Bacillus cereus: Difference between revisions

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Bacillus cereus
	B. cereus on sheep blood agar plate.; B. cereus on sheep blood agar plate.
Scientific classification
Kingdom:	Bacteria;
Phylum:	Firmicutes;
Class:	Bacilli;
Order:	Bacillales;
Family:	Bacillaceae;
Genus:	Bacillus;
Species:	cereus;
Binomial name
	Bacillus cereus; Frankland & Frankland 1887

VisualWikitext

Revision as of 12:27, 6 August 2015

Overview

Bacillus cereus is an endemic, soil-dwelling, Gram-positive, rod shaped, beta hemolytic bacteria that causes foodborne illness.^[1] It is the cause of "Fried Rice Syndrome". B. cereus bacteria are facultative aerobes, and like other members of the genus Bacillus can produce protective endospores.

Pathogenesis

B. cereus is responsible for a minority of foodborne illnesses (2–5%). It is known to create heavy nausea, vomiting, and abdominal periods. ^[2] Generally speaking, Bacillus foodborne illnesses occur due to survival of the bacterial spores when food is improperly cooked.^[3] This problem is compounded when food is then improperly refrigerated, allowing the spores to germinate.^[4] Bacterial growth results in production of enterotoxin, and ingestion leads to two types of illness, diarrheal and emetic syndrome.^[5]

The diarrheal type is associated with a wide-range of foods, has an 8–16 hour incubation time and is associated with diarrhea and gastrointestinal pain. Also know as the long-incubation form of B. cereus food poisoning, it can be difficult to differentiate from poisoning caused by Clostridium perfringens.^[6]
In the emetic form, cooked rice that is improperly refrigerated is the most common cause, leading to nausea and vomiting 1–5 hours after consumption. This form can be difficult to distinguish from other short-term bacterial foodborne pathogens (e.g. Staphylococcus aureus).^[6]

It was previously thought that the timing of the toxin production might be responsible for the two different types, but in fact the emetic syndrome is caused by a toxin called cereulide that is found only in emetic strains and is not part of the 'standard toolbox' of B. cereus. Cereulide a dodecadepsipeptide produced by non-ribosomal peptide synthesis (NRPS), which is somewhat unusual in itself. It was shown independently by two research groups to be encoded on a plasmid, which is called pCERE01 ^[7] or pBCE4810 ^[8]. Interestingly, this plasmid shares a common backbone with the virulence plasmid pXO1, which encodes the anthrax toxin genes in B. anthracis, but with a different pathogenicity island. Periodontal isolates of B. cereus also possess distinct pXO1-like plasmids.

Gallery

A closer view of PHIL 12377, this photograph depicts the colonial morphology displayed by Gram-positive Bacillus cereus bacteria, which was grown on a medium of sheep’s blood agar (SBA), for a 24 hour time period, at a temperature of 37°C. From Public Health Image Library (PHIL). ^[9]
This photograph depicts the colonial morphology displayed by Gram-positive Bacillus cereus bacteria, which was grown on a medium of sheep’s blood agar (SBA), for a 24 hour time period, at a temperature of 37°C. From Public Health Image Library (PHIL). ^[9]
Bacillus cereus showing hemolysis on sheep blood agar. From Public Health Image Library (PHIL). ^[9]
Bacillus cereus showing hemolysis on sheep blood agar. From Public Health Image Library (PHIL). ^[9]
Blood agar and bicarbonate agar plate cultures of Bacillus cereus. From Public Health Image Library (PHIL). ^[9]
Sheep blood agar plate culture of Bacillus anthracis and Bacillus cereus. From Public Health Image Library (PHIL). ^[9]
Bacillus cereus. Gram stain. From Public Health Image Library (PHIL). ^[9]
Bacillus cereus. Leifson flagella stain. From Public Health Image Library (PHIL). ^[9]

Treatment

Antimicrobial Regimen

1. Food poisoning^[10]

Preferred regimen: Food poisoning is usually self-limited and requires no antibiotic therapy.

2. Bacteremia

Preferred regimen: Vancomycin 15 mg/kg IV q12h
Alternative regimen: Clindamycin 600 mg IV q8h
Note (1): Bacillus cereus is commonly resistant to beta-lactams.
Note (2): Pseudobacteremia is transient and usually results from contaminated blood cultures, gloves, or syringes.

3. Meningitis or brain abscess

Preferred regimen: Vancomycin 15 mg/kg IV q12h
Alternative regimen: Clindamycin 600 mg IV q8h
Note: Blood culture isolates are mostly contaminates until proven otherwise, especially in intravenous drug user population.

4. Endophthalmitis

Preferred regimen: Clindamycin 450 μg intravitreal AND Gentamicin 400 μg intravitreal OR Dexamethasone intravitreal AND Vancomycin 15 mg/kg IV q12h
Alternative regimen: Clindamycin 600 mg IV q8h
Note: Ophthalmological consultation, culture ocular fluids, early vitrectomy, and intravitreal antibiotics are necessary.

5. Endocarditis

Preferred regimen: Vancomycin 15 mg/kg IV q12h
Note: Most blood cultures in intravenous drug users are contaminates or represent transient bacteremia.

6. Soft tissue infection

Preferred regimen: Vancomycin 15 mg/kg IV q12h
Alternative regimen: Clindamycin 600 mg IV q8h

7. Pneumonia

Preferred regimen: Vancomycin 15 mg/kg IV q12h
Alternative regimen: Clindamycin 600 mg IV q8h

References

↑ Ryan KJ; Ray CG (editors) (2004). Sherris Medical Microbiology (4th ed. ed.). McGraw Hill. ISBN 0-8385-8529-9.
↑ Kotiranta A, Lounatmaa K, Haapasalo M (2000). "Epidemiology and pathogenesis of Bacillus cereus infections". Microbes Infect. 2 (2): 189–98. PMID 10742691.
↑ Turnbull PCB (1996). Bacillus. In: Baron's Medical Microbiology (Barron S et al, eds.) (4th ed. ed.). Univ of Texas Medical Branch. (via NCBI Bookshelf) ISBN 0-9631172-1-1.CS1 maint: Extra text (link)
↑ McKillip JL (2000). "Prevalence and expression of enterotoxins in Bacillus cereus and other Bacillus spp., a literature review". Antonie Van Leeuwenhoek. 77 (4): 393–9. PMID 10959569.
↑ Ehling-Schulz M, Fricker M, Scherer S (2004). "Bacillus cereus, the causative agent of an emetic type of food-borne illness". Mol Nutr Food Res. 48 (7): 479–87. PMID 15538709.
↑ ^6.0 ^6.1 "Bacillus cereus". Todar's Online Textbook of Bacteriology. Retrieved 2006-04-10.
↑ Hoton FM, Andrup L, Swiecicka I, Mahillon J (2005). "The cereulide genetic determinants of emetic Bacillus cereus are plasmid-borne". Microbiology. 151 (7): 2121–4. PMID 16000702.
↑ Ehling-Schulz M, Fricker M, Grallert H, Rieck P, Wagner M, Scherer S (2006). "Cereulide synthetase gene cluster from emetic Bacillus cereus: structure and location on a mega virulence plasmid related to Bacillus anthracis toxin plasmid pXO1". BMC Microbiol. 6 (20). PMID 16512902.
↑ ^9.0 ^9.1 ^9.2 ^9.3 ^9.4 ^9.5 ^9.6 ^9.7 "Public Health Image Library (PHIL)".
↑ Bartlett, John (2012). Johns Hopkins ABX guide : diagnosis and treatment of infectious diseases. Burlington, MA: Jones and Bartlett Learning. ISBN 978-1449625580.

[1] Ryan KJ; Ray CG (editors) (2004). Sherris Medical Microbiology (4th ed. ed.). McGraw Hill. ISBN 0-8385-8529-9.

[2] Kotiranta A, Lounatmaa K, Haapasalo M (2000). "Epidemiology and pathogenesis of Bacillus cereus infections". Microbes Infect. 2 (2): 189–98. PMID 10742691.

[3] Turnbull PCB (1996). Bacillus. In: Baron's Medical Microbiology (Barron S et al, eds.) (4th ed. ed.). Univ of Texas Medical Branch. (via NCBI Bookshelf) ISBN 0-9631172-1-1.CS1 maint: Extra text (link)

[4] McKillip JL (2000). "Prevalence and expression of enterotoxins in Bacillus cereus and other Bacillus spp., a literature review". Antonie Van Leeuwenhoek. 77 (4): 393–9. PMID 10959569.

[5] Ehling-Schulz M, Fricker M, Scherer S (2004). "Bacillus cereus, the causative agent of an emetic type of food-borne illness". Mol Nutr Food Res. 48 (7): 479–87. PMID 15538709.

[Todar-6] 6.0 ^6.1 "Bacillus cereus". Todar's Online Textbook of Bacteriology. Retrieved 2006-04-10.

[7] Hoton FM, Andrup L, Swiecicka I, Mahillon J (2005). "The cereulide genetic determinants of emetic Bacillus cereus are plasmid-borne". Microbiology. 151 (7): 2121–4. PMID 16000702.

[8] Ehling-Schulz M, Fricker M, Grallert H, Rieck P, Wagner M, Scherer S (2006). "Cereulide synthetase gene cluster from emetic Bacillus cereus: structure and location on a mega virulence plasmid related to Bacillus anthracis toxin plasmid pXO1". BMC Microbiol. 6 (20). PMID 16512902.

[PHIL-9] 9.0 ^9.1 ^9.2 ^9.3 ^9.4 ^9.5 ^9.6 ^9.7 "Public Health Image Library (PHIL)".

[10] Bartlett, John (2012). Johns Hopkins ABX guide : diagnosis and treatment of infectious diseases. Burlington, MA: Jones and Bartlett Learning. ISBN 978-1449625580.

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@@ Line 23: / Line 23: @@
 ==Pathogenesis==
-''B. cereus'' is responsible for a minority of foodborne illnesses (2&ndash;5%). It is known to create heavy nausea, vomiting, and abdominal periods. <ref>{{cite journal | author=Kotiranta A, Lounatmaa K, Haapasalo M | title=Epidemiology and pathogenesis of ''Bacillus cereus'' infections | journal=Microbes Infect | year=2000 | pages=189-98 | volume=2 | issue=2 | id=PMID 10742691}}</ref> Generally speaking, ''Bacillus'' foodborne illnesses occur due to survival of the bacterial spores when food is improperly cooked.<ref>{{ cite book | author = Turnbull PCB | title = Bacillus. ''In:'' Baron's Medical Microbiology ''(Barron S ''et al'', eds.)| edition = 4th ed. | publisher = Univ of Texas Medical Branch | year = 1996 | id = [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=mmed.section.935#939 (via NCBI Bookshelf)] ISBN 0-9631172-1-1 }}</ref> This problem is compounded when food is then improperly refrigerated, allowing the spores to germinate.<ref>{{cite journal | author=McKillip JL | title=Prevalence and expression of enterotoxins in ''Bacillus cereus'' and other ''Bacillus'' spp., a literature review | journal=Antonie Van Leeuwenhoek | year=2000 | pages=393-9 | volume=77 | issue=4 | id=PMID 10959569}}</ref> Bacterial growth results in production of [[enterotoxin]], and ingestion leads to two types of illness, diarrheal and emetic syndrome.<ref>{{cite journal | author=Ehling-Schulz M, Fricker M, Scherer S | title=''Bacillus cereus'', the causative agent of an emetic type of food-borne illness | journal=Mol Nutr Food Res | year=2004 | pages=479-87 | volume=48 | issue=7 | id=PMID 15538709}}</ref>
+* B. cereus is responsible for a minority of foodborne illnesses (2&ndash;5%). It is known to create heavy nausea, vomiting, and abdominal periods. <ref>{{cite journal | author=Kotiranta A, Lounatmaa K, Haapasalo M | title=Epidemiology and pathogenesis of ''Bacillus cereus'' infections | journal=Microbes Infect | year=2000 | pages=189-98 | volume=2 | issue=2 | id=PMID 10742691}}</ref> Generally speaking, ''Bacillus'' foodborne illnesses occur due to survival of the bacterial spores when food is improperly cooked.<ref>{{ cite book | author = Turnbull PCB | title = Bacillus. ''In:'' Baron's Medical Microbiology ''(Barron S ''et al'', eds.)| edition = 4th ed. | publisher = Univ of Texas Medical Branch | year = 1996 | id = [http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=mmed.section.935#939 (via NCBI Bookshelf)] ISBN 0-9631172-1-1 }}</ref> This problem is compounded when food is then improperly refrigerated, allowing the spores to germinate.<ref>{{cite journal | author=McKillip JL | title=Prevalence and expression of enterotoxins in ''Bacillus cereus'' and other ''Bacillus'' spp., a literature review | journal=Antonie Van Leeuwenhoek | year=2000 | pages=393-9 | volume=77 | issue=4 | id=PMID 10959569}}</ref> Bacterial growth results in production of [[enterotoxin]], and ingestion leads to two types of illness, diarrheal and emetic syndrome.<ref>{{cite journal | author=Ehling-Schulz M, Fricker M, Scherer S | title=''Bacillus cereus'', the causative agent of an emetic type of food-borne illness | journal=Mol Nutr Food Res | year=2004 | pages=479-87 | volume=48 | issue=7 | id=PMID 15538709}}</ref>
 :*The diarrheal type is associated with a wide-range of foods, has an 8&ndash;16 hour incubation time and is associated with diarrhea and [[gastrointestinal]] pain. Also know as the ''long-incubation'' form of ''B. cereus'' food poisoning, it can be difficult to differentiate from poisoning caused by ''[[Clostridium perfringens]]''.<ref name=Todar>{{cite web | title=''Bacillus cereus'' | work=Todar's Online Textbook of Bacteriology  | url=http://textbookofbacteriology.net/B.cereus.html | accessdate=2006-04-10}}</ref>
 :*In the emetic form, cooked rice that is improperly refrigerated is the most common cause, leading to nausea and vomiting 1&ndash;5 hours after consumption. This form can be difficult to distinguish from other short-term bacterial foodborne pathogens (e.g. ''[[Staphylococcus aureus]]'').<ref name=Todar />
-It was previously thought that the timing of the toxin production might be responsible for the two different types, but in fact the emetic syndrome is caused by a toxin called cereulide that is found only in emetic strains and is not part of the 'standard toolbox' of ''B. cereus''. Cereulide a dodecadepsipeptide produced by non-ribosomal peptide synthesis (NRPS), which is somewhat unusual in itself. It was shown independently by two research groups to be encoded on a plasmid, which is called pCERE01 <ref>{{cite journal | author=Hoton FM, Andrup L, Swiecicka I, Mahillon J | title=The cereulide genetic determinants of emetic ''Bacillus cereus'' are plasmid-borne. | journal=Microbiology | year=2005 | pages=2121-4 | volume=151 | issue=7 | id=PMID 16000702}}</ref>  or pBCE4810 <ref>{{cite journal | author=Ehling-Schulz M, Fricker M, Grallert H, Rieck P, Wagner M, Scherer S | title=Cereulide synthetase gene cluster from emetic ''Bacillus cereus'': structure and location on a mega virulence plasmid related to ''Bacillus anthracis'' toxin plasmid pXO1. | journal=BMC Microbiol | year=2006 | volume=6 | issue=20 | id=PMID 16512902}}</ref>. Interestingly, this plasmid shares a common backbone with the virulence plasmid pXO1, which encodes the anthrax toxin genes in ''B. anthracis'', but with a different pathogenicity island. Periodontal isolates of ''B. cereus'' also possess distinct pXO1-like plasmids.
+* It was previously thought that the timing of the toxin production might be responsible for the two different types, but in fact the emetic syndrome is caused by a toxin called cereulide that is found only in emetic strains and is not part of the 'standard toolbox' of ''B. cereus''. Cereulide a dodecadepsipeptide produced by non-ribosomal peptide synthesis (NRPS), which is somewhat unusual in itself. It was shown independently by two research groups to be encoded on a plasmid, which is called pCERE01 <ref>{{cite journal | author=Hoton FM, Andrup L, Swiecicka I, Mahillon J | title=The cereulide genetic determinants of emetic ''Bacillus cereus'' are plasmid-borne. | journal=Microbiology | year=2005 | pages=2121-4 | volume=151 | issue=7 | id=PMID 16000702}}</ref>  or pBCE4810 <ref>{{cite journal | author=Ehling-Schulz M, Fricker M, Grallert H, Rieck P, Wagner M, Scherer S | title=Cereulide synthetase gene cluster from emetic ''Bacillus cereus'': structure and location on a mega virulence plasmid related to ''Bacillus anthracis'' toxin plasmid pXO1. | journal=BMC Microbiol | year=2006 | volume=6 | issue=20 | id=PMID 16512902}}</ref>. Interestingly, this plasmid shares a common backbone with the virulence plasmid pXO1, which encodes the anthrax toxin genes in ''B. anthracis'', but with a different pathogenicity island. Periodontal isolates of ''B. cereus'' also possess distinct pXO1-like plasmids.
 ==Gallery==