Enterovirulent E. Coli (EEC) (cont.)

The diagnosis is usually made by an accurate history, physical exam, and analysis of a fecal sample from the patient. A presumptive diagnosis is often made if the patient's history indicates an association with persons, foods, or fluids known to contain E. coli 0157:H7 or other EEC group bacteria; such a presumptive diagnosis is often made during outbreaks of the disease. However, in patients who require hospitalization, a definitive diagnosis is usually sought.

A definitive diagnosis is often made by culture of E. coli strains from a fecal specimens on selective media (sorbitol-MacConkey agar) when colonies react with antiserum directed against specific "O" antigen strains. The selective medium and antiserum help distinguish E. coli serovars from other similar pathogens such as Listeria, Salmonella and Shigella. Other tests include PCR (polymerase chain reaction) and immunofluorescence tests to help identify the E. coli serovar.

The CDC has recommended (2009) that all patients being evaluated for community-acquired diarrhea have their stool samples analyzed by immunologic test systems that detect all types of Shiga toxins as this test will likely detect almost all bacteria that produce Shiga toxins, especially E. coli 0157:H7 strains. The CDC suggests that this test is even better than bacterial culture techniques, but recommends that both culture and immunologic tests should be done at the same time. This is suggested since E. coli that produces Shiga or Shiga-like toxins usually have the potential to be very damaging to the infected person(s).

Source: MedicineNet.com
http://www.medicinenet.com/enterovirulent_e_coli_eec/article.htm