Antimicrobial susceptibility and phylotyping profile of pathogenic Escherichia coli and Salmonella enterica isolates from calves and pigs in Minas Gerais, Brazil

Abstract

The aims of the present study were to determine (i) the profiles of phylogroup and (ii) the antimicrobial susceptibility of pathogenic Escherichia coli strains isolated from calves, and of Salmonella spp. strains isolated from calves and pigs in Minas Gerais State, Brazil. Sixty-one pathogenic E. coli strains and Salmonella spp. (n = 24) strains isolated from fecal samples of calves and Salmonella spp. (n = 39) strains previously isolated from fecal samples of growing/finishing pigs were tested. The minimum inhibitory concentration (MIC) using the agar dilution method was determined for nalidixic acid, amikacin, amoxicillin, ampicillin, cefoxitin, norfloxacin, gentamicin, tetracycline, and trimethoprim-sulfamethoxazole. All E. coli isolates were susceptible to amikacin. Tetracycline was the antimicrobial that presented the higher frequency of resistance among E. coli strains, followed by ampicillin, trimethoprim-sulfamethoxazole, amoxicillin, nalidixic acid, norfloxacin, gentamicin, and cefoxitin. E. coli (n = 61) strains isolated from calves belonged to different phylogroup namely, phylogroup A (n = 26), phylogroup B1 (n = 31), phylogroup E (n = 3), and phylogroup F (n = 1). Phylogroups B2, C, and D were not identified among the E. coli in the present study. All Salmonella spp. (n = 24) strains isolated from fecal samples of calves were susceptible to amikacin, amoxicillin, ampicillin, norfloxacin, gentamicin, tetracycline, and trimethoprim-sulfamethoxazole. Resistance to nalidixic acid and cefoxitin was detected in 16.66 and 8.33 % of the Salmonella spp. strains, respectively. Among the Salmonella spp. (n = 39) strains isolated from fecal samples of pigs, the higher frequency of resistance was observed to tetracycline, followed by amoxicillin, gentamicin, ampicillin, trimethoprim-sulfamethoxazole, nalidixic acid, cefoxitin, and norfloxacin. All strains were susceptible to amikacin. Forty-eight (78.68 %) of the E. coli strains were classified as multidrug-resistant, whereas among Salmonella spp. strains, the percentage of multidrug resistance was 57.14 %, being all multidrug-resistant strains isolated from pigs (92.30 %). The results from the present study indicate a high frequency of antimicrobial resistance among pathogenic E. coli strains isolated from calves and Salmonella spp. strains isolated from pigs and a high rate of susceptibility to most antimicrobials tested among Salmonella spp. strains isolated from calves. Our study highlights the presence of multidrug-resistant strains of E. coli and Salmonella spp. isolated from food-producing animals in Minas Gerais, Brazil.

Caution at choosing a particular colony-forming unit from faecal Escherichia coli: it may not represent the sample profile

“…Overall, 65% (126/195) CFUs analysed belonged to commensal phylo-group B1, corresponding to the animals' healthy status. As in the world literature (Son et al, 2009;Tenaillon et al, 2010;Bessalah et al, 2016;Coura et al, 2017;Souto et al, 2017) we also found the predominance of B1 phylo-group (40/65 CFUs; 61Á5%) in calves, followed by E (13/65; 20%). Similarly, B1 (33/65 CFUs; 50Á8%) predominated in foals, followed by E (14/65 CFUs; 21Á5%) and C (10/65 CFUs; 15Á4%), being a profile previously reported in healthy horses (Smati et al, 2015).…”

Nontyphoid Salmonella carriage, serovar profile and antimicrobial resistance phenotypes in slaughter cattle

“…Apart from this, the profile of our pansusceptible S . Enteritidis isolated from FC was in accordance with (susceptible to at least one: chloramphenicol, amoxicillin/clavulanic acid, ampicillin, ciprofloxacin, cefepime, and sulphamethoxazole/trimethoprim) previous works (Rene et al, ; Souto et al, ). There are also studies indicating resistance of S .…”

“…An additional output in our study is rPCR's performance in reliable utilization with ISO in the rapid and reliable confirmation of Salmonella-suspect isolates from cattle, and particularly from FC samples, demonstrated by an overall substantial, and a perfect agreement between two methods, respectively ( (Rene et al, 2017;Souto et al, 2017).…”

“…There are also studies indicating resistance of S. Enteritidis to tobramycin (Rene et al, 2017), cefoxitin (Souto et al, 2017), and ampicillin and chloramphenicol (Hadimli et al, 2017).…”

<b>Etiological and molecular profile of pathogens causing clinical mastitis, and antimicrobial use in dairy herds</b>

“…However, to the best of our knowledge, this is the first study reporting E. coli of phylogroup C as the cause of CM. In other studies, strains belonging to phylogroup C were associated with intestinal and extra-intestinal infections in humans (CLERMONT et al, 2011), and with fecal samples collected from diarrheal calves (SOUTO et al, 2017). Only four isolates were assigned to the phylogroup C in our study, and few isolates were assigned to the phylogroups B2, D and E. Therefore, further studies with a larger number of strains could better clarify whether these less frequently identified phylogroups in our study are only opportunistic pathogens, or important groups associated with IMI in dairy cows.…”