No abstract

Antimicrobial resistance (AMR) in pathogens is the result of indiscriminate use of antibiotics and consequent metabolic/genetic modulation to evolve survival strategies and clonal-selection in AMR strains. As an alternative to antibiotic treatment, antivirulence strategies are being developed, not only to combat bacterial pathogenesis, but also to avoid emerging antibiotic resistance. Vibrio vulnificus is a foodborne pathogen that causes gastroenteritis, necrotizing wound infections, and sepsis with a high rate of mortality. Here, we developed an inhibitor-screening reporter platform to target HlyU, a master transcriptional regulator of virulence factors in V. vulnificus by assessing rtxA1 transcription under its control. The inhibitor-screening platform includes wild type and ΔhlyU mutant strains of V. vulnificus harboring the reporter construct PrtxA1::luxCDABE for desired luminescence signal detection and control background luminescence, respectively. Using the inhibitor-screening platform, we identified a small molecule, fursultiamine hydrochloride (FTH), that inhibits the transcription of the highly invasive repeat-in-toxin (rtxA1) and hemolysin (vvhA) along with other HlyU regulated virulence genes. FTH has no cytotoxic effects on either host cells or pathogen at the tested concentrations. FTH rescues host cells from the necrotic cell-death induced by RtxA1 and decreases the hemolytic activity under in vitro conditions. The most important point is that FTH treatment does not induce the antivirulence resistance. Current study validated the antivirulence strategy targeting the HlyU virulence transcription factor and toxin-network of V. vulnificus and demonstrated that FTH, exhibits a potential to inhibit the pathogenesis of deadly, opportunistic human pathogen, V. vulnificus without inducing AMR.

deaths were reported out of 120 000 S. aureus infections in 2017. The reasons for the higher rate of MRSA infection and its associated deaths are due to the rapid development of tolerance/resistance to multiple antibiotics drugs (multiple drug resistance, MDR), [5] and the quick adaptability of S. aureus to the host environment via evading the immune system and residing as a persister inside the host cells. Persisters are the cause of secondary and chronic infection with enhanced pathogenesis and resistance, therefore, MRSA persisters are known to be extremely difficult to treat with current antibiotics. [6] Based on these facts, it is conceivable that new resistance-free antibiotics or antistaphylococcal therapies are required not only to cure the lethal MDR MRSA infections but also to bypass the development and dissemination of antibiotic-resistance to avoid the future outbreak of MDR bacterial pathogen infectious disease. [7] In this context, various antistaphylococcal strategies such as antimicrobial peptides (AMPs), [8] enzybiotics, [9] antivirulence agents, [10] gene editing enzymes, [11] bacteriophages, [12] and nanoparticles (NPs) [13,14] are being developed as alternative therapeutic options to antibiotics. Although AMPs, antivirulence agents, or bacteriophages have produced promising results as therapeutic agents yet the development of resistance against Methicillin-resistant Staphylococcus aureus (MRSA) causes diseases ranging from skin infections to lethal sepsis and has become a serious threat to human health due to multiple-drug resistance (MDR). Therefore, a resistance-free antibacterial therapy is necessary to overcome MDR MRSA infections. In this study, an antibacterial nanorobot (Ab-nanobot) is developed wherein a cell wall-binding domain (CBD)-endolysin, acting as a sensor, is covalently conjugated with an actuator consisting of an iron oxide/silica core-shell. The CBD-endolysin sensor shows an excellent specificity to detect, bind, and accumulate on the S. aureus USA300 cell surface even in a bacterial consortium, and in host cell infections. Ab-nanobot specifically captures and kills MRSA in response to medically approved radiofrequency (RF) electromagnetic stimulation (EMS) signal. When Ab-nanobot receives the RF-EMS signal on the cell surface, actuator induces cell death in MRSA with 99.999% removal within 20 min by cell-wall damage via generation of localized heat and reactive oxygen species. The in vivo efficacy of Ab-nanobot is proven using a mice subcutaneous skin infection model. Collectively, this study offers a nanomedical resistance-free strategy to overcome MDR MRSA infections by providing a highly specific nanorobot for S. aureus.

Obesity is a common metabolic disorder caused by a sedentary lifestyle, and a high-fat and a high-glucose diet in the form of fast foods. High-fat diet-induced obesity is a major cause of diabetes and cardiovascular diseases, whereas exercise and physical activity can ameliorate these disorders. Moreover, exercise and the gut microbiota are known to be interconnected, since exercise can increase the gut microbial diversity and contribute to the beneficial health effects. In this context, we analyzed the effect of diet and exercise on the gut microbiota of mice, by next-generation sequencing of the bacterial V4 region of 16S rRNA. Briefly, mice were divided into four groups: chow-diet (CD), high-fat diet (HFD), high-fat diet + exercise (HFX), and exercise-only (EX). The mice underwent treadmill exercise and diet intervention for 8 weeks, followed by the collection of their feces and DNA extraction for sequencing. The data were analyzed using the QIIME 2 bioinformatics platform and R software to assess their gut microbial composition, richness, and diversity. The Bacteroidetes to Firmicutes ratio was found to be decreased manifold in the HFD and HFX groups compared to the CD and EX groups. The gut microbial richness was comparatively lower in the HFD and HFX groups and higher in the CD and EX groups (ACE, Chao1, and observed OTUs). However, the Shannon alpha diversity index was higher in the HFD and HFX groups than in the CD and EX groups. The beta diversity based on Jaccard, Bray–Curtis, and weighted UniFrac distance metrics was significant among the groups, as measured by PERMANOVA. Paraprevotella, Desulfovibrio, and Lactococcus were the differentially abundant/present genera based on the intervention groups and in addition to these three bacteria, Butyricimonas and Desulfovibrio C21c20 were differentially abundant/present based on diet. Hence, diet significantly contributed to the majority of the changes in the gut microbiota.