Serotypes, virulence genes, and intimin types of Shiga toxin (verotoxin)-producing Escherichia coli isolates from cattle in Spain and identification of a new intimin variant gene (eae-xi).
A total of 514 Shiga toxin-producing Escherichia coli (STEC) isolates from diarrheic and healthy cattle in Spain were characterized in this study. PCR showed that 101 (20%) isolates carried stx(1) genes, 278 (54%) possessed stx(2) genes, and 135 (26%) possessed both stx(1) and stx(2). Enterohemolysin (ehxA) and intimin (eae) virulence genes were detected in 326 (63%) and in 151 (29%) of the isolates, respectively. STEC isolates belonged to 66 O serogroups and 113 O:H serotypes (including 23 new serotypes). However, 67% were of one of these 15 serogroups (O2, O4, O8, O20, O22, O26, O77, O91, O105, O113, O116, O157, O171, O174, and OX177) and 52% of the isolates belonged to only 10 serotypes (O4:H4, O20:H19, O22:H8, O26:H11, O77:H41, O105:H18, O113:H21, O157:H7, O171:H2, and ONT:H19). Although the 514 STEC isolates belonged to 164 different seropathotypes (associations between serotypes and virulence genes), only 12 accounted for 43% of isolates. Seropathotype O157:H7 stx(2) eae-gamma1 ehxA (46 isolates) was the most common, followed by O157:H7 stx(1) stx(2) eae-gamma1 ehxA (34 isolates), O113:H21 stx(2) (25 isolates), O22:H8 stx(1) stx(2) ehxA (15 isolates), O26:H11 stx(1) eae-beta1 ehxA (14 isolates), and O77:H41 stx(2) ehxA (14 isolates). Forty-one (22 of serotype O26:H11) isolates had intimin beta1, 82 O157:H7 isolates possessed intimin gamma1, three O111:H- isolates had intimin type gamma2, one O49:H- strain showed intimin type delta, 13 (six of serotype O103:H2) isolates had intimin type epsilon and eight (four of serotype O156:H-) isolates had intimin zeta. We have identified a new variant of the eae intimin gene designated xi (xi) in two isolates of serotype O80:H-. The majority (85%) of bovine STEC isolates belonged to serotypes previously found for human STEC organisms and 54% to serotypes associated with STEC organisms isolated from patients with hemolytic uremic syndrome. Thus, this study confirms that cattle are a major reservoir of STEC strains pathogenic for humans.
Blanco
M
M
Departamento de Microbioloxía e Parasitoloxía, Facultade de Veterinaria, Universidade de Santiago de Compostela, 27002 Lugo, Spain.
Blanco
J E
JE
Mora
A
A
Dahbi
G
G
Alonso
M P
MP
González
E A
EA
Bernárdez
M I
MI
Blanco
J
J
D018829:Adhesins, Bacterial / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics*; D002417:Cattle / Q000382:microbiology; D017931:DNA Primers; D004926:Escherichia coli / Q000145:classification / Q000302:isolation & purification / Q000472:pathogenicity*; D019453:Escherichia coli O157 / Q000145:classification / Q000302:isolation & purification / Q000472:pathogenicity; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D010802:Phylogeny; D012703:Serotyping; D022603:Shiga Toxins / Q000235:genetics*; D013030:Spain; D014774:Virulence / Q000235:genetics*
D018829:Adhesins, Bacterial; D002352:Carrier Proteins; D017931:DNA Primers; D029968:Escherichia coli Proteins; D022603:Shiga Toxins; C073819:eaeA protein, E coli