many more environmental sources. Many of these Bacillus species are irrelevant contaminants. However, the pathogenic potential of the B cereus stands out quite greatly. B cereus is not only a gram positive, spore forming, aerobic bacteria but is also known to have some facultative anaerobic characteristics. When they occur in food they are known to cause food poisoning. Unlike other vegetative pathogens like the E. coli, Listeria monocytogenes, Camplobacter and Salmonella they are more heat and chemical resistant (Ryan and Ray 2004). Illnesses caused by these bacteria are known to exhibit two characteristics; vomiting immediately after eating and longer incubation may result to diarrhea.
Food poisoning as a result of B cereus can manifest itself in two ways; emetic syndrome which occurs just incubation, it is characterized with other many food poisoning pathogens such as staphylococci which result to abdominal cramps, nausea, vomiting and sometimes diarrhea. The second has much resemblance to Clostridium perfringens, with long incubation period and is known as the diarrhea syndrome, it is associated with watery diarrhea and severe abdominal cramps and in most cases vomiting may be observed. In addition B cereus causes ocular infections, skin and wound infection and a number of ocular, central line and invasive diseases such as endocarditis, pneumonia, osteomyelitis, keratitis, panophthalmitis, bacteremia, endophthalmitis, meningitis and brain abscess (Ryan et al 2004). The diarrhea syndrome is as result of a heat-labile enterotoxin produced in vivo. The enterotoxin is known to be cytoxic and is associated with tissue necrosis.
Routes of transmission
It is worthy noting at this point that B cereus is wide spread in nature and can be found not only in dirt and dust but also on water and cereal crops and thus a known contaminant of agricultural raw materials.
Most of starchy foods are closely linked with emetic B cereus toxin outbreak. This is associated with their preparation processes, especially that of fried rice that is known to have been a source of several outbreaks. In its initial preparation and if is stored at temperatures ranging from 15to 40 degrees for a long time, then these toxins that are heat stable will be produced and their inactivation during the subsequent cooking proves futile. On the other hand the diarrhea causing toxin unlike the emetic can be destroyed by heat. They are found in a wide spread types of food such as meat, soups, milk and vegetable items. However, since these toxins cannot resist high temperatures they are destroyed by cooking.
Control of the emetic toxins relies on immediate refrigeration of foods to less than 5 degrees to eradicate toxin growth and formation. Because emetic illnesses are caused by improper handling of the food it is important to heat the food to temperature above 60 degrees to prevent cell growth. However, because these toxins are heat stable it is important to refrigerate them immediately after heating.
Persons suffering from B cereus food poisoning only require supportive treatment. In most cases, oral rehydration is given. In patients with severe dehydration electrolyte replacement and intravenous fluid is recommended.
Antibiotic therapy is however required for those patients with invasive diseases. Some strains of B cereus can produce exotoxins which in essence activate adenylcyclase resulting to enterotoxic activity upon whose injection may lead to localized elevation of vascular permeability as well as necrosis(Ryan et al 2004). In cases of localized infection removal of likely infected foreign bodies may be done. This has occurred in cases involving catheters. As some strain of B cereus produce β-lactamase and therefore resistance to β-lactam antimicrobial therapy. B cereus is susceptible to ciprofloxacin, meropenem, vancomycin and clindamycim and should therefore be used where antibiotic therapy is necessary.