Antibiotic-resistant Bacterial Strains Research Articles

Bacteriological profile of urinary tract infections and antibiotic susceptibility of Escherichia coli in Algeria.

Background and Objectives:Urinary tract infections are one of the most common bacterial infections worldwide. The emergence of antibiotic-resistant bacterial strains is a serious problem and greatest challenge in public health care. The purpose of this study was to determine the prevalence of uropathogenic microorganisms and the antibiotic resistance pattern of Escherichia coli in Algeria.Materials and Methods:Urine samples were collected from 760 outpatients in the hospital of Tizi-Ouzou (Algeria). From the positive cultures, 120 strains of E. coli were isolated and tested for their susceptibility to antibiotics by disk diffusion method on Mueller Hinton agar medium.Results:Among the collected urine specimens, 270 (35.5%) yielded positive cultures for urinary tract infection. Females were more affected with a sex ratio F/M of 1.14. E. coli was the most prevalent isolated bacteria with a rate of 44.44%, followed by Klebsiella pneumoniae (12.21%), Pseudomonas aeruginosa (11.1%) and Proteus mirabilis (5.55%). Isolates of E. coli showed high level of resistance to cephalothin (85.83%), ticarcillin (82.5%), ampicillin (73.3%) and amoxicillin-clavulanic acid (58.33%). Imipenem was the most effective antimicrobial agent.Conclusion:These results highlight the inappropriate utilization of antibiotics and suggest the need to improve prescription practices in our country.

Nanomaterials: The New Antimicrobial Magic Bullet.

Bacterial infections are a significant cause of mortality and morbidity worldwide, despite decades of use of numerous existing antibiotics and constant efforts by researchers to discover new antibiotics. The emergence of infections associated with antibiotic-resistant bacterial strains, has amplified the pressure to develop additional bactericidal therapies or new unorthodox approaches that can deal with antimicrobial resistance. Nanomaterial-based strategies, particularly those that do not rely on conventional small-molecule antibiotics, offer promise in part due to their ability to dodge existing mechanisms used by drug-resistant bacteria. Therefore, the use of nanomaterial-based formulations has attracted attention in the field of antibiotic therapy. In this Review, we highlight novel and emerging nanomaterial-based formulations along with details about the mechanisms by which nanoparticles can target bacterial infections and antimicrobial resistance. A detailed discussion about types and the activities of nanoparticles is presented, along with how they can be used as either delivery systems or as inherent antimicrobials, or a combination of both. Lastly, we highlight some toxicological concerns for the use of nanoparticles in antibiotic therapies.

Restoration of antibacterial activity of inactive antibiotics via combined treatment with a cyanographene/Ag nanohybrid

The number of antibiotic-resistant bacterial strains is increasing due to the excessive and inappropriate use of antibiotics, which are therefore becoming ineffective. Here, we report an effective way of enhancing and restoring the antibacterial activity of inactive antibiotics by applying them together with a cyanographene/Ag nanohybrid, a nanomaterial that is applied for the first time for restoring the antibacterial activity of antibiotics. The cyanographene/Ag nanohybrid was synthesized by chemical reduction of a precursor material in which silver cations are coordinated on a cyanographene sheet. The antibacterial efficiency of the combined treatment was evaluated by determining fractional inhibitory concentrations (FIC) for antibiotics with different modes of action (gentamicin, ceftazidime, ciprofloxacin, and colistin) against the strains Escherichia coli, Pseudomonas aeruginosa, and Enterobacter kobei with different resistance mechanisms. Synergistic and partial synergistic effects against multiresistant strains were demonstrated for all of these antibiotics except ciprofloxacin, which exhibited an additive effect. The lowest average FICs equal to 0.29 and 0.39 were obtained for colistin against E. kobei and for gentamicin against E. coli, respectively. More importantly, we have experimentally confirmed for the first time, that interaction between the antibiotic's mode of action and the mechanism of bacterial resistance strongly influenced the combined treatment’s efficacy.

Effects of Four Antibiotics on the Diversity of the Intestinal Microbiota.

ABSTRACTOral antibiotics remain the therapy of choice for severe bacterial infections; however, antibiotic use disrupts the intestinal microbiota, increasing the risk of colonization by intestinal pathogens. Currently, our understanding of antibiotic-mediated disturbances of the microbiota remains at the level of bacterial families or specific species, and little is known about the effect of antibiotics on potentially beneficial and pathogenic bacteria under the conditions of gut microbiota dysbiosis. Additionally, the question of whether the effects of antibiotics on the gut microbiota are temporary or permanent is controversial. In this study, we used 16S rRNA gene sequencing to evaluate the short- and long-term effects of ampicillin, vancomycin, metronidazole, and neomycin on the murine intestinal microbiota. We found that the changes in the intestinal microbiota reflected the antibiotics’ mechanisms of action and that dysbiosis of the intestinal microbiota led to competition between different bacterial communities. In particular, an increase in Enterococcus, which accompanies a decrease in probiotics-related genera such as Lactobacillus, is commonly seen across antibiotic treatments. In addition, we found that these oral antibiotics had long-term negative effects on the intestinal microbiota and promoted the development of antibiotic-resistant bacterial strains. These results indicate that ampicillin, vancomycin, metronidazole, and neomycin have long-term negative effects and can cause irreversible changes in the diversity of the intestinal microbiota, thereby increasing the risk of host disease.IMPORTANCE The intestinal microbiota is a dynamic community of hundreds of millions of microorganisms that play important roles in human health. However, treatment with antibiotics can disrupt the delicate balance of this community, leading to deleterious effects on the host such as inflammation and enhanced susceptibility to infection. To date, most studies of the effects of antibiotic treatment on the microbiota have focused on specific intestinal pathogens and bacterial families. However, few studies have investigated the effects of antibiotic treatment on the relative abundance of probiotic bacteria, pathogenic bacteria, and opportunistic bacterial pathogens in the gut.

Preparation, characterization, and antibacterial competence of silymarin and its nano-formulation

Nowadays, antibiotic resistance is a serious problem, especially in countries that have unregulated use of antibiotics. We aimed to prepare and characterize Sily-Nano from silymarin to present its antimicrobial activities in comparison to silymarin and gentamycin and provide natural antibacterial from natural sources. Silymarin NPs (Sily-Nano) were prepared using a high-pressure homogenization and characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-visible) spectrum, and scanning electron microscopy (SEM). The antibacterial monitoring of Sily-Nano and silymarin was compared against Escherichia coli UN75 (E.coli-UN75), Enterobacter aerogenes SL3 (E.aerogenes-SL3), Staphylococcus aureus-PS41 (S.aureus-PS41), and Klebsiella pneumoniae-BD29 (K.pneumoniae-BD29). Sily-Nano was effectively prepared and confirmed using FTIR. SEM, with even distribution, and significant bacterial zone inhibition, compared with silymarin. In conclusion, Sily-Nano preparation is an efficient agent, and effective against certain clinical antibiotic-resistant bacterial strains. Sily-Nano has a novel significant inhibitory effect against the antibiotic-resistant strain of K. pneumonia-BD29, Ent. Aerogenes-SL3 and E. coli UN75 when compared with silymarin and the common antibiotic gentamycin. Therefore, sily-Nano is potentially used as an antibacterial and natural sanitizer agent.

Composition-Dependent Cytotoxic and Antibacterial Activity of Biopolymer-Capped Ag/Au Bimetallic Nanoparticles against Melanoma and Multidrug-Resistant Pathogens.

Nanostructured silver (Ag) and gold (Au) are widely known to be potent biocidal and cytotoxic agents as well as biocompatible nanomaterials. It has been recently reported that combining both metals in a specific chemical composition causes a significant enhancement in their antibacterial activity against antibiotic-resistant bacterial strains, as well as in their anticancer effects, while preserving cytocompatibility properties. In this work, Ag/Au bimetallic nanoparticles over a complete atomic chemical composition range were prepared at 10 at% through a green, highly reproducible, and simple approach using starch as a unique reducing and capping agent. The noble metal nanosystems were thoroughly characterized by different analytical techniques, including UV-visible and FT-IR spectroscopies, XRD, TEM/EDS, XPS and ICP-MS. Moreover, absorption spectra simulations for representative colloidal Ag/Au-NP samples were conducted using FDTD modelling. The antibacterial properties of the bimetallic nanoparticles were determined against multidrug-resistant Escherichia coli and methicillin-resistant Staphylococcus aureus, showing a clear dose-dependent inhibition even at the lowest concentration tested (5 µg/mL). Cytocompatibility assays showed a medium range of toxicity at low and intermediate concentrations (5 and 10 µg/mL), while triggering an anticancer behavior, even at the lowest concentration tested, in a process involving reactive oxygen species production per the nanoparticle Au:Ag ratio. In this manner, this study provides promising evidence that the presently fabricated Ag/Au-NPs should be further studied for a wide range of antibacterial and anticancer applications.

Antibacterial activity of Myrtus communis L. and Melaleuca leucadendron var. cajaputi essential oils against antibiotic-resistant bacterial strains

Background: Antimicrobial resistance (AMR) is a global threat to public health. There is a dire need for new antibiotics as AMR threatens our last-resort antibiotics efficacy.1,2 Myrtle plants have been used in folk medicine for centuries. Essential oils from these plants demonstrated therapeutics effects. This study aims to examine the antibacterial activity of essential oils extracted from Myrtus communis L and Melaleuca leucadendron against clinically relevant bacterial pathogens.3Methods: Bacterial growth curves and bactericidal assays were performed on antibiotic-sensitive Staphylococcus aureus (SA) and antibiotic low and high resistant Methicillin-resistant Staphylococcus aureus (MRSA) strains; sensitive and resistant Klebsiella pneumoniae strains (KPS and KPR). Minimum bactericidal concentration (MBC) was performed on 4 strains of colistin sensitive E. coli and 4 colistin resistant E. coli strains. Results: Myrtle essential oils demonstrated a dose-dependent antibacterial activity against all tested strains and inhibited growth even after 24 hours. The tested oils dilutions ranged from 6.15 μl/ml up to 50 μl/ml and inhibited bacterial growth of both antibiotic sensitive and resistant strains of SA, MRSA (Figure 1), and Klebsiella. Further, the incubation of colistin sensitive and colistin-resistant E. coli strains with 50 μl/ml of Myrtle oil for one hour inhibited the growth of all tested strains. The viability of bacteria was tested by spotting on agar plates and further incubation overnight. The data suggest that Myrtle essential oils can effectively kill bacterial pathogens. Conclusion: Essential oils from Myrtus communis L. and Melaleuca leucadendron var. cajaputi possess potent antibacterial activity against antibiotic sensitive and resistant bacterial pathogens. There is a potential for utilizing these antibacterial oils as topical treatment of wound infections.

Improving the synthesis of hemin derivatives and their effect on bacterial biofilms

The emergence of antibiotic-resistant bacterial strains has recently resulted in a large focus on designing new antimicrobial agents, including those based on natural compounds. We have previously synthesized two disubstituted arginine-containing derivatives of hemin (HD) (4) and (5) that demonstrated pronounced antimicrobial activity against planktonic cells in vitro [1, 2]. These HDs are leading and promising for the creation of antibacterial agents on their basis. This research is aimed at improving the synthesis of HDs (4) and (5) to increase their yield, simplify the process and minimize the side reactions, as well as to establish their antimicrobial and destructive effect on biofilms, including those consisting of antibiotic-resistant bacteria. As a result, we were able to increase the yields of the protected dipeptide of ZArg(Z[Formula: see text]SerNH2 (3) and the corresponding HD (4) up to 97 and 93%, respectively, and also to minimize the side reaction of the formation of ornithine-containing HD. For the arginine amide modified HD (5), we have also proposed an improved synthesis scheme. The ability of HD to cause the bacteria death in the composition of formed biofilms, including those consisting of resistant bacteria, was shown. After the effect of HDs on the biofilm at concentrations of 80 and 100 [Formula: see text]g/ml, the CFU decrease was 3–5/ml. The fluorescent microscopy confirmed the bacteria mortality in the biofilm. Electron microscopy showed structural damage (fragmentation) of the formed bacterial biofilm under the effect of HDs.

Synthesis and Encapsulation of Ajuga parviflora Extract with Zeolitic Imidazolate Framework-8 and Their Therapeutic Action against G+ and G- Drug-Resistant Bacteria.

Infectious diseases caused by bacteria have become a public health issue. Antibiotic therapy for infectious disorders, as well as antibiotic overuse, has resulted in antibiotic-resistant bacterial strains. Zeolitic imidazolate framework-8 (ZIF-8) possesses a wide surface area, high porosity, variable functionality, and potential drug carriers. We have established a clear method for making a nanoscale APE@ZIF-8 nanocomposite agent with outstanding antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) and cephalosporin-carbapenem-resistant Escherichia coli (CCREC). We present a unique approach for encapsulating molecules ofAjuga parviflora extract (APE) with ZIF-8. APE@ZIF-8 has a positive charge. By electrostatic contact with the negatively charged bacterial surface of S. aureus and E. coli, APE@ZIF-8 NPs produce reactive oxygen species (ROS) that damage bacterial cell organelles. As a result, the APE@ZIF-8 nanocomposite offers limitless application potential in the treatment of infectious disorders caused by drug-resistant gram-positive and gram-negative bacteria.

Prevalence and associated risk factors of bovine mastitis in Ashulia, Dhaka, Bangladesh

Mastitis is a devastating and critical infectious disease globally including in Bangladesh. Antibiotic treatment can cure the disease, but the cows will be unable to reverse their previous productive condition. Therefore, the identification of the possible risk factors and management of those factors is the only way to minimize the losses in the dairy sector. The present study was conducted to clarify the existing status of the disease and to find out the possible risk factors of the disease to adjust successful control measures. The result exhibited that, 57% of cows in the study area were infected by mastitis. Of these, subclinical mastitis was more predominant (85%) than clinical mastitis (15%). Most of the cows got an infection at 3.5 to 5 years of age in the 3rd to 4th lactation and during the early lactational stage (3 months). Principal component analysis and Pearson correlation matrix analysis revealed that high milk producers, intensive rearing system, improper hygiene during milking, new farms by unskilled farmers, and poor physical condition of the cows showed positive association to mastitis. However, an adaptation of an extensive or semi-intensive rearing system, as well as washing hands and udders before and after milking using antiseptic together with proper training of the farmers on scientific dairy farming, can reduce the prevalence of mastitis in the study area. This will be advantageous in decreasing antibiotic usage and lessening new antibiotic-resistant bacterial strains.

In-silico SCREENING OF FLAVONOIDS AS AgrA INHIBITORS BY MOLECULAR DOCKING, NORMAL MODE ANALYSIS, AND ADMET STUDY

Excessive and prolonged intake of antibiotics results in the emergence of antibiotic-resistant pathogenic bacterial strains. As a consequence, managing bacterial infections with currently available antibiotics is extremely challenging. In order to tackle the bacterial resistance, bacterial communication mechanism, especially bacterial quorum sensing (QS) is targeted. In agr QS system, the various gene expression involved in the secretion of virulence factors can be attenuated by inhibiting the DNA-AgrA interactions. Here, we docked twenty flavonoids with previously homology modeled AgrA proteins together with PDB ID: 4G4K (template protein of the homology models) using the AutoDock tool. Out of twenty flavonoids, three flavonoids (dracorhodin, acacetin, and oroxylin A) exhibited promising binding free energies (<-9.00 kcal/mol). We also performed a normal mode analysis to check the stability of docked complexes. The best-docked complexes are stable as indicated by normal mode analyses. The best three flavonoids (dracorhodin, acacetin, and oroxylin A) possess desirable drug-likeness attributes. Hence, these compounds can act as novel AgrA inhibitors

GC-MS biocomponents characterization and antibacterial potency of ethanolic crude extracts of Camellia sinensis.

Objective:The menace of antibacterial resistance among enteropathogenic bacteria continues to raise therapeutic management concerns within public health system. As a strategy toward alternative control of resistant pathogen proliferation, a folkloric plant (green tea leaves: Camellia sinensis) was collected from Ishaka municipality and characterized for biomolecular components and antibacterial potency.Methods:The bioactive and biomolecular components of the plant’s ethanol extract were characterized using gas chromatography–mass spectrometry. A preliminary in vitro susceptibility test of the extract against characterized multiple antibiotic-resistant potential diarrheagenic bacterial strains was done.Results:The result revealed an exponential increase in susceptibility with a distinctive unit component of the C. sinensis extract at concentrations of 60 and 80 μg/ml. The extract also possessed antibacterial and antioxidant activities while having phytochemical constituents (flavonoids, alkaloids, phenolics, saponin, cardiac glycosides, etc.). The gas chromatography–mass spectrometry analysis further affirmed the potential of the extract by revealing 52 bioactive components/compounds as shown in the chromatogram.Conclusion:The C. sinensis has antimicrobial and antioxidant potentials, and the constituents of the plant might be of therapeutic importance in the management of various diseases, especially those related to Escherichia coli and Salmonella.

Siderophore‑antibiotic conjugates: structural diversity and antibacterial activity

Due to uncontrolled growth of antimicrobial resistance, in the near future humanity may return to the «pre-antibiotic era» with no reliable antimicrobial therapy even for previously easily treatable infectious diseases. One of possible solutions is improved delivery of antibiotics to antibiotic-resistant bacterial strains by conjugating them with siderophores (small molecules secreted by microorganisms to absorb essential Fe(III)). The siderophore-modified antibiotic (sideromycin), like a Trojan horse, permeates the bacterial cell as a complex with Fe(III), allowing the antibiotic to reach its biological target. In this review, we describe the structural diversity of siderophore-antibiotic conjugates with the focus on the structure of sideromycin as well as on the relationship between the structure of sideromycin and its antibacterial activity. We analyze main representatives of various classes of siderophores; the structural diversity of sideromycins and their antibacterial activity discussed in detail.

SERS and advanced chemometrics – Utilization of Siamese neural network for picomolar identification of beta-lactam antibiotics resistance gene fragment

The enormous development and expansion of antibiotic-resistant bacterial strains impel the intensive search for new methods for fast and reliable detection of antibiotic susceptibility markers. Here, we combined DNA-targeted surface functionalization, surface-enhanced Raman spectroscopy (SERS) measurements, and subsequent spectra processing by decision system (DS) for detection of a specific oligonucleotide (ODN) sequence identical to a fragment of blaNDM-1 gene, responsible for β-lactam antibiotic resistance. The SERS signal was measured on plasmonic gold grating, functionalized with capture ODN, ensuring the binding of corresponded ODNs. Designed DS consists of a Siamese neural network (SNN) coupled with robust statistics and Bayes decision theory. The proposed approach allows manipulation with complex multicomponent samples and predefine the desired detection level of confidence and errors, automatically determining the number of required spectra and samples. In constant to commonly used classification-type SNN, our method was applied to analyze samples with compositions previously “unknown” to DS. The detection of targeted ODN was performed with ≥99% level of confidence up to 3 × 10−12 M limit on the background of 10−10 M concentration of similar but not targeted ODNs.

Adaptive Phage Therapy in the Treatment of Patients with Recurrent Pneumonia (Pilot Study)

Aim. To evaluate the safety and efficacy of the adaptive phage therapy technique in patients with recurrent pneumonia in neurological critical care.Material and methods. The clinical study included 83 chronically critically ill patients with severe brain damage. The bacteriophage cocktail selected against specific hospital strains was administered by inhalation to 43 patients. The control group included 40 patients who received conventional antimicrobial therapy. The changes in clinical, laboratory and instrumental parameters, levels of biomarkers, microbiological and PCR tests of bronchoalveolar lavage fluid were assessed, including those in the «phage therapy with antibiotics» (n=29) and «phage therapy without antibiotics» (n=14) subgroups.Results. The groups were comparable in terms of basic parameters (age, sex, diagnosis, organ dysfunction according to APACHE II, use of vasoactive drugs) and the level of airway colonization with antibioticresistant bacterial strains. Good tolerability and absence of clinically significant side effects were observed during inhaled administration of the bacteriophage cocktail. Computed tomography on day 21 showed a significant reduction in lung damage in patients who received bacteriophages. Patients treated with bacteriophages without antibiotics had significantly lower need for mechanical ventilation. The mortality rate on day 28 did not differ significantly and was 4.7% (2/43) in the bacteriophage-treated group vs 5% (2/40) in the control group.Conclusion. The first experience of using the adaptive phage therapy technique in chronically critically ill patients in neurological intensive care demonstrated the safety of inhalational administration of the bacteriophage cocktail. The efficacy of the technique was confirmed by the treatment results obtained in the phage therapy group, which were not inferior to those in the group with conventional antibiotic therapy, while several clinical and laboratory parameters tended to improve even in patients who received bacteriophages and did not receive antibiotics.

Bio colourants from the waste leaves of Ginkgo biloba L. tree: Wool dyeing and antimicrobial functionalization against some antibiotic-resistant bacterial strains

This research focuses on flavonoid-based natural dyes for the coloration and antibacterial finishing of wool fabrics. In the present study, we accessed the suitability of biocolorants from Gingko biloba L. waste/fallen leaves extract to develop colored antibacterial wool fabrics to reduce the environmental pollution and dependency of the textile industry on the synthetic antibacterial agents. Specifically, we present a novel method to counteract the growing antibiotic resistance using G. biloba L. leaves extract as a potent antibacterial agent in conjunction with ampicillin. Natural colorants were extracted in 50% aqueous ethanol at 70 °C for 60 min under acid conditions of pH 3. Before dyeing procedures, the extracted dye powder was assessed for thermal stability by TGA analysis. Structural characterization of the extracted dye was done by UV–visible and FT-IR spectral analysis. Optimal dyeing results were achieved at 90 °C for 70 min with a dye concentration of 50% (o.w.f.). Additionally, dye adsorption (Isotherm constants) and dye performances were effectively reported during this study. Pseudo-second order and sips isotherm model provided the best fitting of experimental data with high regression coefficient (R2 = 0.99). Valuated indicators (color strength (K/S), color characteristics, and fastness properties) of dyed wool fabric were effectively reported in response to washing pretreated with different metallic and natural mordants. The antibacterial potential of extracted natural dye was enhanced in combination with ampicillin (synergism) which can be correlated with the significant reduction in the corresponding MIC values. Fe2+ and Sn2+ salts demonstrated negative effects on the antibacterial performance of the dyed wool fabric, whereas most of the biomordants showed enhanced antibacterial performances. The effective use of the extracted yellow dye from G. biloba L. fallen/waste leaves in textile dyeing and finishing will enhance the industrial applications of the green waste over its normal applications.

Magnetic-Responsive Photosensitizer Nanoplatform for Optimized Inactivation of Dental Caries-Related Biofilms: Technology Development and Proof of Principle.

Conventional antibiotic therapies for biofilm-trigged oral diseases are becoming less efficient due to the emergence of antibiotic-resistant bacterial strains. Antimicrobial photodynamic therapy (aPDT) is hampered by restricted access to bacterial communities embedded within the dense extracellular matrix of mature biofilms. Herein, a versatile photosensitizer nanoplatform (named MagTBO) was designed to overcome this obstacle by integrating toluidine-blue ortho (TBO) photosensitizer and superparamagnetic iron oxide nanoparticles (SPIONs) via a microemulsion method. In this study, we reported the preparation, characterization, and application of MagTBO for aPDT. In the presence of an external magnetic field, the MagTBO microemulsion can be driven and penetrate deep sites inside the biofilms, resulting in an improved photodynamic disinfection effect compared to using TBO alone. Besides, the obtained MagTBO microemulsions revealed excellent water solubility and stability over time, enhanced the aPDT performance against S. mutans and saliva-derived multispecies biofilms, and improved the TBO's biocompatibility. Such results demonstrate a proof-of-principle for using microemulsion as a delivery vehicle and magnetic field as a navigation approach to intensify the antibacterial action of currently available photosensitizers, leading to efficient modulation of pathogenic oral biofilms.

Evaluation of antibiotic resistance and prevalence of multi-antibiotic resistant genes among Acinetobacter baumannii strains isolated from patients admitted to al-yarmouk hospital

Emerging antibiotic resistance in microorganisms particularly multidrug-resistant strains among bacteria are increasing because of misusing antibiotics as well as evolution of antibiotic resistance mechanisms. In this regard, Acinetobacter baumannii is one of the six most common multidrug-resistant microorganisms in hospitals. Recently, carbapenems, as common antibiotics to treat infections of Acinetobacter have not an acceptable efficiency because of the resistance emergence to these antibiotics in many strains. In this study, resistant strains of A. baumannii were isolated and identified as an appropriate preventive strategy to reduce infections in hospitals. Disc diffusion test and PCR method were used to isolate of resistant strains and identify beta-lactamase genes of blaAmpC, blaTEM, blaVIM, and blaSHV. This study showed that these genes were contributed in antibiotic resistance with about 18.4% and ≥53.5% strains expressing all 4 genes and ≥3 genes, respectively. The blaAmpC gene is more prevalent than other genes, and this is probably due to the prevalence or rapid transfer of this beta-lactamase. However, more studies should be performed in a comparative way to isolate and identify other antibiotic-resistant bacterial strains relate to other hospitals.

Green Synthesis of Silver-Peptide Nanoparticles Generated by the Photoionization Process for Anti-Biofilm Application.

An alarming increase in antibiotic-resistant bacterial strains is driving clinical demand for new antibacterial agents. One of the oldest antimicrobial agents is elementary silver (Ag), which has been used for thousands of years. Even today, elementary Ag is used for medical purposes such as treating burns, wounds, and microbial infections. In consideration of the effectiveness of elementary Ag, the present researchers generated effective antibacterial/antibiofilm agents by combining elementary Ag with biocompatible ultrashort peptide compounds. The innovative antibacterial agents comprised a hybrid peptide bound to Ag nanoparticles (IVFK/Ag NPs). These were generated by photoionizing a biocompatible ultrashort peptide, thus reducing Ag ions to form Ag NPs with a diameter of 6 nm. The IVFK/Ag NPs demonstrated promising antibacterial/antibiofilm activity against reference Gram-positive and Gram-negative bacteria compared with commercial Ag NPs. Through morphological changes in Escherichia coli and Staphylococcus aureus, we proposed that the mechanism of action for IVFK/Ag NPs derives from their ability to disrupt bacterial membranes. In terms of safety, the IVFK/Ag NPs demonstrated biocompatibility in the presence of human dermal fibroblast cells, and concentrations within the minimal inhibitory concentration had no significant effect on cell viability. These results demonstrated that hybrid peptide/Ag NPs hold promise as a biocompatible material with strong antibacterial/antibiofilm properties, allowing them to be applied across a wide range of applications in tissue engineering and regenerative medicine.

Ins and Outs: Recent Advancements in Membrane Protein-Mediated Prokaryotic Ferrous Iron Transport

Iron is an essential nutrient for virtually every living organism, especially pathogenic prokaryotes. Despite its importance, however, both the acquisition and the export of this element require dedicated pathways that are dependent on oxidation state. Due to its solubility and kinetic lability, reduced ferrous iron (Fe2+) is useful to bacteria for import, chaperoning, and efflux. Once imported, ferrous iron may be loaded into apo and nascent enzymes and even sequestered into storage proteins under certain conditions. However, excess labile ferrous iron can impart toxicity as it may spuriously catalyze Fenton chemistry, thereby generating reactive oxygen species and leading to cellular damage. In response, it is becoming increasingly evident that bacteria have evolved Fe2+ efflux pumps to deal with conditions of ferrous iron excess and to prevent intracellular oxidative stress. In this work, we highlight recent structural and mechanistic advancements in our understanding of prokaryotic ferrous iron import and export systems, with a focus on the connection of these essential transport systems to pathogenesis. Given the connection of these pathways to the virulence of many increasingly antibiotic resistant bacterial strains, a greater understanding of the mechanistic details of ferrous iron cycling in pathogens could illuminate new pathways for future therapeutic developments.