The purpose of this study was to evaluate effect of chitosan-oligosaccharides(CHIOL) on hydrophobicity of pathogenic E coli including a field isolate from suckling piglet with diarrhea, E coli-0157:H7, and E coli-O149:K88ac. E coli field isolate appeared adhesion of 100% to n-hexadecne between 0.00125% and 0.05% CHIOL. E coli-O157:H7 occurred adhesion of 69% and 64% under the level of 0.00125% and 0.025% CHIOL, respectively. E coli-O149:K88ac showed adhesion of 100% in higher than 0.025% CHIOL. For cationic action, the adhesion of E coli isolate and E coli-O149:K88ac to n-hexadecane were inhibited at level of higher than 10mM Ca2+ but did not induce any difference among the concentrations used(p0.01). However,the adhesion of E coli-O157:H7 to n-hexadecane was inhibited at level of higher than 50mM Ca2+. In a field trial, control piglets showed average mortality of up to 58% during 3 days after the onset of diarrhea. In contrast, the prevalence of E coli-induced diarrhea in CHIOL-treated groups without mortality was dropped down to average 34% on the 1st day after the treatment of CHIOL, and average 2% on the 4th day. After then, piglets with diarrhea was not present. In conclusion, the low concentrations of CHIOL were most likely to associate with the enhancement of hydrophobicit to pathogenic E coli. Calcium inhibited the hydrophobicity of E coli by CHIOL. These results suggested that CHIOL could be played an efficient and reliable role in treating enteric colibacillosis of piglets.

The present work was conducted to investigate the drug susceptibility of microorganisms isolated form canine external ear canals. Antifungal susceptibility test of M pachydermatis(17 strains) was performed by agar dilution method, using 11 antifungal drugs including amphotericin B(A), nystatin(N), pimaricin(P), griseofulvin(G), gifonazole(B), clotrimazole(C), miconazole(M), econazole(E), ketoconazole(K), tolnaftate(T), 5-fluorocytosine(F). All isolates were highly sensitive to K, M, T(geometric mean MIC;GM MIC_0.16 micro gram/ml). Antibacterial susceptibility test against 119 isolates of bacteria was performed by agar dilution method, using 9 antibacterial drugs including erythromycin(ET), chloramphenicol(CP), gentamycin(G), vancomycin(V), ampicillin(AP), amoxacillin(AX), chlortetracycline(CT), ciprofloxacin(CF), enrofloxacine(EF). All isolates of Staphylococcus spp(101 strains) were highly sensitive to EF, CF, G(GM MIC 0.33~1.47 micro gram/ml). In other gram positive cocci(4 strains), they were highly sensitive to EF, CF, V(GM MIC 1~4.76 micro gram/ml) and CT(GM MIC 1 UFL unit/ml). In gram positive rods(13 strains), they were highly sensitive to EF, CF, G(GM MIC_0.19~1 micro gram/ml). In Pseudomonas aeruginosa(1 strain), it was highly sensitive to AX, EF, ET, CF(GM MIC 0.06~1 micro gram/ml) and CT(GM MIC 1 UFL unit/ml). All isolates weren't sensitive to AP(GM MIC 16~32 micro gram/ml).