Localization of the insertion site and pathotype determination of the locus of enterocyte effacement of shiga toxin-producing Escherichia coli strains.
Of 220 Shiga toxin-producing Escherichia coli (STEC) strains collected in central France from healthy cattle, food samples, and asymptomatic children, 12 possessed the eae gene included in the locus of enterocyte effacement (LEE) pathogenicity island. Based on gene typing, we observed 7 different eae espA espB tir pathotypes among the 12 STEC strains and described the new espAbetav variant. As previously observed, the O157 serogroup is associated with eaegamma, O26 is associated with eaebeta, and O103 is associated with eaeepsilon. However, the unexpected eaezeta allele was detected in 5 of the 12 isolates. PCR amplification and pulsed-field gel electrophoresis using the I-CeuI endonuclease followed by Southern hybridization indicated that the LEE was inserted in the vicinity of the selC (three isolates), pheU (two isolates), or pheV (six isolates) tRNA gene. Six isolates harbored two or three of these tRNA loci altered by the insertion of integrase genes (CP4-int and/or int-phe), suggesting the insertion of additional foreign DNA fragments at these sites. In spite of great genetic diversity of LEE pathotypes and LEE insertion sites, bovine strains harbor alleles of LEE genes that are frequently found in clinical STEC strains isolated from outbreaks and sporadic cases around the world, underscoring the potential risk of the bovine strains on human health.
Bertin
Yolande
Y
Laboratoire de Microbiologie, Centre de Recherche INRA de Clermont-Ferrand-Theix, 63122 St-Genès Chapanelle, France.
Boukhors
Karima
K
Livrelli
Valerie
V
Martin
Christine
C
D018829:Adhesins, Bacterial / Q000235:genetics* / Q000378:metabolism; D000483:Alleles; D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism; D015139:Blotting, Southern; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D002417:Cattle; D002648:Child; D002874:Chromosome Mapping; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000382:microbiology; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D009876:Operon; D017422:Sequence Analysis, DNA; D022603:Shiga Toxins / Q000096:biosynthesis*; D014774:Virulence
D018829:Adhesins, Bacterial; D001425:Bacterial Outer Membrane Proteins; D002352:Carrier Proteins; C087863:EaeB protein, E coli; D029968:Escherichia coli Proteins; C102051:EspA protein, E coli; D022603:Shiga Toxins; C073819:eaeA protein, E coli