A Study on the Effect of Ethidium_Bromide on Virulence Factors ( Protease and Biofilm Formation ) by Klebsiella Pneamoniae Isolated from Different Clinical Sources

Abstract

About 145 isolate of Klebsiella species were isolated from different clinical sources for6 month ago from (1-9-2014 )to(1-2-2015).these isolates were identified morphologically and biochemically  and Api 20 kit,thus there was only 22isolates were identified asKlebsiella pneumoniae (15.1%) Protease activity were tested by measuring the diameter of cleared around wells containing  bacterial cells harvested from 18 h of incubation at37c  on skim milk agar medium or by (wells method).The results showed that k4 is the higher isolate of protease production(18mm in diameter)while k2 showed  a lowest protease activity of (12mm in diameter).Biofilm Formation for 22 Klebsiella isolates were tested on congo-red agar mediumand the results showed that all the isolates have (100%) activity by forming dark colonies on congo-red medium In our study, first ttempt was made on the effect of ethidium bromide on the virulence factors of pathogenic bacteria (Klebsiella pneumoniae)at concentrations (10^-1 to 10^-6 )that have an effect at which the 22 isolates of (K.p)loss the protease activity and biofilm formationat these concentrations  while little and normal activities were observed at concentrations (10^-7 to 10^-10) of ethidium bromide on the 22 studied isolates of K. pneumoniae .Also, the results of Agarose –gel electrophoresisof both (normal case)Klebsiella pneumoniae k4 and cured isolates showed the presence ofchromosomal and plasmid DNA bands in the  normal  case while only chromosomal DNA  bands occure with the Klebsiella isolates treated with Ethidium –Bromide at concentrations of (10^-2 to 10^-4).

Keywords: Ethidium –Bromide – Klebsiella – Protease –Biofilm .