title: Prevalence, structure and expression of urease genes in Shiga toxin-producing Escherichia coli from humans and the environment.
abstract: A component of the ure gene cluster in E. coli, ureC, encodes a subunit of urease. We have investigated the distribution of ureC in 202 Shiga toxin-producing E. coli (STEC) strains from Austria belonging to 61 different serotypes. These strains were of human (n=150), animal (n=38), and food (n=14) origin. ureC was present in all 72 E. coli O157:H7 and O157:NM (non-motile) strains, as well as in all 29 strains of serotypes O26:H11/NM, O111:H8/NM and O145:NM. In contrast, none of eight sorbitol-fermenting E. coli O157:NM were ureC-positive. ureC occurred significantly more frequently among STEC that carry eae (113 of 132; 85.6%) than among eae-negative STEC strains (four of 70; 5.7%; p<0.0001). However, only 4 (2%) of the 202 strains (3.4% of ureC positive strains) expressed urease activity. There was no significant association (p=0.56) between urease expression and the source of the isolates (humans vs. animals). Nucleotide sequence analysis of PCR amplicons derived from all seven genes of the ure cluster in STEC of 10 different serotypes demonstrated a high degree of homology (>or=99%), indicating a recent acquisition of not necessarily expressed ure genes.
authors.affiliation: Department of Hygiene, Microbiology and Social Medicine, Innsbruck Medical University and Austrian Reference Laboratory for Enterohaemorrhagic E. coli, Schöpfstr. 41, 6020 Innsbruck, Austria. dorothea.orth@i-med.ac.at
authors.forename: Dorothea
authors.initials: D
authors.lastname: Orth
authors.forename: Katharina
authors.initials: K
authors.lastname: Grif
authors.forename: Manfred P
authors.initials: MP
authors.lastname: Dierich
authors.forename: Reinhard
authors.initials: R
authors.lastname: Würzner
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001317:Austria / Q000453:epidemiology; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology / Q000382:microbiology; D004926:Escherichia coli / Q000145:classification / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology; D019453:Escherichia coli O157 / Q000145:classification / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D005516:Food Microbiology; D006801:Humans; D005810:Multigene Family; D015995:Prevalence; D012703:Serotyping; D022603:Shiga Toxins / Q000096:biosynthesis*; D014510:Urease / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D018829:Adhesins, Bacterial; D029968:Escherichia coli Proteins; D022603:Shiga Toxins; C073819:eaeA protein, E coli; D014510:Urease