title: Effect of subinhibitory concentration of chlorhexidine on Streptococcus agalactiae virulence factor expression.
abstract: The aim of the present study was to investigate the effect of chlorhexidine at subinhibitory concentration (50% minimal inhibitory concentration (MIC)) on the growth, cytolysin expression and phagocytosis of Streptococcus agalactiae ATCC 13813. Bacterial growth with and without chlorhexidine treatment was monitored by turbidity measurements, and exocytolysins were estimated by neutral red uptake assay by the McCoy cell line. The phagocytic process was evaluated using luminol-enhanced chemiluminescence to follow the respiratory burst of polymorphonuclear neutrophils exposed to bacteria. Chlorhexidine-treated culture did not exhibit a detectable decrease in cell growth, and no statistically significant reduction in the respiratory burst of polymorphonuclear neutrophils was observed. However, growth in the presence of chlorhexidine resulted in a significant reduction of S. agalactiae exocytolysins. Although 50% MIC of chlorhexidine did not interfere with S. agalactiae growth and phagocytosis, the knowledge that this concentration was still able to alter some bacterial virulence parameters may be useful in its therapeutic applications.
authors.affiliation: Faculdade de Ciências Farmacêuticas de Araraquara, UNESP-Universidade Estadual Paulista, Araraquara, SP, Brazil.
authors.forename: Denize Maria
authors.initials: DM
authors.lastname: Galice
authors.forename: Cibele
authors.initials: C
authors.lastname: Bonacorsi
authors.forename: Verônica Cristina Gomes
authors.initials: VC
authors.lastname: Soares
authors.forename: Maria Stella Gonçalves
authors.initials: MS
authors.lastname: Raddi
authors.forename: Luiz Marcos da
authors.initials: LM
authors.lastname: Fonseca
mesh_terms: D000818:Animals; D002710:Chlorhexidine / Q000494:pharmacology*; D003603:Cytotoxins / Q000378:metabolism*; D006801:Humans; D049449:Luminescence; D008826:Microbial Sensitivity Tests; D009504:Neutrophils / Q000276:immunology / Q000382:microbiology; D010587:Phagocytosis; D051381:Rats; D016897:Respiratory Burst; D013292:Streptococcus agalactiae / Q000187:drug effects* / Q000254:growth & development / Q000472:pathogenicity*; D014774:Virulence; D037521:Virulence Factors / Q000378:metabolism*
chemical_list: D003603:Cytotoxins; D037521:Virulence Factors; D002710:Chlorhexidine