Gram-positive Research Articles

Investigation of Osteomyelitis Inducing Methicillin-Resistant Staphylococcus aureus Inhibition Effect by Strontium-Substituted Borate Bioactive Glasses.

Borate glass transforms into hydroxycarbonate apatite more rapidly than silicate glass. This research aims to evaluate strontium's structural and biological effects on borate bioactive glass (BBG) and the influence of strontium concentrations (0%, 5%, 10%, and 15% Sr) prepared via the sol-gel method. The study reveals significant findings related to the physicochemical properties of the glass. Immersion of the glass powders in a simulated body fluid (SBF) led to the development of a hydroxyapatite (HAP) layer on the glass surfaces. This transformation was verified through X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) analyses. In particular, 5% strontium exhibited gradual degradation, resulting in particle sizes below 100 nm. The BBG-15%Sr demonstrates heightened pathogenic activity as it shows a significant inhibition zone of 14 mm at 250 μg/mL, surpassing other substituted BBGs. It effectively combats Gram-positive bacteria, completely inhibiting MRSA growth at 50 μg/mL. This underscores its robust biofilm disruption capabilities, eradicating biofilms, even at minimal concentrations after prolonged exposure. C. elegans when subjected to BBG-15%Sr shows less ROS production when compared with the others. Moreover, the results suggest that the modified glass could be a potential material for the treatment of osteomyelitis-affected bone repair.

Synthesis, Antibacterial Effects, and Toxicity of Licochalcone C.

Drug-resistant bacteria constitute a big barrier against current pharmacotherapy. Efforts are urgent to discover antibacterial drugs with novel chemical and biological features. Our work aimed at the synthesis, evaluation of antibacterial effects, and toxicity of licochalcone C (LCC), a naturally occurring chalcone. The synthetic route included six steps, affording a 10% overall yield. LCC showed effects against Gram-positive bacteria (MIC = 6.2-50.0 µg/mL), Mycobacterium species (MIC = 36.2-125 µg/mL), and Helicobacter pylori (MIC = 25 µg/mL). LCC inhibited the biofilm formation of MSSA and MRSA, demonstrating MBIC50 values of 6.25 μg/mL for both strains. The investigations by fluorescence microscopy, using PI and SYTO9 as fluorophores, indicated that LCC was able to disrupt the S. aureus membrane, similarly to nisin. Systemic toxicity assays using Galleria mellonella larvae showed that LCC was not lethal at 100 µg/mL after 80 h treatment. These data suggest new uses for LCC as a compound with potential applications in antibacterial drug discovery and medical device coating.

Synthesis, Mechanism of Action and SAR Studies on the Cyclic Lipopeptide Antibiotic Daptomycin

Synthesis, Mechanism of Action and SAR Studies on the Cyclic Lipopeptide Antibiotic Daptomycin

Cefradine Schiff Bases and their Metal Salts as Potential Anti-Infective Agents

Introduction: A series of schiff bases(3-8) were synthesized by the reaction of cefradine with six different aldehydes/ketones. Method: These Schiff bases (3-8) were treated with different bases/salts (NaOH, KOH, Ca(OH)2, Ba(OH)2, Ag(NO)3) to get their metal salts. The structures of the products were as-certained by spectroscopic data. The synthesized compounds were tested for biological activities against Staphylococcus aureus (gram-positive bacterium) and Escherichia coli (gram-negative bacterium). Results: In general, low activities in most of the synthesized compounds were observed. Conclusion: A general reduction in the activities of most of the synthesized compounds in com-parison to cefradine can be linked to the unavailability of the free amino group of cefradine by its involvement in the synthesis of imine derivatives. conclusion: All the synthesized compounds were evaluated for anti-bacterial activity against two bacterial strains S.aureus and E.coli. Compound 23 shows the best activity against both the strains S. aureus and E.coli. Compounds 18, 5, 11 and 27 show good activity against S. aureus while compounds 5, 26, 27, 3, 13, 18, 19 show good activity against E. coli. other: Reduced activities of most of the synthesized derivatives in comparison to cefradine can be linked to unavailability of free NH2 group of cefradine for any interaction by its involvement in derivatization.

Antibacterial activity of aqueous and methanol extracts of <i>Jatropha tanjorensis</i> and <i>Adansonia digitata</i> against selected clinical bacteria pathogens

The powdered plant parts (bark, stem, and leaf) were extracted with methanol, and cold and hot water using the maceration method. A modified agar well diffusion technique was used for the assessment of the antibacterial activities of the aqueous and methanol extracts of J. tanjorensis and A. digitata. The methanol extract of A. digitata bark gave the highest yield of 75 % while the lowest yield was observed with the cold water extract of A. digitata bark of 33 %. The phytochemical screening showed an abundance of alkaloids, terpernoids, saponins, flavonoids, tannin, glycoside, and phenol. The bark, leaf, and stem of J. tanjorensis and A. digitata showed varying degrees of antibacterial activities. against the Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Proteus spp, and Klebsiella spp) and Gram-positive bacteria (Staphylococcus aureus, Streptococcus pyogenes and Streptococcus pneumonia). The bark, stem, and leaf extract of J. tanjorenis significantly (p < 0.05) inhibited all the pathogens except P. aeruginosa and S. aureus.The result of the minimum bactericidal concentration MBC for the combined extracts of A. digitata and J. tanjorenis subfractions showed that the extracts have greater antibacterial activities at concentrations not lesser than 100 mg/ml. Thus, J. tanjorensis and A. digitata could be used as potent herbal remedies to mitigate the adverse effects of Gram-negative and positive clinical pathogens. Thus, the aim of this study was to evaluate the antibacterial activity of aqueous and methanol extracts of Jatropha tanjorensis and Adansonia digitata against selected Clinical bacteria pathogens.

Early Therapeutic Drug Monitoring Optimizes Teicoplanin Use in Febrile Neutropenic Patients with Hematological Malignancies.

A target trough concentration (Cmin) of teicoplanin ≥ 15-20mg/L between the fourth and sixth day has been suggested for severe infections or management of febrile neutropenia (FN). Owing to no reports discussing the impact of early target attainment on treatment outcomes, this study aimed to evaluate the dose-Cmin relationship and clinical outcome and estimate the optimal early target Cmin for FN in patients with hematological malignancies. This single-center, prospective study enrolled patients with hematological malignancies who were treated with teicoplanin either as an empirical antibiotic for FN or as targeted treatment for Gram-positive bacteria. Blood samples were collected on day three (48h) post-loading doses, day5 (96h), and day8 (when applicable) and determined by ultrahigh-pressure liquid chromatography-triple quadruple mass spectrometry. A total of 117 samples from 47 patients with FN (27 men, 20 women) were consecutively analyzed. A two-tailed αvalue of 0.05 was considered statistically significant. The mean Cmin values at 48h, 96h, and on day8 were 23.4, 21.4, and 27.8mg/L, respectively. The patients achieving Cmin ≥ 20mg/L at 48h had a higher likelihood of treatment success. The areas under the receiver operating characteristic curves were 0.71 for clinical efficacy and the cutoff value of Cmin at 48h was 18.85mg/L (95% confidence interval 0.55-0.87; P = 0.018). The Cmin of teicoplanin after completion of loading doses could predict the treatment response, with a target concentration ≥ 18.85mg/L.

Comparative Genomics Unveils Functional Diversity, Pangenome Openness, and Underlying Biological Drivers among Bacillus subtilis Group.

The Bacillus subtilis group (Bs group), with Bacillus subtilis as its core species, holds significant research and economic value in various fields, including science, industrial production, food, and pharmaceuticals. However, most studies have been confined to comparative genomics analyses and exploration within individual genomes at the level of species, with few conducted within groups across different species. This study focused on Bacillus subtilis, the model of Gram-positive bacteria, and 14 other species with significant research value, employing comparative pangenomics as well as population enrichment analysis to ascertain the functional enrichment and diversity. Through the quantification of pangenome openness, this work revealed the underlying biological drivers and significant correlation between pangenome openness and various factors, including the distribution of toxin-antitoxin- and integrase-related genes, as well as the number of endonucleases, recombinases, repair system-related genes, prophages, integrases, and transfer mobile elements. Furthermore, the functional enrichment results indicated the potential for secondary metabolite, probiotic, and antibiotic exploration in Bacillus licheniformis, Bacillus paralicheniformis, and Bacillus spizizenii, respectively. In general, this work systematically exposed the quantification of pangenome openness, biological drivers, the pivotal role of genomic instability factors, and mobile elements, providing targeted exploration guidance for the Bs group.

In Vitro and In Silico Characterization of N-Formylated Two-Peptide Bacteriocin from Enterococcus faecalis CAUM157 with Anti-Listeria Activity.

Enterococcus faecalis CAUM157 (KACC 81148BP), a Gram-positive bacteria isolated from raw cow's milk, was studied for its bacteriocin production. The antimicrobial activity of CAUM157 was attributed to a two-peptide class IIb bacteriocin with potent activity against food-borne pathogen Listeria monocytogenes and periodontal disease-causing pathogens (Prevotella intermedia KCTC 15693T and Fusobacterium nucleatum KCTC 2488T). M157 bacteriocins exhibit high temperature and pH stability and resist hydrolytic enzyme degradation and detergent denaturation, potentially due to their structural conformation. Based on amino acid sequence, M157A and M157B were predicted to be 5.176kDa and 5.182kDa in size, respectively. However, purified bacteriocins and chemically synthesized N-formylated M157 peptides both showed 5.204kDa (M157A) and 5.209kDa (M157B) molecular mass, confirming the formylation of the N-terminal methionine of both peptides produced by strain CAUM157. Furthermore, the strain demonstrated favorable growth and fermentation with minimal bacteriocin production when cultured in whey-based media, whereas a 1.0% tryptone or soytone supplementation resulted in higher bacteriocin production. Although Ent. faecalis CAUM157 innately harbors genes for virulence factors and antimicrobial resistance (e.g., tetracycline and erythromycin), its bacteriocin production is valuable in circumventing the need for live microorganisms, particularly in food applications for pathogen control.

Combined effect of SAR-endolysin LysKpV475 with polymyxin B and Salmonella bacteriophage phSE-5.

Endolysins are bacteriophage (or phage)-encoded enzymes that catalyse the peptidoglycan breakdown in the bacterial cell wall. The exogenous action of recombinant phage endolysins against Gram-positive organisms has been extensively studied. However, the outer membrane acts as a physical barrier when considering the use of recombinant endolysins to combat Gram-negative bacteria. This study aimed to evaluate the antimicrobial activity of the SAR-endolysin LysKpV475 against Gram-negative bacteria as single or combined therapies, using an outer membrane permeabilizer (polymyxin B) and a phage, free or immobilized in a pullulan matrix. In the first step, the endolysin LysKpV475 in solution, alone and combined with polymyxin B, was tested in vitro and in vivo against ten Gram-negative bacteria, including highly virulent strains and multidrug-resistant isolates. In the second step, the lyophilized LysKpV475 endolysin was combined with the phage phSE-5 and investigated, free or immobilized in a pullulan matrix, against Salmonella enterica subsp. enterica serovar Typhimurium ATCC 13311. The bacteriostatic action of purified LysKpV475 varied between 8.125 μg ml-1 against Pseudomonas aeruginosa ATCC 27853, 16.25 μg ml-1 against S. enterica Typhimurium ATCC 13311, and 32.50 μg ml-1 against Klebsiella pneumoniae ATCC BAA-2146 and Enterobacter cloacae P2224. LysKpV475 showed bactericidal activity only for P. aeruginosa ATCC 27853 (32.50 μg ml-1) and P. aeruginosa P2307 (65.00 μg ml-1) at the tested concentrations. The effect of the LysKpV475 combined with polymyxin B increased against K. pneumoniae ATCC BAA-2146 [fractional inhibitory concentration index (FICI) 0.34; a value lower than 1.0 indicates an additive/combined effect] and S. enterica Typhimurium ATCC 13311 (FICI 0.93). A synergistic effect against S. enterica Typhimurium was also observed when the lyophilized LysKpV475 at ⅔ MIC was combined with the phage phSE-5 (m.o.i. of 100). The lyophilized LysKpV475 immobilized in a pullulan matrix maintained a significant Salmonella reduction of 2 logs after 6 h of treatment. These results demonstrate the potential of SAR-endolysins, alone or in combination with other treatments, in the free form or immobilized in solid matrices, which paves the way for their application in different areas, such as in biocontrol at the food processing stage, biosanitation of food contact surfaces and biopreservation of processed food in active food packing.

Positive effects of Moringa oleifera and Moringa stenopetala seed and leaf extracts against selected bacteria

Moringa oleifera is hailed as the “miracle tree” for its impressive catalog of nutritional, medicinal, and water purification benefits. A (sub)tropical plant with a rapid growth rate (3–5 m in a single season), Moringa has proven beneficial in multiple ways in developing regions around the world. In addition to its high nutrient content and water clarifying properties, Moringa seed and leaf extracts have shown potential as natural antibacterial agents. Based on this, we anticipated that extracts from multiple species of Moringa would exhibit potentially useful antibacterial properties against a range of bacterial species. To explore this, both disk diffusion and minimum inhibitory concentration (MIC) culture techniques were employed to assess the inhibitory effects of seed and leaf extracts from M. oleifera and M. stenopetala against species of bacteria commonly used in research and teaching laboratories. Aqueous seed extracts from both Moringa species showed broad-spectrum activity but were especially effective at inhibiting the growth of Gram-positive bacteria, including species of Staphylococcus, Streptococcus, and Bacillus. Moringa leaf extracts also exhibited antibacterial activity, with ethanolic leaf extracts showing greater efficacy than aqueous leaf extracts in disk-diffusion assays. Temporary acidification (1 h at pH 2) of Moringa seed and leaf extracts had a detrimental effect on their antibacterial activity. MIC assays using Moringa leaf extracts also showed more pronounced inhibition of Gram-positive bacteria (MIC = 12.5% v/v) versus Gram-negative species (MIC = 25% v/v). These results are of particular relevance in tropical areas where pharmaceutical drugs are scarce but Moringa is widely available and often used as a nutritional supplement. Moreover, the rising threat of multi-drug resistant pathogens lends greater importance to the study of antibacterial plant products that ultimately may find application in the clinical setting.

Identification of Secondary Metabolites from Actinomycetes Isolated from the Hilly Region of Nepal

Actinomycetes are a unique class of Gram-positive bacteria with a fungus-like filamentous mycelium. They are often called ‘antibiotics factories’ because they can produce many potent secondary metabolites. At present, multidrug-resistant (MDR) pathogens are the main problem for humans and animals and to overcome this problem, more potent antibiotics are urgently required. Fortunately, Nepal has great geographical and climatic diversity serving as a home for various actinomycetes. This study identified several actinomycetes using morphological and biochemical assays from seven soil samples collected from different elevations in Nepal. The primary objective of this study was to screen the potent metabolites-producing actinomycetes. For this purpose, antimicrobial assays of seven isolates were carried out against Escherichia coli ATCC 25922, Salmonella typhi ATCC 14028, Shigella sonnei ATCC 25931, and Staphylococcus aureus ATCC 43300. The sample BT36 demonstrated the highest zone of inhibition against the tested microorganisms among others. Similarly, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of all isolates were carried out. Among them, the MIC of samples BT36, PT7, and AB1 were found to be 1.952 mg/mL, 0.012 mg/mL, and 0.029 mg/mL, respectively. Ethyl acetate extracts of resulting potent isolates PT7 and AB1 were subjected to mass spectrometric analysis. A total of 22 bioactive compounds were annotated from liquid chromatography-high resolution mass spectroscopy (LC-HRMS), including epopromycin A, myxopyronin B, gilvocarcin HE, and okilactomycin A. It is concluded that this study will be useful in setting up a strategy to isolate useful secondary metabolites from soil microbes from the hilly region of Nepal.

Design, Synthesis and Biological Evaluation of Novel Gypsogenin Derivatives as Potential Anticancer and Antimicrobial Agents.

Natural compounds are important sources for the treatment of chronic disorders such as cancer and microbial infectious disorders. In this research, Gypsogenin and its derivatives (2 a-2 f) have been tested against different cancer cell lines (MCF-7, HeLa, Jurkat and K562 cell lines) and further analyzed for cell proliferation, cell death type, and for act of the mechanism. Cell proliferation was determined by the MTT method and cell death types were analyzed with HO/PI staining. Fibroblast Growth Factor 1 (FGF-1), Interleukin 1 (IL-1), Interleukin 6 (IL-6), and Tumor Necrosis Factor Alpha (TNF-α), key players in breast cancer development and progression, were determined by Elisa kits. Results showed that compound 2 e inhibited the MCF-7 cell line proliferation with an IC50 value of 0.66±0.17 μM with 93.38 % apoptosis rate. Compound 2 e also decreased FGF-1, IL-1, IL-6, and TNF-α levels. Molecular docking studies performed in the binding site of FGFR-1 indicated that compound 2 e formed key hydrogen bonding with Arg627 and Asn568. Besides, compounds 2 a-2 f were evaluated for their antimicrobial activities against gram-negative and gram-positive bacteria and C. albicans via the microdilution method. Overall, compound 2 e stands out as a potential anticancer agent for future studies.

The Significance of Measuring Human Beta Defensin-2 in Patients with Diabetic Foot Ulcer

Background: Approximately one out of every four diabetic patients will acquire a diabetic foot ulcer (DFU) in their lifetime. Human beta-defensin (HBD) promotes wound healing. Objective: To find the correlation between HBD-2 and ulcer grade, diabetic foot infection, and the type of bacterial isolates recovered from bacteriological culture. Methods: We included forty-nine patients with DFU and obtained blood samples and wound swabs from each participant between October 2023 and December 2023. We measure HBA1c using the ARCHITECT c4000 system, and HBD-2 using the ELISA technique. The classification of DFU was done based on Wagner’s method. Swabs from foot ulcers are used for isolation and preliminary identification of bacteria based on standard guidelines. The VITEK® 2 system confirmed the diagnosis. Results: The patients' mean age was 57.31 years, and the male/female ratio was 1.57. Grade 3 was the most common type (57.1%). We observed the highest significant level of HBD-2 in grade one, non-infected DFU patients, and ulcers infected with gram-positive bacteria. Patients infected with Staphylococcus aureus showed the highest HBD-2 level according to the type of isolate, while patients infected with Proteus mirabilis showed the lowest level. Conclusions: HBD-2 levels might reflect the impaired or dysregulated immune response in patients with type 2 diabetes mellitus (T2DM) and have a negative impact on wound healing. The type of bacteria influenced this level, with Staphylococcus aureus infections reporting the highest level.

Evaluation of hemostatic, anti-inflammatory, wound healing, skin irritation and allergy, and antimicrobial properties of active fraction from the ethanol extract of Chromolaena odorata (L.) R.M. King & H. Rob

Ethnopharmacological relevanceChromolaenaodorata (L.) R.M. King & H. Rob, a perennial herb, has been traditionally utilized as a herbal remedy for treating leech bites, soft tissue wounds, burn wounds, skin infections, and dento-alveolitis in tropical and subtropical regions. Aim of the studyThe present study was to analyze the active fraction of C. odorata ethanol extract and investigate its hemostatic, anti-inflammatory, wound healing, and antimicrobial properties. Additionally, the safety of the active fraction as an external preparation was assessed through skin irritation and allergy tests. Materials and methodsThe leaves and stems of C. odorata were initially extracted with ethanol, followed by purification through AB-8 macroporous adsorption resin column chromatography to yield different fractions. These fractions were then screened for hemostatic activity in mice and rabbits to identify the active fraction. Subsequently, the hemostatic effect of the active fraction was assessed through the bleeding time of the rabbit ear artery in vivo and the coagulant time of rabbit blood in vitro. The anti-inflammatory activity of the active fraction was tested on mice ear edema induced by xylene and rat paw edema induced by carrageenin. Furthermore, the active fraction's promotion effect on wound healing was evaluated using a rat skin injury model, and skin safety tests were conducted on rabbits and guinea pigs. Lastly, antimicrobial activities against two Gram-positive bacteria (G+, Staphylococcus aureus and S. epidermidis) and three Gram-negative bacteria (G−, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa) were determined using the plate dilution method. ResultsThe ethanol extract of C. odorata leaves and stems was fractionated into 30%, 60%, and 90% ethanol eluate fractions. These fractions demonstrated hemostatic activity, with the 30% ethanol eluate fraction (30% EEF) showing the strongest effect, significantly reducing bleeding time (P < 0.05). A concentration of 1.0 g/mL of the 30% EEF accelerated cutaneous wound healing in rats on the 3rd, 6th, and 9th day post-operation, with the healing effect increasing over time. No irritation or allergy reactions were observed in rabbits and guinea pigs exposed to the 30% EEF. Additionally, the 30% EEF exhibited mild inhibitory effect on mice ear and rat paw edema, as well as antimicrobial activity against tested bacteria, with varying minimal inhibitory concentration (MIC) values. ConclusionsThe 30% EEF demonstrated a clear hemostatic effect on rabbit bleeding time, a slight inhibitory effect on mice ear edema and rat paw edema, significant wound healing activity in rats, and no observed irritation or allergic reactions. Antibacterial activity was observed against certain clinically isolated bacteria, particularly the G− bacteria. This study lays the groundwork for the potential development and application of C. odorata in wound treatment.

Antimicrobial and antioxidant activities of lignin by-product from sugarcane leaf conversion to levulinic acid and hydrochar

To enhance the sustainability of lignocellulosic biomass utilization process, a significant attention is given to a high-value lignin byproduct of this process. Herein, antimicrobial, antioxidant, and physicochemical properties of lignin in black liquor extracted from sugarcane leaf (SCL) for levulinic acid (LA) and hydrochar production were investigated. The lignin was extracted from SCL through an alkaline pretreatment process using 5–25 wt% of either NaOH or KOH at 120–160 °C. Disk diffusion susceptibility tests, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) revealed that the SCL lignin is effective against Gram-positive bacteria (S. aureus) rather than Gram-negative bacteria (E. coli and S. typhimurium). Different alkaline reagents marginally affected the antimicrobial and antioxidant activities of the lignin. Py-GC/MS analysis results determined that the SCL lignin contained mainly p-hydroxyphenyl (H) and guaiacyl (G) with a small amount of syringyl (S) lignin. Furthermore, the structural alterations and linkages of SCL lignin during alkaline pretreatment were examined using 2D-HSQC NMR, providing valuable insights into the transformation processes. The conversion of delignified SCL to LA through a catalytic hydrothermal process using various acid catalysts indicated that the alkaline pretreatment could enhance LA yield with a maximum yield of 33.4 wt%. Additionally, fuel property characterization of the hydrochar co-product from LA production determined that the hydrochar can be used as a coal substitute.

Listeria Rhombencephalitis: A Case of an Immunocompetent Adult

Listeriosis is one of the most important foodborne diseases, caused by a Gram-positive facultative anaerobic intracellular bacterium found in food and the environment, Listeria monocytogenes. It causes one of the most life-threatening bacterial infections of the central nervous system (CNS). Meningoencephalitis and rhomboencephalitis are the most common forms and immunosuppression represents the main risk factor. In this article, we report a case of severe, invasive Listeria monocytogenes rhombencephalitis in a healthy middle-aged man, admitted to our hospital with meningeal syndrome associated with left VI nerve palsy. No apparent abnormality was found in a head CT and brain magnetic resonance imaging. Following the preliminary LP results, a diagnosis of bacterial meningitis was suspected and empirical antibiotic and antiviral therapy was initiated. Because of the lack of any significant improvement in his clinical status, on day 2 of his admission, a genetic identification of CSF pathogens by high-throughput genome sequencing was performed and identified L. monocytogenes. The Clinical status improved with complete recovery after appropriate antibiotic treatment with sulfamethoxazole-trimethoprim. In conclusion, in an infectious context, pontine involvement should systematically evoke the diagnosis of listeriosis.

Monitoring of antimicrobial resistance in respiratory tract pathogens during the COVID-19 pandemic: A retrospective study.

To understand the distribution and antimicrobial resistance (AMR) of pathogens in respiratory samples in Changle District People's Hospital in Fujian Province in recent years, and provide empirical guidance for infection control and clinical treatment in the region. A retrospective analysis was conducted on 5137 isolates of pathogens from respiratory samples collected from 2019 to 2022. The AMR patterns were systematically analyzed. For research purposes, the data was accessed on October 12, 2023. A total of 3517 isolates were included in the study, including 811 (23.06%) gram-positive bacteria and 2706 (76.94%) gram-negative bacteria. The top 3 gram-positive bacteria were Staphylococcus aureus with 455 isolates (12.94%), Streptococcus pneumoniae with 99 isolates (2.81%), and Staphylococcus hemolytic with 99 isolates (2.81%). The top 3 gram-negative bacteria were Klebsiella pneumoniae with 815 isolates (23.17%), Pseudomonas aeruginosa with 589 isolates (16.75%), and Acinetobacter baumannii with 328 isolates (9.33%). The proportion of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli and K pneumoniae fluctuated between 41.9% and 70.5%, and 18.6% and 20.9%, respectively. The resistance rates of E coli, K pneumoniae, P aeruginosa, and A baumannii to carbapenems were 2.36%, 8.9%, 18.5%, and 19.6%, respectively. The prevalence of methicillin-resistant S aureus (MRSA) was 48.55%, but it decreased to 38.4% by 2022. The resistance rate of Staphylococcus haemolyticus to methicillin was 100%, and 1 case of vancomycin-resistant strain was detected. K pneumoniae, P aeruginosa, A baumannii, and S aureus are the main pathogens in respiratory samples. Although the resistance rates of some multidrug-resistant strains have decreased, ESBL-producing Enterobacteriaceae, carbapenem-resistant bacteria have still increased. Therefore, it is necessary to strengthen the monitoring of pathogen resistance, promote rational use of antibiotics, and promptly report findings.

Systematic alanine and stapling mutational analysis of antimicrobial peptide Chem-KVL

Chem-KVL is a tandem repeating peptide, with 14 amino acids that was modified based on a short peptide from a fragment of the human host defense protein chemerin. Chem-KVL increases cationicity and hydrophobicity and shows broad-spectrum antibacterial activity. To determine the molecular determinants of Chem-KVL and whether staple-modified Chem-KVL would improve antibacterial activity and protease stability or decrease cytotoxicity, we combined alanine and stapling scanning, and designed a series of alanine and staple-derived Chem-KVL peptides, termed Chem-A1 to Chem-A14 and SCL-1 to SCL-7. We next examined their antibacterial activity against several gram-positive and gram-negative bacteria, their proteolytic stability, and their cytotoxicity. Ala scanning of Chem-KVL suggested that both the positively charged residues (Lys and Arg) and the hydrophobic residues (Lue and Val) were critical for the antibacterial activities of Chem-KVL peptide. Of note, Chem-A4 was able to remarkably inhibit the growth of gram-positive and gram-negative bacteria when compared to the original peptide. And the antibacterial activities of stapled SCL-4 and SCL-7 were several times higher than those of the linear peptide against gram-positive and gram-negative bacteria. Stapling modification of peptides resulted in increased helicity and protein stability when compared with the linear peptide. These stapled peptides, especially SCL-4 and SCL-7, may serve as the leading compounds for further optimization and antimicrobial therapy.

Disposable Peptidoglycan-Specific Biosensor for Noninvasive Real-Time Detection of Broad-Spectrum Gram-Positive Bacteria in Exhaled Breath Condensates.

Rapidly identifying and quantifying Gram-positive bacteria are crucial to diagnosing and treating bacterial lower respiratory tract infections (LRTIs). This work presents a field-deployable biosensor for detecting Gram-positive bacteria from exhaled breath condensates (EBCs) based on peptidoglycan recognition using an aptamer. Dielectrophoretic force is employed to enrich the bacteria in 10 s without additional equipment or steps. Concurrently, the measurement of the sensor's interfacial capacitance is coupled to quantify the bacteria during the enrichment process. By incorporation of a semiconductor condenser, the whole detection process, including EBC collection, takes about 3 min. This biosensor has a detection limit of 10 CFU/mL, a linear range of up to 105 CFU/mL and a selectivity of 1479:1. It is cost-effective and disposable due to its low cost. The sensor provides a nonstaining, culture-free and PCR-independent solution for noninvasive and real-time diagnosis of Gram-positive bacterial LRTIs.

Actinobacteria: Smart Micro-Factories for The Health Sector.

Antibiotics are considered "wonder drugs" due to the fact that they are the most extensively utilised medication in the world. They are used to cure a broad spectrum of diseases and lethal infections. A variety of bacteria and fungi produce antibiotics as a result of secondary metabolism; however, their production is dominated by a special class of bacteria, namely Actinobacteria. Actinobacteria are gram-positive bacteria with high G+C content and unparalleled antibiotic-producing ability. They produce numerous polyenes, tetracyclines, β-lactams, macrolides, and peptides. Actinobacteria are ubiquitous in nature and are isolated from various sources, such as marine and terrestrial endophytes of plants and air. They are studied for their relative antibiotic-producing ability along with the mechanism that the antibiotics follow to annihilate the pathogenic agents that include bacteria, fungi, protozoans, helminths, etc. Actinobacteria isolated from endophytes of medicinal plants have amassed significant attention as they interfere with the metabolism of medicinal plants and acquire enormous benefits from it in the form of conspicuous novel antibiotic-producing ability. Actinobacteria is not only an antibiotic but also a rich source of anticancer compounds that are widely used owing to its remarkable tumorigenic potential. Today, amongst Actinobacteria, class Streptomyces subjugates the area of antibiotic production, producing 70% of all known antibiotics. The uniqueness of bioactive Actinobacteria has turned the attention of scientists worldwide in order to explore its potentiality as effective "micronanofactories". This study provides a brief overview of the production of antibiotics from Actinobacteria inhabiting diverse environments and the methods involved in the screening of antibiotics.