Introduction: Antibiotic resistance survey in Gram-negative bacteria has an important role in the management of treatment. The aim of this study was to evaluate antibiotic resistance of Gram-negative bacteria isolated from patients and determination of contamination rate of different wards of hospital to these bacteria.

Methods: Information of 3242 patients from hospital information system of Toohid and Besat hospitals of Sanandaj city in 2013-2014 years was studied. Identification of bacteria using microbiology laboratory methods and antimicrobial susceptibility test according to Clinical and Laboratory Standards using disk diffusion method were performed. For data analysis, SPSS-16 software and chi square (X²) and independent t-test was used.

Results: The number of 2289 (70.60%) of Gram negative bacteria were isolated in this research that 51.46% of Escherichia coli isolates, 43.47% Klebsiella, 44.28% Enterobacter, 58.99% Pseudomonas and 33.33% Morganella showed most resistance to trimethoprim-sulfamethoxazole. In 76.06% of Acinetobacter isolates, 53.26% Serratia, 73.33% Shigella and 76.92% Citrobacter, most resistance was to cefotaxime, tetracycline, trimethoprim- sulfamethoxazole and tetracycline, and ceftriaxone, respectively. Most gram negative bacteria were isolated from women’s ward (625 isolates). A statistically significant association between age of the patient and of antibiotic resistance was observed (P<0.05).

Conclusion: High antibiotic resistance in Gram-negative bacteria was observed. Performance of antibiotic susceptibility tests before drug prescription in the treatment and control of drug resistance is important.