Bacillus cereus; overall discussion

Bacillus cereus is a spore-producing rod-shaped, gram-positive bacterium. It releases toxins that result in vomiting or diarrhea. Bacillus cereus infections are self-limiting, mild, and harmless. Some strains of this bacterium are beneficial as it is used as probiotics for animals. Bacillus cereus is a food-borne bacteria. It also found in soil. It causes fried rice syndrome. Spore formation causes it to survive adverse environments including normal cooking temperatures. This bacterium is also resistant to alcohol treatment. Few strains of this bacterium produce bacteriocins used to kill the other strains of Bacillus cereus or other gram-positive bacteria.

Symptoms of Bacillus cereus food poisoning:
B. cereus causes two types of food poisoning. They are the emetic type and diarrheal type caused by emetic toxins and enterotoxins respectively. Emetic type causes vomiting and diarrheal type causes diarrhea.
Emetic type food poisoning includes:
• nausea,
• vomiting and
• abdominal cramps
These symptoms occur within 1–5 hours of ingestion and last for 6–24 hours.
Diarrheal type food poisoning includes:
• nausea,
• abdominal cramps, and
• watery diarrhea
These symptoms appear within 8–16 hours of ingestion, with recovery usually
within 12–24 hours. It may last for several days in some cases.

Risk Factors:
Persons at any age may be affected by B. cereus infections. But younger children are more susceptible and may be severely affected. Immunocompromised persons may also be affected.

Complications:

This bacterium sometimes may lead the patient to some opportunistic infection such as septicemia, meningitis, pneumonia and localized eye infections.

Antibiotic resistance and susceptibility:
Lactamase production in B. cereus causes its resistance to penicillin and cephalosporin.
Several studies showed that some strains of B. cereus are susceptible to imipenem, vancomycin, chloramphenicol, erythromycin, tetracycline, gentamicin, and ciprofloxacin. And some strains show resistance to clindamycin, cefazolin, and cefotaxime.
Another study concluded that B. cereus shows constant resistance to penicillin, ampicillin, cephalosporin, and trimethoprim. And these strains shows susceptibility to clindamycin, erythromycin, chloramphenicol, vancomycin, aminoglycosides, and tetracycline.
Bacillus cereus strain shows a better susceptibility to newer antibiotics such as gatifloxacin, levofloxacin, moxifloxacin, rifampin, daptomycin, and linezolid.

Treatment

In most case, vancomycin provides successful treatment for B. cereus infection. Other drugs such as imipenem, ciprofloxacin, gentamicin, tetracycline, chloramphenicol, clindamycin and erythromycin have effective ability to treat B. cereus infection. Penicillin and cephalosporin don’t show efficacy against this infection.

Bacteriophage therapy:

BCP-1 is a bacteriophage used against B. cereus infection. This phage can kill only this bacterium. It can’t destroy other gram-positive or gram-negative bacteria and other beneficial bacteria. It has no side effect. So it is safe to use.

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