Serogroups of Escherichia coli strains producing cytotoxic necrotizing factors CNF1 and CNF2

Abstract

The serogroups of 396 necrotizing Escherichia coli of human and bovine origin isolated in Spain between 1979 and 1991 have been determined. The 270 cytotoxic necrotizing factor strains belonged to 22 different O serogroups; however, 84% (226 of 270) were of one of seven serogroups (O2, O4, O6, O14, O22, O75 and O83). Although necrotizing E. coli producing cytotoxic necrotizing factor 2 belonged to 28 different serogroups, only six of them (O1, O3, O15, O55, O88 and O123) accounted for 60% (76 of 126) of cytotoxic necrotizing factor 2 strains. Furthermore, only 3% (4 of 126) of cytotoxic necrotizing factor 2 strains belonged to serogroups most common among strains producing cytotoxic necrotizing factor 1. The majority of necrotizing E. coli producing cytotoxic necrotizing factor 1 were obtained from human extraintestinal infections, whereas cytotoxic necrotizing factor 2 strains were isolated from stools of healthy and diarrhoeic calves.

Measurement of biofilm formation by clinical isolates ofEscherichia coliis method-dependent

“…The determination of O and H antigens was carried out by a previously described method (Blanco et al 1992) using all available O (O1-O185) and H (H1-H56) antisera. All antisera were obtained and absorbed with the corresponding cross-reacting antigens to remove nonspecific agglutinins.…”

Hygienic-sanitary quality of vegetables and evaluation of treatments for the elimination of indigenous E. coli and E. coli O157:H7 from the surface of leaves of lettuce (Lactuca sativa L.)

“…The vegetables were randomly selected from the plants harvested, the edible portions (leaves) were separated using knives previously sanitized with hypochlorite, then placed in clean plastic sealable bags, and transported to the laboratory in were confirmed for the presence of shiga toxin using VERO cells (SALVADORI; DELLA COLLETA; TOMOMASA, 1997) and the Bacto E. coli O157: H7 antiserum assay (BLANCO et al, 1992(BLANCO et al, , 1996. Confirmed populations are expressed as cfu.g -1 of lettuce.…”

“…The plates were incubated at 37 °C for 24 hours before colony counts were obtained. This experiment was repeated three times in duplicate (BLANCO et al, 1992;SINGH et al, 2002;KARAPINAR, 2004KARAPINAR, , 2005. Cell suspensions were diluted in an appropriate amount of water to give a cell number of 10 8 cfu.mL -1 and used immediately for sample inoculation.…”

Detection of virulence factors and antimicrobial resistance patterns in shiga toxin-producing Escherichia coli isolates from sheep

“…Cytotoxic-necrotizing factors (CNFs) can be separated in two types of cytotoxins, CNF1 and CNF2 (Blanco et al 1992). These cytotoxic-necrotizing factors are responsible for diarrheagenic diseases and other clinical signs in young lambs, but data in the literature on the distribution in healthy sheep and human are rather limited.…”