Background and Aim: A vast majority of clinical specimens are contaminated with Klebsiella species. The drug resistance among Klebsiella species is increasing day by day; therefore, antibiotic senility test is necessary before prescribing antibiotics. The aim of this research was to determine the antibiotics resistance patterns of Klebsiella species isolated from clinical specimens of patients using the standard Kirby-Bauer method.

Materials and Methods: The present research was performed on 300 specimens of Klebsiella collected from Imam Khomeini hospital. After identification, drug resistance was investigated through the standard CLSI procedure. The drug sensitivity test was determined for all of the 12 antibiotics using standards of disk diffusion in agar Kirby-Bauer.

Results: The frequency rates of the isolated Klebsiella species were: pneumonia(94%), oxytoca(4%), ozaenae(1%), and rhinoscleromatis(1%). Moreover, in terms of source of infection, the collected samples in order of frequency were: urine, sputum, vagina, scar, stool, and blood, respectively. Altogether, the percentage rates of resistance were as follows: Ampicillin(97%), Amoxycillin(97%), Cefalotin(39%), Gentamicin(30%), Colistin(55%), Nalidixic acid(2%), Chloramphenicol(26%), Kanamycin(17%), Tetracycline(28%), Nitrofuration(44%), Ceftazidime(2%), and Amikacin(0%).

Conclusion: The results showed that the lowest resistance rate obtained was related to Amikacin in all tested Klebsiella; therefore, it can be recommended as the most effective antibiotic.