Aim: To assess economic efficiency of complicated intra-abdomibal infections treatment in real practice compared to alternative scenario (treatment with carbapenem Ertapanem) taking in to account E. coli resistance. Methods: Cost-effectiveness analysis were performed. Mathematic modelling was done to assess prognosis of bacterial resistance. Results: Cost of 1 case of complicated intra-abdomibal infections in real practice is 83048,08 rub compared to 91706,06 rub according to alternative strategy. Cost-effectiveness analysis revealed that real practice of treatment intra-abdomibal infections dominated alternative scenario: less effectiveness lead to lower cost. Additional effectiveness (1,95%) demand additionally443316,97 rub. Taking into account dynamic ofE. Coli resistance ICER during 2011-2015 period decreased up to 40%. Conclusion: Antimicrobial resistance of bacterial agents is important criteria which should be used to estimate economic effectiveness of any medical strategy.