Antibacterial activity of Espand (Peganum harmala) alcoholic extracts against six pathogenic bacteria in planktonic and biofilm forms

Microbial biofilms have attracted interest in recent years because they have become the most important cause of nosocomial infections. This study was aimed to examine the antibacterial activities of Peganum harmala extracts on the development of microbial biofilms and planktonic form of six pathogenic bacteria which include Staphylococcus aureus, Bacillus cereus, Streptococcus pneumoniae, Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae.
Antimicrobial activities of the crude extracts against the planktonic form of bacteria were evaluated by using disc diffusion method, minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) values were determined by a macrobroth dilution technique. Anti- biofilm effects of the extracts were assessed by microtiter plate method.
According to the results, P. harmala extracts could inhibit test bacteria in planktonic form. To inhibit biofilm formation, biofilm metabolic activity and eradication of established biofilms, efficiency of the extracts depended on concentration. The highest inhibitory effects of P. harmala extracts were observed on biofilm formation of S. aureus (90.28%) also, the greatest demolish were observed on S. pneumonia biofilm (77.76%). These extracts cause dramatically decrease the metabolic activity of bacteria in biofilm structures, in this case the decrement of B. cereus were highest (69.98%) compared to other tested bacteria.
Discussion and Therefore, it can be suggested that P.harmala extracts applied as antimicrobial agents against testing bacteria particularly in biofilm forms.