The present invention relates to selected strains of lactic bacteria for use in the treatment of infections caused by pathogenic bacteria belonging to the species Propionibacterium acnes, in particular for use in the preventive and/or curative treatment of dermatitis in general, seborrheic dermatitis, rosacea, eczema and acne. In addition, the present invention relates to a composition which comprises a mixture comprising or, alternatively, consisting of selected strains of lactic bacteria for use in the treatment of infections caused by pathogenic bacteria belonging to the species Propionibacterium acnes, in particular for use in the preventive and/or curative treatment of dermatitis in general, seborrheic dermatitis, rosacea, eczema and acne. The composition comprising said mixture of selected strains of lactic bacteria is formulated in a pharmaceutical form for oral use (novel food, supplement product or medical device or pharmaceutical composition) in the form of powder, dispersible powder, granulate, packets or stick, solution, spray solution, syrup, tablet, capsule, pill or lozenge; or for topical use (composition for medical device or pharmaceutical composition) in the form of cream, ointment, pomade, gel, hydrogel, dispersion, emulsion or spray to be used as such for skin applications, or for transdermal use even in the form of a band aid.