title: Bacteraemia due to non-ESBL-producing Escherichia coli O25b:H4 sequence type 131: insights into risk factors, clinical features and outcomes.
abstract: The epidemiology and outcomes of bloodstream infections (BSIs) caused by Escherichia coli ST131 isolates not producing extended-spectrum β-lactamases (ESBLs) are not well defined despite being more prevalent than ESBL-producers. In this study, risk factors and the impact on outcome of BSIs caused by non-ESBL-producing ST131 E. coli versus non-ST131 E. coli were investigated. A case-control study was performed in two tertiary centres to identify risk factors for ST131. Molecular methods were used to investigate all E. coli isolates from blood cultures for those belonging to O25b:H4-ST131 clonal group. fimH alleles were characterised in ST131 isolates. Multivariate analysis was performed by logistic regression or Cox regression as appropriate. A total of 33 ST131 E. coli cases and 56 controls were studied. ST131 isolates showed higher rates of resistance to ampicillin and ciprofloxacin; fimH alleles were H30 in 14 isolates (42.4%) and H22 in 12 isolates (36.4%). Only recent surgery (OR = 7.03, 95% CI 1.71-28.84; P = 0.007) and unknown source of bacteraemia (OR = 5.37, 95% CI 0.93-30.81; P = 0.05) were associated with ST131. ST131 isolates showed no association with 30-day mortality, therapeutic failure, presentation with severe sepsis/shock or length of stay. Bacteraemia due to non-ESBL-producing O25b:H4-ST131 E. coli showed few differences in terms of risk factors as well as similar outcome to non-ST131 E. coli. These data support the notion that ST131 strains are not less clinically virulent despite showing increased antimicrobial resistance, but also that they are not more virulent than other clonal groups causing BSI.
authors.affiliation: Unidad Clínica Intercentros de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospitales Universitarios Virgen Macarena y Virgen del Rocío, Instituto de Biomedicina de Sevilla (IBiS), Seville, Spain.
authors.forename: Isabel
authors.initials: I
authors.lastname: Morales-Barroso
authors.affiliation: Unidad Clínica Intercentros de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospitales Universitarios Virgen Macarena y Virgen del Rocío, Instituto de Biomedicina de Sevilla (IBiS), Seville, Spain.
authors.forename: Lorena
authors.initials: L
authors.lastname: López-Cerero
authors.affiliation: Unidad Clínica Intercentros de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospitales Universitarios Virgen Macarena y Virgen del Rocío, Instituto de Biomedicina de Sevilla (IBiS), Seville, Spain.
authors.forename: José
authors.initials: J
authors.lastname: Molina
authors.affiliation: Unidad Clínica Intercentros de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospitales Universitarios Virgen Macarena y Virgen del Rocío, Instituto de Biomedicina de Sevilla (IBiS), Seville, Spain.
authors.forename: Mar
authors.initials: M
authors.lastname: Bellido
authors.affiliation: Unidad Clínica Intercentros de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospitales Universitarios Virgen Macarena y Virgen del Rocío, Instituto de Biomedicina de Sevilla (IBiS), Seville, Spain.
authors.forename: María Dolores
authors.initials: MD
authors.lastname: Navarro
authors.affiliation: Unidad Clínica Intercentros de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospitales Universitarios Virgen Macarena y Virgen del Rocío, Instituto de Biomedicina de Sevilla (IBiS), Seville, Spain.
authors.forename: Lara
authors.initials: L
authors.lastname: Serrano
authors.affiliation: Unidad Clínica Intercentros de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospitales Universitarios Virgen Macarena y Virgen del Rocío, Instituto de Biomedicina de Sevilla (IBiS), Seville, Spain.
authors.forename: Verónica
authors.initials: V
authors.lastname: González-Galán
authors.affiliation: Unidad Clínica Intercentros de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospitales Universitarios Virgen Macarena y Virgen del Rocío, Instituto de Biomedicina de Sevilla (IBiS), Seville, Spain.
authors.forename: Julia
authors.initials: J
authors.lastname: Praena
authors.affiliation: Unidad Clínica Intercentros de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospitales Universitarios Virgen Macarena y Virgen del Rocío, Instituto de Biomedicina de Sevilla (IBiS), Seville, Spain; Departamento de Microbiología, Universidad de Sevilla, Seville, Spain.
authors.forename: Alvaro
authors.initials: A
authors.lastname: Pascual
authors.affiliation: Unidad Clínica Intercentros de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospitales Universitarios Virgen Macarena y Virgen del Rocío, Instituto de Biomedicina de Sevilla (IBiS), Seville, Spain; Departamento de Medicina, Universidad de Sevilla, Seville, Spain. Electronic address: jesusrb@us.es.
authors.forename: Jesús
authors.initials: J
authors.lastname: Rodríguez-Baño
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016470:Bacteremia / Q000453:epidemiology* / Q000382:microbiology*; D016022:Case-Control Studies; D015331:Cohort Studies; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000382:microbiology*; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D058885:Multilocus Sequence Typing; D012307:Risk Factors; D065288:Serogroup; D016019:Survival Analysis; D062606:Tertiary Care Centers; D016896:Treatment Outcome
keywords: Bloodstream infection; Escherichia coli; Mortality; Outcome; Risk factors; ST131