| Objective: To study the therapeutic effect of gatifloxacin in rabbitsbacterial peritonitis caused by Escherichia Coli producing CTX-M typeESBLs and to make a primary exploration in the clinical ESBLs-producing-bacterial peritonitis therapy of gatifloxacin.Methods: 1) CTX-M-22 producing the Escherichia Coli was identifiedby three-dimensional test. 2) MIC was determined with the standard agardilution technique. 3) Kinetic parameters forβ-lactamase were detectedspectrophotometrically. 4) Establish rabbits bacterial peritonitis model causedby Escherichia Coli producing CTX-M Type of ESBLs, select the optimalconcentration of Escherichia Coli. Mixture of 10%BaSO4 with 1×108, 2×108,1×109 or 2×109 cfu/ml Escherichia coli producing CTX-M type of ESBLswere injected into the peritoneal cavity of four groups of rabbits respectively.General conditions, body temperature, leucocyte count and the percentage ofneutrophil of the rabbits were closely observed. The greater omentum wasobtained for pathology examination. The data when rabbits died was recordedand the autopsy was performed immediately. All survived rabbits were killed on the 10th day. 5) 126 rabbits bacterial peritonitis model was caused byintra-abdominal injected with a mixture of 2×108 cfu/ml ESBLs-producingEscherichia coli and 10％BaSO4. The rabbits were randomized divided intofour groups, which include group administrated with gatifloxacin (25mg/kg,twice a day), group administrated with ceftazidime (100mg/kg, twice a day),model group and normal control group. Four hours after injected bacteria, theantibiotics were first administered. The temperature, leucocyte counts and thepercentage of neutrophil of the rabbits were closely observed. The time ofrabbit died was recorded and anatomized immediately. Pathology of the greatomentum was examinated.Results: Substrate profiles of CTX-M-22 included Extended Spectrumβ-Lactamase. CTX-M-22 hydrolyzed cefotaxime more efficiently thanceftazidime but didn't hydrolyze gatifloxacin. After the rabbits were injectedwith bacteria, the leucocyte count and the percentage of neutrophil of allrabbits changed obviously. The mortality of the group injected with 2×108cfu/ml Ecoli is moderate (40％), the rabbits of which groupdied in variousperiod, lasted longest fever time. And the pathology of the greater omentumrevealed inflammatory cells infiltration, and some had absecsses. Comparedwith the ceftazidime group and model group, the administration ofgatifloxacin decreased mortality. Gatifloxacin also inhibited the incidence ofabdominal abscess in survived rabbits in comparison with the model group. In addition, the leucocyte counts of the gatifloxacin group were recoverednormal at the end of treatment, while that of the ceftazidime group and modelgroup were still high.Conclusions: CTX-M-22 was a typical CTX-M-ESBLs. Afterintraabdominal injection with 2×108 cfu/ml Escherichia coli and 10％BaSO4,a stable, replicable, moderate infected animal model of bacterial peritonitiswas established, which is similar to clinic in pathology and bacteriology. Thegatifloxacin has good treatment results in the bacterial peritonitis caused byEscherichia coli producing CTX-M type of ESBLs.
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