Incidence of antibiotic resistance in fecal Escherichia coli isolated from commercial swine farms.

Abstract

Sows and pigs from 10 commercial swine farms were sampled to determine patterns of resistance of fecal Escherichia coli to five commonly used antibiotics. Before testing, farms were categorized as high or low antibiotic use based on interviews with the respective producers. On each farm, fecal swabs were obtained from five sows at 7 d postpartum and from five pigs from each sow at 7, 35, and 63 d of age. A total of 6,296 E. coli isolates from 750 pig fecal samples and a total of 462 E. coli isolates from 50 sow fecal samples were tested against apramycin, carbadox, gentamicin, neomycin, and oxytetracycline using a standardized disk diffusion test. Percentage of resistant organisms was compared between pigs at the various stages of growth, between sows and their respective pigs, and between farms of high and low antibiotic use. Incidence of resistance was greater (P < .05) in pigs at 35 or 63 d of age compared with 7 d of age for most antibiotics, and patterns differed between high-use and low-use farms. Resistance differed (P < .05) among E. coli from pigs compared to their respective sows for apramycin and carbadox on low-use farms, whereas incidence of resistance on high-use farms differed (P < .05) between sows and pigs for apramycin and oxytetracycline. These data indicate that patterns of antibiotic resistance are dependent on age of pig and level of antibiotic use.

Antimicrobial Resistance Genes in Enterotoxigenic Escherichia coli O149:K91 Isolates Obtained over a 23-Year Period from Pigs

“…Nevertheless, it remains that the phenotypic resistance observations reported here reflect the general trend observed with E. coli strains isolated from pigs (3,19,31). Although we did not test for resistance to all the antimicrobials which could inhibit the growth of E. coli (other aminoglycosides, quinolones or fluoroquinolones, colistin), most of the resistant isolates were resistant to more than one antimicrobial, especially during the last period (1995 to 2000).…”

“…ETEC serotype O149:K91 has been found more frequently in recent years and is the predominant serotype universally associated with diarrhea in pigs (3,19,31). ETEC strains are also associated with several other serogroups, i.e., O8, O9, O20, O101, O138, and O141 (15).…”

Microbial diversity studies of the porcine gastrointestinal ecosystem during weaning transition

“…During and after birth, the young animal becomes colonised with a variety of microbes from the birth canal and the immediate environment. The microflora remains fairly stable in terms of species composition after this initial colonisation, and for as long as the piglets receive their sow's milk [13]. However, the introduction of solid feed causes major qualitative and quantitative alterations in the microflora.…”

Assessing the effect of a single dose florfenicol treatment in feedlot cattle on the antimicrobial resistance patterns in faecal Escherichia coli

“…Antimicrobial resistance assessment of commensal organisms has been used to study gastrointestinal tract ecology and track environmental organisms to a presumed source [14,16,23]. Commensal E. coli have been used as a monitor of antimicrobial resistance in cattle and swine populations [5,10,30,31].…”