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Spices as Eco-friendly Microbicides: From Kitchen to Clinic
Published in Mahendra Rai, Chistiane M. Feitosa, Eco-Friendly Biobased Products Used in Microbial Diseases, 2022
Bacterial and fungal resistance to antibiotics is related to their ability of forming biofilm that prevents the penetration of the antibacterial agent at the site of infection. It is estimated that 65–80% of all infections are caused by biofilm-related microorganisms, which is the main reason for the ineffectiveness of treatment. Thymol has shown the ability to inhibit biofilms of E. coli, Listeria monocytogenes, Pseudomonas putida and S. aureus. Besides antibacterial action, thymol also exerts antifungal activity towards Candida albicans, and Cryptococcus neoformans.
Green Metal-Based Nanoparticles Synthesized Using Medicinal Plants and Plant Phytochemicals against Multidrug-Resistant Staphylococcus aureus
Published in Richard L. K. Glover, Daniel Nyanganyura, Rofhiwa Bridget Mulaudzi, Maluta Steven Mufamadi, Green Synthesis in Nanomedicine and Human Health, 2021
Abeer Ahmed Qaed Ahmed, Lin Xiao, Tracey Jill Morton McKay, Guang Yang
Despite the use of many different antibiotics to treat bacterial infections, bacteria are exhibiting increasing resistance to them. This is of global concern as there may come a time when no antibacterial agent is effective against specific bacterial infections. For instance, S. aureus is an aerobic gram-positive bacterium, which lives commensal as normal flora in skin, pharynx, perineum and anterior nares, could also lead to bacteremia, infections of skin and soft tissue, hospital-acquired infections, osteomyelitis, joint and bone infections and endocarditis (Sakr et al., 2018; Turner et al., 2019; Troeman et al., 2019). Although S. aureus is commensal, a large number of S. aureus infections could emerge from the patient’s own flora, with a link between S. aureus residing normally in common carriages sites leading to S. aureus infections (Von Eiff et al., 2001; Wertheim et al., 2005; de Jong et al., 2019). S. aureus can evolve into different strains such as MRSA, VISA and VRSA. This occurs due to antibiotic resistance associated with having genes that encode antibiotic-inactivating enzymes, obtaining pre-existing resistance factors though genetic exchange pathways between bacterial cells and producing low-affinity antibiotic-binding proteins that reduces the binding affinities of antibiotics and stepwise mutations in the genes, among others. These mechanisms are described in Sections 3.1–3.3.
Resistance of Acinetobacter spp. to Antimicrobials — Overview of Clinical Resistance Patterns and Therapeutic Problems
Published in E. Bergogne-Bénézin, M.L. Joly-Guillou, K.J. Towner, Acinetobacter, 2020
Strains of A. calcoaceticus var. anitratus were significantly more resistant than var. Iwoffii strains in early studies (Bergogne-Bérézin et al., 1971; Pinter and Kantor, 1971), a finding confirmed by more recent investigations. In a further study with 64 strains isolated in 1973-1974, increased rates of resistance were noted compared with 1971 (Table 7.7), and it is interesting to note that soon after the therapeutic introduction of a new powerful antibacterial agent in the form of carbenicillin, the frequency of resistant strains had risen from 3.5 to 7.2%. Simultaneously, resistance to ampicillin had risen from 39 to 43.3%, and to cephaloridine from 52.5 to 66.6%. There was no change in resistance rates for the other available antibiotics, streptomycin, kanamycin and chloramphenicol, between 1971 and 1974, probably because of the reduced use of these older drugs as newer, more active compounds became available. With tetracyclines, A. glucidolytica was less resistant in 1971 to minocycline (67.3%) than to tetracycline (98.5%). These early studies at Bichat Hospital provided data that were similar to the previous studies cited above, and were followed in 1975 by the start of regular surveillance of Acinetobacter strains isolated from our own and other hospitals in France (see next section).
Discovery of N-quinazolinone-4-hydroxy-2-quinolone-3-carboxamides as DNA gyrase B-targeted antibacterial agents
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2022
Wenjie Xue, Yaling Wang, Xu Lian, Xueyao Li, Jing Pang, Johannes Kirchmair, Kebin Wu, Zunsheng Han, Xuefu You, Hongmin Zhang, Jie Xia, Song Wu
Here, we used the chemical information of the N-thiadiazole-4-hydroxy-2-quinolone-3-carboxamides to identify new GyrB inhibitors. With the essential fragment for GyrB inhibition as the substructure, we searched the Specs database of purchasable compounds for related substances. By testing the compounds in S. aureus GyrB inhibition assay, we discovered that the 4-hydroxy-2-quinolone-3-carboxamide derivative that has an N-quinazolinone moiety inhibits GyrB. To understand the preliminary structure–activity relationship (SAR), we synthesised derivatives and evaluated their activities against GyrB. Representative GyrB inhibitors were submitted for in vitro evaluation of the antibacterial activity against a panel of S. aureus strains. Finally, we studied the cytotoxicity, ADMET profile, and important physicochemical properties of the most active antibacterial agent.
Microneedles for transdermal drug delivery using clay-based composites
Published in Expert Opinion on Drug Delivery, 2022
Farzaneh Sabbagh, Beom Soo Kim
Silver is known as an excellent antibacterial agent. Silver-enriched clays are known to be excellent dressings for wound healing and minimizing the chance of infection [6]. In a study conducted by Tenci et al. [85], a polymer film containing a carvacrol/clay mixture was developed for use in the treatment of infected skin wounds. Various clays were considered, such as palygorskite, montmorillonite, and halloysite. The results showed that while pure clay had no antibacterial activity, carvacrol did have antibacterial properties. Carvacrol loading on palygoskite reduced the minimal inhibitory and minimal bactericidal concentrations of pure carvacrol. This effect may be due to the lower evaporation temperature of carvacrol when it is loaded with clay, and to the prolonged release of carvacrol from hybrids [85]. The metal specification of the clay structure determines the bioavailability of the metal to bacteria [86]. The movement of particles from the clay surface to the cell membrane through water involves the formation of radicals and many chemical reactions that are influenced by bacterial surface complexes and clay mineralization. The oxidation state and pH of the water added to create a plaster is changed mainly by the buffer volume of the clay and the relevant surface area (more than 100 m2/g) [87].
Epidemic Retinitis with Macular Edema –Treatment Outcome with and without Steroids
Published in Ocular Immunology and Inflammation, 2021
Ankush Kawali, Sanjay Srinivasan, Ashwin Mohan, Bharathi Bavaharan, Padmamalini Mahendradas, Bhujang Shetty
Doxycycline is not only an antibacterial agent, but it has also proven to be effective against the dengue virus in experimental studies.13,14 Various antibiotics in tetracycline family including doxycycline possess immunomodulating properties.14,15 Doxycycline is also a well-known matrix metalloprotein inhibitor (MMP) which has been shown to be increased (MMP9) in equine recurrent uveitis in experimental animal models.16,17 Hence, one may wonder if doxycycline can act as an immunomodulating agent in addition to its antibacterial and antiviral properties in ER. A recent clinical placebo control trial has shown a significant reduction in complications of dengue fever in patients who received doxycycline.18 Most of the patients in our series received doxycycline, but in Group 1, we also had six patients treated with ciprofloxacin who also showed clinical and visual improvement (Table 1). Unfortunately, numbers were less for a comparative study. Nevertheless, the treatment outcome between doxycycline group and ciprofloxacin group was not statistically significant (p = .06). Koh et al.5 reported spontaneous resolution of dengue-related retinitis with conservative treatment while Cunnigham et al.9 reported a complete return of vision without any treatment in 13 out of 14 eyes with acute multifocal retinitis of unknown origin. It can be well argued that the resolution of the inflammation in our series was a natural course of the disease and antibiotics had no or less role to play.