ABSTRACT
We asked whether transient Staphylococcus aureus in the oral environment synergistically interacts with orally associated bacterial species such as Actinomyces oris, Candida albicans, Fusobacterium nucleatum, Streptococcus oralis, Streptococcus mutans, and Veillonella dispar (six-species control biofilm 6S). For this purpose, four modified biofilms with seven species that contain either the wild type strain of the S. aureus genotype (USA300-MRSA WT), its isogenic mutant with MSCRAMM deficiency (USA300-MRSA ΔMSCRAMM), a methicillin-sensitive S. aureus (ST72-MSSA-) or a methicillin-resistant S. aureus (USA800-MRSA) grown on hydroxyapatite disks were examined. Culture analyses, confocal-laser-scanning microscopy and proteome analyses were performed. S. aureus strains affected the amount of supragingival biofilm-associated species differently. The deletion of MSCRAMM genes disrupted the growth of S. aureus and the distribution of S. mutans and S. oralis within the biofilms. In addition, S. aureus caused shifts in the number of detectable proteins of other species in the 6S biofilm. S. aureus (USA300-MRSA WT), aggregated together with early colonizers such as Actinomyces and streptococci, influenced the number of secondary colonizers such as Fusobacterium nucleatum and was involved in structuring the biofilm architecture that triggered the change from a homeostatic biofilm to a dysbiotic biofilm to the development of oral diseases.
ABSTRACT
Resumen Staphylococcus aureus se caracteriza por ser la principal causa de bacteriemia nosocomial en el mundo, debido al incremento en la resistencia, a los diferentes factores de patogenicidad y virulencia y la expresión de una gran variedad de proteínas las cuales pertenecen a las moléculas de la matriz adhesiva (MSCRAMM), presentes en la superficie de la bacteria cuya función es la colonización e invasión celular al hospedero y favorecer la formación de biopelícula, El conjunto de estos mecanismos de patogenicidad y virulencia, le permiten a la bacteria persistir en el huésped y en el ambiente, sobreviviendo a factores adversos, al sistema inmune y a los antimicrobianos.
Abstract Staphylococcus aureus is a microorganism characterized by being the main cause of nosocomial bacteremia in different places of the world, due to the different virulence and pathogenicity factors. One of the most important is the biofilm formation, which greatly favors bacterial resistance. For the adhesion of the biofilm to biotic and abiotic surfaces, the microbial surface components recognizing adhesive matrix molecules (MSCRAMM), these proteins play a key role in host cell colonization and invasion by the bacteria.
Subject(s)
Staphylococcus aureus , Bacteremia , Virulence Factors , Immune System , Anti-Infective AgentsABSTRACT
Staphylococcus aureus is a common pathogen that causes subclinical bovine mastitis due to several virulence factors. In this study, we analyzed S. aureus isolates collected from the milk of cows with subclinical mastitis that had 8 possible combinations of bap, icaA, and icaD genes, to determine their capacity to produce biofilm on biotic (bovine primary mammary epithelial cells and HeLa cells) and abiotic (polystyrene microplates) surfaces, and their ability to adhere to and invade these cells. We also characterized isolates for microbial surface components recognizing adhesive matrix molecules (MSCRAMM) and agr genes, and for their susceptibility to cefquinome sulfate in the presence of biofilm. All isolates adhered to and invaded both cell types, but invasion indexes were higher in bovine primary mammary epithelial cells. Using tryptic soy broth + 1% glucose on abiotic surfaces, 5 out of 8 isolates were biofilm producers, but only the bap+icaA+icaD+ isolate was positive in Dulbecco's Modified Eagle's medium. The production of biofilm on biotic surfaces occurred only with this isolate and only on HeLa cells, because the invasion index for bovine primary mammary epithelial cells was too high, making it impossible to use these cells in this assay. Of the 5 biofilm producers in tryptic soy broth + 1% glucose, 4 presented with the bap/fnbA/clfA/clfB/eno/fib/ebpS combination, and all were protected from cefquinome sulfate. We found no predominance of any agr group. The high invasive potential of S. aureus made it impossible to observe biofilm in bovine primary mammary epithelial cells, and we concluded that cells with lower invasion rates, such as HeLa cells, were more appropriate for this assay.