Search

Antimicrobial stewardship programs (ASPs) are effective means to optimize prescribing practices. They are under-utilized in the Middle East where many challenges exist for ASP implementation. We assessed the effectiveness of infectious disease physician-driven post-prescription review and feedback as an ASP in Lebanon. This prospective cohort study was conducted over an 18-month period in the medical, surgical, and intensive care units of a tertiary care hospital. It consisted of three phases: the baseline, intervention, and follow-up. There was a washout period of two months between each phase. Patients aged ≥16 years receiving 48 h of antibiotics were included. During the intervention phase, the AMS team reviewed antimicrobial use within 72 h post-prescription and gave alternate recommendations based on the guidelines for use. The acceptance of the recommendations was measured at 72 h. The primary outcome of the study was days of therapy per 1000 study patient days. A total of 328 patients were recruited in the baseline phase (August–October 2020), 467 patients in the intervention phase (January–June 2021), and 301 patients in the post-intervention phase (September–December 2021). The total days of therapy decreased from 11.46 during the baseline phase to 8.64 during the intervention phase (p < 0.001). Intervention acceptance occurred 88.5% of the time. The infectious disease physician-driven implementation of an ASP was successful in reducing antibiotic utilization in an acute care setting in Lebanon.

Antimicrobial peptides (AMPs), an essential component of innate immunity, are very important resources for human therapeutics to counter the current threat of drug resistance. We have previously established that one such AMP, α-melanocyte stimulating hormone (α-MSH), an endogenous neuropeptide, and its derivatives have potent antimicrobial activity against Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA). However, the immense potential of α-MSH for therapeutic development against staphylococcal infections is marred by its reduced efficacy in the presence of standard microbiological culture medium. To overcome this issue, in this study, we designed a series of five novel analogues of the C-terminal fragment of α-MSH, i.e., α-MSH(6-13), by replacing uncharged and less hydrophobic residues with tryptophan and arginine to increase the hydrophobicity and cationic charge of the peptide, respectively. While all of the peptides showed a preferential interaction with negatively charged phospholipid vesicles, the most hydrophobic and cationic peptide, i.e., Ana-5, exhibited the highest activity against S. aureus cells while maintaining cell selectivity. Moreover, Ana-5 could retain its activity even in complex media like the Mueller Hinton broth and displayed rapid bactericidal activity in the presence of serum. Ana-5 also caused rapid bacterial membrane depolarization, permeabilization, and cell lysis and was able to bind to polyanionic plasmid DNA suggesting a possible dual mode of action of the peptide. Importantly, Ana-5 was able to eradicate intracellular S. aureus in fibroblast cells similar to conventional antibiotics. Collectively, in the present study, we obtained a potent α-MSH-based analogue with excellent staphylocidal potency in microbial growth medium and ex vivo efficacy, which may translate into therapeutic application.

Multiple drug resistant (MDR) Staphylococcus aureus is among the most dreaded pathogens for human health in community as well as nosocomial environments. Here we report self assembling ultra short N-terminal modified peptidomimetics based on a template X-W3R4 (where, X = aromatic organic moiety) that show potent activity against multiple MDR S. aureus strains. The active sequences self assemble in water to form nano vesicle (140–190 nm diameter) with positive surface zeta potential and hydrophobic core of Trp residues/N-terminal tags. Further, lethal membrane depolarisation of MRSA cells and a concentration dependent leakage of calcein dye from artificial bacterial mimic membranes established membrane disruptive mode of action for designed sequences. We demonstrate role of N-terminal tag on nature of self assembly and envisage the origin of antibacterial activity to be conformationally aligned nanovesicles which upon interaction lead to disruption of bacterial cells. The designed cell selective nanovesicles may further be exploited towards in vivo applications as antibacterial agent alone or as vehicles for systemic anti-infective therapy.

2-Butanone thiosemicarbazone ligand was prepared by condensation reaction between thiosemicarbazide and butanone. The ligand was characterized by 1H NMR, 13C NMR, FT-IR, mass spectrometry and UV spectroscopic studies. Docking studies were performed to study inhibitory action against topoisomerase II (Topo II) and ribonucleoside diphosphate reductase (RR) enzymes. Inhibition constants (K i ) of the ligand were 437.87 and 327.4 μM for the two enzymes, respectively. The ligand was tested for its potential anticancer activity against two cancer cell lines MDA-MB-231 and A549 using MTT assay and was found to exhibit good activity at higher doses with an IC50 = 80 μM against human breast cancer cell line MDA-MB-231. On the other hand, no significant activity was obtained against the lung carcinoma cell line A549. Antibacterial activity of the ligand was tested against Staphylococcus aureus and E. coli using the disc diffusion method. Ligand did not exhibit any significant antibacterial activity. Four complexes of Co(III), Fe(II), Cu(II), and Zn(II) were prepared with the ligand and characterized by various spectroscopic studies. Low molar conductance values were obtained for all complexes displaying non-electrolyte nature except in Co(III) complex. As expected, complexation with metal ions significantly increased the cytotoxicity of the ligand against the tested cell lines viz. IC50 values of

The steady rise in antimicrobial resistance poses a severe threat to global public health by hindering treatment of an escalating spectrum of infections. We have previously established the potent activity of α-MSH, a 13 residue antimicrobial peptide, against the opportunistic pathogen Staphylococcus aureus. Here, we sought to determine whether an increase in cationic charge in α-MSH could contribute towards improving its staphylocidal potential by increasing its interaction with anionic bacterial membranes. For this we designed novel α-MSH analogues by replacing polar uncharged residues with lysine and alanine. Similar to α-MSH, the designed peptides preserved turn/random coil conformation in artificial bacterial mimic 1,2-dimyristoyl-sn-glycero-3-phosphocholine:1,2-dimyristoyl-sn-glycero-3-phospho-rac-(1-glycerol) (7:3, w/w) vesicles and showed preferential insertion in the hydrophobic core of anionic membranes. Increased cationic charge resulted in considerable augmentation of antibacterial potency against MSSA and MRSA. With ~18-fold better binding than α-MSH to bacterial mimic vesicles, the most charged peptide KKK-MSH showed enhanced membrane permeabilization and depolarization activity against intact S. aureus. Scanning electron microscopy confirmed a membrane disruptive mode of action for KKK-MSH. Overall, increasing the cationic charge improved the staphylocidal activity of α-MSH without compromising its cell selectivity. The present study would help in designing more effective α-MSH-based peptides to combat clinically relevant staphylococcal infections.

We report herein synthesis and antimicrobial activity of a series of N,N-dibenzyl-cyclohexane-1,2-diamine derivatives. In order to study the structure–activity relationship of substituted dibenzyl-cyclohexane-1,2-diamine derivatives, 44 structurally diverse compounds were synthesized and tested against Gram-positive and Gram-negative bacterial strains. Among them, compounds 17-20, 26, 37, 38 were found to be more active than tetracycline with MIC value ranging 0.0005–0.032 μg/mL and no hemolysis upto 1024 μg/mL in mammalian erythrocytes was observed. Some of the compounds have also shown very promising antifungal activity against Candida albicans, Candida glabrata and Geotrichum candidium.

Two substituted biaryl analogues of colchicine and combretastatin A4, readily available through a one-step, protecting group free Suzuki-Miyaura reaction were discovered to exhibit anticancer activity while simultaneously being of low cytotoxicity to noncancerous cell lines. The compounds were shown to initiate apoptosis selectively via a mechanism involving inhibition of tubulin polymerization.

Toward the discovery of useful therapeutic molecules, we report the design and synthesis of a focused library of new ultrashort N-terminally modified dipeptidomimetics, with or without modifications in the spermine backbone leading to linear (series 1) or branched (series 2) tryptophans, as antimicrobial agents. Eight peptidomimetics in the library showed good antibacterial activity (MICs of 1.77 to 14.2 μg/ml) against methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus epidermidis bacterial strains. Tryptophan fluorescence measurements on artificial bacterial or mammalian mimic membranes and assessment of the MRSA potential depolarization ability of the designed compounds revealed membrane interactions dependent on tryptophan positioning and N-terminal tagging. Among active peptidomimetics, compounds 1c and 1d were found to be nonhemolytic, displaying rapid bactericidal activity (at 4× MIC) against exponentially growing MRSA. Further, scanning electron microscopy of peptidomimetic 1c- and 1d-treated MRSA showed morphological changes with damage to cell walls, defining a membrane-active mode of action. Moreover, peptidomimetics 1c and 1d did not induce significant drug resistance in MRSA even after 17 passages. We also investigated the activity of these molecules against MRSA biofilms. At sub-MIC levels (∼2 to 4 μg/ml), both peptidomimetics inhibited biofilm formation. At concentrations higher than the MIC (35 to 140 μg/ml), peptidomimetics 1c and 1d significantly reduced the metabolic activity and biomass of mature (24-h) MRSA biofilms. These results were corroborated by confocal laser scanning microscopy (live/dead assay). The in vitro protease stability and lower cytotoxicity of peptidomimetics against peripheral blood mononuclear cells (PBMCs) support them being novel staphylocidal peptidomimetics. In conclusion, this study provides two peptidomimetics as potential leads for treatment of staphylococcal infections under planktonic and sessile conditions.

A series of benzyl-[3-(benzylamino-methyl)-cyclohexylmethyl]-amine derivatives with different substitution pattern on the aromatic ring have been prepared and evaluated for their antibacterial activity against Gram-positive and Gram-negative bacterial strains. Most of the compounds exhibit potent activity against Pseudomonas aeruginosa and Staphylococcus epidermidis while compounds 6l and 6m showed antibacterial activity against all the four bacterial strains with MIC values ranging from 0.002 to 0.016 μg/mL and no hemolytic activity up to 512 μg/mL in mammalian erythrocytes was observed.

We report herein, synthesis and mode of action of novel, cell selective, N-terminal tagged tetra-peptide conjugates. Analogues AP1 and AP2 with linoleic acid and p-terphenyl carboxylic acid tagging showed potent activity against Gram-positive and Gram-negative bacterial strains including the clinically relevant pathogen MRSA. For active analogues interaction studies with model bacterial mimic membranes revealed a direct correlation between activity and membrane perturbation. Further, active conjugates showed membrane depolarization and severe bacterial membrane disrupting ability. The hydrophobic–charge–hydrophobic template designed here can be useful in further optimizing end tagged peptidomimetics for therapeutic potential.

Towards therapeutically viable mimics of host defense cationic peptides (HDCPs) here we report the design and synthesis of a small library, based on a novel hydrophobic-dipeptide-spermidine template. Lipidated sequences 11, 14, 15, 16, 18 and 19 exhibited potent activity against susceptible as well as drug resistant Gram-positive and Gram-negative bacterial strains. Structure-activity relationships of the template revealed a hydrophobicity window of 50-70% with minimum +2 charges to be crucial for activity and cell selectivity. Active sequences 14, 15 and 16 exhibited different modes of action based on dipeptide composition as revealed by studies on model membranes, intact bacterial cells and DNA. Further, severe damage to surface morphology of methicillin resistant S. aureus caused by 14, 15 and 16 at 10 × MIC was observed. The present study provides us two active sequences (14 and 16) with a membrane perturbing mode of action, cell selectivity to hRBCs and keratinocytes along with potent activity against clinically relevant pathogen MRSA. The designed template thus may prove to be a suitable probe to optimize sequences for better selectivity and potential to combat a wide range of drug resistant strains in further research.

Cationic antimicrobial peptides (CAMPs) are novel candidates for drug development. Here we describe design of six short and potent CAMPs (SA-1 to SA-6) based on a minimalist template of 12 residues H+HHG+HH+HH+NH2 (where H: hydrophobic amino acid and +: charged hydrophilic amino acid). Designed peptides exhibit good antibacterial activity in micro molar concentration range (1-32 μg/ml) and rapid clearance of Gram-positive and Gram-negative bacterial strains at concentrations higher than MIC. For elucidating mode of action of designed peptides various biophysical studies including CD and Trp fluorescence were performed using model membranes. Further based on activity, selectivity and membrane bound structure; modes of action of Trp rich peptide SA-3 and template based peptide SA-4 were compared. Calcein dye leakage and transmission electron microscopic studies with model membranes exhibited selective membrane active mode of action for peptide SA-3 and SA-4. Extending our work from model membranes to intact E. coli ATCC 11775 in scanning electron micrographs we could visualize different patterns of surface perturbation caused by peptide SA-3 and SA-4. Further at low concentration rapid translocation of FITC-tagged peptide SA-3 into the cytoplasm of E. coli cells without concomitant membrane perturbation indicates involvement of intracellular targeting mechanism as an alternate mode of action as was also evidenced in DNA retardation assay. For peptide SA-4 concentration dependent translocation into the bacterial cytoplasm along with membrane perturbation was observed. Establishment of a non specific membrane lytic mode of action of these peptides makes them suitable candidates for drug development.