The issue of antimicrobial resistance in human medicine

Green-synthesized α-Fe2O3-nanoparticles as potent antibacterial, anti-biofilm and anti-virulence agent against pathogenic bacteria

BACKGROUND

Antimicrobial resistance (AMR) presents a serious threat to health, highlighting the urgent need for more effective antimicrobial agents with innovative mechanisms of action. Nanotechnology offers promising solutions by enabling the creation of nanoparticles (NPs) with antibacterial properties. This study aimed to explore the antibacterial, anti-biofilm, and anti-virulence effects of eco-friendly synthesized α-Fe₂O₃ nanoparticles (α-Fe₂O₃-NPs) against pathogenic bacteria.

METHODS

The α-Fe2O3-NPs were synthesized using a green synthesis method that involved Bacillus sp. GMS10, with iron sulfate as a precursor. The NPs were characterized through ultraviolet-visible (UV-Vis) spectroscopy, Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-ray Spectroscopy (EDX), Dynamic Light Scattering (DLS), Zeta Potential Analysis, X-ray Diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FT-IR). Their antimicrobial activity was assessed against Gram-positive and Gram-negative bacteria. The study also evaluated the effect of the α-Fe2O3-NPs on bacterial cell membrane disruption, biofilm formation, efflux pump inhibition, and swarming motility.

RESULTS

The UV-Visible spectrum showed a peak at 228 nm, indicating plasmon absorbance of the α-Fe2O3-NPs. FESEM revealed spherical NPs (~ 30 nm), and DLS confirmed a hydrodynamic size of 36.3 nm with a zeta potential of -25.1 mV, indicating good stability. XRD identified the rhombohedral α-Fe2O3 phase, and FTIR detected O-H, C-H, C = O, and Fe-O functional groups, suggesting organic capping for stability. Antibacterial assays demonstrated that the α-Fe2O3-NPs had MIC values ranging from 0.625 to 5 µg/mL and MBC values between 5 and 20 µg/mL, with a strong effect against Gram-positive bacteria. The NPs significantly increased membrane permeability, inhibited biofilm formation in S. aureus and E. coli, and disrupted efflux pumps in S. aureus SA-1199B (a fluoroquinolone-resistant strain overexpressing norA). Additionally, the α-Fe2O3-NPs inhibited P. aeruginosa swarming motility.

CONCLUSION

The bacteria-synthesized α-Fe2O3-NPs demonstrated significant antimicrobial activity, particularly against Gram-positive bacteria, and exhibited strong potential for inhibiting biofilm formation and efflux pump activity, offering a promising strategy to address AMR. Focus on further evaluating their therapeutic potential in clinical settings and conducting comprehensive assessments of their safety profiles to ensure their applicability in medical treatments.

CLINICAL TRIAL NUMBER

Not applicable.

Balancing mitigation strategies for viral outbreaks

Control and prevention strategies are indispensable tools for managing the spread of infectious diseases. This paper examined biological models for the post-vaccination stage of a viral outbreak that integrate two important mitigation tools: social distancing, aimed at reducing the disease transmission rate, and vaccination, which boosts the immune system. Five different scenarios of epidemic progression were considered: (ⅰ) the "no control" scenario, reflecting the natural evolution of a disease without any safety measures in place, (ⅱ) the "reconstructed" scenario, representing real-world data and interventions, (ⅲ) the "social distancing control" scenario covering a broad set of behavioral changes, (ⅳ) the "vaccine control" scenario demonstrating the impact of vaccination on epidemic spread, and (ⅴ) the "both controls concurrently" scenario incorporating social distancing and vaccine controls simultaneously. By comparing these scenarios, we provided a comprehensive analysis of various intervention strategies, offering valuable insights into disease dynamics. Our innovative approach to modeling the cost of control gave rise to a robust computational algorithm for solving optimal control problems associated with different public health regulations. Numerical results were supported by real data for the Delta variant of the COVID-19 pandemic in the United States.

Pd-, Cu-, and Ni-Catalyzed Reactions: A Comprehensive Review of the Efficient Approaches towards the Synthesis of Antibacterial Molecules

A strong synthetic tool for many naturally occurring chemicals, polymers, and pharmaceutical substances is transition metal-catalyzed synthesis. A serious concern to human health is the emergence of bacterial resistance to a broad spectrum of antibacterial medications. The synthesis of chemical molecules that are potential antibacterial candidates is underway. The main contributions to medicine are found to be effective in transition metal catalysis and heterocyclic chemistry. This review underlines the use of heterocycles and certain effective transition metals (Pd, Cu, and Ni) as catalysts in chemical methods for the synthesis of antibacterial compounds. Pharmaceutical chemists might opt for clinical exploration of these techniques due to their potential.

Identification of terpenoids as dihydropteroate synthase and dihydrofolate reductase inhibitors through structure-based virtual screening and molecular dynamic simulations

Bacterial infections are rising, and antimicrobial resistance (AMR) in bacteria has worsened the scenario, requiring extensive research to find alternative therapeutic agents. Terpenoids play an essential role in protecting plants from herbivores and pathogens. The present study was designed to focus on in silico evaluation of terpenoids for their affinity towards two necessary enzymes, i.e. DHFR and DHPS, which are involved in forming 5, 6, 7, 8-tetrahydrofolate, a key component in bacterial DNA synthesis proteins. Additionally, to account for activity against resistant bacteria, their affinity towards the L28R mutant of DHFR was also assessed in the study. The structure-based drug design approach was used to screen the compound library of terpenes for their interaction with active sites of DHFR and DHPS. Further, compounds were screened based on their dock score, pharmacokinetic properties, and binding affinities. A total of five compounds for each target protein were screened, having dock scores better than their respective standard drug molecules. CNP0169378 (-8.4 kcal/mol) and CNP0309455 (-6.5 kcal/mol) have been identified as molecules with a higher affinity toward the targets of DHFR and DHPS, respectively. At the same time, one molecule CNP0298407 (-5.8 kcal/mol for DHPS, -7.6 kcal/mol for DHFR, -6.1 kcal/mol for the L28R variant), has affinity for both proteins (6XG5 and 6XG4). All the molecules have good pharmacokinetic properties. We further validated the docking study by binding free energy calculations using the MM/GBSA approach and molecular dynamics simulations.Communicated by Ramaswamy H. Sarma.

1,3,5-Triazine: Recent Development in Synthesis of its Analogs and Biological Profile

Triazine is an important pharmacophore in the field of research for the development of novel medications due to its presence in numerous powerful physiologically active compounds with significant medical potential, such as anti-tumor, anti-viral, anti-inflammatory, anti-microbial, anti- HIV, anti-leishmanial and others. The easy availability of triazine, high reactivity, simple synthesis of their analog, and their notable broad range of biological activities have garnered chemist interest in designing s-triazine-based drugs. The interest of medicinal chemists has been sparked by the structure-activity relationship of these biologically active entities, leading to the discovery of several promising lead molecules. Its importance for medicinal chemistry research is demonstrated by the remarkable progress made with triazine derivatives in treating a variety of disorders in a very short period. Authors have collated and reviewed the medicinal potential of s-triazine analogous to afford medicinal chemists with a thorough and target-oriented overview of triazine-derived compounds. We hope the present compilation will help people from the industry and research working in the medicinal chemistry area.

Crossover-Use of Human Antibiotics in Livestock in Agricultural Communities: A Qualitative Cross-Country Comparison between Uganda, Tanzania and India

Antibiotic use in animal agriculture contributes significantly to antibiotic use globally and is a key driver of the rising threat of antibiotic resistance. It is becoming increasingly important to better understand antibiotic use in livestock in low-and-middle income countries where antibiotic use is predicted to increase considerably as a consequence of the growing demand for animal-derived products. Antibiotic crossover-use refers to the practice of using antibiotic formulations licensed for humans in animals and vice versa. This practice has the potential to cause adverse drug reactions and contribute to the development and spread of antibiotic resistance between humans and animals. We performed secondary data analysis of in-depth interview and focus-group discussion transcripts from independent studies investigating antibiotic use in agricultural communities in Uganda, Tanzania and India to understand the practice of antibiotic crossover-use by medicine-providers and livestock-keepers in these settings. Thematic analysis was conducted to explore driving factors of reported antibiotic crossover-use in the three countries. Similarities were found between countries regarding both the accounts of antibiotic crossover-use and its drivers. In all three countries, chickens and goats were treated with human antibiotics, and among the total range of human antibiotics reported, amoxicillin, tetracycline and penicillin were stated as used in animals in all three countries. The key themes identified to be driving crossover-use were: (1) medicine-providers' and livestock-keepers' perceptions of the effectiveness and safety of antibiotics, (2) livestock-keepers' sources of information, (3) differences in availability of human and veterinary services and antibiotics, (4) economic incentives and pressures. Antibiotic crossover-use occurs in low-intensity production agricultural settings in geographically distinct low-and-middle income countries, influenced by a similar set of interconnected contextual drivers. Improving accessibility and affordability of veterinary medicines to both livestock-keepers and medicine-providers is required alongside interventions to address understanding of the differences between human and animal antibiotics, and potential dangers of antibiotic crossover-use in order to reduce the practice. A One Health approach to studying antibiotic use is necessary to understand the implications of antibiotic accessibility and use in one sector upon antibiotic use in other sectors.

Recent Advances in Multifunctional Antimicrobial Peptides as Immunomodulatory and Anticancer Therapy: Chromogranin A-Derived Peptides and Dermaseptins as Endogenous versus Exogenous Actors

Antimicrobial peptides (AMPs) are produced by all living organisms exhibiting antimicrobial activities and representing the first line of innate defense against pathogens. In this context, AMPs are suggested as an alternative to classical antibiotics. However, several researchers reported their involvement in different processes defining them as Multifunctional AMPs (MF-AMPs). Interestingly, these agents act as the endogenous responses of the human organism against several dangerous stimuli. Still, they are identified in other organisms and evaluated for their anticancer therapy. Chromogranin A (CgA) is a glyco-phosphoprotein discovered for the first time in the adrenal medulla but also produced in several cells. CgA can generate different derived AMPs influencing numerous physiological processes. Dermaseptins (DRSs) are a family of α-helical-shaped polycationic peptides isolated from the skin secretions of several leaf frogs from the Phyllomedusidae family. Several DRSs were identified as AMPs and, until now, more than 65 DRSs have been classified. Recently, these exogenous molecules were characterized for their anticancer activity. In this review, we summarize the role of these two classes of MF-AMPs as an example of endogenous molecules for CgA-derived peptides, able to modulate inflammation but also as exogenous molecules for DRSs, exerting anticancer activities.

Trifluoromethylated Quinolone-Hydantoin Hybrids: Synthesis and Antibacterial Evaluation

A series of new trifluoromethyl-substituted quinolones and hydantoin hybrids has been synthesized and evaluated against Gram-positive bacterium (Staphylococcus aureus MTCC 96) and Gram-negative bacteria (Pseudomonas aeruginosa MTCC 441, Klebsiella pneumonia MTCC 109, and Escherichia coli MTCC 442). Compound  19c, having the 6-propene group on the quinolone ring, showed similar activity to a standard drug (chloramphenicol) by exhibiting MIC values of 50 µg/mL against S. aureus and P. aeruginosa. Physicochemical properties of compound 19c were also determined, which were in line with Lipinski’s rule of five, suggesting the suitability of compound 19c in biological systems. Various types of binding interactions of 19c within the active site of DNA gyrase of S. aureus were also streamlined by molecular docking studies, suggesting its capability to block the catalytic process of the DNA gyrase, which could be the possible reason for its antibacterial potential.

Synthesis and antimicrobial activity of some novel 1,2-dihydro-[1,2,4]triazolo[1,5-a]pyrimidines bearing amino acid moiety

A new series of [1,2,4]-triazole bearing amino acid derivatives 2a-d-9a-d were synthesized under green chemistry conditions via multicomponent reaction using lemon juice as an acidic catalyst. The obtained compounds were characterized by different spectral and elemental analyses. The obtained candidates showed promising antibacterial activity against some standard bacteria and multidrug resistant (MDR) clinical isolates. In contrast to the reference drugs cephalothin and chloramphenicol, the tested compounds showed substantial better MIC values towards the tested MDR strains. The most active compounds 3c, 8a and 9d against MDR bacteria were tested for MBC and MIC index, the results indicted the bacteriostatic activity of these compounds. The most active compounds 2c, 2d, 3c, 8a, 8b, 9a, 9b, 9c and 9d showed a high selectivity index towards antimicrobial activity against K. pneumoniae and MRSA1 compared to mammalian cells, suggesting a good safety profile.

[Methicillin-resistant Staphylococcus aureus in the Americas: systematic review and metanalysis of prevalence in food-producing animalsStaphylococcus aureus resistente a la meticilina en la Región de las Américas: revisión sistemática y metanálisis de la prevalencia en la actividad agropecuaria]

OBJECTIVE

To determine the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in animals used to produce foods in the Americas.

METHOD

A systematic literature review was performed in the following databases: Scopus, Web of Science, MEDLINE, EMBASE, and Virtual Health Library. Articles published in the past 10 years, without language limits, were selected. The outcome of interest was the prevalence of MRSA in food-producing animals. Prevalence rates were meta-analyzed in grouped random effects models using the DerSimonian and Laird method. The geographic distribution of MRSA and the time trend of resistance were also analyzed.

RESULTS

Of 19 studies included, 11 were performed in the United States and 11 analyzed pig samples. Five studies were performed in South America. The samples analyzed in the studies were collected in farming, processing, and retail sites. MRSA prevalence in the Americas was 7.6% (95%CI: 5.6-9.5%), and was higher in pigs [12.6% (95%CI: 7.0-18.2%)] followed by bovine cattle [2.4% (95%CI: 1.2-3.7%)] and poultry [1.8% (95CI%: 0.3-3.4%)]. MRSA prevalence was higher in pigs in North America and bovine cattle in Latin America. There was no significant variation in MRSH prevalence along the 10-year period analyzed.

CONCLUSIONS

MRSA prevalence in food-producing animals in the Americas was higher in pigs, without significant changes across time.

The pathogenic microbial flora and its antibiotic susceptibility pattern in odontogenic infections

Suppurative head and neck infections of odontogenic origin are the most frequent type of head and neck infections. According to the literature, 7-10% of all antibiotics are currently prescribed for their treatment. Since penicillin was invented, the overall antibiotic sensitivity and resistance pattern of the isolated pathogenic microflora has continuously changed. The response of microorganisms to antibiotics and the development of resistance to their action is a purely evolutive process characterized by genetic mutations, acquisition of genetic material or alteration of gene expression and metabolic adaptations. All this makes challenging and difficult the correct choice of empirical antibiotic treatment for head and neck space infections even today. The aim of this paper was to evaluate the literature and to evidence the most frequent locations of odontogenic head and neck infections, the dominant pathogenic microbial flora, the genetic mutations and metabolic changes necessary for bacteria in order to aquire antibiotic resistance and as well its susceptibility and resistance to common antibiotics. We also aimed to highlight the possible changes in bacterial resistance to antibiotics over time, and to assess whether or not there is a need for fundamental changes in the empirical antibiotic treatment of these infections and show which these would be.

Influence of the T to S mutation at the STMK motif on antibiotic resistance of penicillin binding protein 1A: A comprehensive computational study

The emergence of antibiotic resistance has attracted the attention of scientists and scientific circles over the decades. β-Lactam antibiotics resistance is a worldwide therapeutic challenge in bacterial infections, mediated through several mechanisms of which mutations in Penicillin Binding Proteins (PBPs) are an important issue, making critical therapeutic problems in the human population. Accordingly, investigating the dynamic structures of mutant variants could result in a profound understanding of such a specific resistance. Therefore, this work investigated structural properties sampled by all-atom molecular dynamics (MD) simulations, umbrella sampling, and binding free energy calculations for both a wild-type and a cefotaxime-resistant T to S mutant of PBP1A. The T to S mutation significantly reduces the binding affinity of cefotaxime (a frequently clinically-administrated β-lactam antibiotic) as the PBP1A inhibitor. In the conventional MD simulations presented here, more fluctuations of the mutant's active site cleft margins were detected. The cleft of the mutant protein also opened remarkably more than the wild-type's cleft and displayed more flexibility. Thus, our findings have shown that flexibility of cleft margins of the active site in the mutant PBP1A immediately results in the catalytic cleft opening. In addition, binding free energy calculation suggests that reducing hydrophobic contacts and increasing the polar contribution in the binding energy may play an important role in cefotaxime resistance.

Pyrrole: An insight into recent pharmacological advances with structure activity relationship

Pyrrole is a heterocyclic ring template with multiple pharmacophores that provides a way for the generation of library of enormous lead molecules. Owing to its vast pharmacological profile, pyrrole and its analogues have drawn much attention of the researchers/chemists round the globe to be explored exhaustively for the benefit of mankind. This review focusses on recent advancements; pertaining to pyrrole scaffold, discussing various aspects of structure activity relationship and its bioactivities.

Synthesis and characterization of novel dimerics-triazine derivatives as potential anti-bacterial agents against MDR clinical isolates

Several dimerics-triazine Schiff bases displayed more potent anti-bacterial activity compared with ampicillin trihydrate. They revealed significantly low MIC values towards the tested MDR strains and showed a high selectivity index towards antimicrobial activity againstK. pneumoniaeandMRSA1compared to mammalian cells.

New antimicrobial flavonoids and chalcone from Colutea armata

Colucins A (1) and B (2), new flavonoids and colucone (3), the new chalcone derivative, have been isolated from the CHCl₃-soluble fraction of the whole plant of Colutea armata along with luteolin (4), luteolin 7-O-β-D-glucoside (5), isoliquiritigenin (6), trans-caffeic acid (7) and stigmasterol (8) reported for the first time from this species. Their structures were elucidated by spectroscopic techniques including MS and 2D-NMR spectroscopy. Compounds 1 and 2 showed significant antimicrobial activity against two Gram positive and three Gram negative bacterial strains while 3 was moderately active.

Synthesis, characterization and evaluation of 1,3,5-triazine aminobenzoic acid derivatives for their antimicrobial activity

Background

Replacement of chloride ions in cyanuric chloride give several variants of 1,3,5-triazine derivatives which were investigated as biologically active small molecules. These compounds exhibit antimalarial, antimicrobial, anti-cancer and anti-viral activities, among other beneficial properties. On the other hand, treatment of bacterial infections remains a challenging therapeutic problem because of the emerging infectious diseases and the increasing number of multidrug-resistant microbial pathogens. As multidrug-resistant bacterial strains proliferate, the necessity for effective therapy has stimulated research into the design and synthesis of novel antimicrobial molecules.

Results

1,3,5-Triazine 4-aminobenzoic acid derivatives were prepared by conventional method or by using microwave irradiation. Using microwave irradiation gave the desired products in less time, good yield and higher purity. Esterification of the 4-aminobenzoic acid moiety afforded methyl ester analogues. The s-triazine derivatives and their methyl ester analogues were fully characterized by FT-IR, NMR (¹H-NMR and ¹³C-NMR), mass spectra and elemental analysis. All the synthesized compounds were evaluated for their antimicrobial activity. Some tested compounds showed promising activity against Staphylococcus aureus and Escherichia coli.

Conclusions

Three series of mono-, di- and trisubstituted s-triazine derivatives and their methyl ester analogues were synthesized and fully characterized. All the synthesized compounds were evaluated for their antimicrobial activity. Compounds (10), (16), (25) and (30) have antimicrobial activity against S. aureus comparable to that of ampicillin, while the activity of compound (13) is about 50% of that of ampicillin. Compounds (13) and (14) have antimicrobial activity against E. coli comparable to that of ampicillin, while the activity of compounds (9–12) and (15) is about 50% of that of ampicillin. Furthermore, minimum inhibitory concentrations values for clinical isolates of compounds (10), (13), (14), (16), (25) and (30) were measured. Compounds (10) and (13) were more active against MRSA and E. coli than ampicillin. Invitro cytotoxicity results revealed that compounds (10) and (13) were nontoxic up to 250 µg/mL (with SI = 10) and 125 µg/mL (with SI = 5), respectively.Graphical abstract

Understanding the culture of antimicrobial prescribing in agriculture: a qualitative study of UK pig veterinary surgeons

OBJECTIVES

The use of antimicrobials in food-producing animals has been linked with the emergence of antimicrobial resistance in bacterial populations, with consequences for animal and public health. This study explored the underpinning drivers, motivators and reasoning behind prescribing decisions made by veterinary surgeons working in the UK pig industry.

METHODS

A qualitative interview study was conducted with 21 veterinary surgeons purposively selected from all UK pig veterinary surgeons. Thematic analysis was used to analyse transcripts.

RESULTS

Ensuring optimum pig health and welfare was described as a driver for antimicrobial use by many veterinary surgeons and was considered a professional and moral obligation. Veterinary surgeons also exhibited a strong sense of social responsibility over the need to ensure that antimicrobial use was responsible. A close relationship between management practices, health and economics was evident, with improvements in management commonly identified as being potential routes to reduce antimicrobial usage; however, these were not always considered economically viable. The relationship with clients was identified as being a source of professional stress for practitioners due to pressure from farmers requesting antimicrobial prescriptions, and concern over poor compliance of antimicrobial administration by some farmers.

CONCLUSIONS

The drivers behind prescribing decisions by veterinary surgeons were complex and diverse. A combination of education, improving communication between veterinary surgeons and farmers, and changes in regulations, in farm management and in consumer/retailer demands may all be needed to ensure that antimicrobial prescribing is optimal and to achieve significant reductions in use.

Synthesis, characterization and biological studies of some novel 3-fluorosalicylaldehyde based amine derivatives

A series of biologically important substituted 3-fluorosalicylaldehyde derivatives (1a-h) with various primary amines were synthesized by using ionic liquid (1-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) as an efficient catalyst. A new series of Schiff base derivatives (1a-h) were synthesized and characterized by IR, NMR ((1)H, (13)C, (1)H-(1)H COSY and HSQC), mass spectra and elemental analysis. Further crystal structure of compound 1a was evaluated by single crystal X-ray diffraction techniques. All the synthesized compounds were screened for in vitro antimicrobial activity against a panel of selected bacterial and fungal strains using Streptomycin and Amphotericin B as standards. Most of the synthesized compounds demonstrated moderate effects on both antibacterial and antifungal activities at minimum inhibitory concentrations (MIC's).

Synthesis and evaluation of some novel chromone based dithiazoles as antimicrobial agents

Novel substituted 1,2,4-dithiazolylchromones 3a-j were synthesized by the reaction of 3-formylchromones (1a-j) with two equivalents of p-chlorothiobenzamide (2) in dry xylene and characterized spectroscopically (IR, (1)H and (13)C NMR, mass) and elemental analysis. All synthesized compounds were screened for in vitro antimicrobial activity against various pathogenic bacterial and fungal strains and were found to possess good to moderate inhibitory potential against all tested strains. Antimicrobial results reveal that compounds bearing lipophilic electron withdrawing groups such as chloro and bromo displayed significant inhibitory potential against both bacterial and fungal strains. Particularly, compound 3c displayed significant inhibitory against bacterial strains and compound 3h exhibits significant inhibitory potential in comparison to standard drug fluconazole against fungal strain S. cerevisiae.

Simultaneous immunochemical detection of four banned antibiotic growth promoters in raw and cooked poultry tissue

Spiramycin, tylosin, bacitracin and virginiamycin are among a group of antibiotic growth promoters that have been banned in the European Union since the 1999 Council. This was due to concerns over the development of resistant bacteria emerging between humans and animals with the threat of antibiotics no longer being able to be used effectively to treat human infections. A sensitive and fast immunochemical method is presented for the determination of these four antibiotic growth promoters simultaneously in poultry tissue. The method employs methanol extraction followed by sample clean-up by solid-phase extraction (SPE) with determination by enzyme-linked immunoabsorbant assay (ELISA). The limit of detection (LOD) was less than 1 ng g(-1) and the detection capability (CCβ) was 3 ng g(-1) or less for all four antibiotic growth promoters. Validation was completed with both raw and cooked chicken, therefore either matrix could be used for the monitoring of these banned drugs. In a feeding trial no residues of either bacitracin or virginiamycin were found in medicated birds even without a withdrawal period. In the case of tylosin and spiramycin much higher residues level were detected immunochemically than was the case by mass spectrometry.

Synthesis and biological evaluation of novel 2,4,6-triazine derivatives as antimicrobial agents

A series of 2,4,6-trisubstituted [1,3,5]triazines were synthesized and evaluated for their antimicrobial activity against two representative Gram-positive, Gram-negative bacteria and two fungi. Biological data revealed that among all the compounds screened, compounds 3f, 3g, 3h, 3i, 3m, 3o and 3p found to have promising antimicrobial activity against all the selected pathogenic bacteria and fungi. Out of the synthesized compounds seven analogues have shown MIC in the range of 6.25-12.5 μg/mL. These compounds were generally nontoxic and may prove useful as antimicrobial agents.

An efficient synthesis of highly functionalized novel chromeno[4,3-b]pyrroles and indolizino[6,7-b]indoles as potent antimicrobial and antioxidant agents

A facile and efficient synthesis of novel chromeno[4,3-b]pyrroles has been accomplished by intramolecular 1,3-dipolar cycloaddition which on subsequent Pictet-Spengler cyclisation in presence of p-toluenesulfonic acid yielded indolizino[6,7-b]indoles. The synthesized chromenopyrroles and indolizinoindoles were evaluated for their antimicrobial and antioxidant activities. Compounds 7b, 7e, 7a and 7d exhibited respectively, good antibacterial and antifungal activities against tested pathogens when compared to reference control.

Membrane interactions and dynamics of a 21-mer cytotoxic peptide: a solid-state NMR study

We have investigated the membrane interactions and dynamics of a 21-mer cytotoxic model peptide that acts as an ion channel by solid-state NMR spectroscopy. To shed light on its mechanism of membrane perturbation, (31)P and (2)H NMR experiments were performed on 21-mer peptide-containing bicelles. (31)P NMR results indicate that the 21-mer peptide stabilizes the bicelle structure and orientation in the magnetic field and perturbs the lipid polar head group conformation. On the other hand, (2)H NMR spectra reveal that the 21-mer peptide orders the lipid acyl chains upon binding. (15)N NMR experiments performed in DMPC bilayers stacked between glass plates also reveal that the 21-mer peptide remains at the bilayer surface. (15)N NMR experiments in perpendicular DMPC bicelles indicate that the 21-mer peptide does not show a circular orientational distribution in the bicelle planar region. Finally, (13)C NMR experiments were used to study the 21-mer peptide dynamics in DMPC multilamellar vesicles. By analyzing the (13)CO spinning sidebands, the results show that the 21-mer peptide is immobilized upon membrane binding. In light of these results, we propose a model of membrane interaction for the 21-mer peptide where it lies at the bilayer surface and perturbs the lipid head group conformation.

Reduced susceptibility to amoxicillin of oral streptococci following amoxicillin exposure

As antibiotic pressure often triggers bacterial resistance, the use of short-duration therapies is increasingly recommended. The objective of the present study was to evaluate both the clinical efficiency and the impact on oral streptococci of a 3 day versus a 7 day amoxicillin therapy for odontogenic infection requiring tooth extraction. On day 0, patients were randomly assigned to a 3 day or 7 day amoxicillin treatment. The tooth was extracted on day 2 and the post-operative follow-up was carried out on day 9. Oral flora was collected on days 0, 9 and 30, and the susceptibility of the streptococci to amoxicillin was determined. The results showed that treatment with amoxicillin for 3 or 7 days had a similar clinical efficiency, and also induced similar selection of oral streptococci with reduced susceptibility to amoxicillin, suggesting that the selection of strains with reduced susceptibility to amoxicillin is a rapid phenomenon, appearing even with short-duration therapies.

Antimicrobial resistance in zoonotic bacteria: lessons learned from host-specific pathogens

The relative contribution of veterinary and human clinical treatments to the selection of antimicrobial resistance in zoonotic pathogens remains controversial. In this review, we consider bacterial pathogens that differ in host specificity and address their resistance profiles: pathogens that only occur in the human host, pathogens that are specific to particular food-producing animals and pathogens that occur in both host types. Compared with those pathogens restricted to a single animal host, pathogens found in both human and animal hosts appear to have higher incidences of resistance. However, the most urgent and severe resistance problems occur with pathogens exclusively infecting humans. Differences exist in the available genetic repertoire of a bacterial species and these are reflected in the observed resistance patterns; it is important to note that different bacterial species do not automatically result in similarly resistant populations when they undergo comparable selection in different host species. Thus, within a bacterial species, prevalence of resistance can differ between populations isolated from different hosts. For some species, fluctuations in dominant subpopulations, for instance particular serotypes, can be the most important factor determining resistance. The frequently expressed opinion that veterinary use of antimicrobials is at the heart of many resistance problems may be an oversimplification of the complex forces at play.

Prediction of antibiotic resistance proteins from sequence-derived properties irrespective of sequence similarity

Increasing antibiotic resistance has become a worldwide challenge to the clinical treatment of infectious diseases. The identification of antibiotic resistance proteins (ARPs) would be helpful in the discovery of new therapeutic targets and the design of novel drugs to control the potential spread of antibiotic resistance. In this work, a support vector machine (SVM)-based ARP prediction system was developed using 1308 ARPs and 15587 non-ARPs. Its performance was evaluated using 313 ARPs and 7156 non-ARPs. The computed prediction accuracy was 88.5% for ARPs and 99.2% for non-ARPs. A potential application of this method is the identification of ARPs non-homologous to proteins of known function. Further genome screening found that ca. 3.5% and 3.2% of proteins in Escherichia coli and Staphylococcus aureus, respectively, are potential ARPs. These results suggest the usefulness of SVMs for facilitating the identification of ARPs. The software can be accessed at SARPI (Server for Antibiotic Resistance Protein Identification).

Prescription of medicines by medical students of Karachi, Pakistan: a cross-sectional study

BACKGROUND

Prescription of medicines by non-doctors is an issue with serious global implications. To our knowledge prescription of drugs by medical and non-medical students has not been studied before. We aimed to determine the practice and attitudes of drug prescription by medical students and: a) how non-medical students respond to this practice, b) How this compares with the attitudes and practices of non-medical students.

METHODS

A cross-sectional study was conducted on a sample of 600 students randomly selected from 2 medical and 2 non-medical universities. Ethical requirements were ensured and data was collected using self administered questionnaires. The Chi square tests and logistic univariate regression analyses were performed using SPSS v 14 to identify associations and differences.

RESULTS

A total of 572 forms were completed and the sample consisted of 295 medical students and 277 non-medical students with no significant difference in their demographic profile. Of the 295 medical students 163 (55.3%) had prescribed a medicine independently and most (48.5%) said that they did this 2-3 times a year. The commonest reasons for this were 'previous experience' (68.7%), 'problem too trivial' (34.4%) and 'we knew everything about the condition' (31.3%). One-third (33.6%) of the undergraduate medical students thought that it was alright to independently diagnose an illness while a vast majority (78.3%) thought that it was alright for them to prescribe medicines to others. Common prescriptions were pain-killers, antipyretics, antiallergics and antibiotics. Medical students who prescribed medicines were of lesser age (CI = 1.366-1.887) and more likely to belong to the 1st (CI = 3.588-21.731), 2nd (CI = 2.059- 10.869) or 3rd (CI = 4.331-26.374) year of medical college. One-third (33.9%) of the non-medical students reported that a medical student had prescribed medicines to them and 21.3% said that they trusted medical students and would follow their advice blindly. Many students thought it alright for medical students to diagnose and treat illnesses. A similar proportion of non-medical students (58.5%) reported prescribing medicines to others.

CONCLUSION

Prescription of medicines by non-doctors is rampant and urgent corrective measures are warranted. We have highlighted areas for future research and intervention and have given a few recommendations.

Analysis of non-hospital antibacterial pharmacotherapy in Poland

OBJECTIVES

The aim of this research was to analyze the antibacterial drug consumption pattern in a 1-million-plus strictly defined population in Poland. We assessed outpatient antibiotic sales (ATC J01) in relation to patient age and season of the year, and sought to determine the group of patients with the most frequent recurrence of bacterial diseases.

METHODS

The Lubuskie Regional Unit of the National Health Fund (NHF) and the Central Statistical Office (GUS) were the main sources of data. For the period 2002-2005, data on outpatient sales of antibiotics (ATC J01) in Lubuskie Province were collected and expressed in DDD (defined daily dose; World Health Organization anatomical therapeutic chemical (ATC)/DDD version 2006) per 1000 inhabitants per day (DID).

RESULTS

During the period 2002-2005, the average level of antibiotic use amounted to 19.8 DID in the Lubuskie population. During the 3-year period, 64.3% of the population was treated with antibiotics. This value varied for different age groups. Of the patients, 22.7% utilized 62.6% of a 3-year supply of antibiotic therapy in the province; a small 1.9% of the population used 10.0% of the supply. The seasonal variation of antibiotic consumption in different age groups showed a strong tendency to be flatter as the older age groups were analyzed.

CONCLUSIONS

The data gained from the payers, i.e., the healthcare system, is a very valuable source of information for pharmacoepidemiological studies. Our study shows that seasonal variation in antibiotic use is strictly linked with the age of patients. Special attention should be paid to the relatively small group of patients that utilizes a significant percentage of the year's supply. We have established an effective way to present recurrence data (a map showing the infectious disease incidence). This could be a very useful tool for comparing antibiotic consumption in different countries.

Antibacterial thymol derivatives isolated from Centipeda minima

Two new monoterpenoids, 8,10-dihydroxy-9(2)-methylbutyryloxythymol (1) and 10-hydroxy-8,9-dioxyisopropylidene-thymol (2), together with five known thymol derivatives: 8,9,10-trihydroxythymol (3), thymol-beta-glucopyranoside (4), 9-hydroxythymol (5), 8,10-dihydroxy-9-isobutyryloxythymol (6), and 8-hydroxy-9,10-diisobutyryloxythymol (7), were isolated from Centipeda minima. Their structures were identified by means of spectroscopic analyses. Interestingly, compound 2 is not an extraction artifact according to a close HPLC examination of material after extraction by analytical MeOH at ambient temperature. The antibacterial activities of compounds 1-7 were evaluated against eight microbial strains by the agar dilution method.