ABSTRACT
In order to know that Streptococcus exist in health swine herd,2 204 cases of nose swabs were collected in swine from different areas in Dongbei three province of northeast China.Seed swab to Streptococcus culture medium,24 hours after culturing,gram staining with becteria culture,gram positive Streptococcus were identified with PCR technology,then farther identified serotype with Streptococcus suis 1,2,7,9 serotype special primers.The results showed that Streptococcus exist rate in swine herd of Heilongjiang,Jinlin,Liaoning is 29 %,27 %,34 %,respectively.PCR typing assay indicated that 155 strains of Streptococcus suis were isolated including 7 strains of 1 serotype,39 strains of 2 serotype,4 strains of 7 serotype,11 strains of 9 serotype,94 strains of other serotype in three province of northeast China.
ABSTRACT
Temporins are a kind of small,hydrophobic and C-terminus amidated antimicrobial peptides from Rana species.They are effective against bacteria,fungi,yeast,protozoa and viruses.Two novel temporins named as temporin-La(LLRHWKILEKYLanifc) and temporin-Lb(LFRHVVKIFEK.Ylamid.) were cloned from Lithobates catesbeianus.Synthetic peptides of temporin-La and temporin-Lb showed strong antimicrobial activities against bacteria tested,especially Gram-positive bacteria.Besides,temporin-La showed no haemolytic activity to rabbit erythrocytes at the concentration of 250 mg/L while temporin-Lb showed weak haemolytic activity(LC50≈ 230 μmol/L).Transmission electron microscopy showed that temporin-La and temporin-Lb induced different effects on bacterial structure of Staphylococcus aureus.
ABSTRACT
The susceptibility to 9 kinds of antibiotics of 393 animal pathogenic E. coli isolated from clinical samples was determined from 2000 to 2003. The resistance to TC, GM, CMP, AMP, RA, KM, FT, SM and CIP were 93.89%, 57.76%,78.63%, 77.86%, 92.11% ,47.33%, 46.82%, 76.84% and 74.81%, respectively. The isolates could be classified into eight classes according to the number of drugs to which srains were resistant. The resistance spectrum of the isolates varied from 2to 9 kinds of the above drugs. The strains that were resistant to seven kinds of drugs were more than 80 percent. The resistance rates of swine origin strains to GM,AMP and KM were higher than those of poultry origin strains, while the resistance rates of poultry origin strains to TC, CMP, SM and CIP were higher remarkably than those of swine origins. The frequency of resistance increased from 2000 to 2003,which was from 67.33% to 90.58% for CMP, 71.29% to 84.81% for AMP, 73.76%to 80.10% for SM and 61.88% to 88.48% for CIP. At the same time, the resistance rate of GM decreased from 61.39% to 53.92%. Thirty-seven strains (95 %) could make all the Kunming mice die within 72 h injected intraperitoneally with the culmice three times in vivo. The pathogenicity of wild strains with drug resistance acquired naturaly to mice did not decline.