title: Subinhibitory concentrations of phenyl lactic acid interfere with the expression of virulence factors in Staphylococcus aureus and Pseudomonas aeruginosa clinical strains.
abstract: The discovery of intra- and intercellular communication systems (quorum sensing systems) regulating bacterial virulence has afforded a novel opportunity to control infectious bacteria, without interfering with their growth. In this study, we investigated the ability of subinhibitory concentrations (sIC) of phenyl lactic acid (PLA), known to be produced by Lactobacillus probiotic strains, to attenuate the virulence and pathogenicity of Pseudomonas aeruginosa (as experimental model of intercellular bacterial communication in Gram-negative bacteria) and Staphylococcus aureus (as experimental model of intercellular bacterial communication in Gram-positive bacteria) by interfering with the coordinated expression of different virulence factors implicated in the pathogenicity of these opportunistic strains. Our results showed that sIC of PLA decreased the ability of the tested strains to adhere both to the cellular and inert substrata and induced changes in the adherence patterns as well as in the cell morphology. The sIC of PLA induced a significant decrease of sheep red blood cells haemolysins, lecithinase and caseinase and stimulated lipase and gelatinase production by Pseudomonas strains. The sIC of PLA induced an important and constant increase of the Pseudomonas growth inhibition zones diameters for all tested antibiotics, demonstrating the potential use of PLA in the design of new synergic antimicrobial associations active on multiresistant and biofilm-growing P, aeruginosa strains. The present study has proved the role of sIC of PLA released by Lactobacillus probiotic strains in the attenuation of P. aeruginosa and S. aureus virulence and pathogenicity, by interfering with different processes depending on cell density and regulated by quorum sensing (i.e. growth rate, expression of adhesion molecules and secretion of soluble, enzymatic factors) and altering the success of these pathogens in the colonization of a sensitive host and the development of an infectious process. Our results demonstrate that this probiotic soluble products could be used as a new, ecological anti-infective strategy with great therapeutic and preventive value in the biomedical field (especially in the treatment of chronic infections produced by multiresistant and biofilm forming microorganisms), but also in the management of the environmental quality, agriculture and industrial field by reducing the chemical burden delivered in the external medium and by preventing the surfaces colonization with microorganisms and the development of natural biofilms.
authors.affiliation: Department of Microbiology, Faculty of Biology, University of Bucharest, Aleea Portocalelor 1-3, Bucharest 060101, Romania. carmen_balotescu@yahoo.com
authors.forename: Mariana-Carmen
authors.initials: MC
authors.lastname: Chifiriuc
authors.forename: Lia-Mara
authors.initials: LM
authors.lastname: Diţu
authors.forename: Otilia
authors.initials: O
authors.lastname: Banu
authors.forename: Coralia
authors.initials: C
authors.lastname: Bleotu
authors.forename: Olguţa
authors.initials: O
authors.lastname: Drăcea
authors.forename: Marcela
authors.initials: M
authors.lastname: Bucur
authors.forename: Cristina
authors.initials: C
authors.lastname: Larion
authors.forename: Anca Michaela
authors.initials: AM
authors.lastname: Israil
authors.forename: Veronica
authors.initials: V
authors.lastname: Lazăr
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001422:Bacterial Adhesion / Q000187:drug effects; D003851:Deoxyribonucleases / Q000096:biosynthesis; D018093:Gelatinases / Q000096:biosynthesis; D006460:Hemolysin Proteins / Q000096:biosynthesis; D007773:Lactates / Q000008:administration & dosage*; D007778:Lactobacillus / Q000378:metabolism; D008049:Lipase / Q000096:biosynthesis; D008666:Metalloendopeptidases / Q000096:biosynthesis; D008826:Microbial Sensitivity Tests; D010740:Phospholipases / Q000096:biosynthesis; D011552:Pseudomonas Infections / Q000382:microbiology / Q000517:prevention & control; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000378:metabolism* / Q000472:pathogenicity; D053038:Quorum Sensing; D012756:Sheep; D013203:Staphylococcal Infections / Q000382:microbiology / Q000517:prevention & control; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000378:metabolism* / Q000472:pathogenicity; D014774:Virulence / Q000187:drug effects; D037521:Virulence Factors / Q000096:biosynthesis*
chemical_list: D000900:Anti-Bacterial Agents; D006460:Hemolysin Proteins; D007773:Lactates; D037521:Virulence Factors; C017648:3-phenyllactic acid; D003851:Deoxyribonucleases; D010740:Phospholipases; D008049:Lipase; D018093:Gelatinases; D008666:Metalloendopeptidases; C030895:caseinase