Verotoxin-producing Escherichia coli
|Verotoxin-producing E. coli|
|Classification and external resources|
Verotoxin-producing Escherichia coli consists of strains of the bacterium Escherichia coli that, when infecting humans, have been linked with the severe complication hemolytic-uremic syndrome (HUS). They are known by a number of names, including enterohemorrhagic E. coli (EHEC), shiga-like toxin-producing E. coli (STEC or SLTEC), hemolytic uremic syndrome–associated enterohemorrhagic E. coli (HUSEC) and verocytotoxin- or verotoxin-producing E. coli (VTEC).
All these E. coli strains produce Shiga-like toxin (also known as verotoxin), a major cause of foodborne illness. These are distinguished from other pathotypes of intestinal pathogenic E. coli including enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), enteroinvasive E. coli (EIEC), enteroaggregative E. coli (EAEC), and diffusely adherent E. coli (DAEC).
The best known of these strains is O157:H7, but non-O157 strains cause an estimated 36,000 illnesses, 1,000 hospitalizations and 30 deaths in the United States yearly. Food safety specialists recognize "Big Six" strains; O26, O45, O103, O111, O121, and O145. A 2011 outbreak in Germany was caused by another STEC, O104:H4. This strain has both enteroaggregative and enterohemorrhagic properties. Both the O145 and O104 strains can cause hemolytic-uremic syndrome; the former strain shown to account for 2% to 51% of known HUS cases; an estimated 56% of such cases are caused by O145 and 14% by other EHEC strains.
EHECs that induce bloody diarrhea lead to HUS in 10% of cases. The clinical manifestations of postdiarrheal HUS include acute renal failure, microangiopathic hemolytic anemia, and thrombocytopenia. The verocytotoxin (shiga-like toxin) can directly damage renal and endothelial cells. Thrombocytopenia occurs as platelets are consumed by clotting. Hemolytic anemia results from intravascular fibrin deposition, increased fragility of red blood cells, and fragmentation.
Antibiotics are of questionable value and have not shown to be of clear clinical benefit. Antibiotics that interfere with DNA synthesis, such as fluoroquinolones, have been shown to induce the Stx-bearing bacteriophage and cause increased production of toxins. Attempts to block toxin production with antibacterials which target the ribosomal protein synthesis are conceptually more attractive. Plasma exchange offers a controversial but possibly helpful treatment. The use of antimotility agents (medications that suppress diarrhea by slowing bowel transit) in children under 10 years of age or in elderly patients should be avoided, as they increase the risk of HUS with EHEC infections.
- Karch H, Tarr P, Bielaszewska M (2005). "Enterohaemorrhagic Escherichia coli in human medicine.". Int J Med Microbiol 295 (6-7): 405–18. doi:10.1016/j.ijmm.2005.06.009. PMID 16238016.
- Woo Kyun Bae, Youn Kyoung Lee, Min Seok Cho, Seong Kwon Ma, Soo Wan Kim, Nam Ho Kim, and Ki Chul Choi (2006-06-30). "A Case of Hemolytic Uremic Syndrome Caused by Escherichia coli O104:H4". Yonsei Med J 47 (3): 437–439. doi:10.3349/ymj.2006.47.3.437. PMC 2688167. PMID 16807997. Two sentences were taken from this source verbatim.
- Zach Mallove (26 April 2010). "Lawyer Battles FSIS on Non-O157 E. coli". Food Safety News. Retrieved 2 June 2011.
- Zhang X, McDaniel AD, Wolf LE, Keusch GT, Waldor MK, Acheson DW. Quinolone antibiotics induce Shiga toxin-encoding bacteriophages, toxin production, and death in mice. J Infect Dis. 2000 Feb;181(2):664-70. PMID 10669353.