Resistant Bacterial Strains Research Articles

Adaptive Resilience: Unraveling the Path of Heavy Metal Tolerance in Multidrug Resistant Pathogens

Co-existence of heavy metal tolerance and antibiotic resistance in bacterial strains pose potential threats to human health and environment. In recent decades, heavy metal pollution has caused selective pressure that leads to the development of multiple drug resistance among bacterial populations. Escherichia coli, Pseudomonas aeruginosa and Staphylococcus cohnii were used in the study. Out of 8 antibiotics tested, it was observed that E.coli was resistant to four, S.cohnii and P. aeruginosa were resistant only to three antibiotics. The isolates were found to grow at high concentration of copper (CuSO4) and varying degrees of chromium (K2Cr2O7) with all the three being sensitive to mercuric chloride (HgCl2). E. coli, S. cohnii and P. aeruginosa were inhibited at 0.84±0.05, 6.79±0.07 and 2.54±0.02 μM ml-1 respectively by chromium salt; similarly, E. coli, S. cohnii and P. aeruginosa had a MIC of 1.56±0.03 μM ml-1, 1.25±0.05 μM ml-1 and 1.56±0.05μM ml-1 and for copper, E. coli, S. cohnii and P. aeruginosa had a MIC of 8.20±0.05, 9.20±0.01, 7.18±0.05μM ml-1 respectively. Further studies were carried out by agarose gel electrophoresis and SDS-PAGE for the characterization of R-plasmid and heavy metal stress protein among the isolated bacteria. The qPCR was used for identification of antimicrobial resistant genes. A phylogenetic study was performed on S. cohnii to understand its evolutionary traits. The results provide insight into the co-occurrence of antibiotic resistance and heavy metal tolerance in clinically important bacterial communities, which may create severe health issues in the coming decades.

MICROBIOLOGICAL ASSESSMENT OF INDOOR AIR QUALITY OF STUDENT HOSTELS AND CANTEENS IN A NIGERIAN UNIVERSITY CAMPUS: RISKS ON STUDENTS’ HEALTH

Microbial air contaminants affect the quality of air we breathe and these microbial air contaminants can settle on body parts, clothes, food etc. which poses a serious threat to human health. Therefore, the level of bacterial contamination in various in-door air of the students’ hostels and canteens of Kaduna State University (KASU) and their antibiotics susceptibility patterns was studied. A total of 44 samples were collected from the rooms (18), toilets (18) of the students hostels and canteen (8) of KASU; using the settle plate method. Gram staining and standard biochemical methods were used to identify the bacterial isolates and antibiotic susceptibility testing was determined by disc diffusion method. The bacteria load was between 1.2 x 103 to 6.7 x 103 cfu/ml3. A total of 30 bacteria isolates were identified, Staphylococcus aureus had the highest (9, 30%) occurrence, followed by Streptococcus spp (6, 20%), Bacillus subtilis and Clostridium spp had similar (4, 13.2%) occurrence, The antibiotic susceptibility testing carried out revealed that the Gram negative and Gram positive bacteria isolates were more susceptible to vancomycin (75%, 43.5%), tetracycline (75%, 47.8%) and gentamicin (50%, 43.5%) while high resistance was observed with chloramphenicol (100%, 73.9%), ceftriaxone (100%, 100%), cefoxitin (100%, 73.9%), amoxicillin/clavulanic acid (100%, 87%), and trimethoprim/sulphamethoxazole (100%, 78%). All the indoor samples were contaminated with pathogenic bacteria and there was high level of multidrug resistance. This is very dangerous to the students’ health because it can be a source of transmission infections and antibiotic resistant bacterial strains.

MAST® D72C test: a novel option for ESBL, AmpC and carbapenemase detection.

The MAST® D72C test is a phenotypical test which can detect ESBL and AmpC production in Enterobacterales. It can also identify the suspected presence of carbapenemase. The aim of the present study was to assess the sensitivity and specificity of this test and to discuss its usefulness in laboratories, especially those that use only an automated AST system. The performance of the MAST® D72C test was assessed against a collection of 119 non-redundant Enterobacterales isolates characterized for their content in β-lactamases, and compared with that of the reference double disk synergy test. β-lactamase content was established from phenotypic and genotypic analyses to collect a broad diversity of resistance mechanisms and bacterial strains, including 30 ESBL-producing strains, 32 strains overproducing chromosomal AmpC, 10 strains producing plasmid-encoded AmpC, 12 carbapenemase-producing strains, 13 strains combining the production of several β-lactamases, and 22 strains that produced other β-lactamases. The sensitivity and specificity for ESBL-detection were comparable with those of the synergy test, 75 versus 72.5%, and 94.9 versus 93.7%, respectively. The sensitivity and specificity for AmpC-detection were 71.7% and 100%, respectively, and sensitivity reached 78.7% if we excluded carbapenem-resistant isolates. Carbapenemase-detection sensitivity was 90%. These results show that the MAST® D72C test can be a useful tool for the detection of ESBL- and AmpC-production in clinical laboratories.

Oxidative Stress Response Mechanisms Sustain the Antibacterial and Antioxidant Activity of Quercus ilex.

The development of new natural antibiotics is considered as the heart of several investigations in the nutraceutical field. In this work, leaves of Quercus ilex L. treated by tropospheric ozone (O3) and nitrogen (N) deposition, exhibited a clear antimicrobial efficacy against five multi-drug resistant (MDR) bacterial strains (two gram-positive and three gram-negative). Under controlled conditions, it was studied how simulated N deposition influences the response to O3 and the antibacterial and antioxidant activity, and antioxidant performance. The extraction was performed by ultra-pure acetone using two different steps. A higher antioxidant activity was measured in the presence of interaction between O3 and N treatments on Quercus leaves. At the same time, all organic extracts tested have shown bacteriostatic activity against all the tested strains with a MIC comprised between 9 and 4 micrograms/mL, and a higher antioxidant efficacy shown by spectrophotometric assay. Stronger antimicrobial activity was found in the samples treated with O3, whereas N-treated plants exhibited an intermediate antibacterial performance. This performance is related to the stimulation of the non-enzymatic antioxidant system induced by the oxidative stress, which results in an increase in the production of antimicrobial bioactive compounds.

Synthesis of a tetralone derivative of ampicillin to control ampicillin-resistant Staphylococcusaureus

Due to the rapid emergence of antibiotic resistant new bacterial strains and new infections, there is an urgent need for novel or newly modified and efficient alternatives of treatment. However, conventional antibiotics are still used in therapeutic settings but their efficacy is uncertain due to the rapid evolution of drug resistance. In the present study, we have synthesized a new derivative of conventional antibiotic ampicillin using SN2-type substitution reaction. NMR and mass analysis of the newly synthesized derivative of ampicillin confirmed it as ampicillin-bromo-methoxy-tetralone (ABMT). Importantly, ABMT is revealed to have efficient activity against Staphylococcus aureus (S. aureus) with a MIC value of 32 μg ml−1 while ampicillin was not effective, even at 64 μg ml−1 of concentration. Electron microscopy results confirmed the membrane-specific killing of S. aureus at 1 h of treatment. Additionally, molecular docking analysis revealed a strong binding affinity of ABMT with β-lactamase via the formation of a closed compact bridge. Our findings, avail a new derivative of ampicillin that could be a potential alternative to fight ampicillin-resistant bacteria possibly by neutralizing the β-lactamase action.

Tebuconazole promotes spread of a multidrug-resistant plasmid into soil bacteria to form new resistant bacterial strains

The development of antibiotic resistance threatens human and environmental health. Non-antibiotic stressors, including fungicides, may contribute to the spread of antibiotic resistance genes (ARGs). We determined the promoting effects of tebuconazole on ARG dissemination using a donor, Escherichia coli MG1655, containing a multidrug-resistant fluorescent plasmid (RP4) and a recipient (E. coli HB101). The donor was then incorporated into the soil to test whether tebuconazole could accelerate the spread of RP4 into indigenous bacteria. Tebuconazole promoted the transfer of the RP4 plasmid from the donor into the recipient via overproduction of reactive oxygen species (ROS), enhancement of cell membrane permeability and regulation of related genes. The dissemination of the RP4 plasmid from the donor to soil bacteria was significantly enhanced by tebuconazole. RP4 plasmid could be propagated into more genera of bacteria in tebuconazole-contaminated soil as the exposure time increased. These findings demonstrate that the fungicide tebuconazole promotes the spread of the RP4 plasmid into indigenous soil bacteria, revealing the potential risk of tebuconazole residues enhancing the dissemination of ARGs in soil environments.

DISCRETE OPTIMIZATION OF THE IMPLEMENTATION STAGES OF PHARMACEUTICAL DEVELOPMENT FOR A SPRAY TREATMENT FOR ORAL DISEASES

Introduction. All over the world more than 3.5 billion people suffer from oral diseases, which can lead to endogenous infectious diseases and create conditions for external infections. The growing antimicrobial resistance of bacterial strains is a global health threat. Oligoalkyleneguanidine polymers may be promising compounds to solve this problem. The spray form for the application of these substances is the most optimal. The aim of the study is to apply discrete optimization to implement the stages of pharmaceutical development of a spray based on branched oli-gohexamethyleneguanidine for the treatment of oral diseases. Material and methods. Experiments are carried out using various equipment and samples with different compositions have been developed. The implementation of the pharmaceutical development stages was carried out using a discrete optimization algorithm. Results. When implementing discrete optimization in pharmaceutical development, it is necessary to prioritize criteria and limitations using the target quality profile of the drug being developed. As a result of the optimization cycles carried out, the optimal composition was selected, which corresponds to the target quality profile, including such parameters as pH, dynamic viscosity, sterilizing filtration, adhesion of the formulations to the oral mucosa and the spray torch. A discrete optimization was carried out, taking into account the wetting edge angle and particle size distribution. The optimal com-position was sample No. 8, which has pseudoplastic properties, provides unhindered spraying and prevents the composition from draining from the mucous membrane of the oral cavity. Conclusion. During the study, the optimal ratio of components was determined and the development of a spray based on oligohexamethyleneguani-dine with the implementation of stages of pharmaceutical development for discrete optimization was proposed.

A Study of the Synergistic Effects of Essential Oils from Origanum compactum and Origanum elongatum with Commercial Antibiotics against Highly Prioritized Multidrug-Resistant Bacteria for the World Health Organization.

The irrational use of antibiotics has favored the emergence of resistant bacteria, posing a serious threat to global health. To counteract antibiotic resistance, this research seeks to identify novel antimicrobials derived from essential oils that operate through several mechanisms. It aims to evaluate the quality and composition of essential oils from Origanum compactum and Origanum elongatum; test their antimicrobial activity against various strains; explore their synergies with commercial antibiotics; predict the efficacy, toxicity, and stability of compounds; and understand their molecular interactions through docking and dynamic simulations. The essential oils were extracted via hydrodistillation from the flowering tops of oregano in the Middle Atlas Mountains in Morocco. Gas chromatography combined with mass spectrometry (GC-MS) was used to examine their composition. Nine common antibiotics were chosen and tested alone or in combination with essential oils to discover synergistic effects against clinically important and resistant bacterial strains. A comprehensive in silico study was conducted, involving molecular docking and molecular dynamics simulations (MD). O. elongatum oil includes borneol (8.58%), p-cymene (42.56%), thymol (28.43%), and carvacrol (30.89%), whereas O. compactum oil is mostly composed of γ-terpinene (22.89%), p-cymene (15.84%), thymol (10.21%), and (E)-caryophyllene (3.63%). With O. compactum proving to be the most potent, these essential oils showed antibacterial action against both Gram-positive and Gram-negative bacteria. Certain antibiotics, including ciprofloxacin, ceftriaxone, amoxicillin, and ampicillin, have been shown to elicit synergistic effects. To fight resistant bacteria, the essential oils of O. compactum and O. elongatum, particularly those high in thymol and (E)-caryophyllene, seem promising when combined with antibiotics. These synergistic effects could result from their ability to target the same bacterial proteins or facilitate access to target sites, as suggested by molecular docking simulations. Molecular dynamics simulations validated the stability of the examined protein-ligand complexes, emphasizing the propensity of substances like thymol and (E)-caryophyllene for particular target proteins, opening the door to potentially effective new therapeutic approaches against pathogens resistant to multiple drugs.

Synthesis of multifunctional silver oxide, zinc oxide, copper oxide and gold nanoparticles for enhanced antibacterial activity against ESKAPE pathogens and antioxidant, anticancer activities using Momordica cymbalaria seed extract

Rising emergence in public health due to antibiotic-resistant of ESKAPE pathogens, diseases related to oxidative damage and cancer has driven the urgent need to develop potent therapeutics for resistant bacterial strains, free radical scavenging and cancer. The present study involves Momordica cymbalaria seed extracts mediated synthesis of metal nanoparticles and to evaluate its ameliorative potency against ESKAPE pathogens, free radicals and cancer cells. The study includes therapeutic approaches to target pathogenic biofilms relating phyto-therapeutics with nanotechnology. In the present investigation, we have synthesized four metal oxide nanoparticles of Silver, Zinc, Copper (Ag2O, ZnO and CuO), and Gold nanoparticles (Au NPs) using the seed extracts of M. cymbalaria. The synthesized nanoparticles were characterized by various biophysical techniques like X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) Field-Emission Scanning Electron Microscopy (FESEM) with energy-dispersive X-ray spectroscopy (EDX) and High-Resolution Transmission Electron Microscopy (HR-TEM) with Selected Area Electron Diffraction (SAED). Agar well diffusion methods, or Antimicrobial methods (MIC, MBC, and MBIC), DPPH/ABTS free radical scavenging assay, MTT/apoptotic studies and protein/DNA damage inhibition assays were performed to evaluate the antibacterial, anticancer and antioxidant activities. Crystalline properties of metal oxides NPs were established by XRD pattern and the presence of alcohol or phenol, ketone, and amine groups in M. cymbalaria seed was confirmed by FTIR analysis. That participates in the reduction of Ag+, Cu+, Zn+, and Au+ ions to NPs. All the nanoparticles showed dose-dependent antibacterial, anticancer and antioxidant activity. Protein and DNA oxidation inhibition assays demonstrated an efficient quenching effect of proxy radicals by all the NPs. Therefore, M. cymbalaria -mediated synthesis of metal NPs can be used as an alternative to toxic physical or chemically mediated synthesis that can be applied to develop multifunctional nanoparticles as efficient therapeutics.

Synergistic antibacterial activity and inhibition of TiO2 nanotube arrays and loaded antibiotics against gram-positive and gram-negative bacteria

Introduction: Implantable medical devices continue to be vulnerable to bacterial infections. The unrelenting formation of antibiotic resistant bacterial strains not only exacerbates these infections but also renders the current treatment strategies impotent. The need is greater than ever for innovative and effective approaches to counteract drug-resistant bacteria. This study examines the innate antibacterial properties of TiO2 nanotube arrays (TNAs) and their ability to locally deliver antibiotics to inactivate gram-positive and gram-negative bacteria, in vitro.Methods: Using a two-step electrochemical anodization process, TNAs with a diameter of ∼100 nm and a length of ∼5 µm were grown on titanium substrates.Results and Discussion: After 24 h of incubation, as-fabricated TNAs showed 100% clearance of Escherichia coli, and 97% clearance of Staphylococcus aureus growth. The antibiotic-loaded TNAs demonstrated sustained slow-release of cefotaxime and imipenem measured over 14 days. In vitro bacterial studies revealed the capability of cefotaxime- and imipenem-loaded TNAs in completely inhibiting the growth with 100% clearance of Klebsiella pneumoniae after 24 and 48 h of incubation. Bacterial inhibition assay revealed a significantly enlarged inhibition zone difference of 18 mm around the imipenem-loaded TNAs against K. pneumoniae compared to the as-fabricated TNAs which was maintained for 7 days with ∼10 μgmL−1 of antibiotic released from the TNAs which was found to be lower than the dose required to completely eradicate multidrug resistant bacteria when used in conjunction with the antibacterial TNAs. The results of our study highlight the potential of TNAs as a versatile platform for addressing treatment strategies related to bacterial infections and antibiotic resistance in implantable medical devices.

Bacteriophages as a potential substitute for antibiotics: A comprehensive review.

Over the years, the administration of antibiotics for the purpose of addressing bacterial infections has become increasingly challenging due to the increased prevalence of antimicrobial resistance exhibited by various strains of bacteria. Multidrug-resistant(MDR) bacterial species are rising due to the unavailability of novel antibiotics, leading to higher mortality rates. With these conditions, there is a need for alternatives in which phage therapy has made promising results. Phage-derived endolysins, phage cocktails, and bioengineered phages are effective and have antimicrobial properties against MDRand extensively drug-resistant strains. Despite these, it has been observed that phages can give antimicrobial activity to more than one bacterial species. Thus, phage cocktail against resistant strains provides broad spectrum treatment and magnitude of effectivity, which is many folds higher than antibiotics. Many commercially available endolysins such as Staphefekt SA.100, Exebacase (CF-301), and N-Rephasin®SAL200 are used in biofilm penetration and treating plant diseases. The role of CMP1 phage endolysin in transgenic tomato plants in preventing Clavibacter michiganensis infection and the effectiveness of phage in protecting Atlantic salmon from vibriosis have been reported. Furthermore, phage-derived endolysin therapy, such as TSPphg phage exogenous treatment, can aid in disrupting cell walls, leading to bacterial cell lysis. As animals in aquaculture and slaughterhouses are highly susceptible to bacterial infections, effective phage therapy instead of antibiotics can help treat poultry animals, preserve them, and facilitate disease-free trade. Using bioengineered phages and phage cocktails enhances the effectiveness by providing a broad spectrum of phages and target specificity. Research is currently being conducted on clinical trials to confirm the efficacy of engineered phages and phage cocktails in humans. Although obtaining commercial approval may be time-consuming, it will be beneficial in the postantibiotic era. This review provides an overview of the significance of phage therapy as a potential alternative to antibiotics in combating resistant bacterial strains and its application to various fields and emphasizes the importance of safeguarding and ensuring treatment efficacy.

Detection of Coliform Bacteria in Raw Milk Samples Collected from Industrial Cities of Pakistan

Antibiotics and heavy metals-resistant bacteria in livestock environments can result in economic losses and raise public health and environmental problems. There is a crisis in the world's access to and pipeline for antibiotics. Objective: To screen raw milk samples collected from three different industrial cities Gujranwala, Lahore, and Sheikhupura, situated in the province of Punjab, Pakistan. Methods: In this regard, a total of 26 samples were having 84 coliform strains. Separated coliform colonies were processed for Gram's staining, catalase, indole production, and Simmon's citrate and motility tests. Results: Metal resistance of bacterial strains was also checked and 39.5% and 45.23% of bacteria were found to be resistant to ZnCl2 1% and 0.5%. 69.045% and 77.38% bacteria were found to be resistant to CuSo4 salt solution1% and 0.5%. 17.85% and 27% bacteria were found to be resistant to Na2CrO4 salt solution1% and 0.5% respectively. 80% of bacteria were found to be resistant to Cefuroxime, 26.19% to Cephradine, 84.52% to Aztroeonam 41.67% to Erythromycin, 91.667% to Trimethoprim 89.28% to Lincomycins. Conclusions: The raw milk samples were not only contaminated with coliforms but the bacteria were also resistant to heavy metals and certain antibiotics which might be considered indicative of industrial and anthropogenic pollution. Cephradine, 84.52% to Aztroeonam 41.67% to Erythromycin, 91.667% to Trimethoprim 89.28% to Lincomycins. Conclusions: The raw milk samples were not only contaminated with coliforms but the bacteria were also resistant to heavy metals and certain antibiotics which might be considered indicative of industrial and anthropogenic pollution.

In vitro antimicrobial activity of the novel antimicrobial peptide mytimacin-4 and its influence on the microbial community and quality of pork during refrigerated storage

The excessive use of antibiotics and chemical preservatives has led to the emergence of resistant bacterial strains, which has had an adverse impact on food safety. The utilization of antimicrobial peptides (AMPs) in food preservation has garnered attention due to their ability to maintain the quality of food while reducing the likelihood of bacteria developing resistance. Mytimacin-4, an antimicrobial peptide rich in cysteine and positively charged, has been identified in Mytilus galloprovincialis and has been reported to possess antibacterial activity. However, the specific effect of mytimacin-4 on bacteria is still not well understood. Hence, this study aimed to prepare mytimacin-4 using a Pichia pastoris expression system and to investigate its antibacterial properties and mechanism. Our findings indicate that mytimacin-4 exhibits rapid and sustained bactericidal effects against bacteria and no cytotoxicity or hemolytic activity. Additionally, microscopy techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), and fluorescence microscopy have demonstrated that mytimacin-4 disrupts the integrity of bacterial membranes, damages intracellular structures, and binds to bacterial DNA. Furthermore, mytimacin-4 had a great antimicrobial effect against the dominant bacteria of pork, improving the abundance and variety of bacterial flora during refrigeration and controlling the rise in pH, total volatile basic nitrogen (TVBN), and thiobarbituric acid reactive substances (TBARS) in pork, preserving the freshness of pork during storage at 4 °C. Moreover, mytimacin-4 demonstrated significant antibacterial effects against three types of bacteria in a pork spoilage model. Overall, mytimacin-4 holds great potential as a food preservative for storage purposes.

High prevalence of carbapenem resistance and clonal expansion of blaNDM gene in Klebsiella pneumoniae isolates in an Iranian referral pediatric hospital

BackgroundThe increasing global concern regarding antibiotic resistance necessitates in-depth studies to comprehend the phenotypic and genotypic characteristics of resistant bacterial strains. This study aimed to investigate the prevalence, antibiotic resistance profiles, and molecular characteristics of carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates in an Iranian referral pediatrics hospital. Methods: In this study, we examined CRKP isolates collected from hospitalized pediatric patients across various wards. The isolates underwent antimicrobial susceptibility testing, the polymerase chain reaction (PCR) analysis for carbapenemase genes (blaNDM, blaVIM and blaIMP), and genetic relatedness assessment using pulsed-field gel electrophoresis (PFGE).ResultsAmong 166 K. pneumoniae isolates, 54 (32.5%) exhibited resistance to carbapenems. Notably, all these resistant isolates were resistant to imipenem, with 35 (65%) displaying resistance to both imipenem and meropenem. Of the 54 CRKP isolates, 24 (44%) were metallo-β-lactamases (MBL)-producing. The prevalence of the blaNDM gene among CKCP and MBL-producing isolates was 20% (n = 11) and 44% (n = 24), respectively. The blaVIM and blaIMP genes were not detected in any of the isolates. Twenty-six CRKP isolates (48%) were recovered from ICUs. PFGE analysis of CRKP isolates revealed 20 clusters, with cluster S being the most prevalent, comprising 24% of the total (n = 13).ConclusionOur study reveals a concerning prevalence of carbapenem resistance in K. pneumoniae isolates. Specifically, the detection of the blaNDM gene in 20% of CRKP isolates, with a significant proportion (82%) observed in isolated CRKP from the ICUs and emergency departments, underscores the potential clonal expansion of these resistant strains within these critical hospital wards.

Levofloxacin loaded chitosan and poly-lactic-co-glycolic acid nano-particles against resistant bacteria: Synthesis, characterization and antibacterial activity

BackgroundWith the global increase in antibacterial resistance, the challenge faced by developing countries is to utilize the available antibiotics, alone or in combination, against resistant bacterial strains. We aimed to encapsulate the levofloxacin (LVX) into polymeric nanoparticles using biodegradable polymers i.e. Chitosan and PLGA, estimating their physicochemical characteristics followed by functional assessment as nanocarriers of levofloxacin against the different resistant strains of bacteria isolated from biological samples collected from tertiary care hospital in Lahore, Pakistan. MethodsLVX-NPs were synthesized using ion gelation and double emulsion solvent-evaporation method employing chitosan (CS) and poly-lactic-co-glycolic acid (PLGA), characterized via FTIR, XRD, SEM, and invitro drug release studies, while antibacterial activity was assessed using Kirby-Bauer disc-diffusion method. ResultsData revealed that the levofloxacin-loaded chitosan nanoparticles showed entrapment efficiency of 57.14% ± 0.03 (CS-I), 77.30% ± 0.08(CS-II) and 87.47% ± 0.08 (CS-III). The drug content, particle size, and polydispersity index of CS-I were 52.22% ± 0.2, 559 nm ± 31 nm, and 0.030, respectively, whereas it was 66.86% ± 0.17, 595 nm ± 52.3 nm and 0.057, respectively for CS-II and 82.65% ± 0.36, 758 nm ± 24 nm and 0.1, respectively for CS-III. The PLGA-levofloxacin nanoparticles showed an entrapment efficiency of 42.80% ± 0.4 (PLGA I) and 23.80% ± 0.4 (PLGA II). The drug content, particle size and polydispersity index of PLGA-I were 86% ± 0.21, 92 nm ± 10 nm, and 0.058, respectively, whereas it was 52.41% ± 0.45, 313 nm ± 32 nm and 0.076, respectively for PLGA-II. The XRD patterns of both polymeric nanoparticles showed an amorphous nature. SEM analysis reflects the circular-shaped agglomerated nanoparticles with PLGA polymer and dense spherical nanoparticles with chitosan polymer. The in-vitro release profile of PLGA-I nanoparticles showed a sustained release of 82% in 120 h and it was 58.40% for CS-III. Both types of polymeric nanoparticles were found to be stable for up to 6 months without losing any major drug content. Among the selected formulations, CS-III and PLGA-I, CS-III had better antibacterial potency against gram+ve and gram-ve bacteria, except for K. pneumonia, yet, PLGA-I demonstrated efficacy against K. pneumonia as per CSLI guidelines. All formulations did not exhibit any signs of hemotoxicity, nonetheless, the CS-NPs tend to bind on the surface of RBCs. ConclusionThese data suggested that available antibiotics can effectively be utilized as nano-antibiotics against resistant bacterial strains, causing severe infections, for improved antibiotic sensitivity without compromising patient safety.

Chromium-stress alleviation study using plant growth promoting rhizobacteria for maize ( Zea mays L.)

Heavy metal contamination is one of the major environmental threats due to industrialization and urbanization. Among various heavy metals, chromium is of recent concern because it is considered the most hazardous metal pollutant in the environment. Its toxicity alters the process of germination and various other growth parameters ultimately affecting its yield. While maize (Zea mays L.) is one of the most widely cultivated cereal crop being used for fodder, feed and food purposes. It is multipurpose cereal crop and is also used as raw material for different industries. Hence, it is mandatory to come up with effective eco-friendly technique to remediate chromium (Cr) to protect the environment from its toxic impacts. During current research, plant microbe interaction was carried out with Cr resistant strains of Bacillus cereus (3a), Pseudomonas aeruginosa (DS4), Bacillus nitratireducens (TP8), Enterobacter cloacae (A9G) and Pseudomonas sp. (B3) that were selected to observe their beneficial impact on corn (Zea mays L.) growth in presence of Cr stress (150 & 300 µg/mL). Results have indicated that growth and biochemical parameters were enhanced due to bacterial inoculation. In comparison to control, maximum increment in shoot length, number of leaves, root length and fresh weight of inoculated plants was noted up to 46, 115, 76, and 42% respectively. Maximum increment in protein and chlorophyll content of inoculated plants was noted up to 304 and 71% respectively as compared to control. The present study suggests the use of above-mentioned highly chromium resistant bacterial strains to remediate chromium contaminated sites and to improve agricultural production.

Chestnut Honey Is Effective against Mixed Biofilms at Different Stages of Maturity.

The irresponsible overuse of antibiotics has increased the occurrence of resistant bacterial strains, which represents one of the biggest patient safety risks today. Due to antibiotic resistance and biofilm formation in bacteria, it is becoming increasingly difficult to suppress the bacterial strains responsible for various chronic infections. Honey was proven to inhibit bacterial growth and biofilm development, offering an alternative solution in the treatment of resistant infections and chronic wounds. Our studies included chestnut honey, valued for its high antibacterial activity, and the bacteria Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, and S. epidermidis, known to form multi-species biofilm communities. Minimum inhibitory concentrations (MIC) of chestnut honey were determined for each bacterial strain. Afterwards, the mixed bacterial biofilms were treated with chestnut honey at different stages of maturity (incubation times: 2, 4, 6, 12, 24 h). The extent of biofilm inhibition was measured with a crystal violet assay and demonstrated by scanning electron microscopy (SEM). As the incubation time increased and the biofilm became more mature, inhibition rates decreased gradually. The most sensitive biofilm was the combination MRSA-S. epidermidis, with a 93.5% inhibition rate after 2 h of incubation. Our results revealed that chestnut honey is suitable for suppressing the initial and moderately mature stages of mixed biofilms.

A Vancomycin-Templated DNA-Encoded Library for Combating Drug-Resistant Bacteria.

It is an urgent need to tackle the global crisis of multidrug-resistant bacterial infections. We report here an innovative strategy for large-scale screening of new antibacterial agents using a whole bacteria-based DNA-encoded library (DEL) of vancomycin derivatives via peripheral modifications. A bacterial binding affinity assay was established to select the modification fragments in high-affinity compounds. The optimal resynthesized derivatives demonstrated excellently enhanced activity against various resistant bacterial strains and provided useful structures for vancomycin derivatization. This work presents the new concept in a natural product-templated DEL and in antibiotic discovery through bacterial affinity screening, which promotes the fight against drug-resistant bacteria.

Green synthesis, characterization and antimicrobial activity of iron oxide nanoparticles with tigecycline against multidrug resistant bacterial strains

ObjectivesThe current study focused on the green synthesis of iron oxide nanoparticles (IONPs) using Salvia officinalis leaf extract, aiming to control nosocomial infections caused by drug-resistant bacterial pathogens. The nanoparticles were characterized and evaluated for antibacterial effectiveness. MethodsThe disc diffusion assay was utilized to determine the synergistic antibacterial efficiency of the biogenic IONPs against three nosocomial bacterial pathogens namely, methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli and Pseudomonas aeruginosa strains. Results and conclusionThe change of color of ferric nitrate solution from orange to black color after addition of the extract preliminary indicated the formation of biogenic IONPs. The phytosynthesized IONPs were characterized using UV–Vis spectroscopy indicating the formation of a broad band at 349 nm. Moreover, X-ray powder diffraction (XRD) analysis revealed the formation of diffraction peaks positioned at 2 theta degrees of 24.80°, 33.41°, 35.03°, 41.28°, 49.15°, 53.41°, 57.37°, 62.40° and 64.31°, corresponding to lattice planes of (012), (104), (110), (202), (024), (116), (214) and (300), respectively. The phytosynthesized nanoparticles revealed a high antibacterial activity against the concerned pathogens at the concentration of 200 µg/disc with relative inhibitory zones of 21.14 ± 0.16, 17.26 ± 0.26, and 20.56 ± 0.62 mm, respectively against E. coli, P. aeruginosa and MRSA strains. The biogenic IONPs revealed the highest synergistic activity with tigecycline antibiotic against E. coli followed by MRSA and P. aeruginosa strains with relative increase in fold of inhibition values (IFA) of 1.79, 1.29 and 0.93, respectively. In conclusion, the water extract of S. officinalis facilitated the green fabrication of IONPs with distinctive physicochemical properties and synergistic antibacterial activity against the tested nosocomial bacterial pathogens.

Easy and versatile cellulosic support inhibiting broad spectrum strains: synergy between photodynamic antimicrobial therapy and polymyxin B.

Despite advances achieved in the health field over the last decade, infections caused by resistant bacterial strains are an increasingly important societal issue that needs to be addressed. New approaches have already been developed to overcome this problem. Photodynamic antimicrobial chemotherapy (PACT) could provide a promising alternative method to eradicate microbes. This approach has already inspired the development of innovative surfaces. Interesting results were achieved against Gram-positive bacteria, but it also appeared that Gram-negative strains, especially Pseudomonas aeruginosa, were less sensitive to PACT. However, materials coated with cationic porphyrins have already proven their wide-spectrum activity, but these materials were not suitable for industrial-scale production. The main aim of this work was the design of a large-scale evolutionary material based on PACT and antibiotic prophylaxis. Transparent regenerated cellulose has been simply impregnated with a usual cationic porphyrin (N-methylpyridyl) and an antimicrobial peptide (polymyxin B). In addition to its photophysical properties, this film exhibited a wide-spectrum bactericidal activity over 4days despite daily application of fresh bacterial inoculums. The efficiency of PACT and polymyxin B combination could help to reduce the emergence of bacterial multi-resistant strains and we believe that this kind of material would provide an excellent opportunity to prevent bacterial contamination of bandages or packaging.