Detection Of β-lactamases In Bacteria From Swine And Avian And Primary Study For Their Inhibitor, Sulbactam

In order to overcome drug resistance of theβ-lactamases producing bactera, in the paper, detection of β-lactamases in bactera from swine and avain and primary study for their inhibitor,sulbactam were done.At first, for the familiarβ-lactam antibiotics ,microbial sensitivity were carried out with two fold dilution methord. Further detection of the β-lactamases from the resisting-Ampicillin strains were done with different methods: Iodimetric analysis, Racinage and Nitrocefin-based test.At the same time, the minimal inhibitory concentrations(MICs) of sulbactam combining Ampillin to the β-lactamase producing strains were measured; Extendβ-lactamase(ESBLs) were prepared from the induced O78?许昌F和O78?荥阳R,which have been induced by Ceftiofur and Ceftriaxone respectively;the action of ESBLs hydrolyzing β-lactam antibiotics and sulbactam inhibiting ESBLs were observed in the last.The results of antimicrobial susceptibility in vitro showed that: the MICs of Cephalexin to the standard strains was in the range of 0.125－8μg/ml,to the clinical strains was 0.156－8μg/ml.It has the same susceptibility to the standard and clinical strains. The third Cephalosporin have potent activity against all kinds of clinical and standard strains: the MICs of Ceftriaxone to the bacteria were in the range of 0.00625－0.06μg/ml; Ceftiofur were 0.00625－0.8μg/ml.But to Ampicillin and Amoxicillin,the results were different ,most of clinical E.colis were resisted to them,the MICs were more than 500μg/ml.From the above ,we can draw the conclusion: bacterial resistance were related to the frequency of antibiotics used .Also, the third Cephalosporin can kill and inhibit clinical bacteria commendably.The results of the detection ofβ-lactamases indicated that the total clinical E.colis have Producedβ-lactamases. At the same time,combination of sulbactam with Amoxicillin,which can induce the MIC for twenty times from 500μg/ml to 12.5μg/ml.So we can say thatthe main cause of the resistance to the β-lactam antibiotics shoud be related to Producingβ-lactamases.Additionally ,the better proportion of sulbactam and Amoxicillin shoud be 1:4 in the veterinary clinic,if the cost were considerated.From the test,no one bacterium produced ESBLs currently,but it produced ESBLs after induced with the third Cephalosporin. We can infer that the clinical strains will produce ESBLs in the future ,with the use of the third Cephalosporin.But the results of microbial sensitivity in vitro were susceptibile to to the third Cephalosporin.In order to gain the best therapeutic effect ,we shoud detect the ESBLs first in the veterinary clinic.