Gram-positive Research Articles

Fabrication of bamboo nanocellulose fibril-based food packaging with dual-antimicrobial property

The development of cellulose-based packaging films with excellent antimicrobial properties and biocompatibility has garnered significant attention. In this work, nanocellulose fibrils (NCFs) derived from from bamboo parenchyma cells were utilized to fabricate nanocomposite film with antimicrobial properties. This system exhibited distinct release behaviors for two antimicrobial agents, with the slow release of Ag nanoparticle (AgNP) in the initial stage contributed to delaying food spoilage, while the subsequent pH change in the microenvironment facilitated the release of essential oil of sour orange blossoms (SEO) for secondary antimicrobial activity. Additionally, the composite film demonstrated improved thermal stability and UV blocking capacity. Moreover, AgNP has been proven to enhance the mechanical properties, with the tensile strength of the novel composite film increasing by 34.85 % compared to control group. The water vapor permeability and oxygen permeability of the novel composite film were reduced, which could potentially reduce weight loss and slow down the rate of after-ripening. Following the acidification treatment, the films containing EO@MPN (essential oil encapsulated with metal-polyphenol network) component performed different antimicrobial patterns, indicating their pH-responsive antimicrobial capabilities, and they are effective against both Gram-positive and Gram-negative bacteria. After a 24-h exposure to a food simulant, the release amount of Ag was measured at 67.6 μg/dm2, within the acceptable limit, and the release profile of Ag was characterized. Cytotoxicity and Live/Dead staining tests confirmed that the novel composite film film had no significant toxicity, thus making it safe for application in food preservation. Furthermore, in a 15-day preservation experiment with mangoes, the novel composite film demonstrated the best performance, underscoring its potential as a sustainable antimicrobial packaging material.

A-260 Mapping pediatric urinary tract infections: trends, prevalence and sensitivity to antimicrobials

Abstract Background Urinary tract infections (UTIs) rank among the most prevalent bacterial infections in pediatric populations, with neonates being particularly susceptible. Moreover, UTIs have a propensity for recurrence, posing ongoing health challenges. Prompt diagnosis of pediatric UTIs is crucial for timely and effective treatment, averting potential long-term complications. While clinical signs often suggest UTI diagnosis, additional tests like urinalysis and urine culture are vital to identify the causative pathogen and its antibiotic sensitivity. This study aims to quantify microorganism prevalence in positive pediatric urine tests and assess their antimicrobial resistance profiles. The purpose is, therefore, to offer scientific basis so that there is greater agility in establishing the diagnosis of UTIs in children and indicating the best antibiotic to be used empirically to prevent late consequences. Methods Between January and December 2019, a cross-sectional study was carried out with urine samples from children and adolescents collected in the database of the Clinical Analysis Laboratory of Cuiabá - MT in 2019. Only records of samples collected in the study were included in the study. laboratory of patients of both sexes, age range 1 month to 15 years. Bacterial analyzes were classified according to Gram positive, Gram negative (glucose fermenters or non-fermenters) and the sensitivity profile was standardized according to the Clinical and Laboratory Standards Institute (2019). The data were subjected to descriptive statistical analysis. Results Of the 532 positive urine samples from pediatric patients, enterobacteria were responsible for 435 (81.76%) with E. coli (64.1%) and Proteus mirabilis (15.8%) being the most isolated bacteria, in relation to Gram-positive bacteria 64 (12.03%) main bacteria was Enterococcus faecalis (81.2%) and non-glucose fermenters for 33 (6.2%) corresponding to Pseudomonas aeruginosa. E. coli, with 279 cases, was the most frequently isolated microorganism, representing (64.1%) of the cases. Females were the most affected, in 83.5% there was growth of Enterobacteria, in the Pseudomonas aeruginosa group, 51.5% of cases were female. and in Gram+ girls represented 56.2%. In those tested only for E. coli, the highest sensitivity was observed in fosfomycin (97.82%). Enterobacteriaceae showed high susceptibility to meropenem (99.8%), ertapenem (99.8%), ceftriaxone (93.8%), and ceftazidime (93.6%), but exhibited considerable resistance to sulfamethoxazole/trimethoprim (35.5%), amoxicillin (33.4%) and ampicillin (29.2%). Pseudomonas aeruginosa and gram positive bacteria were sensitive to all antibiotics tested. Conclusions The data indicate that E. coli continues to be the predominant agent in pediatric UTIs, particularly affecting females and the very young age group < 3 years. Regarding sensitivity profiles, bacteria were more sensitive to carbapenems and aminoglycosides. Early diagnosis is crucial to preventing long-term complications associated with UTIs in children. Consequently, this research provides a scientific basis for faster UTI diagnosis and empirical antibiotic selection in pediatrics, which may prevent late adverse outcomes.

Bioremediation of textile wastewater using Bacillus cereus isolated from refinery site: Comparative analysis of free and immobilized cells systems

The textile industries consume a considerable amount of freshwater and discharge untreated or semi-treated pollutants to the environment. Azo dyes, generally employed in textile manufacturing industries, have a hazardous impact on the ecosystem. Incomplete treatment of wastewater containing azo dyes discharges into the aquatic system, which has recalcitrant and toxic properties. Hence, the need for cost-effective and high-performing technologies is essential. In this direction, bacterial degradation is considered an economically viable and efficient technique for the treatment of Active blue (AB) dye. Polyurethane foam (PUF) is a low-cost and hydrophilic material with a microporous structure, which offers an excellent surface-to-volume ratio. Hence, PUF was preferred for the immobilization of isolated bacterial species. For this, a dye-degrading gram-positive bacteria namely Bacillus cereus GS2 IIT (BHU) was isolated from the petroleum sludge. A comparative analysis between free and immobilized cell systems was carried out by varying the process parameters, i.e., batch time, pH, temperature, glucose concentration, and initial AB dye concentration. The corresponding optimum conditions were found to be 6.0 days, 6.5, 30 °C, 1.0 g/L, and 50 mg/L, respectively. The immobilized cell system exceeds the dye removal efficiency (RE) by 10. 7 % compared to the free cell system. The packed bed bioreactor could be able to deliver 98.56 % of dye removal at an inlet loading rate of 30 mg/L d and 50 mg/L of initial dye concentration.

Hydroxyapatite layer evolution on silica-based (45S10P) bioactive glass-ceramic nanoparticles doped with Zn2+ ions: Augmentation of in vitro bioactivity, antibacterial activity and textural modification for bone regeneration

Zinc-incorporated bioactive glasses (BG) and bioactive glass-ceramic (BGC) nanoparticles (BGC-NPs) represent highly adaptable, biodegradable, and bioactive materials in tissue engineering and regenerative medicine. This study delves into the synthesis, characterization and biomedical implications of Zn2+ ions-doped 45S10P spherical BGC-NPs, employing analytical techniques and in vitro assays. The resulting (Zn2++ 45S10P) BGC-NPs, prepared using a modified Strober's method, exhibited spherical morphology with excellent dispersion, as verified by TEM, FE-SEM, and DLS analyses. XRD, FTIR, and FESEM analysis revealed an augmented hydroxyapatite (HAp) layer formation with increasing zinc content. Zeta potential analysis showcased a shift from negative to positive values after immersion in simulated body fluid (SBF), indicating the bioactive potential of the developed BGC-NPs. Hemocompatibility assays indicated the biocompatibility of all BGC-NPs, demonstrating minimal hemolytic effects with incorporating Zn2+ ions below a standard threshold (<5 % lysis). Further, the migration assay revealed the potentiality of the BGC-NPs to stimulate the migration of HeLa cells. Cell viability assays employing MG-63 osteoblast-like cells highlighted enhanced cell viability over time, underscoring their non-toxic nature and potential for tissue regeneration. Antibacterial assays displayed significant inhibitory effects against Gram-negative compared to Gram-positive bacteria, underscoring their potential for anti-infection applications. Overall, the results affirm the promising prospects of Zinc incorporation into 45S10P BGC-NPs for bone tissue regeneration applications.

A-288 Active Surveillance Cultures: Frequency of Microorganisms and Phenotypic Resistance Profile From Brazilian Public Hospitals After COVID-19 Pandemic Peak

Abstract Background Surveillance cultures are routinely used by public health authorities to screen for multidrug-resistant bacteria. Recently, the overuse of antibiotics intensified by the COVID-19 pandemic worldwide brought concerns about potential impacts on the acquisition and/or selective pressure of resistance genes, that in general carried by plasmids, which contribute to the rapid resistance spread within specific bacterial populations. The purpose of this study was to determine the prevalence of multidrug-resistant (MDR) organisms recovered from surveillance cultures (rectal, anal, nasal, and axillary) isolated from several Brazilian public hospitals. Methods Surveillance samples were analyzed from 1st January to 31st December 2023. All the swab samples were collected from patients admitted from high-risk settings or transferred from areas with high rates of MDR organisms. All clinical specimens were inoculated onto a selective media (ChromID media, bioMerieux) and incubated at 35±2°C for 18-24 h. The screening test was performed to Gram-negative bacilli (GNB) using the antibiotics ertapenem, imipenem and meropenem and for Gram-positive Cocci (GPC) screening was tested oxacillin (methicillin) and vancomycin using disc diffusion method. Bacteria identification was performed by MALDI-TOF mass spectrometry (Vitek-MS and bioMerieux) and as required, the minimal inhibitory concentrations (MIC) of antibiotics were determined using the Vitek 2 System (bioMerieux). Results A total of 71,064 rectal swab samples were processed. 4,652/71,064 (6.5%) samples showed positive results for the presence of 5.255 MDR microorganisms. Out of which, 4,477/5,255 (85.2%) were Gram-negative Bacilli (GNB) and 778/5,255 (14.8%) were Gram-positive Cocci (GPC). The majority of the isolated carbapenems resistance was Klebsiella spp. [2,791/5,255 (53.1%)], which the Klebsiella pneumoniae was the predominant species, followed by Acinetobacter baumannii [1,268/5,255 (24.1%)], Pseudomonas aeruginosa [263/5,255 (5%)], Enterobacter spp. [96/5255 (1.8%)], Serratia spp. [31/5,255 (0.6%)], Citrobacter spp. [22/5,255 (0.4%)], and others BGN [6/5,255 (0.2%)]. The resistance to vancomycin and methicillin were observed in 10% (525/5,255) of Enterococcus spp. and 4.8% (253/5,255) of Staphylococcus aureus, respectively. Conclusions The study found that K. pneumoniae carbapenem-resistant and Enterococcus spp. vancomycin-resistant were the main Gram-negative and Gram-positive organisms recovered from surveillance culture samples. However, our data draws attention to the increased cases of carbapenem-resistant Acinetobacter baumannii as the second most frequent pathogen isolated from surveillance samples after the last wave of COVID-19 pandemic. Active surveillance culture for target microorganisms followed by contact precautions to minimize the chance of transmitting MDR organisms from colonized to non-colonized patients consist of an important activity of infection control policy.

Rapid multiplex PCR panel for pneumonia in hospitalised patients with suspected pneumonia in the USA: a single-centre, open-label, pragmatic, randomised controlled trial

The clinical utility of rapid multiplex respiratory specimen PCR panels for pneumonia for patients with suspected pneumonia is undefined. We aimed to compare the effect of the BioFire FilmArraypneumonia panel (bioMérieux, Salt Lake City, UT, USA) with standard of care testing on antibiotic use in a real-world hospital setting. We conducted a single-centre, open-label, pragmatic, randomised controlled trial at the Mayo Clinic, Rochester, MN, USA. Hospitalised patients (aged ≥18years) with suspected pneumonia, from whom expectorated or induced sputum, tracheal secretions, or bronchoalveolar lavage fluid respiratory culture samples (one per individual) could be collected during index hospitalisation, were eligible for inclusion. Samples from eligible participants were randomly assigned (1:1) with a computerised tool to undergo testing with either the BioFire FilmArray pneumonia panel, conventional culture, and antimicrobial susceptibility testing (intervention group) or conventional culture and antimicrobial susceptibility testing alone (control group). Antimicrobial stewardship review in both groups involved an assessment and recommendations for antibiotic modifications based on clinical data and the results from the BioFire FilmArray pneumonia panel, conventional culture, or both. The primary outcome was median time to first antibiotic modification (ie, escalation or de-escalation of antibiotics against Gram-negative and Gram-positive bacteria) within 96h of randomisation, assessed with the Wilcoxon rank-sum test and analysed in a modified intention-to-treat population. This trial is registered with ClinicalTrials.gov (NCT05937126). Between Sept 15, 2020, and Sept 19, 2022, 1547patients were screened for eligibility, of whom 1181 (76·3%) were randomly assigned: 582 (49·3%) to the intervention group and 599 (50·7%) to the control group. In total, 1152participants were included in the modified intention-to-treat analysis, 589 (51·1%) in the control group and 563(48·9%) in the intervention group. For the modified intention-to-treat population, median time to any first antibiotic modification was 20·4h (95% CI 18·0-20·4) in the intervention group and 25·8h (22·0-28·7) in the control group (p=0·076). Median time to any antibiotic escalation was 13·8h (9·2-19·0) in the intervention group and 24·1h (19·5-29·6) in the control group (p=0·0022). Median time to escalation of antibiotics against Gram-positive organisms was 10·3h (6·2-30·9) in the intervention group and 24·6h (19·5-37·2) in the control group (p=0·044); median time to escalation of antibiotics against Gram-negative organisms was 17·3h (10·8-23·3) in the intervention group and 27·2h (21·3-33·9) in the control group (p=0·010). Median time to any antibiotic de-escalation did not differ between groups (p=0·37). Median time to first de-escalation of antibiotics against Gram-positive organisms was 20·7h (17·8-24·0) in the intervention group and 27·8h (22·9-33·0) in the control group (p=0·015); median time to first de-escalation of antibiotics against Gram-negative organisms did not differ between groups (p=0·46). Clinical use of the BioFire FilmArray pneumonia panel might lead to faster antibiotic escalations, including for Gram-negative or Gram-positive bacteria, and faster antibiotic de-escalations directed at Gram-positive bacteria. Additional research is needed regarding antimicrobial de-escalation, especially when antibiotics with broad Gram-negative spectrum are being used, by use of rapid diagnostics in patients with lower respiratory tract infection. bioMérieux.

Epirubicin/folic acid and meropenem loaded on graphene oxide-gelatin can be used as a novel candidate for anti-cancer and antibacterial drug development

Resistance to meropenem and epirubicin poses a significant global threat, particularly in developing nations with constrained health resources. To overcome this problem, nanotechnology provides several promising solutions, including drug delivery systems that can improve the effectiveness of drugs. The objectives of this work is to characterize the anticancer mechanism of Graphene Oxide (GO) coated with Gelatin (Gel) and conjugated with the anticancer drug Epirubicin (EPi), along with functionalization with Folic Acid in SK-OV3 cancer cell lines for the first time. Furthermore, meropenem was loaded onto Graphene Oxide-Gelatin (GO-Gel) to improve its efficacy. The nanocomposites were characterized using FT-IR, XRD, FESEM and EDX. The viability of the ovarian cancer cell lines (SKOV3) and normal ovarian cell lines (HUVEC) after treatment with GO-Gel, Graphene Oxide-Gelatin-Folic acid (GO-Gel-FA), free Epi and Graphene Oxide-Gelatin-Folic acid/ Epirubicin (GO-Gel–FA/Epi) nanocomposite, was studied by the MTT assay. Expression of the TNFα, Bax, Bcl-2, and NF-κB in the GO-Gel–FA/Epi nanocomposite treated cells, were investigated by qRT-PCR. Disc diffusion assay was utilized to assess the antimicrobial activity of free mer and GO-Gel-Mer nanocomposite against two gram-positive bacteria and two gram-negative bacteria. Results demonstrated that The GO-Gel–FA/Epi nanocomposite showed greater cytotoxic effects on SKOV3cells than normal HUVEC cells. The expression of the Bax was upregulated, while the expression of the Bcl-2, TNFα and NF-κB was reduced in GO-Gel–FA/Epi nanocomposite-treated cells. The Graphene Oxide-Gelatin-Meropenem (GO-Gel-Mer) nanocomposite showed a controlled release within 45 h. GO-Gel-Mer nanocomposite showed much more activity against bacteria in comparison to free Mer. GO-Gel-FA/Epi nanocomposite possesses strong anti-proliferative properties against SK-OV3 cancer cells and indicated promising inhibitory candidate for anticancer therapy. The novel synthesized GO-Gel-Mer nanocomposite can be used as an effective antimicrobial nanomaterial against a range of microbial pathogens, including gram-negative and gram-positive bacteria.

Microbiological Profile and Antimicrobial Susceptibility Pattern of Uropathogens Isolated From Pregnant Women Attending a Tertiary Care Hospital in Central India.

Urinary tract infections (UTIs) are more common in females than males, and during pregnancy, frequency is increased due to hormonal changes affecting the anatomy and physiology. If not treated on time, complications may develop in both the mother and fetus. This study aimed to analyze the microbiological (bacterial and yeast) profile of the isolated uropathogens and their antimicrobial susceptibility. Aseptically collected urine specimens were processed by the standard loop method. Identification of uropathogens was done by standard microbiological tests, and antimicrobial susceptibility was performed as per the Clinical and Laboratory Standards Institute (CLSI) guidelines. Out of 400 study participants, UTI was detected in 26.75% (107/400) of cases. Overall, Escherichia coli (42.99%, 46/107) was the most frequently isolated uropathogen followed by Candida species (20.56%, 22/107), whereas, among gram-positive bacteria, Enterococcus faecalis (7.47%, 8/107) was the commonest. Among Enterobacterales, extended-spectrum beta-lactamase (ESBL) and AmpC beta-lactamase (AmpC) production was observed in 19.35% (12/62, eight E. coli and four Klebsiella) and 6.45% (4/62, all E. coli) isolates, respectively. However, all the gram-negative organisms showed 100% (n=70) sensitivity to carbapenems. Among staphylococci, 50% (2/4) of isolates were methicillin-resistant, and high-level aminoglycoside resistance (HLAR) was observed in 75% (6/8) of Enterococcus faecalis isolates, but all were sensitive to vancomycin, linezolid, and nitrofurantoin. Among Candida species, non-albicans Candida (NAC) species (59%, 13/22) outweigh the number of Candida albicans (41%, 9/22), with Candida tropicalis (22.72%, 5/22) being the commonest NAC. All the Candida species were susceptible to voriconazole, whereas fluconazole resistance was observed in 31.81% (7/22) of Candida isolates, with a higher percentage in NAC species (22.72%, 5/22) than in Candida albicans (9.09%, 2/22). UTIs in pregnancy are caused by a spectrum of both gram-negative bacilli and gram-positive cocci. Moreover, there is a rise of both Candida albicans and NAC species as uropathogens, with the emergence of fluconazole resistance. There is an increased prevalence of asymptomatic bacteriuria in pregnancy, which necessitates the screening of pregnant females for UTI using culture and antimicrobial susceptibility testing.

Enhancing the antioxidant, antimicrobial resistance, and anticancer potency of plant-mediated SnO2 and Se doped P-SnO2 NPs by Justicia adhatoda: An in vitro approach

In this work, plant-mediated SnO2 NPs were green synthesized using Justicia adhatoda plant leaf extract, and the synthesized SnO2 powder was doped with Se nanorods at various concentrations (10 %, 20 %, and 30 %). The synthesized sample was characterized using XRD, HRSEM, SEM-EDAX, SEM-EDS, TEM, UV–Vis, and FTIR spectra. Furthermore, we investigated the antibacterial activity of P-SnO2 NPs and Se-doped P-SnO2 NPs at various concentrations of selenium (10 %, 20 %, and 30 %) against three gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumonia) and one gram-positive bacteria (Staphylococcus aureus) using the agar disc diffusion method. Furthermore, an antioxidant activity (DPHH) and cytotoxicity study (HepG2) were performed. Morphological analysis was used to identify the P-SnO2 nanoparticle shape as spherical in shape and the Se nanoparticle shape as a nanorod. The TEM image reveals that 30 % of the Se-doped P-SnO2 NPs exhibit an inner core structure. The TEM image used to identify the size of P-SnO2 NPs is 64 nm, and the Se nanorod is 4.06 nm. The 30 % Se-doped P-SnO2 NPs demonstrate good bacterial activity compared to P-SnO2, and 10 % and 20 % Se-doped P-SnO2 nanoparticles. Antioxidant activity: 30 % Se-doped P-SnO2 NPs show an excellent IC50 value compared to others; the IC50 values of 30 % Se-doped P-SnO2 NPs are 33.71 µg/ml. The cytotoxicity of 30 % Se-doped P-SnO2 NPs exhibits an IC50 value of 121 µg/ml against the HepG2 cell line. So, it is very useful for medicinal applications.

Three hepcidins from the spotted knifejaw (Oplegnathus punctatus) promote antimicrobial activity via TLR/NFκB pathway

Hepcidin belongs to a class of small cationic antimicrobial peptides rich in cysteine. It is synthesized by liver and is widely involved in host antimicrobial, antiviral and other immune responses. We identified and characterized three hepcidin genes (OpHep1, OpHep2 and OpHep3) in spotted knifejaw. All the OpHeps shared high identities with hepcidins in other teleost, containing alpha helix and β-sheets. Three OpHeps were all detected in healthy tissues, with the abundant expression in liver. They were significantly increased after Vibrio harveyi infection in the six immune-relevant tissues (liver, kidney, spleen, gill, skin and intestine). OpHeps knockdown in spotted knifejaw liver cells affected the mRNA levels of inflammation-related genes, including il1β, il6, il8, and nfκb. Further, the recombinant hepcidin proteins were effective in suppressing the growth of both Gram-negative and Gram-positive bacteria. To identify the function of OpHeps in vivo, we performed the overexpression of three OpHeps in zebrafish, and found OpHeps could significantly induce immune-related genes expression in transgenic zebrafish, including myd88, il10, il21, il16, tlr1, tlr3 and lysozyme. When infected with V. harveyi, OpHeps transgenic zebrafishes had a higher survival rate than wild-type zebrafishes. The expression of myd88, il10, il8, il1β, nfκb and lysozyme were all significantly up-regulated in transgenic fishes during bacterial infection. In summary, these results indicated that hepcidin could protect fish fight against pathogen through TLR/NFκB signaling cascade and Lysozyme. Three OpHeps would be potential targets for prevention of bacterial infections in aquaculture industry of spotted knifejaw, which provided a new idea for the molecular breeding of fish disease resistance.

Viability and antibacterial properties of Ba2-x AgxFeMoO6(x=0.0, 0.05) double perovskite oxides

Double perovskite Ba2FeMoO6 (BFMO) and doped with Ag ions were synthesized via the sol-gel method. The structural and antibacterial properties and viability of the samples were systematically investigated. The results of the Rietveld refinement indicated that both samples exhibited a single phase with cubic structure and space group Fm-3m. The substitution of Ag ions led to an increase in the unit cell and lattice parameters of BFMO, resulting in a change in the sample's morphology. The direct band gap (∼2eV) was measured for samples by Diffuse Reflectance Spectroscopy (DRS). Antibacterial activity of the Ba2FeMoO6 and Ba1.95Ag0.05FeMoO6 samples was assessed on the Gram-positive bacteria (Staphylococcus aureus) and the Gram-negative bacteria (Escherichia coli) using the spread plate method. The results showed that the samples were effective against Staphylococcus aureus but not against Escherichia coli. The sample doped with Ag ions showed a higher antibacterial effect than the pristine sample. An MTT assay of the normal fibroblast cell line treated with an Ag-doped sample showed a higher percentage of viability.

Biocompatible and Safe Decellularized Spinach With Antibacterial and Wound Healing Activity.

Creating acellular vascularized constructs from animal and plant tissue is one of the well-known strategies for scaffold assembly. Decellularization takes an important position among these strategies. The most common method is chemical decellularization. This approach employs high concentrations of detergents, primarily Triton X-100, sodium dodecyl sulfate (SDS), and sodium hypochlorite (SH). In this work, novel techniques for decellularizing spinach were developed using detergents frequently utilized in laboratories. Spinach leaves were decellularized using Tween-20, SDS, and SH at low concentrations to generate an acellular plant matrix for tissue engineering. We measured the quantities of DNA and protein, as well as the decellularization using hematoxylin and eosin (H&E) staining. The biocompatibility and capacity of the biostructures to stimulate fibroblast wound healing were assessed using MTT and the Scratch assay. The antibacterial activity of the scaffolds was also tested against a gram-positive bacterium, Staphilococcus aureus, which is a common pathogen associated with wound healing. The best shape, evident vascularization, and good biocompatibility were seen in the Tween-20 decellularized samples at 1% concentration at 21°C and 37°C through the enhancement of cell proliferation and wound healing. In terms of antibacterial activity, all scaffold samples had a significant effect on Staphilococcus aureus, where the number of bacterial colonies in all six scaffold groups became zero after 4 h of treatment. The scaffolds also showed a 100% kill rate on Staphilococcus aureus, which could avoid wound infection during the repair process, and that can be suggested as a scaffold for tissue engineering applications and an important constituent for pharmacological activities.

Species diversity of potato endophytic bacteria in Yakutia

Abstract Potato is an important agricultural crop, and the development of methods to increase its resistance to diseases and yields increase is a current task. One of the approaches to solving this problem is to study potato endophytic microorganisms and their potential use as biocontrol agents. Some of the endophytes act as stimulators of plant growth and development, and some as pathogens of various diseases. In many cases, they not only do not harm the host plant, but even have a beneficial effect on the growth and development. Some endophytes may be antagonists against various phytopathogenic microorganisms. The purpose of our research is to isolate and characterize endophytic bacteria from potato plants of the Yakutyanka variety. It was found that of the 45 isolates, 30 (66%) are nonspore-forming, and the remaining 15 (34%) are spore-forming. The main number of isolates 38 (65%) are gram-negative bacteria and only 7 (15%) are gram-positive bacteria. The main amount of endophytic bacteria in the potato plant is contained in the roots, and the least amount of bacteria is in the leaves and stems. The endophytic microbiota can be very diverse. There are more than 200 genera of microorganisms that can live inside plants. These microorganisms belong to different groups as bacteria, fungi and viruses. The isolated bacterial species were mainly of the following phylum: Proteobacteria, Bacteroidetes, Actinobacteriota, Verrucomicrobiota, Bdellovibrionota, Proteobacteria, Firmicutes, Bdellovibrionota. Lysobacter antibioticus, a representative of the Pseudomonadota phylum, and Peredibacter starrii, a representative of the Bdellovibrionota phylum, are of interest for further study. In the future, research will continue to identify their stimulating, protective features for the use and development of biological products, taking into account natural and climatic conditions, to improve the yield and quality of potatoes.

Polydopamine-modified 3D flower-like ZnMoO4 integrated MXene-based label-free electrochemical immunosensor for the food-borne pathogen Listeria Monocytogenes detection in milk and seafood

Listeria monocytogenes is a gram-positive bacterium that causes listeriosis in humans. This contaminates the ready-to-eat food products and compromises their safety. Thus, detecting its presence in food samples with high sensitivity and reliability is necessary. Herein, we propose a label-free electrochemical immunosensor based on a mussel-inspired polydopamine-modified zinc molybdate/MXene (PDA@ZnMoO4/MXene) composite for effective and rapid detection of L. monocytogenes in food products. Spectrophotometry approaches were employed to examine the resulting composites. Voltammetry and impedimetry techniques were used to confirm the step-by-step assembly of the immunosensor and its sensitive detection of L. monocytogenes in various food products, such as milk and smoked seafood. The results demonstrated the practicality of the constructed immunosensor, with an appreciable linearity of 10–107 CFU/ ml and a reasonably low detection limit (LOD, 12 CFU/ml). Moreover, the immunosensor exhibited excellent selectivity for microbial cocktails and acceptable repeatability, reproducibility, and storage stability. Thus, we believe that the proposed sensitive, reliable, and label-free immunosensor based on the PDA surface modification technique for detecting L. monocytogenes can be extended to monitor various food-borne pathogens to ensure food safety.

Folic acid functionalized Ag@MOF(Ag) decorated carboxymethyl starch nanoparticles as a new doxorubicin delivery system with inherent antibacterial activity

Considering the benefits of controlled drug delivery in cancer treatment, as well as the importance of biological macromolecules in this area, herein, the pre-synthesized carboxymethyl starch (CMS) was converted to CMS nanoparticles (CMS NPs) in one easy nanoprecipitation way. Thereafter, the Ag@MOF(Ag) was in situ synthesized in the presence of pre-prepared CMS NPs (CMS NPs/Ag@MOF(Ag)). Eventually, the functionalization with folic acid (FA) obtained the CMS NPs/Ag@MOF(Ag)-FA. The success of the accomplished process was approved by doing several techniques, including FT-IR, XRD, EDX, AFM, etc. The SEM analysis showed a combination of rod-like and spherical-like morphology for the fabricated bio-nanocomposite. The generated CMS NPs/Ag@MOF(Ag)-FA with a surface area of 10.595 m2/g displayed a pore size of 13.666 nm and 82.99 % of doxorubicin (DOX) loading efficiency (DOX@CMS NPs/Ag@MOF(Ag)-FA). The 38.46 % and 58.19 % of loaded DOX were released respectively within 240 h at pH 7.4 and pH 5.0, referring to the pH-responsivity of the constructed system. 27.25 % of inhibitory effects on HeLa cells were obtained for the drug-loaded bio-nanocomposite. The CMS NPs/Ag@MOF(Ag)-FA also displayed an inherent antibacterial activity towards two common gram-negative and gram-positive bacteria. All of these results can contribute to developing polysaccharide-based porous systems in controlled cancer therapy.

Optimizing phage-based mutant recovery and minimizing heat effect in the construction of transposon libraries in Staphylococcus aureus

Staphylococcus aureus (S. aureus), particularly Methicillin-resistant S. aureus (MRSA), poses a significant global public health threat, necessitating advanced methodologies to enhance our understanding of this organism at the omics levels. This study introduces a refined protocol for constructing and curing high-density transposon mutant (tn-mutant) libraries in S. aureus, addressing the challenges associated with low transductant yields, and the complex genetic manipulation mechanism in Gram-positive bacteria. Our methodology employs a Himar1 transposon based on a two-plasmid system, leveraging Himar1’s high insertional efficiency in AT-rich organisms. Enhanced transduction efficiency was achieved through chloramphenicol pre-treatment and the use of modified enriched media. Complementing this, an optimized plasmid curing procedure ensured a representative and stable tn-mutant library. The protocol was successfully applied to multiple S. aureus strains, demonstrating an increase in mutant recovery and reduced post-curing impact. The method offers a robust approach for Transposon Insertion Sequencing (TIS) applications in S. aureus, enabling deeper insights into survival, resistance, and pathogenicity mechanisms. This protocol holds a significant potential for accelerating the construction of tn-mutant libraries in various S. aureus strains.

Investigation of Antimicrobial Compounds Produced by Endolichenic Fungi in Different Culture Media.

Continuous use of synthetic fungicides has led to explosive emergence of fungicide-resistant microbes. Therefore, there are urgent needs for environmentally friendly antimicrobial agents with novel modes of action. This study investigated endolichenic fungi (ELF) as a source of antimicrobial compounds against various plant pathogens. We utilized an One Strain MAny Compounds (OSMAC) approach to enhance the chemical diversity of fourteen ELF. This involved cultivation of ELF in four growth media and subsequently assessing antimicrobial activities of culture extracts. Nearly half of the culture extracts exhibited antimicrobial activity against a Gram-positive bacterium, but showed minimal activity against Gram-negative bacteria tested. Notably, culture extracts from two ELF, Chaetomium globosum and Nodulisporium sp., demonstrated significant inhibitory effects against plant pathogenic fungi. LC-MS/MS-based metabolome profiling confirmed the presence of known bioactive compounds like cyclic dipeptides and chaetoglobosins. These findings highlight the effectiveness of combining OSMAC and metabolomics for identifying antimicrobial agents for agricultural use.

Dalbavancin-resistant Staphylococcus epidermidis in vivo selection following a prosthetic joint infection: phenotypic and genomic characterization.

Dalbavancin is a lipoglycopeptide antibiotic with a wide spectrum of activity against Gram-positive bacteria, including MDR isolates. Its pharmacokinetic properties and administration patterns could be useful for the treatment of bone and joint infections, especially prosthetic joint infections (PJIs). We report the case of an 80-year-old man who experienced an acute periprosthetic joint infection of his right total knee arthroplasty (TKA). A DAIR procedure was done with tissue sampling, which allowed identification of a linezolid-resistant MDR S. epidermidis (LR-MDRSE) strain. The patient was then treated with dalbavancin (four injections). We studied the phenotypic and genomic evolution of the strains and plasma through concentrations of dalbavancin at different points in time. After four injections (1500 mg IV) of dalbavancin over a 6 month period, the dalbavancin MIC increased 4-fold. Calculated fAUC0-24/MIC ratios were 945, 1239 and 766.5, respectively, at Days 49, 71 and 106, assuming an MIC of 0.032 mg/L. The PFGE dendrogram revealed 97% similarity among all the isolates. These results suggest acquisition by the S. epidermidis strain of dalbavancin resistance when the patient underwent dalbavancin treatment. A 4-amino-acid deletion in the walK gene coinciding with the emergence of phenotypic resistance was revealed by WGS without any other relevant indels. Despite dalbavancin treatment with pharmacokinetic management, emerging dalbavancin resistance in S. epidermidis was observed, resulting in treatment failure. This outcome led to a prosthesis revision and long-term suppressive antibiotic therapy, with no recurrence of PJI after an 18 month follow-up.

Computational and in vitro analyses of the antibacterial effect of the ethanolic extract of Pluchea indica L. leaves.

The most common gram-negative, Escherichia coli, and gram-positive bacteria, Bacillus spp., have evolved different mechanisms that have caused the emergence of multi-drug resistance. As a result, drugs that block the bacterial growth cycle are needed. Here, in silico and in vitro studies were performed to assess compounds in the Pluchea indica leaf extract, a medicinal plant, that can inhibit bacterial proteins. Briefly, P. indica leaves were extracted using ethanol. The crude extract was then subjected to gas chromatography-mass spectrometry for metabolite screening. Molecular docking simulations with rhomboid protease (Rpro) (Protein data bank ID number: 3ZMI from E. coli and filamenting temperature-sensitive mutant Z (FtsZ) protein data bank ID number: 2VAM from Bacillus subtilis were performed. Moreover, the well diffusion method was used to confirm the antibacterial activity of P. indica leaf extract. A total of 10 compounds were identified in the P. indica extract and used for computational analysis. Based on drug-likeness prediction, P. indica compounds may be drug-like molecules. Binding affinity tests indicated that 10,10-Dimethyl-2,6-dimethylenebicyclo(7.2.0)undecan-5.β.-ol and 11,11-Dimethyl-4,8-dimethylenebicyclo(7.2.0)undecan-3-ol had the most negative values. Accordingly, these compounds may be potential ligands that bind to bacterial proteins. The root mean square fluctuation values was <2 Å, indicating stable fluctuation binding for the ligand-protein complex. According to in vitro antibacterial assays, a high concentration (50%) of the P. indica extract markedly inhibited E. coli and B. subtilis, with inhibitory zone diameters of 31.86±1.63 and 21.09±0.09 mm, respectively. Overall, the compounds in the P. indica leaf extract were identified as functional inhibitors of E. coli and B. subtilis proteins via in silico analysis. This may facilitate development of antibacterial agents.

Safety and efficacy of personalised versus standard dosing of linezolid in patients with sepsis (SePkLin): a pragmatic, multicentre, randomised, controlled and superiority clinical trial protocol.

Linezolid is a broadly used antibiotic to treat complicated infections caused by gram-positive bacteria. Therapeutic drug monitoring of linezolid concentrations is recommended to maximise its efficacy and safety, mainly haematological toxicity. Different pharmacokinetic/pharmacodynamic targets have been proposed to improve linezolid exposure: the ratio of the area under the concentration-time curve during a 24-hour period to minimum inhibitory concentration (MIC) between 80 and 120; percentage of time that the drug concentration remains above the MIC during a dosing interval greater than 85% and the trough concentration between 2 and 7 mg/L. This clinical trial aims to evaluate the safety, efficacy and the clinical and economic utility of personalised dosing of linezolid using Bayesian forecasting methods to attain pharmacokinetic/pharmacodynamic targets, known as model-informed precision dosing. This is a pragmatic, multicentre, randomised, parallel, controlled, phase IV and low intervention trial. Participants will be randomly assigned 1:1 to each group (n=346 per group). Control group will receive the standard dose of linezolid. Intervention group will receive personalised dosage of linezolid based on pharmacokinetic-pharmacodynamic adjustments. The primary outcome will be the incidence of thrombocytopenia in both groups. This protocol was approved by the Ethical Committee of the Investigation with Medicines of Galicia (code 2022/140) and authorised by the Spanish Agency for Medicines and Medical Devices. The trial is implemented in accordance with the Declaration of Helsinki and the international ethical and scientific quality standard, the Good Clinical Practice. The results will be published in peer-reviewed journals. EudraCT registration code: 2022-000144-30.