Chroococcus

[[Escherichia coli O157:H7. Image courtesy of OutBreak, Inc. Copyright 2005 - 2007.]]

Classification

Phylum: Proteobacteria

Class: Gamma Proteobacteria

Order: Enterobacteriales

Family: Enterobacteriaceae

Genus: Escherichia

Species: E. coli

Description

Escherichia coli O157:H7 is an enterohemorrhagic strain of the bacterium Escherichia coli.[1] Escherichia coli O157:H7 is one of the four recognized classes of enterovirulent E. coli which can cause gastroenteritis in human.

Unique characteristics

Escherichia coli O157:H7 has some Unique characteristics: c Cannot metabolize sorbitol Poor growth at 44-45.5 °C Lacking beta-glucuronidase activity Tolerates low pH well [2]

Toxicity

E. coli O157:H7 infection often causes severe bloody diarrhea and abdominal cramps; sometimes the infection causes non-bloody diarrhea or no symptoms. Vomiting occurs in about half of persons and fever, usually not high, occurs less than one-third of the time. On the second or third day of illness, stools may become bloody in 30% to 75% of cases. The illness resolves in 5 to 10 days. Infants and the elderly are most susceptible. The incubation period is usually 3-4 days, although rarely the incubation can be as short as 12 hours or as long as 8 days. Most of the time there is no long-term effects. Asymptomatic infection can occur.[3]

Treatment

Antibiotics are not used with this type of infection. Most people usually recovery within five to 10 days. Sometimes people will develop hemolytic uremic syndrome (HUS),life-threatening disease. Blood transfusions and kidney dialysis can treat HUS.

References

1. Karch H, Tarr P, Bielaszewska M (2005). Enterohaemorrhagic Escherichia coli in human medicine. Int J Med Microbiol 295 (6-7): 405–18. PMID 16238016.

2. Geoff Copper, Rebecca Young, Claire Campbell,. Guyton Durnin, Linha Phan, Leah McKay. (2006) Escherichia coli O157:H7

3. CALVIN B. JOHNSON (2006).Escherichia coli O157:H7 (E. Coli)