Antibiotic Susceptibility and Virulence Factors inEscherichia colifrom Sympatric Wildlife of the Apuan Alps Regional Park (Tuscany, Italy)

Abstract

Today a growing number of studies are focusing on antibiotic resistance in wildlife. This is due to the potential role of wild animals as reservoirs and spreaders of pathogenic and resistant bacteria. This study focused on isolating and identifying Escherichia coli from the feces of wild animals living in the Apuan Alps Regional Park (Tuscany, Italy) and evaluating some of their antibiotic resistance and pathogenicity traits. Eighty-five fecal samples from different species were studied. Seventy-one E. coli were identified by matrix assisted laser desorption ionization-time of flight mass spectrometry analysis, subjected to antibiograms and polymerase chain reaction for the detection of antibiotic resistance genes and pathogenicity factors. The highest resistance rates were found against cephalothin (39.4%) and ampicillin (33.8%), followed by amoxicillin/clavulanic acid (15.5%), streptomycin (12.7%), and tetracycline (5.6%). Regarding resistance genes, 39.4% of the isolates were negative for all tested genes. The remaining isolates were positive for bla CMY-2 , sul2, strA-strB and aadA1, tet(B), and tet(A), encoding resistance to beta-lactams, trimethoprim/sulfamethoxazole, streptomycin, and tetracycline, respectively. With regard to virulence factors, 63.4% of the isolates were negative for all genes; 21.1% carried astA alone, which is associated with different pathotypes, 9.9% carried both escV and eaeA (aEPEC); single isolates (1.4%) harbored escV (aEPEC), escV associated with astA and eaeA (aEPEC), astA with stx2 and hlyA (EHEC) or astA and stx1, stx2, and hlyA (EHEC). These results show that wildlife from nonanthropized environments can be a reservoir for antibiotic-resistant microorganisms and suggest the need for a deeper knowledge on their origin and diffusion mechanisms through different ecological niches.

Pathotypes and Antimicrobial Susceptibility of Escherichia Coli Isolated from Wild Boar (Sus scrofa) in Tuscany

“…In the present study, the most detected gene coding for Shiga-like toxins was stx2. This is in line with other investigations conducted in Europe on wild boar [17] and in Italy on wild mammals sharing the same ecosystem [22]. However, it is interesting to note that a study carried out on birds in the same geographic area reported stx1 as the most common gene [49], suggesting a possible clustering of strains in relation to animal species.…”

“…However, some studies showed circulation of this pathotype in wild animals too [10]. In particular, concerning wild boar, our results are not dissimilar from those of other studies carried out in Europe, where the percentage of positive animals ranged between 3% and 30% [17][18][19][20][21][22]. In the present study, the most detected gene coding for Shiga-like toxins was stx2.…”

“…None of the isolates belonged to ETEC or EIEC; which is in line with other investigations. Indeed, these pathotypes are not frequently isolated from asymptomatic animals [10,22,57].…”

“…In Poland, 28.2% and 30.9% STEC and EPEC, respectively, were isolated from rectal swabs of wild boar [21]. In Italy, a recent investigation carried out on different wild animals identified one EPEC and one EHEC isolate from a small number of wild boar [22]. On the other hand, no positive samples among wild boar were detected for EHEC in a survey carried out in Sweden [23].…”

“…In Italy, information about the antimicrobial resistance of wild boar E. coli is limited. Resistance to ampicillin, amoxicillin-clavulanic acid, and streptomycin was recorded in a survey conducted in Central Italy, but only a limited number of samples from wild boar were analyzed [22]. Other authors examined higher numbers of animals, but their work focused only on ESBL, revealing the presence of ESBL-producing E. coli in 0.9% of samples [35].…”