Tetracycline resistance genes in Pasteurella multocida isolates from bovine, ovine, caprine and swine pneumonic lungs originated from different Greek prefectures

Abstract

The aim of the present work was to analyze the antibiotic resistance of Pasteurella multocida isolates
from sheep, goats, cattle and pigs originated from eight different Greek prefectures, to determine the
class(es) of the tet genes, to investigate any possible association with plasmids or/and chromosomes
and to study the geographical distribution of the resistant isolates. Eighteen out to one hundred
isolates were resistant to tetracycline with a minimal inhibitory concentration (MIC) higher than 128
μg/ml. The tetH gene was found in thirteen (72.2%) and the tetB gene was found in four isolates (22.2%).
After treatment with the restriction enzymes EcoRV, EcoRI, PstI and BspHI, the tetB gene showed a new
polymorphism. Partial sequencing of the tetH and tetB genes revealed five polymorphisms in the tetB
gene and two polymorphisms in the tetH gene; phylogenetic and molecular evolutionary analyses were
also conducted. Both tetB and tetH genes revealed patterns clearly differentiated from the rest of
Pasteurella species meaning that the genes could be transferred from a non Pasteurella species. The
results presented provide further knowledge and evidence of the role played by commensals as of
resistance determinants.