Background and Aim: This study aimed to isolate phages able to lyse some strains of multiple drug-resistant (MDR)-Klebsiella pneumoniae (named vB_Kp1 and vB_Kp2) and Enterobacter aerogenes (named vB_Ea1) from swage. Materials and Methods: Different K. pneumoniae and E. aerogenes strains were isolated from clinical specimens during January-September 2018 in three hospitals of Amol, Mazandaran, Iran. Kirby-Bauer disc diffusion method was used to determine the resistance profiles of these isolates using different antibiotics. The MDR strains were selected for investigating the effect of isolated phages from wastewater and hospital sewage. The presence of phage was confirmed by plaque formation. The isolated bacteriophages were enriched, concentrated, and stained. Afterwards, a transmitting electron microscope (TEM) was applied to observe the morphology of the bacteriophages. Phage identification tests, including host range and one-step growth, were performed. Results: The TEM analysis revealed that three phages had an icosahedral capsid and long contractile tail being classified as a member of the Myoviridae family. Phages were able to lyse 14 (56%) of the 25 MDR isolated bacterial strains. The one-step growth curve showed large bursts and short latent times. Conclusion: The formation of clear plaques demonstrates the high lyse power of phages. Therefore, they have good potential for further analysis for clinical use as a therapeutic agent in the future.

Background & objectives: Amikacin is one of the key second-line drugs for treatment of tuberculosis. Mutations at the codons 1400, 1401and1483 of the 16srRNA gene are associated with resistance to amikacin. The purpose of this study was to detect these mutations using PCR-RFLP method in multi-drug resistant (MDR) strains of Mycobacterium tuberculosis showing resistance to amikacin.Methods: Susceptibility of strains (n=100) against first and second–line anti-tuberculosis drugs was performed by proportional method. Based on antimicrobial resistance pattern 97 strains were analyzed by PCR-RFLP method. Rrs1096 and rrs1539 primers were used to amplify a 460bp region of the rrs gene. Then, the PCR products were digested using Tai 1 and Dde1 restriction enzymes. The results were analyzed by the SPSS software using Chi-square test.Results: Based on results from proportional method, 63 strains (64.9%) were MDR (Multiple Drug Resistant), 26 (26.8%) and 8 (8.2%) strains were susceptible and non-MDR, respectively. Also, 13.4% and 6.1% of the strains were XDR (Extensively Drug Resistant) and TDR (Totally drug resistant) respectively. Using PCR-RFLP method, 7 (7.2%) strains were resistant and 90 (92.7%) strains were susceptible to amikacin respectively. Moreover, we found that the mutation at the codon 1400 was the most frequent mutations responsible for resistance to amikacin.Conclusion: The PCR-RFLP method can be used as a supplemental method to detect resistance to amikacin; however to increase our knowledge, mutatuions in several number of codons in rrs gene need to be studied.