Frequency of zoonotic enteric pathogens and antimicrobial resistance in wild boar (Sus scrofa), Iberian ibex (Capra pyrenaica) and sympatric free-ranging livestock in a natural environment (NE Spain)
PhD Thesis defense by Nora Navarro González at the Faculty of Veterinary Medicine of the Autonomus University of Barcelona
July 10th, 2013
The transmission of zoonotlc pathogens from wildlife to livestock, and vice versa, is a cause of global concern since wild ungulates are becoming more abundant and widely distributed throughout Europe, even in urban areas. In parallel, in the European Union some food-borne zoonoses are increasing in frequency each year. To compound these factors, antimicrobial resistance is a global threat and should be monitored to prevent its spread. The purpose of this Thesis was to investigate whether selected zoonotic pathogens are shared between free-ranging livestock and sympatric wild ungulates (wild boar -Sus seroJa -and Iberian ibex -Capra pyrenoica) in a natural environment in NE Spain. Additionally, we explored if antimicrobial resistance in pathogens and indicator bacteria is also distributed among those host species. Furthermore, the abovementioned pathogens and antimicrobial resistance were investigated in an urban wild boar population in Barcelona, Spain. 5almonella prevalence was higher in wild boars co-habiting with cattle (35.67%, el 95% 28.19 43.70) than in wild boar from cattle-free areas (17.54 %, el 95% 8.74 -29.91). Moreover, the probability of a wild boar being a Salmonella carrier increased with cattle herd size, and serotype richness was higher in wild boars co-habiting with cattle. The finding of a S. Enteritidis strain resistant to ciprofloxacin and nalidixic acid in wild boars is cause for public health concern. The different Salmone/la prevalence in cattle (21.92%, 95% el 13.10-33.14) and in Iberian ibex (0.96%, 95% el 0.2-2.8) and t he lack of shared serotypes suggest no association. Please see Study I and II for more details. Prevalence of E. coli 0157:H7 was low at 3.41% in wild boars (95% el 0.94 -8.52) and 1.88% in Iberian ibex (95% el 0.39 -5.38), and was not isolated from livestock faeces (see 5tudy 111). With regards to Campylobaeter spp., faecal samples from Iberian ibex were negative. C. jejuni was carried by one wild boar (0.67%, 95% el 0.02 -3.66), while this was the predominant specíes in cattle at 9.09% (95% el 3.02 -19.95). C. lanienae was the most frequent species in wild boar at 12% (95% el 7.27 -18.3) and was concurrently isolated from one COW. These results (Study IV) suggest that Iberian ibex do not play an important role in the epidemiology of Campylobacter, and that despite wild boar and cattle having their own predominant Campylobacter species, there is a potential spill-over of C. lanienae and C. jejuni. Both wild and domestic animals appeared to be low-significance reservoirs of antimicrobial resistance, as stated in Study 111. The frequency of resistance in indicator E. colí was low, ranging from O to 7.9%. Remarkably, one isolate carried by wild boar showed resistance to a
third-generation cephalosporin and fluoroquinolone-resistance was detected in isolates from cattle and wild boar. We suggest the potential of wild boar as a sentinel for antimicrobial resistance ih a broad range of environmental conditions. Salmonella enterica was found in 5% (95% el 0.61-16.91) of urban wild boars in Study V, and
Campylobacter coli in 4.88% (95% el 0.6-16.53). Other thermophilic Campylobacter were moderately prevalent (19. 51%, 95% el 8.82-34.87), while C. jejuni and E. coli 0157:H7 were not found. Antimicrobial resistance was most frequent in Enterococcus faecium (95% of the
isolates were resistant to at least one antimicrobial agent), followed by Enterococcus faecalis (50%) and Escherichia coli (10%). We report for the first time resistance to linezolid in wildlife.
These results have implications for public health, and thus, further research is needed on wildlife in urban environments
