TY - JOUR
T1 - Competitive effect of commensal faecal bacteria from growing swine fed chlortetracycline-supplemented feed on β-haemolytic Escherichia coli strains with multiple antimicrobial resistance plasmids
AU - Poole, T. L.
AU - Callaway, T. R.
AU - Bischoff, K. M.
AU - Loneragan, G. H.
AU - Anderson, R. C.
AU - Nisbet, D. J.
PY - 2012/9
Y1 - 2012/9
N2 - 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 ton-1)-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 ml-1 (P < 0·05) 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. No claim to US Government works. Journal of Applied Microbiology
AB - 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 ton-1)-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 ml-1 (P < 0·05) 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. No claim to US Government works. Journal of Applied Microbiology
KW - Antimicrobials
KW - Food safety
KW - Intestinal microbiology
UR - http://www.scopus.com/inward/record.url?scp=84865287558&partnerID=8YFLogxK
U2 - 10.1111/j.1365-2672.2012.05365.x
DO - 10.1111/j.1365-2672.2012.05365.x
M3 - Article
C2 - 22716900
AN - SCOPUS:84865287558
SN - 1364-5072
VL - 113
SP - 659
EP - 668
JO - Journal of Applied Microbiology
JF - Journal of Applied Microbiology
IS - 3
ER -