Gram Positive
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2021 ◽  
Mariana Barbalho Farias da silva ◽  
Ericka Arregue Lemos ◽  
Renata E. Vollú ◽  
Fernanda Abreu ◽  
Alexandre S. Rosado ◽  

Abstract A gram-positive, nitrogen-fixing and endospore-forming strain, designated P121T, was isolated from the gut of the armored catfish (Parotocinclus maculicauda) and identified as a member of the genus Paenibacillus based on the sequences of the 16S rRNA encoding gene, rpoB, gyrB and nifH genes and phenotypic analyses. The most closely related species to strain P121T were Paenibacillus rhizoplanae DSM 103993T, Paenibacillus silagei DSM 101953T and Paenibacillus borealis DSM 13188T, with similarity values of 98.9%, 98.3% and 97.6%, respectively, based on 16S rRNA gene sequences. Genome sequencing revealed a genome size of 7,513,698 bp, DNA G + C content of 53.9 mol% and the presence of the structural nitrogenase encoding genes (nifK, nifD and nifH) necessary for nitrogen fixation. Digital DNA-DNA hybridization (dDDH) experiments and average nucleotide identity (ANI) analyses between strain P121T and the type strains of the closest species demonstrated that the highest values were below the thresholds of 70% dDDH (42.3% with P. borealis) and 95% ANI (84.28% with P. silagei) for bacterial species delineation, indicating that strain P121T represents a distinct species. Its major cellular fatty acid was anteiso-C15:0 (42.4%), and the major isoprenoid quinone was MK-7. Based on physiological, genomic, biochemical and chemotaxonomic characteristics, we propose that strain P121T represents a novel species for which the name Paenibacillus piscarius sp. nov. is proposed (type strain = DSM 25072 = LFB-Fiocruz 1636).

2021 ◽  
Vol 8 ◽  
Nazanin Mansouri Shirazi ◽  
Niloofar Eslahi ◽  
Adeleh Gholipour-Kanani

Keratin protein has been applied for biomedical applications due to its biocompatibility, biodegradability, mechanical resistance, and bioavailability. Tragacanth gum (TG) as a polysaccharide-based biopolymer has wound healing and antimicrobial properties. In this study, keratin was extracted from protein-based chicken feather by using reduction hydrolysis (sodium sulfide), and nanogels of keratin and TG composites at different ratios were produced by using the chemical cross-linking method. Then, cinnamon (5 and 10%) as an antibacterial herbal extract was added to the nanogels and coated on cotton fabric. The morphology and size of the composite nanogels, chemical structure, biological, and antibacterial properties were evaluated. According to DLS results, TGK2:1 (ratio of TG to keratin = 2:1) had the minimum size (80 nm) and PDI (0.1), and therefore, this sample was chosen as the optimum one. FESEM and TEM images showed the semi-spherical shape of the produced nanogels. FTIR spectra revealed the possible hydrogen bonding between the components, and the formation of disulfide bonds after the addition of hydrogen peroxide was confirmed by XPS. After loading cinnamon into the nanogels, an increase in size was observed from 80 nm for free-nanogel to 85 and 105 nm for 5 and 10% extract-loaded nanogels, respectively. Besides, more cinnamon was released from the treated fabrics by increasing time and cinnamon concentration. The antibacterial test exhibited good antibacterial properties against both Gram-positive and Gram-negative bacteria. Finally, MTT assay approved the biocompatibility of the produced nanogels for potential use in medical textiles.

Eliza Depoorter ◽  
Tom Coenye ◽  
Peter Vandamme

Burkholderia cepacia complex strain R-12632 produces ditropolonyl sulfide, an unusual sulfur-containing tropone, via a yet unknown biosynthetic pathway. Ditropolonyl sulfide purified from a culture of strain R-12632 inhibits the growth of various Gram-positive and Gram-negative multidrug resistant bacteria, with minimum inhibitory concentration (MIC) values as low as 16 μg/ml. In the present study we used a transposon mutagenesis approach combined with metabolite analyses to identify the genetic basis for antibacterial activity of strain R-12632 against Gram-negative bacterial pathogens. Fifteen of the 8304 transposon mutants investigated completely lost antibacterial activity against Klebsiella pneumoniae LMG 2095. In these loss-of-activity mutants, nine genes were interrupted. Four of those genes were involved in assimilatory sulfate reduction, two in phenylacetic acid (PAA) catabolism and one in glutathione metabolism. Via semipreparative fractionation and metabolite identification, it was confirmed that inactivation of the PAA degradation pathway or glutathione metabolism led to loss of ditropolonyl sulfide production. Based on earlier studies on the biosynthesis of tropolone compounds, the requirement for a functional PAA catabolic pathway for antibacterial activity in strain R-12632 indicated that this pathway likely provides the tropolone backbone for ditropolonyl sulfide. Loss of activity observed in mutants defective in assimilatory sulfate reduction and glutathione biosynthesis suggested that cysteine and glutathione are potential sources of the sulfur atom linking the two tropolone moieties. The demonstrated antibacterial activity of the unusual antibacterial compound ditropolonyl sulfide warrants further studies into its biosynthesis and biological role. Importance Burkholderia bacteria are historically known for their biocontrol properties and have been proposed as a promising and underexplored source of bioactive specialized metabolites. Burkholderia cepacia complex strain R-12632 inhibits various Gram-positive and Gram-negative resistant pathogens and produces numerous specialized metabolites, among which ditropolonyl sulfide. This unusual antimicrobial has been poorly studied and its biosynthetic pathway remained unknown. In the present study, we performed transposon mutagenesis of strain R-12632 and performed genome and metabolite analyses of loss-of-activity mutants to study the genetic basis for antibacterial activity. Our results indicate that the phenylacetic acid catabolism, assimilatory sulfate reduction and glutathione metabolism are necessary for ditropolonyl sulfide production. These findings contribute to understanding the biosynthesis and biological role of this unusual antimicrobial.

Ankita J. Sachla ◽  
Alexander J. Alfonso ◽  
John D. Helmann

Bacillus subtilis is a well-characterized Gram-positive model organism and a popular platform for biotechnology. Although many different CRISPR-based genome editing strategies have been developed for B. subtilis , they generally involve the design and cloning of a specific guide RNA (gRNA) and repair template for each application.

2021 ◽  
Hobby Aggarwal ◽  
Priya Pathak ◽  
Vishal Singh ◽  
Yashwant Kumar ◽  
Manoharan Shankar ◽  

Abstract Background: Inducible nitric oxide synthase (iNOS) has emerged as a crucial regulator of host metabolism and gut microbiota activity. The present study examines the role of the gut microbiome in determining host metabolic functions in absence of iNOS.Results: Insulin resistant and dyslipidemic iNOS-/- mice displayed reduced microbial diversity, with a higher relative abundance of the gram-positive bacteria, Allobaculum and Bifidobacterium, and altered serum metabolites linked with the metabolic dysregulation. Vancomycin, which largely depletes gram-positive bacteria, reversed the insulin resistance (IR), dyslipidemia, and related metabolic abnormalities in iNOS-/- mice. Such correction in metabolic markers was accompanied by reduced the expression of genes involved in fatty acid synthesis in liver and adipose tissue, decreased lipid uptake by adipose tissue and enhanced lipid efflux by liver and intestine. Rescue of IR in vancomycin treated iNOS-/- mice was associated with the alterations in the select serum metabolites such as 10-hydroxydecanoate, indole-3-ethanol, allantoin, hippurate, sebacic acid, aminoadipate, and ophthalmate, along with improvement in phosphatidylethanolamine to phosphatidylcholine (PE/PC) ratio.Conclusions: Vancomycin-mediated depletion of gram-positive bacteria negates the detrimental metabolic effect, dyslipidemia and IR, observed in iNOS-/- mice.

2021 ◽  
Vol 11 (1) ◽  
Darren Shu Jeng Ting ◽  
Eunice Tze Leng Goh ◽  
Venkatesh Mayandi ◽  
Joanna M. F. Busoy ◽  
Thet Tun Aung ◽  

AbstractBacterial keratitis (BK) is a major cause of corneal blindness globally. This study aimed to develop a novel class of antimicrobial therapy, based on human-derived hybrid host defense peptides (HyHDPs), for treating BK. HyHDPs were rationally designed through combination of functional amino acids in parent HDPs, including LL-37 and human beta-defensin (HBD)-1 to -3. Minimal inhibitory concentrations (MICs) and time-kill kinetics assay were performed to determine the concentration- and time-dependent antimicrobial activity and cytotoxicity was evaluated against human corneal epithelial cells and erythrocytes. In vivo safety and efficacy of the most promising peptide was examined in the corneal wound healing and Staphylococcus aureus (ATCC SA29213) keratitis murine models, respectively. A second-generation HyHDP (CaD23), based on rational hybridization of the middle residues of LL-37 and C-terminal of HBD-2, was developed and was shown to demonstrate good efficacy against methicillin-sensitive and methicillin-resistant S. aureus [MIC = 12.5–25.0 μg/ml (5.2–10.4 μM)] and S. epidermidis [MIC = 12.5 μg/ml (5.2 μM)], and moderate efficacy against P. aeruginosa [MIC = 25-50 μg/ml (10.4–20.8 μM)]. CaD23 (at 25 μg/ml or 2× MIC) killed all the bacteria within 30 min, which was 8 times faster than amikacin (25 μg/ml or 20× MIC). After 10 consecutive passages, S. aureus (ATCC SA29213) did not develop any antimicrobial resistance (AMR) against CaD23 whereas it developed significant AMR (i.e. a 32-fold increase in MIC) against amikacin, a commonly used treatment for BK. Pre-clinical murine studies showed that CaD23 (0.5 mg/ml) achieved a median reduction of S. aureus bioburden by 94% (or 1.2 log10 CFU/ml) while not impeding corneal epithelial wound healing. In conclusion, rational hybridization of human-derived HDPs has led to generation of a potentially efficacious and safe topical antimicrobial agent for treating Gram-positive BK, with no/minimal risk of developing AMR.

Polymers ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 3116
Thien Bui-Thuan Do ◽  
Tien Ngoc-Thuy Nguyen ◽  
Minh Hieu Ho ◽  
Nghi Thi-Phuong Nguyen ◽  
Thai Minh Do ◽  

(1) Background: Wounds with damages to the subcutaneous are difficult to regenerate because of the tissue damages and complications such as bacterial infection. (2) Methods: In this study, we created burn wounds on pigs and investigated the efficacy of three biomaterials: polycaprolactone-gelatin-silver membrane (PCLGelAg) and two commercial burn dressings, Aquacel® Ag and UrgoTulTM silver sulfadiazine. In vitro long-term antibacterial property and in vivo wound healing performance were investigated. Agar diffusion assays were employed to evaluate bacterial inhibition at different time intervals. Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and time-kill assays were used to compare antibacterial strength among samples. Second-degree burn wounds in the pig model were designed to evaluate the efficiency of all dressings in supporting the wound healing process. (3) Results: The results showed that PCLGelAg membrane was the most effective in killing both Gram-positive and Gram-negative bacteria bacteria with the lowest MBC value. All three dressings (PCLGelAg, Aquacel, and UrgoTul) exhibited bactericidal effect during the first 24 h, supported wound healing as well as prevented infection and inflammation. (4) Conclusions: The results suggest that the PCLGelAg membrane is a practical solution for the treatment of severe burn injury and other infection-related skin complications.

2021 ◽  
Vol 62 (9) ◽  
pp. 1292-1299
Sang Yoon Kim ◽  
Tae Hoon Kim ◽  
Sang Joon Lee ◽  
Han Jo Kwon

Purpose: To report the first case of Curtobacterium endophthalmitis within 6 hours after open globe injury, with extensive phlebitis and secondary subretinal neovascularization. Case summary: A 53-year-old man with hypersensitivity to beta-lactam antibiotics was admitted due to visual disturbance in the left eye experienced while working in a rural area. Fundus examination was impossible due to a full-layer corneal laceration and traumatic cataract in the left eye. B-scan ultrasonography and orbital computed tomography showed no shadowing of retained intraocular foreign bodies. After a corneal scraping smear, primary closure, lensectomy, and vitrectomy were performed. Organic material was observed in a focal area of pale macula, accompanied by extensive retinal phlebitis in the mid-periphery. After diagnosing acute bacterial endophthalmitis, intravitreal vancomycin and dexamethasone were injected. Curtobacterium pusillum was cultured on an automated microbial identification system. Intravenous vancomycin and oral clarithromycin were administered for 2 weeks. After 3 months, endophthalmitis had not recurred, and the visual acuity reached 20/100. However, subretinal neovascularization was newly detected under the damaged macula. No complications of neovascularization were observed until 6 months after primary closure. Conclusions: Curtobacterium pusillum can induce acute endophthalmitis through direct penetration in cases of ocular trauma, and may be accompanied by extensive phlebitis and secondary subretinal neovascularization. In cases of open globe injury sustained in rural areas, acute endophthalmitis caused by a rare Gram-positive bacillus, such as Curtobacterium species, should be considered.

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Dongkai Sun ◽  
Peishan Cong ◽  
Fengju Guan ◽  
Shuai Liu ◽  
Lijiang Sun ◽  

Objective. We sought to analyze the distribution and antibiotic sensitivity of pathogens in hospitalized patients and to provide a scientific reference for the rational application of antibiotics. Methods. From January 2014 to December 2018, urine cultures from patients in our hospital were collected and analyzed retrospectively for the presence, distribution, and drug sensitivity of pathogens. Results. A total of 42,854 midstream urine cultures were collected from which 11,891 (27.75%) pathogens were isolated, including 8101 (68.13%) strains of gram-negative bacteria, 2580 (21.69%) strains of gram-positive bacteria, and 1210 (10.18%) strains of fungi. Escherichia coli and Enterococci were the most common species of gram-negative and gram-positive bacteria, respectively. Drug sensitivity varied among different pathogens. Clear drug resistance was observed in bacteria, while fungus exhibited relatively lower resistance. Conclusion. Pathogens responsible for urinary tract infections in hospitalized patients are diversiform and display resistance to some antibiotics. Drug resistance monitoring should be enhanced to optimize antimicrobial therapy.

2021 ◽  
Fang Li ◽  
Fan Lu ◽  
Luming Zhang ◽  
Longzhu Li ◽  
Mingyao Xing ◽  

Abstract Background: Central line-associated bloodstream infection (CLABSI) is a common hospital infection. The increasing use of peripherally inserted central catheters and fully implanted venous ports, data on the epidemiological and clinical characteristics of CLABSI in the overall central venous catheter (CVC) population remain limited. The Medical Information Mart for Intensive Care (MIMIC IV) database is a free, open, and public resource research database. The purpose of this study was to describe the risk factors and clinical characteristics of CLABSI in MIMIC IV.Methods: A total of 31,116 patients were included in this study. General information, CVC-related information, comorbidity information, microbiological information, and antibiotic use information were extracted to describe and analyze the clinical characteristics of patients with CLABSI.Results: According to the occurrence of CLABSI, 31,116 patients were divided into the NO CLABSI group (n=30,395) and CLABSI group (n=721). The total indwelling duration of CVC was 439,239.6 days, The incidence of CLABSI is 2.32% and 1.64/1000 catheter days. The risk factors for CLABSI were the number of CVC type, duration of CVC, number of antibiotic type, duration of antibiotics, and femoral vein and internal jugular vein intubation. The in-hospital mortality of the CLABSI group was higher than that of the NO CLABSI group, but no statistical significance was observed (P>0.05). Gram-positive (G+) cocci and Gram-negative (G-) bacilli accounted for 80% and 16.93% of positive bacteria in catheter culture. G+ cocci and G- bacilli accounted for 59.45% and 25.62% of positive bacteria in blood culture. Drugs with the highest resistance rates in catheter culture included penicillin G benzathine, oxacillin, and erythromycin. The most commonly used antibiotics for the treatment of CLABSI included vancomycin, cefepime, piperacillin tazobactam, and cefazolin.Conclusions: This study investigated independent risk factors for CLABSI and their association with in-hospital mortality and described the etiological characteristics, drug sensitivity, and the distribution of antibiotics used for treatment.

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