| The objective of the study was to investigate the production and resisrance of extended-spectrumβ- laetmases(ESBLs) in Escherichia coli and Riemerella anatipestifer isolated from ducks.So as to investigate rational use of antibiotics in clinic,prevent and control the outbreak of extend-spectrumβ-lactamases isolates.The methods were follows:Detecting ESBLs by the method of double-disc synergy test ,proforming antimicrobial susceptibility tests against 30 kinds of commonly used antibacterial drugs by the disk diffusion and broth dilution methods recommended by CLSI(NCCLS)respectively, the isolates were 32 Eschefichia coil and 16 Riemerella anatipestifer from all kinds of clinical duck samples from March,2006 to July,2007.the principle of cobined administration could greatly increase activities against ESBLs bacteria that were resistant to multi- antibacterial agents.We detected that the combination of ceftriaxone and gatifloxacin could effectly depress the multiple resistant induced by ESBLs-producing and non- ESBLs-producing isolates.Meanwhile,we performed the protocol designed by checker-board method and the minimum inhibitory concentrations(MICs)of ceftriaxone, gatifloxacin alone and combine against 32 isolates of E.coli.48 pathogens isolated from ducks were identificated with VITEK-32 and were detected for ESBLs .Results revealed that there were 7 Escheria coli,0 Riemerella anatipestifer producing ESBLs,the rates of ESBLs were 21.87%(7/32),0%(0/16)respectively. ESBLs-producing isolates showed multi-drug resistance to the cephalosporins,aminoglycosides,quinolones and many other antibiotics,but were hypersensitive to imipenem, meropenem, cefoxitin . the resistant rates against amoxicillin, ampicillin and ceftiofur were 100%. The susceptibility rate of ESBLs-producing and non-ESBLs-producing isolates to amoxicillin-clavulanic acid,ampicillin-sulbactam,cefoperazone- sulbactam and so on enzyme inhibitor composites were all higher than it toβ-lactam antibiotics alone.it indicated enzyme inhibitor could partly solve this resistance. More considerably, cobined administration against extended-spectrumβ-lactamases were key measure for preventing and controlling the infection from ESBLs pathogenic bacteria.The result certificated cephalosporins combined with quinolones,such as the cobination of ceftriaxone and gatifloxacin appearancing the most conspicuous antimicrobial activity to three kinds of pathogenic bacteria.Results 0f MIC50 of ceftriaxone alone against producing ESBIs E.coli was 7.43μg/mL, but MIC50 of ceftriaxone combined with gatifloxacin was reduced to 1.69μg/mL.Th e incidences of the FIC index less than 0.5,from 0.5 to 1.from 1 to 2 and more than 2 were 85.71%,14.29%,0%and 0%,respectively.Then combination of ceftriaxone with gatfloxacin shifted the curve of concentration—inhibition rate against both bacteria to the left,compared with the ceftriaxone and gatfloxacin alone . The conclusion indicated that ceftriaxone combined with gatifloxacin against 32 strains of E.coli were mainly synergistic, they could be one of the key measures which effectively solve the infection from ESBLs - producing isolates ,non-ESBLs - producing isolates,too.The key factor of the study on new prepatation was to increase the solubility and palatability of gatfloxacin,then they could be prepared dissolubility preparation.The inclusion compounds were prepared by saturated solution method and orthogonal design . The physicochemical characteristics of gat-β-cyclodextrin inclusion compounds were measured through three methods such as phase solubility diagram,differential scarnning calorlmetry and X-ray diffraction.Results indicated the optimum preparation conditions for gat–β-cycdextrin inclusion compounds were:gatfloxcin:β-CD:1:3(mole ratio).the inclusion temperature 60°C and the inclusion time was 1 hour. The solubility of gatfloxcin was increased 13.44 times and the stability of inclusion complexes were greatly increased,too.Conclusion indicated the technique ofβ-CD inclusion could effectly increase the solubility ,palatability and stability of all kinds of medicine feedstocks which were non-water-solubility, bitter in taste or instability.The technique would be the key measure to prepare dissolubility preparation in veterinary drugs.
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