Virulence patterns in a murine sepsis model of ST131 Escherichia coli clinical isolates belonging to serotypes O25b:H4 and O16:H5 are associated to specific virotypes.
Escherichia coli sequence type (ST)131 is an emerging disseminated public health threat implicated in multidrug-resistant extraintestinal infections worldwide. Although the majority of ST131 isolates belong to O25b:H4 serotype, new variants with different serotypes, STs using the discriminative multilocus sequence typing scheme of Pasteur Institute, and virulence-gene profiles (virotypes) have been reported with unknown implications on the pattern of spread, persistence and virulence. The aim of the present study was to compare virulence in a mouse subcutaneous sepsis model of representative ST131 clinical isolates belonging to 2 serotypes (O25b:H4, O16:H5) and nine virotypes and subtypes (A, B, C, D1, D2, D3, D4, D5 and E). Fourteen out of the 23 ST131 isolates tested (61%) killed 90 to 100% of mice challenged, and 18 of 23 (78%) at least 50%. Interestingly, different virulence patterns in association with virotypes were observed, from highly rapid lethality (death in less than 24 h) to low final lethality (death at 7 days) but with presence of an acute inflammation. This is the first study to assess virulence of ST131 isolates belonging to serotype O16:H5, which exhibited virotype C. In spite of their low virulence-gene score, O16:H5 isolates did not show significant differences in final lethality compared with highly virulent O25b:H4 isolates of virotypes A, B and C, but killed mice less rapidly. Significant differences were found, however, between virotypes A, B, C (final lethality ≥80% of mice challenged) and virotypes D, E. Particularly unexpected was the low lethality of the newly assigned virotype E taking into account that it exhibited high virulence-gene score, and the same clonotype H30 as highly virulent O25b:H4 isolates of virotypes A, B and C. In vivo virulence diversity reported in this study would reflect the genetic variability within ST131 clonal group evidenced by molecular typing.
Laboratorio de Referencia de E. coli (LREC), Departamento de Microbioloxía e Parasitoloxía, Facultade de Veterinaria, Universidade de Santiago de Compostela (USC), Lugo, Spain.
Azucena
A
Mora
Laboratorio de Referencia de E. coli (LREC), Departamento de Microbioloxía e Parasitoloxía, Facultade de Veterinaria, Universidade de Santiago de Compostela (USC), Lugo, Spain.
Ghizlane
G
Dahbi
Laboratorio de Referencia de E. coli (LREC), Departamento de Microbioloxía e Parasitoloxía, Facultade de Veterinaria, Universidade de Santiago de Compostela (USC), Lugo, Spain.
Cecilia
C
López
Laboratorio de Referencia de E. coli (LREC), Departamento de Microbioloxía e Parasitoloxía, Facultade de Veterinaria, Universidade de Santiago de Compostela (USC), Lugo, Spain.
Rosalía
R
Mamani
Laboratorio de Referencia de E. coli (LREC), Departamento de Microbioloxía e Parasitoloxía, Facultade de Veterinaria, Universidade de Santiago de Compostela (USC), Lugo, Spain.
Juan
J
Marzoa
IAME, UMR 1137, INSERM, Paris, France; Univ Paris Diderot, Sorbonne Paris Cité, Paris, France.
Sara
S
Dion
IAME, UMR 1137, INSERM, Paris, France; Univ Paris Nord, Sorbonne Paris Cité, Paris, France.
Bertrand
B
Picard
Laboratorio de Referencia de E. coli (LREC), Departamento de Microbioloxía e Parasitoloxía, Facultade de Veterinaria, Universidade de Santiago de Compostela (USC), Lugo, Spain.
Miguel
M
Blanco
Unidade de Microbioloxía Clínica, Hospital Universitario Lucus Augusti (HULA), Lugo, Spain.
María Pilar
MP
Alonso
IAME, UMR 1137, INSERM, Paris, France; Univ Paris Diderot, Sorbonne Paris Cité, Paris, France.
Erick
E
Denamur
Laboratorio de Referencia de E. coli (LREC), Departamento de Microbioloxía e Parasitoloxía, Facultade de Veterinaria, Universidade de Santiago de Compostela (USC), Lugo, Spain.
Jorge
J
Blanco
D018830:Adhesins, Escherichia coli / Q000235:genetics; D000818:Animals; D021461:Animals, Outbred Strains; D004926:Escherichia coli / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000382:microbiology*; D005260:Female; D036781:Fimbriae Proteins / Q000235:genetics; D014644:Genetic Variation; D006801:Humans; D051379:Mice; D058885:Multilocus Sequence Typing; D010802:Phylogeny; D018805:Sepsis / Q000382:microbiology*; D065288:Serogroup; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics
D018830:Adhesins, Escherichia coli; D037521:Virulence Factors; C058769:fimH protein, E coli; D036781:Fimbriae Proteins