R) Gram-negative bacteria [11,12]. Decreased susceptibility to colistin and tigecycline are justified
R) Gram-negative bacteria [11,12]. Decreased susceptibility to colistin and tigecycline are justified by encoded intrinsic resistance and the presence of mobile colistin and tigecycline resistance genes [13,14]. A transferable plasmid-derived colistin resistance gene mcr-1 was identified to become responsible for resistance occurrence worldwide [15,16]. It must be considered that colistin has been extensively administered for the prevention, treatment, metaphylaxis and growth promotion in veterinary medicine for many years [17,18]. Among food-producing animals, many research have reported a notable prevalence of colistin resistance in poultry [191]. It need to be stressed that there has been an alarming boost of bacteria resistant to third-generation cephalosporins, which reinforces the suspicion of possible “non-official” use in chicks at hatch [22,23]. Essentially, it is actually known that the usage of cephalosporins in poultry and other species was prohibited by the Food and Drug Administration [24], due to the fact they may very well be accountable for triggering resistance to these classes of antimicrobials in humans. During the final decade, a Goralatide MedChemExpress progressive boost in ESBL E. coli associated with a multi-resistance profile has also been documented on chicken farms [25]. This, in turn, has triggered concern for public overall health, as poultry meat is widely consumed, both for its nutritional characteristics along with the financial positive aspects associated with low charges [26]. Furthermore, the diffusion of ESBL could lead to unsuccessful therapeutic Benidipine Formula remedy in human infections and also demand the usage of “last resort antibiotics” (e.g., carbapenems) causing an enhanced resistance to these antibiotic classes [27,28]. Within this situation, poultry producers have turned to option production systems, such as organic (O) and antibiotic-free (AF) farming, depending on the lack of antimicrobial use, unless animal welfare is at risk [29]. In our work, we aimed to investigate the antibiotic susceptibility of commensal E. coli, in particular towards antimicrobials utilised in human therapy, isolated in organic, antibiotic-free and traditional (C) broilers on farms and at slaughter. The diffusion of ESBL E. coli was also assayed. two. Final results With respect to antimicrobial susceptibility, O and AF samplings showed larger prevalence of E. coli-resistant strains to tigecycline than C (29.3 in O, 20.7 in AF, and ten.three in C) (Figure 1) with an odds ratio (OR) of three.59 (p = 0.01) for O (Table 1). All E. coli strains isolated from O, AF and C had minimal inhibitory concentration (MIC) values for tigecycline inside 1 /mL (Table S1). The O samplings showed the highest prevalence of E. coli-resistant strains for azithromycin (29.3 vs. 10.3 in AF and six.9 in C) with OR = 4.39 (p = 0.001), and for gentamicin (32.eight vs. 22.4 in AF and 12.1 in C) with OR = two.34 (p = 0.02) when when compared with the C systems (Figure 1 and Table 1). The MIC values for one of the most azithromycin-resistant E. coli strains isolated from O samplings have been higher than 64 /mL (Table S1). The O samplings exhibited the lowest prevalence of resistance of E. coli to cefotaxime and ceftazidime-resistant strains. The prevalence prices of E. coli cefotaxime-resistant strains have been 29.3 in O, 36.2 in AF and 51.7 in C with OR = 0.39 (p = 0.01) and also the prevalence of ceftazidime-resistant strains was 8.6 in O, 10.three in AF and 31 in C with an OR of 0.36 (p = 0.02) (Figure 1 and Table 1).Antibiotics 2021, ten,(Table 1). No statistical differences were discovered inside the multi-resi.