title: Assessment of antibiotic resistance of Escherichia coli isolates and screening of Salmonella spp. in wild ungulates from Portugal.
abstract: Antibiotic resistance is an emerging global problem. Wild animals are rarely exposed to antibiotics and therefore low levels of antibiotic resistance are expected. However, the growing interactions of these animals with humans and livestock may have a huge impact on their bacterial flora. This study aimed to assess the levels of antibiotic resistance in Escherichia coli isolated from widespread wild ungulates in Portugal. The interpretation of inhibition zone diameters was performed according to clinical breakpoints and epidemiological cut-offs, determined with the normalized resistance interpretation (NRI) method. For clinical breakpoints, 16% of the isolates were resistant to at least one antibiotic, including ampicillin (10%), tetracycline (9%), streptomycin (5%) co-trimoxazole (4%), amoxicillin/clavulanic acid (1%) and cefoxitin (1%). The levels of resistance detected in E. coli strains isolated from wild boar were statistically different for ampicillin and co-trimoxasol. According to NRI cut-offs, 10% of the population showed a non-wild-type phenotype against at least one antibiotic, also including tetracycline (9%), co-trimoxazole (6%), streptomycin (4%), ampicillin (2%) and amoxicillin/clavulanic acid (1%). Considering this parameter of comparison, no statistically different levels of resistance were identified between E. coli recovered from the three wild ungulates. Screening of Salmonella spp., which can be potentially pathogenic, was also performed, revealing that its prevalence was very low (1.5%). The study demonstrated that wild ungulates from Portugal are also reservoirs of antibiotic-resistant bacteria.
authors: CESAM, Department of Biology, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal. Electronic address: dianadias@ua.pt.
authors: Diana
authors: D
authors: Dias
authors: CESAM, Department of Biology, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal. Electronic address: rita.torres@ua.pt.
authors: Rita T
authors: RT
authors: Torres
authors: Department of Microbiology and Tumor Biology-MTC, Clinical Microbiology, Karolinska Institute, Karolinska Hospital L2:02, Stockholm SE-17176, Sweden.
authors: Göran
authors: G
authors: Kronvall
authors: CESAM, Department of Biology, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal. Electronic address: cfonseca@ua.pt.
authors: Carlos
authors: C
authors: Fonseca
authors: CESAM, Department of Biology, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal. Electronic address: smendo@ua.pt.
authors: Sónia
authors: S
authors: Mendo
authors: CESAM, Department of Biology, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal. Electronic address: tcaetano@ua.pt.
authors: Tânia
authors: T
authors: Caetano
mesh_terms: D000818:Animals; D000835:Animals, Wild; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D052978:Disk Diffusion Antimicrobial Tests; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D008403:Mass Screening; D011174:Portugal / Q000453:epidemiology; D015995:Prevalence; D012481:Salmonella Infections, Animal / Q000453:epidemiology / Q000382:microbiology*; D019779:Salmonella enterica / Q000187:drug effects* / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents
keywords: Antibiotic resistance; Clinical breakpoint; ECOFF; Fecal samples; Normalized resistance method; Wildlife