Inhibitor-resistant TEM- and OXA-1-producing Escherichia coli isolates resistant to amoxicillin-clavulanate are more clonal and possess lower virulence gene content than susceptible clinical isolates.
In a previous prospective multicenter study in Spain, we found that OXA-1 and inhibitor-resistant TEM (IRT) β-lactamases constitute the most common plasmid-borne mechanisms of genuine amoxicillin-clavulanate (AMC) resistance in Escherichia coli. In the present study, we investigated the population structure and virulence traits of clinical AMC-resistant E. coli strains expressing OXA-1 or IRT and compared these traits to those in a control group of clinical AMC-susceptible E. coli isolates. All OXA-1-producing (n = 67) and IRT-producing (n = 45) isolates were matched by geographical and temporal origin to the AMC-susceptible control set (n = 56). We performed multilocus sequence typing and phylogenetic group characterization for each isolate and then studied the isolates for the presence of 49 virulence factors (VFs) by PCR and sequencing. The most prevalent clone detected was distinct for each group: group C isolates of sequence type (ST) 88 (C/ST88) were the most common in OXA-1 producers, B2/ST131 isolates were the most common in IRT producers, and B2/ST73 isolates were the most common in AMC-susceptible isolates. The median numbers of isolates per ST were 3.72 in OXA-1 producers, 2.04 in IRT producers, and 1.69 in AMC-susceptible isolates; the proportions of STs represented by one unique isolate in each group were 19.4%, 31.1%, and 48.2%, respectively. The sum of all VFs detected, calculated as a virulence score, was significantly higher in AMC-susceptible isolates than OXA-1 and IRT producers (means, 12.5 versus 8.3 and 8.2, respectively). Our findings suggest that IRT- and OXA-1-producing E. coli isolates resistant to AMC have a different and less diverse population structure than AMC-susceptible clinical E. coli isolates. The AMC-susceptible population also contains more VFs than AMC-resistant isolates.
Laboratorio de Antibióticos, Bacteriología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain jesus.oteo@isciii.es.
Jesús
J
Oteo
Servei de Microbiologia, Hospital Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain.
Juan José
JJ
González-López
Laboratorio de Antibióticos, Bacteriología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain.
Adriana
A
Ortega
Servei de Microbiologia, Hospital Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain.
J Natalia
JN
Quintero-Zárate
Servicio de Microbiología-INIBIC, Complejo Hospitalario Universitario A Coruña, A Coruña, Spain.
Germán
G
Bou
Servicio de Microbiología, Hospital General Universitario Gregorio Marañón, Madrid, Spain.
Emilia
E
Cercenado
Departamento de Microbiología, Facultad de Medicina, Sevilla, Spain.
María Carmen
MC
Conejo
Servicio de Microbiología, Hospital Universitario Marqués de Valdecilla-IFIMAV, Santander, Spain Departamento de Biología Molecular, Universidad de Cantabria, Santander, Spain.
Luis
L
Martínez-Martínez
Servei de Microbiologia, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain.
Ferran
F
Navarro
Servicio de Microbiología, Hospital Son Espases, Palma de Mallorca, Spain.
Antonio
A
Oliver
Servei de Microbiologia, Hospital Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain.
Rosa M
RM
Bartolomé
Laboratorio de Antibióticos, Bacteriología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain Consejo Superior de Investigaciones Científicas, Madrid, Spain.
José
J
Campos
D019980:Amoxicillin-Potassium Clavulanate Combination / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial / Q000187:drug effects*; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000382:microbiology*; D006801:Humans; D017720:Molecular Epidemiology; D058885:Multilocus Sequence Typing; D010802:Phylogeny; D014774:Virulence / Q000187:drug effects / Q000235:genetics; D037521:Virulence Factors / Q000235:genetics; D065093:beta-Lactamase Inhibitors / Q000494:pharmacology*; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000187:drug effects* / Q000235:genetics
D000900:Anti-Bacterial Agents; D037521:Virulence Factors; D065093:beta-Lactamase Inhibitors; D019980:Amoxicillin-Potassium Clavulanate Combination; C039404:beta-lactamase OXA-2; D001618:beta-Lactamases; C034413:beta-lactamase TEM-1