Impact of the Use of β-Lactam Antimicrobials on the Emergence of Escherichia coli Isolates Resistant to Cephalosporins under Standard Pig-Rearing Conditions

Abstract

The aim of this study was to evaluate if the treatments with ceftiofur and amoxicillin are risk factors for the emergence of cephalosporin resistant (CR) E. coli in a pig farm during the rearing period. One hundred 7-day-old piglets were divided into two groups, a control (n ‫؍‬ 50) group and a group parenterally treated with ceftiofur (n ‫؍‬ 50). During the fattening period, both groups were subdivided in two. A second treatment with amoxicillin was administered in feed to two of the four groups, as follows: group 1 (untreated, n ‫؍‬ 20), group 2 (treated with amoxicillin, n ‫؍‬ 26), group 3 (treated with ceftiofur, n ‫؍‬ 20), and group 4 (treated with ceftiofur and amoxicillin, n ‫؍‬ 26). During treatment with ceftiofur, fecal samples were collected before treatment (day 0) and at days 2, 7, 14, 21, and 42 posttreatment, whereas with amoxicillin, the sampling was extended 73 days posttreatment. CR E. coli bacteria were selected on MacConkey agar with ceftriaxone (1 mg/liter). Pulsed-field gel electrophoresis (PFGE), MICs of 14 antimicrobials, the presence of cephalosporin resistance genes, and replicon typing of plasmids were analyzed. Both treatments generated an increase in the prevalence of CR E. coli, which was statistically significant in the treated groups. Resistance diminished after treatment. A total of 47 CR E. coli isolates were recovered during the study period; of these, 15 contained bla CTX-M-1 , 10 contained bla CTX-M-14 , 4 contained bla CTX-M-9 , 2 contained bla CTX-M-15 , and 5 contained bla SHV-12 . The treatment with ceftiofur and amoxicillin was associated with the emergence of CR E. coli during the course of the treatment. However, by the time of finishing, CR E. coli bacteria were not recovered from the animals.

Advances in the Analysis of Veterinary Drug Residues in Food Matrices by Capillary Electrophoresis Techniques

“…In particular, in veterinary medicine, ceftiofur and cefquinome are specifically used to treat respiratory diseases and exudative epidermitis, and meningitis, respectively. Cefquinome had MRL values more restrictive than those of ceftiofur (50-200 µg/kg vs. 100-6000 µg/kg) [2], but the use of ceftiofur must be carefully evaluated as its use could develop E. coli resistance [85,86].…”

Effects of feeding pasteurized waste milk to dairy calves on phenotypes and genotypes of antimicrobial resistance in fecal Escherichia coli isolates before and after weaning

“…Feeding waste milk (WM) to dairy calves increased the prevalence of resistant bacteria to the antimicrobials used in the farm, but also to other antimicrobials that were not used (Aust et al, 2013;Pereira et al, 2014a;Maynou et al, 2017). Cameron-Veas et al (2015) demonstrated the capacity of resistant strains to transfer β-lactam resistance genes to other bacteria by conjugation in pigs parentally treated with ceftiofur (EFT). In this study, the transconjugants also exhibited resistance to antimicrobial classes other than β-lactams, suggesting co-selection of resistance genes by genetic linkage to others.…”

Amplification of Antimicrobial Resistance in Gut Flora of Patients Treated with Ceftriaxone

“…However, although the use of broad-spectrum cephalosporins has been implicated in the emergence of resistance (15,16), few studies demonstrated a clear association between amplification of resistance and drug exposure. Animal studies in pigs found an increase in the prevalence of resistant E. coli within the first week of treatment with ceftiofur and amoxicillin (11). Similar studies in calves showed a 14% increase in fecal bacteria resistant to ceftriaxone within 3 days after treatment.…”

“…Previous studies found a relationship between the qPCR ratio and surveillance cultures, indicating that this ratio reflects colonization by resistant bacteria. Antibacterial treatment may select for a wide range of cephalosporin resistance genes from different families and microorganisms (11,12). In the present study, we studied the effect of antibiotic treatment on bla CTX-M genes normalized by the total bacterial load by using the 16S rRNA genes with a method developed earlier (9).…”