Ampicillin Resistance and Transferable β-Lactamase Plasmids of Gram Negative Rods Isolated from Bovine Mastitis

젖소 유방염유래(乳房炎由來) Gram 음성간균(陰性桿菌)의 Ampicillin 내성(耐性) 및 전달성(傳達性) β-Lactamase Plasmids

One hundred and twenty seven strains of Gram-negative rods (72 E. coli, 45 Klebsieila pneumoniae, 8 Enterobacter spp. and 2 Pseudomonas aeruginosa) isolated from bovine mastitis were examined for resistance to ampicilin, carbenicillin and cefazolin, ${\beta}$-lactamase activity and transferable ${\beta}$-lactamase plasmids. Stains resistant to ampicillin were 13.9% in E. coli, 93.3% in Klebsiella pneumoniae, 87.5% in Enterobacter. spp. and all in Pseudomonas aeruginosa, Resistance of E. coli, Klebsiella pneumoniae and Enterobacter spp. to ampicillin was due to the ${\beta}$-lactamases, but all Pseudomonas aeruginosa exhibited a high level of the non-enzymic resistance. Transferable plasmid-mediated ${\beta}$-lactamase synthesis was demonstrated in 61.9% of Klebsiella pneumoniae, 50% of E. coli and 42.9% of Enterobacter spp. The same ${\beta}$-lactamase plasmids specified different resistance levels to various ${\beta}$-lactam antibiotics in different recipients.