Genetic Exchange of Multidrug Efflux Pumps among Two Enterobacterial Species with Distinctive Ecological Niches

AcrAB-TolC is the major multidrug efflux system in Enterobacteriaceae recognizing structurally unrelated molecules including antibiotics, dyes, and detergents. Additionally, in Escherichia coli it mediates resistance to bile salts. In the plant pathogen Erwinia amylovora AcrAB-TolC is required for virulence and phytoalexin resistance. Exchange analysis of AcrAB-TolC was conducted by complementing mutants of both species defective in acrB or tolC with alleles from either species. The acrB and tolC mutants exhibited increased susceptibility profiles for 24 different antibiotics. All mutants were complemented with acrAB or tolC, respectively, regardless of the taxonomic origin of the alleles. Importantly, complementation of E. amylovora mutants with respective E. coli genes restored virulence on apple plants. It was concluded that AcrAB and TolC of both species could interact and that these interactions did not yield in altered functions despite the divergent ecological niches, to which E. coli and E. amylovora have adopted

Interaction of Folk Medicinal Plants with Levofloxacin against Escherichia Coli

The present study was conducted to assess the in vitro activities of folk medicinal plants in combination with levofloxacin against TG1 and mutant KAM3-1(∆acrB-∆tolC) Escherichia coli strains. Plants were chosen based on their traditional use in combination with antibiotics among laymen. Standard protocols were followed to examine the antimicrobial activity of plant extracts and levofloxacin against E. coli in term of their minimum inhibitory concentrations (MICs) and to evaluate the plant extracts-levofloxacin interaction using checkerboard method. Among the twelve plants investigated, Thymus vulgaris, Zingiber officinale, Teucrium polium, Matricaria chamomilla and Curcuma longa had the best antimicrobial activities against E. coli strains with MIC values at 250 μg/ml. It is noteworthy to mention that other folk plants extracts reveled no effects against E coli strains. Furthermore, additive interactions were observed between levofloxacin and T. polium or T. vulgaris against E. coli wild-type TG1 strain. There was no antagonism being observed in this study. The detection of additive interaction between the extracts and levofloxacin demonstrates the prospective of these folk medicinal plants as a source of compounds to modulate antibiotic resistance

Genomic Distribution and Divergence of Levansucrase-Coding Genes in Pseudomonas syringae

In the plant pathogenic bacterium, Pseudomonas syringae, the exopolysaccharide levan is synthesized by extracellular levansucrase (Lsc), which is encoded by two conserved 1,296-bp genes termed lscB and lscC in P. syringae strain PG4180. A third gene, lscA, is homologous to the 1,248-bp lsc gene of the bacterium Erwinia amylovora, causing fire blight. However, lscA is not expressed in P. syringae strain PG4180. Herein, PG4180 lscA was shown to be expressed from its native promoter in the Lsc-deficient E. amylovora mutant, Ea7/74-LS6, suggesting that lscA might be closely related to the E. amylovora lsc gene. Nucleotide sequence analysis revealed that lscB and lscC homologs in several P. syringae strains are part of a highly conserved 1.8-kb region containing the ORF, flanked by 450-452-bp and 49-51-bp up- and downstream sequences, respectively. Interestingly, the 450-452-bp upstream sequence, along with the initial 48-bp ORF sequence encoding for the N-terminal 16 amino acid residues of Lsc, were found to be highly similar to the respective sequence of a putatively prophage-borne glycosyl hydrolase-encoding gene in several P. syringae genomes. Minimal promoter regions of lscB and lscC were mapped in PG4180 by deletion analysis and were found to be located in similar positions upstream of lsc genes in three P. syringae genomes. Thus, a putative 498-500-bp promoter element was identified, which possesses the prophage-associated com gene and DNA encoding common N-terminal sequences of all 1,296-bp Lsc and two glycosyl hydrolases. Since the gene product of the non-expressed 1,248-bp lscA is lacking this conserved N-terminal region but is otherwise highly homologous to those of lscB and lscC, it was concluded that lscA might have been the ancestral lsc gene in E. amylovora and P. syringae. Our data indicated that its highly expressed paralogs in P. syringae are probably derived from subsequent recombination events initiated by insertion of the 498-500-bp promoter element, described herein, containing a translational start site

Synthesis of 1,2,3-Triazolo[4,5-h]quinolone Derivatives with Novel Anti-Microbial Properties against Metronidazole Resistant Helicobacter pylori

Helicobacter pylori infection can lead to gastritis, peptic ulcer, and the development of mucosa associated lymphoid tissue (MALT) lymphoma. Treatment and eradication of H. pylori infection can prevent relapse and accelerate the healing of gastric and duodenal ulcers as well as regression of malignancy. Due to the increasing emergence of antibiotic resistance among clinical isolates of H. pylori, alternative approaches using newly discovered antimicrobial agents in combination with the standard antibiotic regimens for the treatment of H. pylori are of major importance. The purpose of the present study was to investigate the effect of newly synthesized 8-amino 7-substituted fluoroquinolone and their correspondent cyclized triazolo derivatives when either alone or combined with metronidazole against metronidazole-resistant H. pylori. Based on standard antimicrobial susceptibility testing methods and checkerboard titration assay, all of the tested compounds showed interesting antimicrobial activity against 12 clinical strains of H. pylori, with best in vitro effect for compounds 4b and 4c. Fractional inhibitory concentration (FIC) mean values showed synergistic pattern in all compounds of Group 5. In addition, additive activities of some of the tested compounds of Group 4 were observed when combined with metronidazole. In contrast, the tested compounds showed no significant urease inhibition activity. These results support the potential of new fluoroquinolone derivatives to be useful in combination with anti-H. pylori drugs in the management of H. pylori-associated diseases

Formulating co-loaded nanoliposomes with gallic acid and quercetin for enhanced cancer therapy

Cancer is considered one of the top global causes of death. Natural products have been used in oncology medicine either in crude form or by utilizing isolated secondary metabolites. Biologically active phytomolecules such as gallic acid and quercetin have confirmed antioxidant, anti-bacterial, and neoplastic properties. There is an agreement that microorganisms could mediate oncogenesis or alter the immune system. This research project aims to develop a novel formulation of co-loaded gallic acid and quercetin into nanoliposomes and investigate the efficacy of the free and combined agents against multiple cancerous cell lines and bacterial strains. Thin-film hydration technique was adopted to synthesize the nanocarriers. Particle characteristics were measured using a Zetasizer. The morphology of nanoliposomes was examined by scanning electron microscopy, Encapsulation efficiency and drug loading were evaluated using High-Performance Liquid Chromatography. Cytotoxicity was determined against Breast Cancer Cells MCF-7, Human Carcinoma Cells HT-29, and A549 Lung Cancer Cells. The antibacterial activities were evaluated against Acinetobacter baumannii, Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa, and Staphylococcus aureus. Therapeutic formulas were categorized into groups: free gallic acid, free quercetin, free-mix, and their nano-counterparts. Findings revealed that drug loading capacity was 0.204 for the mix formula compared to 0.092 and 0.68 for free gallic acid and quercetin, respectively. Regarding the Zeta potential, the mix formula showed more amphiphilic charge than the free quercetin and free gallic acid formulas (P-values 0.003 and 0.002 receptively). On the contrary, no significant difference in polydispersity indices was reported. Lung cancerous cells were the most affected by the treatments. The best estimated IC50 values were observed in breast and lung cancer lines for the nano-gallic acid and co-loaded particles. The nano-quercetin formula exhibited the least cytotoxicity with an IC50 value of ≥200 μg/mL in both breast (MCF-7) and colorectal adenocarcinoma cell lines (HT-29) with no activity against the lung. A remarkable improvement in the efficacy of quercetin was measured after mixing it with gallic acid against the breast and lungs. The tested therapeutic agents exhibited antimicrobial activity against gram-positive bacteria. Nano-liposomes can either enhance or reduce the cytotoxicity activity of active compounds depending on the physical and chemical properties of drug-loaded and type of cancer cells