Infectious diseases are the second most important cause of human death worldwide; Staphylococcus aureus (S. aureus) is a very common human pathogenic microorganism that can trigger a variety of infectious diseases, such as skin and soft tissue infections, endocarditis, osteomyelitis, bacteremia, and lethal pneumonia. Moreover, according to the sensitivity to antibiotic drugs, S. aureus can be divided into methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA). In recent decades, due to the evolution of bacteria and the abuse of antibiotics, the drug resistance of S. aureus has gradually increased, the infection rate of MRSA has increased worldwide, and the clinical anti-infective treatment for MRSA has become more difficult. Accumulating evidence has demonstrated that the resistance mechanisms of S. aureus are very complex, especially for MRSA, which is resistant to many kinds of antibiotics. Therefore, understanding the drug resistance of MRSA in a timely manner and elucidating its drug resistance mechanism at the molecular level are of great significance for the treatment of S. aureus infection. A large number of researchers believe that analyzing the molecular characteristics of S. aureus can help provide a basis for designing effective prevention and treatment measures against hospital infections caused by S. aureus and further monitor the evolution of S. aureus. This paper reviews the research status of MSSA and MRSA, the detailed mechanisms of the intrinsic antibiotic resistance and the acquired antibiotic resistance, the advanced research on anti-MRSA antibiotics and novel therapeutic strategies for MRSA treatment.

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Prevalence and Therapies of Antibiotic-Resistance in Staphylococcus aureus.

Quorum sensing is a cell-to-cell communication system that exists widely in the microbiome and is related to cell density. The high-density colony population can generate a sufficient number of small molecule signals, activate a variety of downstream cellular processes including virulence and drug resistance mechanisms, tolerate antibiotics, and harm the host. This article gives a general introduction to the current research status of microbial quorum-sensing systems, focuses on the role of quorum-sensing systems in regulating microbial resistance mechanisms, such as drug efflux pump and microbial biofilm formation regulation, and discusses a new strategy for the treatment of drug-resistant bacteria proposed by using quorum quenching to prevent microbial resistance.

Quorum-Sensing Regulation of Antimicrobial Resistance in Bacteria.

Food industries are facing ry faces a great challenge due to contamination of food products with different microbes such as bacteria, fungi, viruses, parasites etc. These microbes deteriorate food items both by producing different toxins during pre and post-harvest processing. They not only deteriorate food but also contaminate them with different toxins. Mycotoxins are one of theamong most potent and well-studied toxic food contaminant of fungal origin causing severe health hazard to human health hazard. UseApplication of synthetic chemicals as food preservatives in food system pose a real scourge in the present scenario is being discouraged due to their bio-incompatibility, and non-biodegradability and environmental non-sustainability. Therefore, plant based antimicrobials including essential oils have developed cumulative interest come up as potential replacement alternative of these popular synthetic preservatives because of their ecofriendly nature and generally recognized as safe (GRAS) status. However, the practical Worldwide utilization of essential oils as plant based and efficient antimicrobial in the food industry is challenging due to their volatile nature, less solubility and high instability. The recent application of different delivery strategies viz. nanoencapsulation, active packaging and polymer based coating are effectively addressed these challenges and improve the bioefficacy as well as controlled release of essential oils. This challenge can be overcome by nanoencapsulation. Nanoencapsulation is an interesting and emerging technique that raises the physico-chemical properties, as well as slow release of essential oils for improving food safety. This article provides an detailed overview on essential oils for preservation of stored foods against bacteria, fungi and mycotoxins of antimicrobial plant based food preservatives, their along with specialized mechanismmode of action and technological advancement by using different delivery systems for their effective application in food and agricultural industries smart green preservative.in their application for food preservation.

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Essential Oils and Their Application in Food Safety

Anti-oxidant, antibacterial, anti-biofilm, and anti-quorum sensing activities of four essential oils against multidrug-resistant bacterial clinical isolates.

The biofilm matrix can be considered to be a shared space for the encased microbial cells, comprising a wide variety of extracellular polymeric substances (EPS), such as polysaccharides, proteins, amyloids, lipids and extracellular DNA (eDNA), as well as membrane vesicles and humic-like microbially derived refractory substances. EPS are dynamic in space and time and their components interact in complex ways, fulfilling various functions: to stabilize the matrix, acquire nutrients, retain and protect eDNA or exoenzymes, or offer sorption sites for ions and hydrophobic substances. The retention of exoenzymes effectively renders the biofilm matrix an external digestion system influencing the global turnover of biopolymers, considering the ubiquitous relevance of biofilms. Physico-chemical and biological interactions and environmental conditions enable biofilm systems to morph into films, microcolonies and macrocolonies, films, ridges, ripples, columns, pellicles, bubbles, mushrooms and suspended aggregates — in response to the very diverse conditions confronting a particular biofilm community. Assembly and dynamics of the matrix are mostly coordinated by secondary messengers, signalling molecules or small RNAs, in both medically relevant and environmental biofilms. Fully deciphering how bacteria provide structure to the matrix, and thus facilitate and benefit from extracellular reactions, remains the challenge for future biofilm research. In this Review, Flemming et al. revisit our understanding of the biofilm matrix, focusing on the diversity of the extracellular polymeric substance components and novel aspects of mechanisms and consequences of their functional interactions. 

The biofilm matrix: multitasking in a shared space

Biofilm is a mode of living employed by many pathogenic and environmental microbes to proliferate as multicellular aggregates on inert inanimate or biological substrates. Several microbial diseases are associated with biofilms that pose challenges in treatment with antibiotics targeting individual cells. Bacteria in biofilms secrete exopolymeric substances that contribute to architectural stability and provide a secure niche to inhabiting cells. Quorum sensing (QS) plays essential roles in biofilm development. Pathogenic bacteria in biofilms utilize QS mechanisms to activate virulence and develop antibiotic resistance. This review is a brief overview of biofilm research and provides updates on recent understandings on biofilm development, antibiotic resistance and transmission, and importance of QS mechanisms. Strategies to combat biofilm associated diseases including anti-biofilm substances, quorum quenching molecules, bio-surfactants and competitive inhibitors are briefly discussed. The review concludes with updates on recent approaches utilized for biofilm inhibition and provides perspectives for further research in the field.

Kartik Rawat

Papers

Biofilms: Architecture, Resistance, Quorum Sensing and Control Mechanisms.

Critical pathways of oral squamous cell carcinoma: molecular biomarker and therapeutic intervention

Edelfosine reactivates latent HIV-1 reservoirs in myeloid cells through activation of NF-κB and AP1 pathway.

Mechanistic Insights into the Role of Edelfosine in Reactivating Latent HIV-1