ABSTRACT
Objective To study the relation of the porin at the out membrane with resistance to cefoxitin in Enterobacter cloaceae. Methods The extended spectrum beta lactamase(ESBLs) was detected by phenotypic confirmatory test according to NCCLS M100 S9;the beta lactamase and out membrane protein(OMP) was extracted by ultrasonication,the beta lactamase was detected by ultraviolet spectrophotometer,the composition of OMP was analyze by SDS PAGE. Results The 6 strains in 9 strains of Enterobacter cloaceae with resistance to cefoxitin lost 18 kda protein band and did not product hydrolase to cefoxitin and 5 strains was ESBLs positive. 2 strains producing hydrolase to cefoxitin did not lose the 18 kda protein. One strain with resistance to cefoxitin was producing ESBLs but did not defect the 18kda protein band and product hydrolase to cefoxitin. Conclusion The defect of the 18 kda protein band is nearly relation with resistance to cefoxitine in Enterobacter cloaceae.