the antimicrobial effect of lactoferrin on gram-negative and gram-positive bacteria

background lactoferrin is a multipurpose protein of the transferrin domestic. it is a spherical glycoprotein with a molecular weight of about 80 kda which is widely found in secretory discharges, such as milk, saliva, tear, and nasal secretions. lactoferrin is also found in secondary granules of polymorphonuclear leukocytes (pmn) and is released by some acinar cells. it also shows antibacterial activity in vitro. the antimicrobial activity of lactoferrin is due to its ability to bind to iron and make it unavailable to bacteria. lactoferrin is a major component of the immune system; antibacterial activity is an important component of the innate immunity of the body. objectives the purpose of this study was to evaluate the effect of lactoferrin on two different species of gram-negative and gram-positive bacteria. materials and methods the purity of lactoferrin was assessed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (sds-page). gram-positive and gram-negative bacteria were collected from different clinical specimens such as wound, blood, secretions, urine, stool, and sputum from namazi hospital of shiraz. the colony counting assays were conducted according to the clinical and laboratory standards institute (clsi) and american society for testing and materials (astm) g22-76 guidelines. results the results showed lactoferrin to be effective on both gram-positive (staphylococcus epidermidis, bacillus cereus) and gram-negative (campylobacter jejuni, salmonella) bacteria. however, it was more effective on the gram-positive rather than the gram-negative bacteria. conclusions lactoferrin is able to bind to iron as one of its important features. it plays an important role in signal transduction and is anticancer, anti-adhesion, immune-modulatory, and antiviral. regarding the increase of resistance to antibiotics, it is necessary to explore novel antimicrobial drugs.