ABSTRACT
In ocular infections (OIs) caused by Staphylococcus epidermidis, biofilms composed mainly of poly-N-acetylglucosamine (PNAG) have been widely studied, but PNAG-independent biofilms have not. Therefore, we searched for a relationship between the ica operon (involved in PNAG-biofilm) and the biochemical composition of biofilms in isolates from OI. Isolates from OI (n = 62), from healthy conjunctiva (HC; n = 45) and from healthy skin (HS; n = 53), were used to detect icaA and icaD genes, and the insertion sequence 256 (IS256) using PCR. The compositions of the biofilms were determined by treatment with NaIO4, proteinase K and DNase I. Multilocus sequence typing (MLST) was performed to characterize the isolates, and the expression of aap and embp genes was determined by real-time qPCR. A strong relationship between the icaA(-)/icaD(-)/IS256(-) genotype and protein- or protein/extracellular DNA (eDNA)-biofilm composition was found in the isolates from OI (53.6%), whereas the icaA(+)/icaD(+)/IS256(-) genotype and carbohydrate-biofilm was most prevalent in isolates from HC (25%) and HS (25%). Isolates with an icaA(-)/icaD(-)/IS256(-) genotype and protein-biofilm phenotype were predominantly of the ST2 lineage, while carbohydrate-biofilm-producing strains were mainly of the ST9 lineage. The protein-biofilm-producing strains had higher expression levels of aap gene than carbohydrate-biofilm-producing strains; while embp gene did not have the same pattern of expression. These results suggest that S. epidermidis strains with icaA(-)/icaD(-)/IS256(-) genotype and protein- or protein/eDNA-biofilms have a stronger ability to establish in the eye than S. epidermidis strains with icaA(+)/icaD(+)/IS256(-) genotype and PNAG-biofilms.
Subject(s)
Biofilms/growth & development , Eye Infections/epidemiology , Staphylococcal Infections/epidemiology , Staphylococcus epidermidis/isolation & purification , Staphylococcus epidermidis/physiology , Virulence Factors/deficiency , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , DNA Transposable Elements , DNA, Bacterial/genetics , DNA, Bacterial/metabolism , Eye Infections/microbiology , Genes, Bacterial , Genotype , Humans , Multilocus Sequence Typing , Polymerase Chain Reaction , Polysaccharides, Bacterial/metabolism , Staphylococcal Infections/microbiology , Staphylococcus epidermidis/classification , Staphylococcus epidermidis/geneticsABSTRACT
Dam methylation is an essential factor involved in the virulence of an increasing number of bacterial pathogens including Salmonella enterica. Lack of Dam methylation causes severe attenuation in animal models. It has been proposed that dysregulation of Dam activity is potentially a general strategy for the generation of vaccines against bacterial pathogens. In this review, we focus our attention on the role of methylation by Dam protein in regulating bacterial gene expression and virulence in Salmonella enterica.
Subject(s)
Salmonella enterica/pathogenicity , Site-Specific DNA-Methyltransferase (Adenine-Specific)/physiology , Virulence Factors/physiology , Animals , Disease Models, Animal , Gene Expression Regulation, Bacterial , Models, Biological , Salmonella Infections, Animal/microbiology , Salmonella Vaccines/genetics , Salmonella Vaccines/immunology , Salmonella enterica/cytology , Salmonella enterica/enzymology , Salmonella enterica/physiology , Site-Specific DNA-Methyltransferase (Adenine-Specific)/deficiency , Vaccines, Attenuated/genetics , Vaccines, Attenuated/immunology , Virulence , Virulence Factors/deficiencyABSTRACT
Algunas características descritas como factores de virulencia para el género Colletotrichum sp. tales como la masa del micelio producido, la esporulación, la actividad poligalacturonasa y el pH del medio, fueron evaluadas durante el cultivo de C. gloeosporioides f. alatae en tres medios líquidos (Czapeck, caldo Martin y caldo papa), utilizados comúnmente para el desarrollo de hongos y en el medio de cultivo Czapeck adicionado con extracto de tubérculo de ñame como única fuente de carbono. Al cabo de 17 días de crecimiento, se obtuvieron los niveles máximos de los parámetros mencionados, al utilizar este último medio, respecto a los otros medios de cultivo evaluados. El medio de cultivo implementado con extracto de tubérculo de ñame, suministró los requerimientos nutricionales del hongo para el desarrollo de factores relacionados con los mecanismos de infección que pueden participar en su patogenicidad.