title: Escherichia coli in bacteremia: O-acetylated K1 strains appear to be more virulent than non-O-acetylated K1 strains.
abstract: A total of 174 blood isolates of Escherichia coli, collected during a 5-year period at the University Hospital Utrecht, were serotyped with rabbit sera against 171 O antigens and 73 capsule (K) antigens. The four most prevalent O-antigen serotypes were O6 (n = 22), O18 (n = 19), O1 (n = 19), and O2 (n = 15). Thirty-one strains were not typeable with any of the O-antigen-typing sera. Of the 148 strains that were subjected to K-antigen serotyping, 34 strains lacked a K antigen and 41 were not typeable with the K-antigen-specific antisera used in the study. K1 was by far the most frequently found K-antigen serotype; this was followed by K2, K53, K5, K13, K7, K(A)28, and K15. Strains possessing a K1 antigen were further classified as either O-acetyl-positive (n = 12) or O-acetyl-negative (n = 21) strains. Retrospective analysis of patients infected with different E. coli isolates--nonencapsulated (n = 23), O-acetylated K1 (n = 12), and non-O-acetylated K1 (n = 21)--revealed clinical differences. More patients suffered from sepsis (94% versus 74%), and a higher rate of mortality was found in the group infected with K1 isolates (18 versus 9%) than in the group infected with nonencapsulated isolates. More patients with severe sepsis (25 versus 10%) and a higher mortality (33 versus 10%) were found in the group infected with O-acetylated K1 isolates than in the group infected with non-O-acetylated isolated. Also, the hospitalization of these patients was prolonged. Thus, O-acetylated E. coli K1 strains seem to be more virulent than non-O-acetylated K1 strains.
authors.affiliation: Eijkman-Winkler Institute for Medical Microbiology, University Hospital Utrecht, The Netherlands.
authors.forename: H
authors.initials: H
authors.lastname: Frasa
authors.forename: J
authors.initials: J
authors.lastname: Procee
authors.forename: R
authors.initials: R
authors.lastname: Torensma
authors.forename: A
authors.initials: A
authors.lastname: Verbruggen
authors.forename: A
authors.initials: A
authors.lastname: Algra
authors.forename: M
authors.initials: M
authors.lastname: Rozenberg-Arska
authors.forename: K
authors.initials: K
authors.lastname: Kraaijeveld
authors.forename: J
authors.initials: J
authors.lastname: Verhoef
mesh_terms: D000107:Acetylation; D000942:Antigens, Bacterial; D000954:Antigens, Surface; D016470:Bacteremia / Q000382:microbiology*; D004926:Escherichia coli / Q000145:classification / Q000276:immunology / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000382:microbiology*; D006801:Humans; D019081:O Antigens; D011135:Polysaccharides, Bacterial / Q000737:chemistry*; D012703:Serotyping; D014774:Virulence / Q000276:immunology
chemical_list: D000942:Antigens, Bacterial; D000954:Antigens, Surface; C030659:K antigens; D019081:O Antigens; D011135:Polysaccharides, Bacterial