Abstract

Background: Prevalence extension of antibiotic resistant bacteria has raised concerns about control of infections especially nosocomial infections. Many attempts have been done to replace antibiotics or limit their use. The use of antimicrobial agents produced by bacteria as antibiotic replacement has been promising in recent years. The goal of this study was to isolate Bacillus strains and evaluate their antimicrobial activity against some standard pathogens and clinical antibiotic resistant strains.

Materials and Methods: In the present study, Bacillus strains were isolated from various resources and identified by 16S rDNA PCR method. Then, the phylogenetic tree of the isolates was constructed and antimicrobial activity of the isolates was investigated against some standard pathogens and clinical antibiotic resistant strains using spotting and well diffusion methods.

Results: Eight Bacillus strains were isolated from 15 different samples. Based on the molecular identification, the isolates were identified as B.pumilus, B.coagulans, B.licheniformis, B.endophitycus and B.amiloliquefaciens. The results showed that isolates have antimicrobial activity against meticilin-resistant Staphylococcus aureus, vancomycin resistant enterococci, Klebsiella, Acinetobacter, Salmonella, Shigella, Listeria, Streptococcus and Escherichia coli.

Conclusion: In this study, isolated Bacillus strains produced antimicrobial agents against pathogens and antibiotic resistant strains and inhibited their growth.