Search

Objectives To elucidate the importance of a region in QacA predicted to be important in antimicrobial substrate recognition. Methods A total of 38 amino acid residues within or flanking putative transmembrane helix segment (TMS) 12 of QacA were individually replaced with cysteine using site-directed mutagenesis. The impact of these mutations on protein expression, drug resistance, transport activity and interaction with sulphhydryl-binding compounds was determined. Results Accessibility analysis of cysteine-substituted mutants identified the extents of TMS 12, which allowed for refinement of the QacA topology model. Mutation of Gly-361, Gly-379 and Ser-387 in QacA resulted in reduced resistance to at least one bivalent substrate. Interaction with sulphhydryl-binding compounds in efflux and binding assays demonstrated the role of Gly-361 and Ser-387 in the binding and transport pathway of specific substrates. The highly conserved residue Gly-379 was found to be important for the transport of bivalent substrates, commensurate with the role of glycine residues in helical flexibility and interhelical interactions. Conclusions TMS 12 and its external flanking loop is required for the structural and functional integrity of QacA and contains amino acids directly involved in the interaction with substrates.

The increasing emergence of antimicrobial resistance in staphylococcal bacteria is a major health threat worldwide due to significant morbidity and mortality resulting from their associated hospital- or community-acquired infections. Dramatic decrease in the discovery of new antibiotics from the pharmaceutical industry coupled with increased use of sanitisers and disinfectants due to the ongoing COVID-19 pandemic can further aggravate the problem of antimicrobial resistance. Staphylococci utilise multiple mechanisms to circumvent the effects of antimicrobials. One of these resistance mechanisms is the export of antimicrobial agents through the activity of membrane-embedded multidrug efflux pump proteins. The use of efflux pump inhibitors in combination with currently approved antimicrobials is a promising strategy to potentiate their clinical efficacy against resistant strains of staphylococci, and simultaneously reduce the selection of resistant mutants. This review presents an overview of the current knowledge of staphylococcal efflux pumps, discusses their clinical impact, and summarises compounds found in the last decade from plant and synthetic origin that have the potential to be used as adjuvants to antibiotic therapy against multidrug resistant staphylococci. Critically, future high-resolution structures of staphylococcal efflux pumps could aid in design and development of safer, more target-specific and highly potent efflux pump inhibitors to progress into clinical use.

Background: Loop-mediated isothermal amplification (LAMP) is a cost-effective, rapid, and specific method for the detection of bacterial pathogens within a sample. Methods: We designed and evaluated a new quantitative LAMP primer set specific to the ctxB gene for the rapid measurement of the load of toxigenic V. cholerae DNA in the reaction. Unlike the previously reported LAMP assays for V. cholerae detection, our LAMP primer set was able to detect and quantify toxigenic V. cholerae DNA with a detection limit of 2.8 pg of the ctxB gene equivalent to 8.3 copies of genomic DNA per reaction. Results: Our LAMP assay was found to be highly specific with no amplification detected in non-toxigenic V. cholerae bacterial strains. Thus, the ctxB-based LAMP assay developed in this study can serve as a simple, sensitive, specific, and quantitative molecular tool for the monitoring and epidemiological study of cholera. Conclusions: Overall, the low cost and simplicity of the LAMP assay can make it a preferable molecular method in the detection of pathogenic organisms.

Sequence analysis of dnaE, hlyA, and asd housekeeping genes were used to determine the genetic relatedness of our collection of Vibrio cholerae isolated from patients and surface waters over a 5-year period in Iran. The results showed 41, 17, and 9 variable sites throughout the sequenced fragments of dnaE (837 bp), hlyA (495 bp), and asd (295 bp), respectively. The results from sequence typing showed that all our clinical isolates were grouped in the same cluster. Eleven genotypes were identified among the environmental isolates. One environmental isolate was found to be in close genetic relatedness with our clinical isolates. One V. cholerae isolate showed a single-locus variant in the dnaE. For each of the studied genetic loci 10, 7, and 7 sequence types were observed for dnaE, hlyA, and asd, respectively. Only asd sequence analysis could make the distinction between the classical and El Tor isolates which emphasizes on selection of housekeeping locus with better discrimination power for analysis of different groups of isolates. Overall, the results indicated that surface waters in Tehran are a pool of non-toxigenic V. cholerae strains which are rarely related to clinical toxigenic isolates. In addition, our results verified that housekeeping gene sequence analysis could be a suitable approach for determination of the relatedness between clinical and environmental V. cholerae isolates.

Aims: To study the genetic relatedness between V. cholerae isolates from Iran and other countries based on housekeeping gene recA sequence analysis. Methods and Results: A 995-bp region of the recA gene from 24 V. cholerae isolates obtained from human and surface water origins in Iran over a 5-year period was sequenced and compared with the sequence data from the isolates belonging to other places. Cluster analysis of the constructed dendrogram based on recA sequence divergence for our clinical isolates showed one sequence type (ST), whereas environmental isolates revealed eight STs. Interestingly, one of our environmental isolates was intermixed with clinical isolates in the largest cluster containing the epidemic strains. Our 24 isolates plus 198 global isolates available in the GenBank showed 77 sequence types (STs) with at least one nucleotide difference. Conclusions: Our result suggested that recA sequencing is a reliable analysis method for understanding the relatedness of the local isolates with the isolates obtained elsewhere. Significance and Impact of the Study: Understanding the genetic relatedness between V. cholerae isolates could give insights into the health care system for better control and prevention of the cholera.

Nowadays adjuvants are extensively used as immuno-stimulatory and immuno-modulatory compounds as components of subunit and combination vaccine formulations. The adjuvants of microbial origin are more frequently used among currently used licensed or experimental adjuvants. The outer membrane vesicle (OMV) of Neisseria meningitidis is among the newly studied components of microbial origin, which could be applied as an adjuvant. Although the potency of OMV as a carrier (conjugated to a hapten) is now proven, the adjuvant properties of OMV have particular significance as a potential target for protective immunity. Since it has immune-stimulatory activity, OMV has been utilized in vaccine development. This commentary reviews the different applications of OMV as potential adjuvant in the field of vaccine development.

Tumor and especially breast cancer is among the most common causes of death worldwide. Finding novel nanosized therapeutic compounds have important role to decrease the chance of death and increase the survival. Cancer cells are highly attractive to glucose [with a nanosize bimolecular structure 1nm] as an energy source more than normal cell and nanosized therapeutics due to possessing different pharmacokinetic and pharmacodynamic have advantageous over classical dosage forms in cancer therapy. The aim of the study was to synthesize Glucosamin-Porphyrin-Tamoxifen [TPG] nanosized complex as a novel selective biocompatible anti breast cancer agent. After the synthesis procedure, this complex was purified and then tested In Vitro on breast cancer cells [MCF-7] in the absence or presence of the red light and found totally successful. The results showed a good anti breast cancer activity mediated by the activation of TNF-α and necrosis/apoptosis pathways for the nanosized complex with no alteration effects on blood PT/APTT and glucose or hexokinase levels/ activity. TPG nanoconjugate seems to be very good opponents to current anti breast cancer drugs and needs to be further investigated in near future.