Abstract: ObjectiveTo assess the efficacy of the D-R model for defining trends in the appearance of ceftazidime-resistant Escherichia coli. MethodsActual data related to the manifestation of ceftazidime-resistant E. coli spanning years 1996~2009 were collected from the China National Knowledge Infrastructure(CNKI). The novel D-R model and the GM(1,1) model were used to fit current data and from this, predict trends in the appearance of the drug-resistant phenotype. The results were evaluated by Relative Standard Error(RSE), Mean Absolute Deviation(MAD) and Mean Absolute Error(MAE). ResultsActual data originated from 430 publications encompassing 1004 citations of resistance. Resultsfrom the D-R model showed a rapid increase in the appearance of ceftazidime-resistant E. coli in China. These results were considered accurate based upon the minor values calculated for RSE, MAD and MAE, and D-R model better than those generated by the GM(1,1) model. ConclusionThe D-R model can be adapted to accurate fitting and predicting trends in the appearance of ceftazidime-resistant E. coli. The results show a close relationship between temporary trend and resistance rates presumed by D-R model. The results post rules of "increase-control-decrease-increase" in clinic and "steady-quickly increase-steady" in theory of ceftazidime-resistant E. coli. Those rules suggest that the less use of ceftazidime in quick increase period, the more decrease of resistance in E. coli. But in the steady period, whatever control or not of using of ceftazidime, it has less meaning. The rules may be generally ascribed to bacteria resistance to drugs.

Key words: D-R model, drug-resistance, fit, predication