SUMMARY
Klebsiella pneumoniae is dangerous pathogens that can cause severe diseases. This study included isolation of 50 isolates of K.pneumoniaefrom different clinical sources from different hospitals in Baghdad city, the number and percentage of isolates according to the sources (urine, blood, sputum, burns, ear swabs, pus, wounds and stool ) were 22(44%), 11(22%), 4(8%), 4(8%), 3(6%), 3(6%), 2(4%) and 1(2%) respectively. The ability to form biofilm was carried out using Tissue culture plate methods (-TCP-). The results showed that 80% of the isolates were producer biofilm; the genetic study was used to detect the presence of mrkA, mrkD genes that are believed to be responsible of biofilm production. The ratio was mrkA 87.5% and mrkD 50% before exposure to U.V.light to reduce to 43.7% mrkA and 18.7% mrkD in isolates after exposure to U.V.light source.