Sixteen isolates of lactic acid bacteria were isolated from dairy products collected from Baghdad markets. The isolates were identified into 4 genera; Lactobacillus (6 isolates), Lactococcus (2 isolates), Pediococcus (4 isolates) and Leuconstec (4 isolates). Later, further identification of lactobacillus showed the isolates belonged to Lb. plantarum (Lb.1 and Lb.3), Lb. bulgaricus (Lb.4), Lb. acidophilus (Lb.2), Lb. brevis (Lb.5) and Lb. fermentum (Lb.6).Fifty bacterial isolates were obtained from comedones and pustules of twenty patients that suffering from sever acne vulgaris. These isolates were identified as, three species of bacteria isolated from comedone (Propionibacterium acne, Staphylococcus epidermidis and Staphylococcus aureus), and five species isolated from pustules (Staphylococcus epidermidis, Propionibacterium acne, Proteus mirabilis, Staphylococcus aureus and Escherichia coli).Antibiotic sensitivity test was performed for Lb. plantarum (Lb.1 and Lb.3) isolates. Results showed that both isolates were resistant to streptomycin, penicillin G and trimethprim, but sensitive to amoxicillin, chloromphenicol, cloxacillin, rifampin and ampiclox. Regarding the bacterial isolates causing acne vulgaris, they were sensitive to doxycycline, ciprofloxacin, neomycin, clindamycin and rifampin, but resistant to ampicillin, amoxicillin, ampiclox, methoprim, tetracycline and cefalexine.The inhibition activity of Lb. plantarum (Lb.3) against acne vulgaris isolates was tested on solid and in liquid media. It was found that Lb.3 isolates when grown on solid media had better inhibitory activity against all pathogenic isolates, but the incubation period 36 hr. was chosen as the preferred period in this approach while the result of Lb.3 isolate when grown in liquid media showed that Lb.3 isolate had inhibition activity against gram positive bacteria tested at 36, 48 and 72 hr. but gram negative bacteria was not effected. When the filtrate was concentrated to 3 times fold, it became had showed markedly inhibition activity against all bacterial isolates of sever acne vulgaris.When bacteriocin of Lb.3 isolate was extracted and purified to test it's inhibition activity against the sever acne vulgaris isolates, result showed that it had inhibitory effect on Gram's positive and gram negative bacteria. However, the activity greater on gram positive than on gram negative bacteria.Protein quantity of concentrated filtrate and the bacteriocin was determined. Results showed that it was equal to 4 mg / ml in filtrate and 5 mg / ml in the partially purified bacteriocin.Minimum inhibitory concentration of concentrated filtrate was estimated and showed that 80 % was the preferred value that inhibited all type of bacterial causes of sever acne vulgaris (Staphylococcus epidermidis, Propionibacterium acne, Proteus mirabilis, Staphylococcus aureus and Escherichia coli) and used in treating the patients.The result of treatment showed that after 2 weeks of treatment with filtrate, acne completely or almost completely healing in most patient (up to 95 %), with the presence of simple skin dryness as the only reported side effect during the period of treatment.
