Tackling Multiple-Drug-Resistant Bacteria With Conventional and Complex Phytochemicals

Emerging antibiotic resistance in bacteria endorses the failure of existing drugs with chronic illness, complicated treatment, and ever-increasing expenditures. Bacteria acquire the nature to adapt to starving conditions, abiotic stress, antibiotics, and our immune defense mechanism due to its swift evolution. The intense and inappropriate use of antibiotics has led to the development of multidrug-resistant (MDR) strains of bacteria. Phytochemicals can be used as an alternative for complementing antibiotics due to their variation in metabolic, genetic, and physiological fronts as well as the rapid evolution of resistant microbes and lack of tactile management. Several phytochemicals from diverse groups, including alkaloids, phenols, coumarins, and terpenes, have effectively proved their inhibitory potential against MDR pathogens through their counter-action towards bacterial membrane proteins, efflux pumps, biofilms, and bacterial cell-to-cell communications, which are important factors in promoting the emergence of drug resistance. Plant extracts consist of a complex assortment of phytochemical elements, against which the development of bacterial resistance is quite deliberate. This review emphasizes the antibiotic resistance mechanisms of bacteria, the reversal mechanism of antibiotic resistance by phytochemicals, the bioactive potential of phytochemicals against MDR, and the scientific evidence on molecular, biochemical, and clinical aspects to treat bacterial pathogenesis in humans. Moreover, clinical efficacy, trial, safety, toxicity, and affordability investigations, current status and developments, related demands, and future prospects are also highlighted.

Exploring Phytochemicals for Combating Antibiotic Resistance in Microbial Pathogens

Antibiotic resistance or microbial drug resistance is emerging as a serious threat to human healthcare globally, and the multidrug-resistant (MDR) strains are imposing major hurdles to the progression of drug discovery programs. Newer antibiotic-resistance mechanisms in microbes contribute to the inefficacy of the existing drugs along with the prolonged illness and escalating expenditures. The injudicious usage of the conventional and commonly available antibiotics in human health, hygiene, veterinary and agricultural practices is proving to be a major driver for evolution, persistence and spread of antibiotic-resistance at a frightening rate. The drying pipeline of new and potent antibiotics is adding to the severity. Therefore, novel and effective new drugs and innovative therapies to treat MDR infections are urgently needed. Apart from the different natural and synthetic drugs being tested, plant secondary metabolites or phytochemicals are proving efficient in combating the drug-resistant strains. Various phytochemicals from classes including alkaloids, phenols, coumarins, terpenes have been successfully demonstrated their inhibitory potential against the drug-resistant pathogens. Several phytochemicals have proved effective against the molecular determinants responsible for attaining the drug resistance in pathogens like membrane proteins, biofilms, efflux pumps and bacterial cell communications. However, translational success rate needs to be improved, but the trends are encouraging. This review highlights current knowledge and developments associated challenges and future prospects for the successful application of phytochemicals in combating antibiotic resistance and the resistant microbial pathogens.

Is it Worth Combining Solidago virgaurea Extract and Antibiotics against Uropathogenic Escherichia coli rods? An In Vitro Model Study

European goldenrod (Solidago virgaurea L.) has long been applied in traditional medicine and recommended in the prophylaxis of urinary tract infections (UTIs). However, research describing the antibacterial properties of goldenrod is very limited. Therefore, the aim of the study was to determine the effect of S. virgaurea extract on the survival and biofilm formation of uropathogenic Escherichia coli. The interactions between the goldenrod extract and antibiotics used in UTIs were established. The influence of the extract on the duration of the post-antibiotic effects (PAE) and post-antibiotic sub-MIC effects (PASME) of amikacin and ciprofloxacin were determined. Extract composition was analyzed using coupled UHPLC/MS and the spectrophotometric method. The survival of bacteria was established using the serial dilution assay. The crystal violet assay for biofilm quantification was also used. PAE and PASME were investigated using the viable count method. The obtained results indicate that S. virgaurea extract limits the survival of planktonic forms of bacteria and reduces 24-h biofilm. However, the combination of S. virgaurea extract with antibiotics weakens their antibacterial activity and shortens the duration of PAE and PASME. Therefore, when deciding to use a combination of S. virgaurea extract and amikacin/ciprofloxacin, it is necessary to take into account their antagonistic activity.

Anti-Bacterial Effects of Essential Oils against Uropathogenic Bacteria

Given the increasing antimicrobial resistance in urinary tract infections (UTI), alternative strategies need to be investigated. Determination of minimal inhibitory and bactericidal concentrations of essential oils from cajeput, lemongrass, tea tree, and thyme in artificial urine, revealed bactericidal activity of all four tested essential oils against seven uropathogenic species with values ranging between 0.78–50 mg/mL. Tea tree and thyme essential oils were more efficient than lemongrass and cajeput. In addition, antibiotic-resistant strains showed similar susceptibility as antibiotic-sensitive strains, suggesting no cross-resistance between antibiotics and these essential oils. Checkerboard assays revealed a synergistic activity of the combination of thyme and tea tree. Furthermore, the combination with thyme and tea tree essential oils increased the activity of fosfomycin and pivmecillinam, but not nitrofurantoin, against Escherichia coli. This study provides a basis for further investigation of the potential of thyme and tea tree oil as an alternative or additional treatment of UTI.