U.S. flag

An official website of the United States government

Dot gov

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Https

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

PubAg

Main content area

Competitive effect of commensal faecal bacteria from growing swine fed chlortetracycline-supplemented feed on beta-haemolytic Escherichia coli strains with multiple antimicrobial resistance plasmids

Author:
T. L. Poole, T. R. Callaway, K. M. Bischoff, G. H. Loneragan, R. C. Anderson, D. J. Nisbet
Source:
Journal of Applied Microbiology 2012 v.113 pp. 659-668
ISSN:
1364-5072
Subject:
anaerobic conditions, antibiotic resistance, bacteria, bacterial communities, chlortetracycline, commensalism, competitive exclusion, enterotoxigenic Escherichia coli, experimental diets, feces, feed supplements, hemolysis, microbial competition, microbial growth, multiple drug resistance, mutation, pathogen survival, plasmids, population, strains, swine, swine feeding
Abstract:
Aims: To determine the differences in competitive fitness among Escherichia coli strains with different plasmid profiles when grown in suspension with commensal faecal bacteria from growing swine fed chlortetracycline-supplemented or unsupplemented diets. Methods and Results: Five multiple drug-resistant (MDR) E. coli strains that possessed 0, 2, 6 or 8 plasmids were inoculated into anoxic faecal cultures from swine fed an unsupplemented (control) or chlortetracycline (50 g ton1)-supplemented (experimental) diet. On days 21 of chlortetracycline supplementation, faecal growth competition studies were performed. MDR E. coli were enumerated at 0, 6 and 24 h. The plasmid-free strain was below culturable limits in both the control and experimental cultures by 24 h. For each plasmid-bearing strain, there was no statistically significant difference in population CFU ml1 (P < 005) between the control and experimental cultures. Conclusions: There was no significant effect on the faecal microflora, owing to the inclusion of chlortetracycline, in the swine diets, that affected the growth of E. coli in the competition studies employed. Furthermore, these results suggest that the cost of maintaining plasmids in these E. coli strains had little influence on survivability. Significance and Impact of Study: Mutations that led to antimicrobial resistance may have a greater impact on survivability than multiple plasmid carriage.
Agid:
58189
Handle:
10113/58189