Oligomerization of RNAIII-Inhibiting Peptide Inhibits Adherence and Biofilm Formation of Methicillin-Resistant Staphylococcus aureus In Vitro and In Vivo

Potential role of probiotics in reducing Clostridioides difficile virulence: Interference with quorum sensing systems

Opportunistic pathogenic bacteria may cause disease after the normally protective microbiome is disrupted (typically by antibiotic exposure). Clostridioides difficile is one such pathogen having a severe impact on healthcare facilities and increasing costs of medical care. The search for new therapeutic strategies that are not reliant on additional antibiotic exposures are currently being explored. One such strategy is to disrupt the production of C. difficile virulence factors by interfering with quorum sensing (QS) systems. QS has been well studied in other bacteria, but our understanding in C. difficile is not so well understood. Some probiotic strains or combinations of strains have been shown to be effective in the treatment or primary prevention of C. difficile infections and may possess multiple mechanisms of action. One mechanism of probiotics might be the inhibition of QS, but their role has not been clearly defined yet. A literature search was conducted using standard databases (PubMed, Google Scholar) from database inception to August 2020. The objective of this paper is to update our understanding of how QS leads to toxin production by C. difficile, which is important in pathogenesis, and how QS inhibitors or probiotics may disrupt this pathway. We found two main QS systems for C. difficile (Agr and Lux systems) that are involved in C. difficile pathogenesis by regulating toxin production, motility and adherence. Probiotics and other QS inhibitors targeting QS systems may represent important new directions of therapy and prevention of CDI.

Emerging Nanomedicine Therapies to Counter the Rise of Methicillin-Resistant Staphylococcus aureus

In a recent report, the World Health Organisation (WHO) classified antibiotic resistance as one of the greatest threats to global health, food security, and development. Methicillin-resistant Staphylococcus aureus (MRSA) remains at the core of this threat, with persistent and resilient strains detectable in up to 90% of S. aureus infections. Unfortunately, there is a lack of novel antibiotics reaching the clinic to address the significant morbidity and mortality that MRSA is responsible for. Recently, nanomedicine strategies have emerged as a promising therapy to combat the rise of MRSA. However, these approaches have been wide-ranging in design, with few attempts to compare studies across scientific and clinical disciplines. This review seeks to reconcile this discrepancy in the literature, with specific focus on the mechanisms of MRSA infection and how they can be exploited by bioactive molecules that are delivered by nanomedicines, in addition to utilisation of the nanomaterials themselves as antibacterial agents. Finally, we discuss targeting MRSA biofilms using nano-patterning technologies and comment on future opportunities and challenges for MRSA treatment using nanomedicine.

Therapeutic Targeting of the Staphylococcus aureus Accessory Gene Regulator (agr) System

Staphylococcus aureus can cause numerous different diseases, which has been attributed to its large repertoire of virulence factors, many of which are under the control of the accessory gene regulator (agr) quorum sensing system. Under conditions of high cell density, agr increases the production of many virulence factors, decreases expression of several colonization factors, and is intimately associated with the pathogenesis and biofilm formation of S. aureus. This review summarizes our current understanding of the molecular mechanisms underlying agr quorum sensing and the regulation of agr expression. The discussion also examines subgroups of agr and their association with different diseases, and concludes with an analysis of strategies for designing drugs and vaccines that target agr to combat S. aureus infections.

Antibiofilm agents: A new perspective for antimicrobial strategy

Biofilms are complex microbial architectures that attach to surfaces and encase microorganisms in a matrix composed of self-produced hydrated extracellular polymeric substances (EPSs). In biofilms, microorganisms become much more resistant to antimicrobial treatments, harsh environmental conditions, and host immunity. Biofilm formation by microbial pathogens greatly enhances survival in hosts and causes chronic infections that result in persistent inflammation and tissue damages. Currently, it is believed over 80% of chronic infectious diseases are mediated by biofilms, and it is known that conventional antibiotic medications are inadequate at eradicating these biofilm-mediated infections. This situation demands new strategies for biofilm-associated infections, and currently, researchers focus on the development of antibiofilm agents that are specific to biofilms, but are nontoxic, because it is believed that this prevents the development of drug resistance. Here, we review the most promising antibiofilm agents undergoing intensive research and development.

Upregulated effects of miR-7 in methicillin-resistant Staphylococcus aureus

The aim of the study was to investigate the characteristic function of the upregulated effects of miR-7 in methicillin-resistant Staphylococcus aureus (MRSA). After separating the MRSA in clinic, the expression of miR-7 mRNA was tested by reverse transcription polymerase chain reaction. The overexpression, inhibition of miR-7, and control group were established by plasmid in vitro. Following transfection of the bacterial strain, the effect of β-lactam antibiotics in minimum inhibitory concentration (MIC) was observed using the microporous dilution method, and antibacterial effects in vitro were observed using the dynamic growth curve method. The expression of miR-7 in sensitive MRSA was upregulated distinctly, with significant difference (P<0.05). MIC and the number of bacteria in the miR-7 overexpression group significantly increased while the inhibition group decreased prominently, with significant difference (P<0.05). The control and null plasmid groups revealed no significant difference. In conclusion, miR-7 upregulated the antimicrobial activity of MRSA, and the intervention of its expression may become a possible antibacterial target.