Anti-Infective Agents - Volume 21, Issue 3, 2023

Enterococcus faecalis is a common opportunistic pathogen that can infect various tissues in the human body and in particular, the oral cavity. It has been implicated in periodontal disease, oral mucosal lesions in immunocompromised patients, peri-implantitis, peri-radicular abscesses, and root canal infections. They are also most prevalent in secondary endodontic infections and are recognized as treatment-resistant bacteria in the root canal. Virulence factors help in this pathogenicity as some factors aid its adherence to the surface. It has become a research focus in recent times for its resistance to various antibiotics like vancomycin and so, the search for alternative therapeutic approaches has also evolved. Although various chemical irrigants such as sodium hypochlorite (NaOCl), chlorhexidine (CHX), iodine potassium iodide (IKI), calcium hydroxide (Ca(OH)2) and chlorine dioxide (ClO2) have been used for years, the use of plant extracts and essential oils have attracted the researchers to explore their activity against various dental pathogens like E. faecalis. Recently, it has been found that the phages are more effective in treating biofilm than antibiotics and it has also been observed that they are effective when used in combination with antibiotics. In this review, we have presented various treatment strategies that have been in use for treating dental infections and also discussed future therapeutic approaches, which, may help unfold promising novel strategies.

Background: Test substrates are routinely used in laboratories to test the efficacy of various reactions, and while many substrates have found success as test substrates, not much is known about their potential intrinsic properties. On that note, some bromoaniline compounds were synthesized and repurposed by studying their antibacterial activity. Methods: The in-vitro antibacterial tests were done against S. aureus, K. pneumoniae, B. subtilis, and E. coli. Tests were carried out to understand the mode of action of the compounds where changes in permeability and integrity of cell membrane resulting in the leakage of UV absorbing materials were observed. Computational studies were performed by employing density functional theory (DFT) in the Gaussian09 software for determining the reactivity of the studied compounds. Molecular docking studies were executed to define the interaction of the synthesized compounds with microbial target proteins, Dihydrofolate reductase (PDB ID: 3SRW) and DNA gyrase subunit B (PDB ID: 1KZN). Results: The compound’s response to the mode of action tests showed alteration in the membrane permeability and its antimicrobial effectiveness at different pH contributed it to being a potential antibiotic. The results of DFT studies revealed that the molecular descriptors indicate better reactivity of compound 8b which is in agreement with the experiments performed. Molecular docking studies revealed that interactions of the compounds at the active sites of target proteins depict that the compounds are likely to bind to the protein enhancing their potential as antibacterial agents. Conclusions: This work concludes that simple molecules synthesized effortlessly through a simple and environmentally benign pathway, can pose as a good therapeutic agent.

Nutritionally variant streptococci (NVS) were assumed to be nutritional mutants of the viridans group of streptococci, but they are now considered as other Streptococcus species. Due to their difficult nature, to date, the detection and treatment of NVS are challenging. This review aims at a compilation of a comprehensive study on literature reporting the microbiological characteristics of NVS species, their detection, and treatment strategies with an emphasis on large-scale research experimentations. According to the literature, the classification of these Streptococci has changed several times, interpreting the scientific literature of Abiotrophia and Granulicatella spp. NVS strains exhibit pleomorphic cellular morphologies, and they can be distinguished from other streptococci by their biochemical reactions and molecular tests. They have been isolated from clinical specimens including pus, synovial fluid, and blood, in addition to their involvement in endocarditis. Treatment of NVS is challenging due to its difficult nature and the complexity of antimicrobial susceptibility testing. Early diagnosis is critical for initiating proper therapy and avoiding fatal consequences. Microbiologists and clinicians ought to be cautious of these isolates, which are easy to overlook due to their difficult nature and the challenges in retrieving from clinical samples. Hence largescale research is required to identify additional detection techniques, infrastructure, and treatment options.

Background: The emerging antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) are a pressing global concern. Furthermore, the limited number of available antifungal agents requires the discovery of new antimicrobials. Introduction: This paper focused on the isolation and characterization of an actinobacterium designated S10, the study of its antimicrobial activity, on the one hand, and the optimization of antifungal production using statistical methods, on the other hand. Methods and Results: A haloalkaliphilic actinobacterium designated S10 was isolated from a wastewater treatment plant in the Souk-El-Tenine region (Bejaia, Algeria). This strain showed a broad spectrum of activity against bacteria (B. subtilis, L. innocua, M. luteus, S. aureus, MRSA, E. coli, P. aeruginosa, S. Typhi, and V. cholerae), molds (A. niger, G. geotricum, and F. oxysporum) and a pathogenic yeast (C. albicans). The extracellular enzymes producer Nocardiopsis sp. S10 was identified based on morphological, chemical, and 16S rRNA gene sequencing analysis. The best antimicrobial production was achieved on Mincer-Sea-Water (MSW) solid medium, and the antibiotics produced were extracted with ethyl acetate. For antifungal production, central composite design (CCD) and response surface methodology (RSM) were used to optimize the culture medium formulation. Conclusion: Optimal antifungal activity was achieved using a mixture of 2 g. L^-1 starch, 2 g. L^-1 of yeast extract and 2.75 g. L^-1 of peptone at pH = 9.2. The application of the statistical approach stimulated a good yield of anti-C. albicans activity, corresponding to an increase of 72.22% compared to the non-optimized conditions.

Introduction: Drug development has a great deal to gain from the therapeutic and preventative actions of medicinal plants and their derivatives. In order to introduce active medicinal herbs and phytochemicals against viral infections of the respiratory system, we tried to focus on a vast amount of data. Methods: From 2000 to the present, articles from Web of Science, Scopus, ScienceDirect, Pub- Med, and Google Scholar were taken into consideration. A combination of respiratory viral infection with keywords of medicinal plants, phytochemicals, flavonoids, saponins, phenolics, terpenoids, alkaloids, and natural products has been used, as well as keywords of antiviral medicinal plants, and antiviral phytochemicals. Pure antiviral compounds and plants with activity against viruses other than respiratory viruses were disregarded and excluded from consideration. Results: More than eighty phytochemicals and sixty herbs that were subjected to in vitro and in vivo investigations were documented. The current study collects information on multiple medicinal plants, including Camellia sinensis, Sambucus nigra, Pelargonium sidoides, Echinacea purpurea, and Glycyrrhiza glabra, which have been shown to have effective antiviral properties through experimental research. The main antiviral phytochemicals were terpenoids, alkaloids, and flavonoids. Additionally, chemicals including resveratrol, quercetin, chlorogenic acid, amentoflavone A, biochanin, and glycyrrhizin demonstrated efficacy against many viral infections. Conclusion: For the management of viral infections, the current review on the development of novel antiviral medications is strongly advised. It also provides a possibility to discover anti- COVID-19 lead compounds and can offer supportive treatment in this pandemic situation.