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Hajer Radhouani, Luís Pinto, Céline Coelho, Alexandre Gonçalves, Roberto Sargo, Carmen Torres, Gilberto Igrejas, Patrícia Poeta, Detection of Escherichia coli harbouring extended-spectrum β-lactamases of the CTX-M classes in faecal samples of common buzzards (Buteo buteo), Journal of Antimicrobial Chemotherapy, Volume 65, Issue 1, January 2010, Pages 171–173, https://doi.org/10.1093/jac/dkp403
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Sir,
In recent years, infections due to Escherichia coli harbouring extended-spectrum β-lactamases (ESBLs) of the CTX-M classes have dramatically increased among human populations, particularly in the community setting.1 There exist just a few previous reports in which ESBLs were detected in faecal E. coli isolates of wild animals,2 but, to our knowledge, never in faecal E. coli isolates of buzzards (Buteo buteo).
Thirty-three faecal samples from buzzards of Portugal were recovered from September 2007 to February 2008 and were studied for the presence of ESBL-producing E. coli isolates. All the faecal samples were collected individually from each buzzard and obtained in collaboration with CRATAS (Centre of Collecting, Welcome and Handling of Wild Animals). This centre is located in the University of Trás-os-Montes and Alto Douro and receives injured animals. None of the buzzards had been previously fed by humans or had received antibiotics. Most of the animals inhabited the Pêneda Gêres Natural Park or other rural conservation areas of Portugal. Faecal samples were screened for the presence of ESBLs using Levine agar (Oxoid Limited, UK) supplemented with 2 mg/L cefotaxime (Levine–CTX) (Sigma–Aldrich, USA). Two colonies with typical E. coli morphology were selected and identified by classical biochemical methods (Gram, catalase, oxidase, indole, Methyl Red–Voges–Proskauer, citrate and urease) and by the API 20E system (BioMérieux, La Balme Les Grottes, France) from each positive faecal sample. Susceptibility to 16 antibiotics (ampicillin, amoxicillin/clavulanic acid, cefoxitin, cefotaxime, ceftazidime, aztreonam, imipenem, gentamicin, amikacin, tobramycin, streptomycin, nalidixic acid, ciprofloxacin, sulfamethoxazole/trimethoprim, tetracycline and chloramphenicol) (Oxoid Limited, UK) was determined by the CLSI disc diffusion method3 for all recovered E. coli isolates. E. coli ATCC 25922 was used as a quality-control strain. Isolates resistant to third-generation cephalosporins (i.e. cefotaxime or ceftazidime) were selected for further studies (one per faecal sample, or two if they presented different phenotypes of antibiotic resistance). The double disc diffusion test (cefotaxime, ceftazidime and aztreonam in the presence or absence of amoxicillin/clavulanic acid)3 was performed to detect ESBL production.
