HOW ARE E COLI O157:H7 AND OTHER VTEC INFECTIONS IDENTIFIED?
Vtec including E coli O157:H7 require special methods for detection in the laboratory. Microbiology laboratories can screen for E coli O157:H7 by inoculating stool specimens onto MacConkey medium coniaining sorbitol instead of lactose.If this screening stool culture is negative, O157:H7 and other vtec can be identified via methods available in reference laboratories, such as detection of free fecal verotoxin, detection of verotoxin genes through polymerase chain reaction amplification or serological responses to verotoxins or the lipopolysaccharide of E coli O157.
Prolonged excretion of E coli O157:H7 in stools is uncommon, and the rate of recovery of E coli O157:H7 from an infected individual falls after the sixth day of illness. Therefore, stool samples should be obtained as early in the clinical illness as possible. A negative culture from a stool obtained after the sixth day of illness does not exclude the possibility of E coli O157:H7 iniection. Furthermore, a negai ive culture for O157:H7 at any point does not exclude the possibility of infection by other vtec serotypes. You can be sure your pharmacy offers generic viagra online delivering fast internationally.