title: Hemolytic activity of Prevotella intermedia and Prevotella nigrescens strains: influence of abiotic factors in solid and liquid assays.
abstract: The influence of growth medium, hemin and menadione, blood source and atmosphere of incubation on the expression of hemolytic activity of 25 strains of Prevotella intermedia and Prevotella nigrescens was evaluated. The best hemolytic activity was observed for samples of both species growing in brain heart infusion agar and incubated in Brewer-like anaerobic jars for 48 h. Hemolysis was less intense and occurred later in the presence of hemin and menadione in solid media. beta-Hemolysis was detected for medium supplemented with horse or human blood and alpha-hemolysis was observed when sheep blood was used. These results suggesting some specificity for the hemolytic activity were also observed in liquid assays in which sheep erythrocytes were found to be resistant to hemolysis while horse and human cells where lysed. In liquid assays, the hemolytic activity of all studied strains remained stable in the pH range of 6.0 to 8.5 and was not altered by iron-scavenging compounds or atmosphere of incubation. The phenomenon of hot/cold hemolysis was ruled out as the mechanism of action of P. intermedia and P. nigrescens hemolysin.
authors.affiliation: Laboratório de Microbiologia Oral e Anaeróbios, Departamento de Microbiologia, ICB/UFMG. Av. Antônio Carlos, 6627, Pampulha, Belo Horizonte, Minas Gerais, CEP 31270-901, Brazil.
authors.forename: Tarcília Aparecida
authors.initials: TA
authors.lastname: Silva
authors.forename: Paulo Henrique
authors.initials: PH
authors.lastname: Rodrigues
authors.forename: Renata Novaes
authors.initials: RN
authors.lastname: Ribeiro
authors.forename: Fátima Soares M
authors.initials: FS
authors.lastname: Noronha
authors.forename: Luiz de Macêdo
authors.initials: Lde M
authors.lastname: Farias
authors.forename: Maria Auxiliadora R
authors.initials: MA
authors.lastname: Carvalho
mesh_terms: D000818:Animals; D003470:Culture Media; D006427:Hemin / Q000494:pharmacology; D006461:Hemolysis / Q000187:drug effects; D006736:Horses; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000502:physiology; D018720:Prevotella / Q000472:pathogenicity*; D018713:Prevotella intermedia / Q000472:pathogenicity*; D012756:Sheep; D024483:Vitamin K 3 / Q000494:pharmacology
chemical_list: D003470:Culture Media; D024483:Vitamin K 3; D006427:Hemin; D007501:Iron