Impact of Ceftiofur Injection on Gut Microbiota and Escherichia coli Resistance in Pigs

Abstract

Resistance to extended-spectrum cephalosporins (ESCs) is an important health concern. Here, we studied the impact of the administration of a long-acting form of ceftiofur on the pig gut microbiota and ESC resistance in Escherichia coli. Pigs were orally inoculated with an ESC-resistant E. coli M63 strain harboring a conjugative plasmid carrying a gene conferring resistance, bla CTX-M-1 . On the same day, they were given or not a unique injection of ceftiofur. Fecal microbiota were studied using quantitative PCR analysis of the main bacterial groups and quantification of short-chain fatty acids. E. coli and ESC-resistant E. coli were determined by culture methods, and the ESC-resistant E. coli isolates were characterized. The copies of the bla CTX-M-1 gene were quantified. After ceftiofur injection, the main change in gut microbiota was the significant but transitory decrease in the E. coli population. Acetate and butyrate levels were significantly lower in the treated group. In all inoculated groups, E. coli M63 persisted in most pigs, and the bla CTX-M-1 gene was transferred to other E. coli. Culture and PCR results showed that the ceftiofurtreated group shed significantly more resistant strains 1 and 3 days after ESC injection. Thereafter, on most dates, there were no differences between the groups, but notably, one pig in the nontreated group regularly excreted very high numbers of ESC-resistant E. coli, probably leading to a higher contamination level in its pen. In conclusion, the use of ESCs, and also the presence of high-shedding animals, are important features in the spread of ESC resistance.

Escherichia coli Probiotic Strain ED1a in Pigs Has a Limited Impact on the Gut Carriage of Extended-Spectrum-β-Lactamase-Producing E. coli

“…Bearing this in mind, we decided to evaluate the impact of the oral administration of E. coli strains on the excretion of ESCR Enterobacteriaceae in feces and their survival in manure through an experimental model of ESCR E. coli infection (16). The E. coli M63 strain used in this model seemed to be very well suited to the pig microbiota and persisted in all groups up to the end of the trials.…”

“…This isolate, named UB12/059-3, was then made resistant to rifampin and used as a receptor for in vitro conjugation with an ESCR E. coli isolate obtained from a healthy pig at a slaughterhouse and previously shown to contain a bla CTX-M-1 gene. The resulting transconjugant, E. coli M63, belongs to the B1 phylogenetic group and contains resistance genes bla CTX-M-1 , bla CMY-59 , aadA5, sul2, and dfrA17 (16). It is resistant to cefotaxime, rifampin, streptomycin, and trimethoprim-sulfamethoxazole.…”

“…During the week, daily clinical examinations consisted of evaluations for general clinical signs and recording of rectal temperatures. Individual fecal samples were collected from all animals on day 0 before inoculation and on days 1, 3, 7, 10, 13, 17, 22, and 28 (the first trial) and days 3,8,10,13,16,20,23,27, and 31 (the second trial). The fecal samples were stored at Ϫ70°C until analysis.…”

Rare Spontaneous Loss of Multiresistance Gene Carrying IncI/ST12 Plasmid in Escherichia coli in Pig Microbiota

“…Four different trials were conducted in 2012 to 2013, using the previously described ESBL-producing E. coli M63 strain (5). The experiments were performed in accordance with French animal welfare regulations, and the protocols were approved by the ANSES/ENVA/UPEC ethics committee (ComEth approval no.…”

“…Briefly, E. coli M63 was obtained by conjugation between a randomly chosen pansusceptible E. coli isolate, UB12/059-3, obtained from a specific-pathogen-free pig of our herd, made resistant to 250 mg/liter rifampin, and an ESC-resistant E. coli isolate, 05-M63-1, from our slaughter pig strain collection. Thus, E. coli M63 is resistant to rifampin because of chromosomal mutations, and sequencing of the ESC resistance plasmid showed that it was an IncI1/ST12 plasmid harboring the bla CTX-M-1 , bla CMY-2 , sul2, dfrA17, and aadA5 genes (5). The E. coli M63 cultures used for pig inoculation were prepared in cefotaxime (CTX)-supplemented medium.…”