MRSA and MSSA: The Mechanism of Methicillin Resistance and the Influence of Methicillin Resistance on Biofilm Phenotype of Staphylococcus aureus

Staphylococcus aureus (S. aureus), which is one of the most common causes of indwelling device–associated, nosocomial, and community-acquired infections, can produce biofilm as a virulence factor. Methicillin-resistant S. aureus (MRSA) that is resistant to β-lactam antibiotics causes life-threatening infections. Biofilm producer strains of S. aureus that causes indwelling device–associated infections resist to antimicrobials and immune system. The combination of methicillin resistance and the ability of biofilm formation of S. aureus makes treatment difficult. Methicillin resistance of S. aureus can affect biofilm phenotype of S. aureus; the mecA gene of MRSA increases biofilm production by inactivating accessory gene regulator (agr) quorum sensing regulator system, which is a two-component regulator system of virulence factor production. The aim of this review is to determine virulence factors of S. aureus, resistance mechanisms of methicillin, and the influence of methicillin resistance on biofilm phenotype of S. aureus

The Methods for Detection of Biofilm and Screening Antibiofilm Activity of Agents

Biofilm producer microorganisms cause nosocomial and recurrent infections. Biofilm that is a sticky exopolysaccharide is the main virulence factor causing biofilm-related infections. Biofilm formation begins with attachment of bacteria to biotic surface such as host cell or abiotic surface such as prosthetic devices. After attachment, aggregation of bacteria is started by cell-cell adhesion. Aggregation continues with the maturation of biofilm. Dispersion is started by certain conditions such as phenol-soluble modulins (PSMs). By this way, sessile bacteria turn back into planktonic form. Bacteria embedded in biofilm (sessile form) are more resistant to antimicrobials than planktonic bacteria. So it is hard to treat biofilm-embedded bacteria than planktonic forms. For this reason, it is important to detect biofilm. There are a few biofilm detection and biofilm production methods on prosthetics, methods for screening antibacterial effect of agents against biofilm-embedded microorganism and antibiofilm effect of agents against biofilm production and mature biofilm. The aim of this chapter is to overview direct and indirect methods such as microscopy, fluorescent in situ hybridization, and Congo red agar, tube method, microtiter plate assay, checkerboard assay, plate counting, polymerase chain reaction, mass spectrometry, MALDI-TOF, and biological assays used by antibiofilm researches

Staphylococcal Biofilms: Pathogenicity, Mechanism and Regulation of Biofilm Formation by Quorum-Sensing System and Antibiotic Resistance Mechanisms of Biofilm-Embedded Microorganisms

Staphylococcal infections are reported to cause very important problems in hospitalized and immunocompressed patients worldwide due to their tough and irresponsive treatment by antibiotics. Biofilm-embedded bacteria that gain resistance to immune defense and antibiotics by antibiotic degrading enzymes, efflux pumps, and certain gene products of which expression are changed by the quorum sensing cause chronic and recurrent infections such as indwelling device–associated infections. Biofilm-embedded sessile community has heterogeneous cells that have wide range of different responds to each antimicrobials. Staphylococcus epidermidis (S. epidermidis) and Staphylococcus aureus (S. aureus) that are mostly known pathogenic strains can induce gene expression of biofilm that has an important role in the pathogenesis of staphylococcal infections and causes bacterial attachment and colonization on biotic such as tissues or abiotic surfaces such as prosthetic surfaces that may act as a substrate for microbial adhesion when microorganisms exposed to stress conditions. This expressed and matured biofilm causes bacterial spread to whole body, consequently, spread of infection in to whole body. It is hard to treat biofilm infections, and new agents are being researched to prevent formation and dissemination of biofilm. Defining the virulence and the role of biofilm of S. epidermidis and S. aureus in chronic and recurrent infections such as indwelling device–associated infections, the mechanism and the global regulation of biofilm production by quorum-sensing system, inactivation of biofilm formation, and the resistance patterns of biofilm-embedded microorganism against antimicrobials are important

Antimicrobials, Antibiotic Resistance, Antibiofilm Strategies and Activity Methods

To prevent bacterial adherence, invasion and infection, antimicrobials such as antibiotics are being used and vastly researched nowdays. Several factors such as natural selection, mutations in genes, the presence of efflux pumps, impermeability of the cell wall, structural changes in enzymes and receptors, biofilm formation, and quorum sensing cause microorganisms to develop resistance against antimicrobials. Isolates that synthesize extended spectrum-β-lactamases (ESBL), induced β-lactamases (IBL), carbapenamases, metallo-β-lactamases (MBLs), and New Delhi metallo-β-lactamases (NDM) have emerged. Determining virulence factors such as biofilms and the level of antimicrobial activities of antimicrobial agents alone and in combination with appropriate doses against microorganisms is very important for the diagnosis, inhibition, and prevention of microbial infection. The goal of this book is to provide information on all these topics

Effects of Fermented Sumach on the Formation of Slime Layer of Staphylococcus aureus

Objective: Staphylococcus aureus (S. aureus) is one of the most commonly isolated bacterial pathogens in hospitals, and the most frequent cause of nosocomial infections. Nosocomial staphylococcal foreign-body infections related to biofilm formation are a serious threat, demanding new therapeutic and preventive strategies. Implantation of intravenous catheters and surgical implantation of prosthetic implants carry a risk of infection. In order to prevent all these effects of biofilms, a study was designed to observe the possible antibacterial effect of sumach (Rhus coriaria) on the biofilm formation of S. aureus. Material and Methods: The influence of varying concentrations of sumach on the formation of biofilms by 13 strains of Staphylococcus aureus was tested by a microelisa assay. Results: The significant differences between varying concentrations of sumach (0.1, 0.2, 0.5 and 1.0 µl/ml) were observed in four methicillin resistant Staphylococcus aureus (MRSA) and nine methicillin sensitive Staphylococcus aureus (MSSA) (p<0.05). In bacteria, a dose-related decrease in the formation of slime, which is a major virulence factor of staphylococcal infections, was observed. Conclusion: In our study, using 0.1, 0.2, 0.5 and 1.0 µl/ml of sumach, thirteen strains lost, 17%, 22%, 28% and 48% respectively of their capacity to produce biofilms. Sumach, which is a herbal product, can decrease the formation of biofilm, which is a major virulence factor in staphylococcal infections