title: Sub-inhibitory concentrations of penicillin G induce biofilm formation by field isolates of Actinobacillus pleuropneumoniae.
abstract: Actinobacillus pleuropneumoniae is a Gram-negative bacterium and causative agent of porcine pleuropneumonia. This is a highly contagious disease that causes important economic losses to the swine industry worldwide. Penicillins are extensively used in swine production and these antibiotics are associated with high systemic clearance and low oral bioavailability. This may expose A. pleuropneumoniae to sub-inhibitory concentrations of penicillin G when the antibiotic is administered orally. Our goal was to evaluate the effect of sub-minimum inhibitory concentration (MIC) of penicillin G on the biofilm formation of A. pleuropneumoniae. Biofilm production of 13 field isolates from serotypes 1, 5a, 7 and 15 was tested in the presence of sub-MIC of penicillin G using a polystyrene microtiter plate assay. Using microscopy techniques and enzymatic digestion, biofilm architecture and composition were also characterized after exposure to sub-MIC of penicillin G. Sub-MIC of penicillin G significantly induced biofilm formation of nine isolates. The penicillin G-induced biofilms contained more poly-N-acetyl-D-glucosamine (PGA), extracellular DNA and proteins when compared to control biofilms grown without penicillin G. Additionally, penicillin G-induced biofilms were sensitive to DNase which was not observed with the untreated controls. Furthermore, sub-MIC of penicillin G up-regulated the expression of pgaA, which encodes a protein involved in PGA synthesis, and the genes encoding the envelope-stress sensing two-component regulatory system CpxRA. In conclusion, sub-MICs of penicillin G significantly induce biofilm formation and this is likely the result of a cell envelope stress sensed by the CpxRA system resulting in an increased production of PGA and other matrix components.
authors.affiliation: Groupe de recherche sur les maladies infectieuses du porc, Faculté de médecine vétérinaire, Université de Montréal, C. P. 5000, St-Hyacinthe, Québec J2S 7C6, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Hathroubi
authors.affiliation: Groupe de recherche sur les maladies infectieuses du porc, Faculté de médecine vétérinaire, Université de Montréal, C. P. 5000, St-Hyacinthe, Québec J2S 7C6, Canada.
authors.forename: S-È
authors.initials: SÈ
authors.lastname: Fontaine-Gosselin
authors.affiliation: Groupe de recherche sur les maladies infectieuses du porc, Faculté de médecine vétérinaire, Université de Montréal, C. P. 5000, St-Hyacinthe, Québec J2S 7C6, Canada.
authors.forename: Y D N
authors.initials: YD
authors.lastname: Tremblay
authors.affiliation: Groupe de recherche sur les maladies infectieuses du porc, Faculté de médecine vétérinaire, Université de Montréal, C. P. 5000, St-Hyacinthe, Québec J2S 7C6, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Labrie
authors.affiliation: Groupe de recherche sur les maladies infectieuses du porc, Faculté de médecine vétérinaire, Université de Montréal, C. P. 5000, St-Hyacinthe, Québec J2S 7C6, Canada. Electronic address: mario.jacques@umontreal.ca.
authors.forename: M
authors.initials: M
authors.lastname: Jacques
mesh_terms: D000117:Acetylglucosamine / Q000378:metabolism; D016977:Actinobacillus pleuropneumoniae / Q000187:drug effects* / Q000254:growth & development; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001426:Bacterial Proteins / Q000378:metabolism; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D008826:Microbial Sensitivity Tests; D010400:Penicillin G / Q000494:pharmacology* / Q000627:therapeutic use; D011001:Pleuropneumonia / Q000188:drug therapy / Q000662:veterinary*; D011494:Protein Kinases / Q000378:metabolism; D013045:Species Specificity; D013552:Swine; D013553:Swine Diseases / Q000188:drug therapy* / Q000382:microbiology*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; C113831:poly-N-acetyl glucosamine; C085504:CpxR protein, Bacteria; D011494:Protein Kinases; C092472:CpxA protein, bacteria; D010400:Penicillin G; D000117:Acetylglucosamine
keywords: Actinobacillus pleuropneumoniae; Biofilm; CpxRA; Penicillin G; Poly-N-acetyl-d-glucosamine (PGA); eDNA