Staphylococcal biofilm formation and development: Related diseases, host immune responses and therapy

Various biomolecular and regulatory factors are involved in adhesion, biofilm formation and host immune evasion of staphylococcal species. Adherence of staphylococcal species to either biotic or abiotic surfaces are a critical first event in the establishment of infection with these serious pathogens. A variety of proteinaceous and non-proteinaceous adhesins are known to mediate attachment to a multitude of host factors, such as extracellular matrix, and plasma proteins, and human host cells or inter-bacterial cell adhesins, which is essential for biofilm accumulation. Formation of the biofilm is a two-step process: (1) adherence of the pathogen to a surface and (2) further progression by accumulation of cells to form multilayered cell clusters. Biofilm is one of the important virulence factor of staphylococci that plays a role in many device-related infections such as native valve endocarditis, otitis media, urinary tract infections, cystic fibrosis, and acute septic arthritis, The increasing prevalence of antibiotic resistant strains and the vast ability of bacteria to evade host immune defenses are becoming more and more important for medical infections. The present review focuses on the role of specific cell surface adhesins, the ica operon, accumulation-associated proteins and quorumsensing systems in the adhesion and infection processes of the Gram-positive pathogens, Staphylococcus epidermidis and Staphylococcus aureus. In addition, we will discuss staphylococcal biofilm-associated diseases and host immune responses, along with the current and future therapeutic strategies for staphylococcal biofilm infections including chemotherapeutic, vaccine and the nanotechnology applications.