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The aim of the present study was to evaluate retrospectively the antimicrobial susceptibility rate, the trends in antimicrobial susceptibility and the antimicrobial multi-resistance of E.coli strains isolated from swine samples in Italy from 2002 to 2011.
Four-hundred forty-two F4+ pathogenic Escherichia coli isolated from diseased pigs with diarrhea in Northern Italy from 2002 to 2011 were analyzed for their susceptibility to 13 antimicrobials by disk diffusion method: aminosidine (60 μg), apramycin (15 μg), cefquinome (10 μg), colistin (10 μg), danofloxacin (5 μg), enrofloxacin (5 μg), erythromycin (15 μg), florfenicol (30 μg), flumequine (30 μg), gentamicin (10 μg), marbofloxacin (5 μg), tetracycline (30 μg) and trimethoprim-sulphametoxazole (1,25/23,75 μg). On the basis of antimicrobial multi-resistance the strains were attributed to three classes: I. resistant to 2-5 antimicrobials; II. resistant to 6-10 antimicrobials; III. resistant to > 10 antimicrobials.
During the study observation period a statistically significant decreasing trend (P<0.05) in susceptibility was recorded for enrofloxacin (from 85,5% to 10,7%), marbofloxacin (from 94,6% to 39,3%), flumequine (from 50,9% to 7,1%), danofloxacin (from 78,4% to 20%), aminosidine (from 54,6% to 28,6%), florfenicol (from 90,2% to 35,7%), cefquinome (from 96,2% to 56%). A decrease in susceptibility (not statistically significant) was also observed for gentamicin (from 36% to 14,3%), apramycin (from 38,2% to 17,9%), trimethoprimsulphametoxazolo (from 25% to 10,7%), tetracycline (from 2,6% to 0%) and erythromycin (from 7,6% to 0%). Susceptibility rate to colistin (from 41,8% to 46,4%) did not change over the study period.
A significant decrease of susceptibility to antimicrobials and a significant increase of multi-resistant strains (classes II and III) of E.coli F4+ was observed from 2002 to 2011. This indicates the need for continued surveillance studies so that appropriate strategies can be developed to contrast the development of resistance in these and other pathogens.
Luppi A., Bonilauri P., Gherpelli Y., Merialdi G., Maioli G., Biasi G., Dottori M. Antimicrobial resistance of swine Escherichia coli F4+ strains isolated in Italy from 2002 to 2011. IPVS, 2012.