title: Biofilm is associated with chronic streptococcal meningoencephalitis in fish.
abstract: Biofilms are aggregates of attached microbial organisms whose existence on tissues is often recognised as a mechanism for the establishment of most chronic diseases. Herein we investigated the ability of piscine Streptococcus agalactiae, an important aquatic pathogen, for adaptation to this sessile lifestyle in vitro and in the brain of a tilapia fish model. Piscine S. agalactiae exhibited a weak attachment to polystyrene plates and expressed a low biofilm phenotype under the study conditions. Furthermore, fluorescent in situ hybridization and confocal laser scanning microscopy revealed discrete aggregates of attached S. agalactiae within brain tissues and around meningeal surfaces. They were embedded in an exopolysaccharide containing matrix, intractable to inflammatory response and showed some level of resistance to penicillin despite proven susceptibility on sensitivity test. Intracellular bacterial aggregates were also observed, moreover, antibody mediated response was not demonstrated during infection. Nucleated erythrocytes appear to facilitate brain invasion possibly via the Trojan horse mechanism leading to a granulomatous inflammation. We have demonstrated that biofilm is associated with persistence of S. agalactiae and the development of chronic meningoencephalitis in fish.
authors.affiliation: Molecular Pathology Laboratory, Department of Veterinary Pathology and Microbiology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
authors.forename: A I
authors.initials: AI
authors.lastname: Isiaku
authors.affiliation: Molecular Pathology Laboratory, Department of Veterinary Pathology and Microbiology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia. Electronic address: mdsabri@upm.edu.my.
authors.forename: M Y
authors.initials: MY
authors.lastname: Sabri
authors.affiliation: Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
authors.forename: M Y
authors.initials: MY
authors.lastname: Ina-Salwany
authors.affiliation: Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
authors.forename: M D
authors.initials: MD
authors.lastname: Hassan
authors.affiliation: Molecular Pathology Laboratory, Department of Veterinary Pathology and Microbiology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
authors.forename: P N
authors.initials: PN
authors.lastname: Tanko
authors.affiliation: Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
authors.forename: M B
authors.initials: MB
authors.lastname: Bello
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001344:Autopsy; D018441:Biofilms; D002908:Chronic Disease; D024881:Drug Resistance, Bacterial; D005393:Fish Diseases / Q000175:diagnosis / Q000382:microbiology*; D005399:Fishes; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D008590:Meningoencephalitis / Q000662:veterinary*; D008826:Microbial Sensitivity Tests; D010641:Phenotype; D013290:Streptococcal Infections / Q000662:veterinary*; D013291:Streptococcus / Q000187:drug effects / Q000502:physiology*; D013292:Streptococcus agalactiae / Q000187:drug effects; D017210:Tilapia
chemical_list: D000900:Anti-Bacterial Agents
keywords: Biofilm; Erythrocyte; Fish; Meningoencephalitis; Persistence; Streptococcus