Title |
Comparison of antibiotic resistance and copper tolerance of Enterococcus spp. and Lactobacillus spp. isolated from piglets before and after weaning |
Author |
Xueting Zou1, Mengwei Weng1, Xu Ji1, Rong Guo1, Weijiang Zheng1, and Wen Yao1,2* |
Address |
1College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, 210095, P. R. China, 2Key lab of Animal Physiology and Biochemistry, Ministry of Agriculture, Nanjing, 210095, P. R. China |
Bibliography |
Journal of Microbiology, 55(9),703–710, 2017,
|
DOI |
10.1007/s12275-017-6241-x
|
Key Words |
Enterococcus spp., Lactobacillus spp., antibiotic
resistance, copper tolerance, swine |
Abstract |
In China, antimicrobials and copper are used extensively as
growth-promoting agents for piglets. This study aimed to
characterize the role of in-feed copper in the emergence of
copper-tolerant and antibiotic-resistant Enterococcus and
Lactobacillus isolates in Chinese pig farms. Feces of the same
eight piglets from four litters at 7 and 55 days old and their
mothers were traced in order to isolate Enterococcus spp.
and Lactobacillus spp.. The minimum inhibitory concentrations
of 10 antimicrobials and copper sulfate were determined
using an agar dilution method. The feed levels of Cu2+ for
lactating sows, suckling piglets, and weaned piglets were 6,
177, and 18 mg/kg, respectively. All the 136 Enterococcus isolates
were sensitive to vancomycin; and the resistance rates
to penicillin, enrofloxacin, and high level streptomycin resistance
increased significantly after weaning. For the 155 Lactobacillus
isolates, the resistance rates to ampicillin, chloramphenicol,
tetracycline, and enrofloxacin were significantly
higher in weaned piglets. The ratios of copper tolerant Enterococcus
and Lactobacillus isolates both increased significantly
after weaning (P < 0.05). A phenotypic correlation was observed
after classifying the isolates into two groups (CuSO4
MIC50 < 16 or 16 for enterococci; CuSO4 MIC50 < 12 or 12 for lactobacilli) and comparing the antimicrobial-resistant
percentage of two groups. On species level, a significant
increase of E. faecalis to enrofloxacin was observed in
line with the increase of copper MIC (P < 0.05). The findings
revealed the changes of the antibiotic resistance and copper
tolerance level of enterococci and lactobacilli between suckling
and weaned piglets and demonstrated that there might
be a strong association between in-feed copper and increased
antibiotic resistance in enterococci and lactobacilli in Chinese
intensive swine farms. |