scholarly journals Physicochemical Properties That Enhance Discriminative Antibacterial Activity of Short Dermaseptin Derivatives

2006 ◽  
Vol 50 (8) ◽  
pp. 2666-2672 ◽  
Author(s):  
Shahar Rotem ◽  
Inna Radzishevsky ◽  
Amram Mor
Keyword(s):  
Antimicrobial Peptides ◽  
Physicochemical Properties ◽  
Culture Media ◽  
Gram Negative Bacteria ◽  
Terminal Sequence ◽  
Binding Properties ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Cytoplasmic Membranes

ABSTRACT Antimicrobial peptides are widely believed to exert their effects by nonspecific mechanisms. We assessed the extent to which physicochemical properties can be exploited to promote discriminative activity by manipulating the N-terminal sequence of the 13-mer dermaseptin derivative K4-S4(1-13) (P). Inhibitory activity determined in culture media against 16 strains of bacteria showed that when its hydrophobicity and charge were changed, P became predominantly active against either gram-positive or gram-negative bacteria. Thus, conjugation of various aminoacyl-lysin moieties (e.g., aminohexyl-K-P) led to inactivity against gram-positive bacteria (MIC50 > 50 μM) but potent activity against gram-negative bacteria (MIC50, 6.2 μM). Conversely, conjugation of equivalent acyls to the substituted analog M4-S4(1-13) (e.g., hexyl-M4-P) led to inactivity against gram-negative bacteria (MIC50 > 50 μM) but potent activity against gram-positive bacteria (MIC50, 3.1 μM). Surface plasmon resonance experiments, used to investigate peptides' binding properties to lipopolysaccharide-containing idealized phospholipid membranes, suggest that although the acylated derivatives have increased lipophilic properties with parallel antibacterial behavior, hydrophobic derivatives are prevented from reaching the cytoplasmic membranes of gram-negative bacteria. Moreover, unlike modifications that enhanced the activity against gram-positive bacteria, which also enhanced hemolysis, we found that modifications that enhanced activity against gram-negative bacteria generally reduced hemolysis. Thus, compared with the clinically tested peptides MSI-78 and IB-367, the dermaseptin derivative aminohexyl-K-P performed similarly in terms of potency and bactericidal kinetics but was significantly more selective in terms of discrimination between bacteria and human erythrocytes. Overall, the data suggest that similar strategies maybe useful to derive potent and safe compounds from known antimicrobial peptides.

scholarly journals Bacterial Profile and Antibiogram of Hospital-Acquired Pneumonia and Ventilator-Associated Pneumonia Patients in ICU of Raden Mattaher Hospital Jambi

2020 ◽  
Vol 26 (3) ◽  
Author(s):  
Sotianingsih Sotianingsih ◽  
Samsirun H. ◽  
Lipinwati Lipinwati
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Culture Media ◽  
Sensitivity Test ◽  
Sputum Culture ◽  
Klebsiella Pneumonia ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Acinetobacter Baumanii ◽  
Gram Negative ◽  
Gram Positive Bacteria

Pneumonia is defined as an inflammation of the lungs caused by microorganisms (bacteria, viruses, fungi, parasites). This research aimed to determine the pneumonia-causing bacteria along with the sensitivity and the antibiotic resistance test. This research was a descriptive study with samples of ICU pneumonia patients at Raden Mattaher Regional Hospital during the study period. All samples were consecutively selected. Samples for blood culture were incubated in the BactAlert device, whereas the sensitivity test was then performed using Vitex instruments. Sputum was previously enriched with BHI media and then cultured on culture media, and sensitivity test with the Vitex instruments was carried out. Of the 354 ICU patients during the study period, 30 patients (11.8%) had pneumonia, but only 19 patients could undergo sputum culture. Five of 19 patients were infected with Gram-positive bacteria, and 14 patients were infected with Gram-negative bacteria. The most commonly found bacteria were Klebsiella pneumonia (36.84%), followed by Acinetobacter baumanii (21.05%) and Pseudomonas aeruginosa (10.53%). Gram-negative bacteria obtained from sputum culture in this study were resistant to almost all antibiotic groups, especially penicillin, cephalosporin, quinolone, and tetracycline groups. Gram-positive bacteria obtained from sputum culture in this study were resistant to the penicillin antibiotic. The most commonly found bacteria were Klebsiella pneumonia (36.84%), followed by Acinetobacter baumanii (21.05%) and Pseudomonas aeruginosa (10.53%). The bacteria cultured from the sputum showed multidrug resistance mainly to the penicillin and cephalosporin antibiotic. This research data can be used to consider the treatment of pneumonia patients to decide more appropriate therapy.

scholarly journals Microbiology of lower respiratory tract infection in workers of garment industry of Kathmandu

2015 ◽  
Vol 10 (3) ◽  
pp. 14-22
Author(s):  
S Pant ◽  
KR Bhusal ◽  
S Manandhar
Keyword(s):  
Tract Infection ◽  
Respiratory Tract ◽  
Respiratory Tract Infection ◽  
Lower Respiratory Tract Infection ◽  
Lower Respiratory Tract ◽  
Culture Media ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria

By mistake the wrong PDF was loaded for this article. The correct PDF was loaded on 19th September 2016. OBJECTIVES This study was designed with the objectives of describing the distribution pattern of microorganisms responsible for causing LRTI in the workers of garment industries.MATERIALS AND METHODS A total of 198 cases of suspected person of Lower Respiratory Tract infection (LRTI) LRTI were included in this study. This study was conducted between November 2009 to April 2010. Specimen for the study was expectorated sputum. Gram-stain, Ziehl-Neelsen stains and culture were performed.RESULTS On direct microscopic examination, 20.51% were Gram positive bacteria, 79.48% were Gram negative bacteria and 4% were smear positive AFB. On culture sensitivity examination, 22% percent showed growth of different bacteria in different culture media. The bacteria isolated from the samples included Klebsiella pneumoniae (15.38%), Proteus mirabilis (15.38%) and Citrobacterfruendii (15.38%). Gram Negative bacteria were found most susceptible to Ciprofloxacin (92.30%, 24/26) and Amikacin (92.30%, 24/26). Similarly, Gram Positive bacteria were found most susceptible to Ciprofloxacin (100%, 8/8) followed by Cloxacillin and Cephalexin (87.5%, 7/8). Smear positive AFB was significantly associated with not using the protective measures (mask) by workers and presence of symptoms (cough for more than two weeks, night sweat, hemoptysis and anorexia) (p=0.031). Culture positivity was significantly associated with symptoms like production of purulent sputum (p=0.045).CONCLUSION There was insignificant association between LRTI and risk factors present in working room of garment industries. Most of the isolates were sensitive to Ciprofloxacin and resistance to Ampicillin and Cephalexin.Journal of College of Medical Sciences-Nepal, 2014, Vol-10, No-3, 14-22

scholarly journals Antimicrobial Peptide Resistance Genes in the Plant Pathogen Dickeya dadantii

2016 ◽  
Vol 82 (21) ◽  
pp. 6423-6430 ◽  
Author(s):  
Caroline Pandin ◽  
Martine Caroff ◽  
Guy Condemine
Keyword(s):  
Antimicrobial Peptides ◽  
Bacterial Resistance ◽  
Soft Rot ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Dickeya Dadantii ◽  
Gram Negative ◽  
Content Type ◽  
Gram Positive Bacteria ◽  
New Genes

ABSTRACTModification of teichoic acid through the incorporation ofd-alanine confers resistance in Gram-positive bacteria to antimicrobial peptides (AMPs). This process involves the products of thedltXABCDgenes. These genes are widespread in Gram-positive bacteria, and they are also found in a few Gram-negative bacteria. Notably, these genes are present in all soft-rot enterobacteria (PectobacteriumandDickeya) whosedltDXBACoperons have been sequenced. We studied the function and regulation of these genes inDickeya dadantii.dltBexpression was induced in the presence of the AMP polymyxin. It was not regulated by PhoP, which controls the expression of some genes involved in AMP resistance, but was regulated by ArcA, which has been identified as an activator of genes involved in AMP resistance. However,arcAwas not the regulator responsible for polymyxin induction of these genes in this bacterium, which underlines the complexity of the mechanisms controlling AMP resistance inD. dadantii. Two other genes involved in resistance to AMPs have also been characterized,phoSandphoH.dltB,phoS,phoH, andarcAbut notdltDmutants were more sensitive to polymyxin than the wild-type strain. Decreased fitness of thedltB,phoS, andphoHmutants in chicory leaves indicates that their products are important for resistance to plant AMPs.IMPORTANCEGram-negative bacteria can modify their lipopolysaccharides (LPSs) to resist antimicrobial peptides (AMPs). Soft-rot enterobacteria (DickeyaandPectobacteriumspp.) possess homologues of thedltgenes in their genomes which, in Gram-positive bacteria, are involved in resistance to AMPs. In this study, we show that these genes confer resistance to AMPs, probably by modifying LPSs, and that they are required for the fitness of the bacteria during plant infection. Two other new genes involved in resistance were also analyzed. These results show that bacterial resistance to AMPs can occur in bacteria through many different mechanisms that need to be characterized.

scholarly journals Identification of Ly2 members as antimicrobial peptides from zebrafish Danio rerio

2017 ◽  
Vol 37 (1) ◽  
Author(s):  
Xuemin Liu ◽  
Xuwen Cao ◽  
Su Wang ◽  
Guangdong Ji ◽  
Shicui Zhang ◽  
...  
Keyword(s):  
Antimicrobial Peptides ◽  
Recombinant Proteins ◽  
Mammalian Cells ◽  
Multidrug Resistant ◽  
Scatchard Analysis ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
E Coli ◽  
Gram Positive Bacteria

The emergence of multidrug-resistant (MDR) microbes caused by overuse of antibiotics leads to urgent demands for novel antibiotics exploration. Our recent data showed that Ly2.1–3 (a novel lymphocyte antigen 6 (Ly6) gene cluster) were proteins with cationic nature and rich in cysteine content, that are characteristic of antimicrobial peptides (AMPs) and their expression were all significantly up-regulated after challenge with lipopolysaccharide (LPS). These strongly suggested that Ly2.1–3 are potential AMPs, but firm evidence are lacking. Here, we clearly showed that the recombinant proteins of Ly2.1–3 were capable of killing Gram-negative bacteria Aeromonas hydrophila and Escherichia coli, while they had little bactericidal activity against the Gram-positive bacteria Staphylococcus aureus and Bacillus subtilis. We also showed that recombinant proteins Ly2.1–3 (rLy2.1–3) were able to bind to the Gram-negative bacteria A. hydrophila, E. coli and the microbial signature molecule LPS, but not to the Gram-positive bacteria S. aureus and B. subtilis as well as the microbial signature molecule LTA. Moreover, the Scatchard analysis revealed that rLy2.1–3 could specifically bind to LPS. Finally, we found that Ly2.1–3 were not cytotoxic to mammalian cells. All these together indicate that Ly2.1–3 can function as AMPs.

scholarly journals Increasing the Antimicrobial Activity of Nisin-Based Lantibiotics against Gram-Negative Pathogens

2018 ◽  
Vol 84 (12) ◽  
Author(s):  
Qian Li ◽  
Manuel Montalban-Lopez ◽  
Oscar P. Kuipers
Keyword(s):  
Antimicrobial Peptides ◽  
Outer Membrane ◽  
Rational Design ◽  
Bacterial Species ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Content Type ◽  
Gram Positive Bacteria ◽  
Lipid Ii

ABSTRACTLantibiotics are ribosomally synthesized and posttranslationally modified antimicrobial compounds containing lanthionine and methyl-lanthionine residues. Nisin, one of the most extensively studied and used lantibiotics, has been shown to display very potent activity against Gram-positive bacteria, and stable resistance is rarely observed. By binding to lipid II and forming pores in the membrane, nisin can cause the efflux of cellular constituents and inhibit cell wall biosynthesis. However, the activity of nisin against Gram-negative bacteria is much lower than that against Gram-positive bacteria, mainly because lipid II is located at the inner membrane, and the rather impermeable outer membrane in Gram-negative bacteria prevents nisin from reaching lipid II. Thus, if the outer membrane-traversing efficiency of nisin could be increased, the activity against Gram-negative bacteria could, in principle, be enhanced. In this work, several relatively short peptides with activity against Gram-negative bacteria were selected from literature data to be fused as tails to the C terminus of either full or truncated nisin species. Among these, we found that one of three tails (tail 2 [T2; DKYLPRPRPV], T6 [NGVQPKY], and T8 [KIAKVALKAL]) attached to a part of nisin displayed improved activity against Gram-negative microorganisms. Next, we rationally designed and reengineered the most promising fusion peptides. Several mutants whose activity significantly outperformed that of nisin against Gram-negative pathogens were obtained. The activity of the tail 16 mutant 2 (T16m2) construct against several important Gram-negative pathogens (i.e.,Escherichia coli,Klebsiella pneumoniae,Acinetobacter baumannii,Pseudomonas aeruginosa,Enterobacter aerogenes) was increased 4- to 12-fold compared to that of nisin. This study indicates that the rational design of nisin can selectively and significantly improve its outer membrane-permeating capacity as well as its activity against Gram-negative pathogens.IMPORTANCELantibiotics are antimicrobial peptides that are highly active against Gram-positive bacteria but that have relatively poor activity against most Gram-negative bacteria. Here, we modified the model lantibiotic nisin by fusing parts of it to antimicrobial peptides with known activity against Gram-negative bacteria. The appropriate selection of peptidic moieties that could be attached to (parts of) nisin could lead to a significant increase in its inhibitory activity against Gram-negative bacteria. Using this strategy, hybrids that outperformed nisin by displaying 4- to 12-fold higher levels of activity against relevant Gram-negative bacterial species were produced. This study shows the power of modified peptide engineering to alter target specificity in a desired direction.

scholarly journals Intracellular and Extracellular extracts activity of Oscillatoria limnetica and Chroococus minor against some Bacteria and Fangi

2011 ◽  
Vol 8 (1) ◽  
pp. 478-483
Author(s):  
Baghdad Science Journal
Keyword(s):  
Culture Media ◽  
Inhibition Zone ◽  
Antagonistic Activity ◽  
Diffusion Method ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Extracellular Products ◽  
Antibacterial And Antifungal

In this study Oscillatoria limnetica and Chroococus minor were isolated ?purified and identification from water canal around Baghdad University Campus. The water of this canals originally from Tigris River. BG-11 culture media was used for their cultivation in suitable laboratory conditions (25c°, 200µE/m2/sec) for 16:8 hrs. Light: dark. Each culture was harvested at the end of exponential phase .Organic solvents used for extraction were Ethanol? Hexane and Methanol 95% to extract the crude active Intracellular and Extracellular substances, and evaporated down to dryness .Antibacterial and antifungal activity of these different extracts were evaluated against 6 strains of gram positive bacteria and gram negative bacteria in addition to fungi, Agar diffusion method was used in this evaluation. Results showed that the extracellular products which extracted by hexane and the extracellular products which extracted by ethanol from Oscillatoria limnetica were have higher antagonistic activity against bacteria and Fungi comparing with methanol extracts .However higher antibacterial and antifungal were obtained against the studied strains of comparing with methanol and ethanol extracts of the same algae products. The gram positive bacteria studied revealed higher susceptibility to attack by the intracellular and extracellular extracts comparing with the gram negative bacteria. These extracts revealed higher antibacterial activity against Bacillus subtilise and the average of inhibition zone were 26, 22 mm. for intracellular and extracellular products of O.limnetica respectively. However, C. minor intracellular products extract has the antagonistic activity against Staphylococcus aureus with 28 mm inhibition zone

Rapid demonstration of septic or infectious arthritis due to Gram-negative bacteria

1992 ◽  
Vol 50 (1) ◽  
pp. 686-687
Author(s):  
Jacob S. Hanker ◽  
Paul R. Gross ◽  
Beverly L. Giammara
Keyword(s):  
Chronic Arthritis ◽  
Blood Cultures ◽  
Gram Negative Bacteria ◽  
Infectious Arthritis ◽  
Bacterial Arthritis ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria

Blood cultures are positive in approximately only 50 per cent of the patients with nongonococcal bacterial infectious arthritis and about 20 per cent of those with gonococcal arthritis. But the concept that gram-negative bacteria could be involved even in chronic arthritis is well-supported. Gram stains are more definitive in staphylococcal arthritis caused by gram-positive bacteria than in bacterial arthritis due to gram-negative bacteria. In the latter situation where gram-negative bacilli are the problem, Gram stains are helpful for 50% of the patients; they are only helpful for 25% of the patients, however, where gram-negative gonococci are the problem. In arthritis due to gram-positive Staphylococci. Gramstained smears are positive for 75% of the patients.

Antibacterial activity of magnesium oxide nanoparticles prepared by Calcination method

2019 ◽  
Vol 10 (03) ◽  
Author(s):  
Elaf Ayad Kadhem ◽  
Miaad Hamzah Zghair ◽  
Sarah , Hussam H. Tizkam, Shoeb Alahmad Salih Mahdi ◽  
Hussam H. Tizkam ◽  
Shoeb Alahmad
Keyword(s):  
Antibacterial Activity ◽  
Magnesium Oxide ◽  
Diffusion Method ◽  
Oxide Nanoparticles ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Magnesium Oxide Nanoparticles ◽  
Agar Disc

magnesium oxide nanoparticles (MgO NPs) were prepared by simple wet chemical method using different calcination temperatures. The prepared NPs were characterized by Electrostatic Discharge (ESD), Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD). It demonstrates sharp intensive peak with the increase of crystallinty and increase of the size with varying morphologies with respect to increase of calcination temperature. Antibacterial studies were done on gram negative bacteria (E.coli) and gram positive bacteria (S.aureus) by agar disc diffusion method. The zones of inhibitions were found larger for gram positive bacteria than gram negative bacteria, this mean, antibacterial MgO NPs activity more active on gram positive bacteria than gram negative bacteria because of the structural differences. It was found that antibacterial activity of MgO NPs was found it has directly proportional with their concentration.

BAKTERI PADA KARANG SCLERACTINIA DI KAWASAN PERAIRAN BUNAKEN, MOROTAI DAN RAJA AMPAT

2020 ◽  
Vol 8 (1) ◽  
pp. 122
Author(s):  
Eghbert Eghbert Elvan Eghbert Elvan Ampou ◽  
Iis Iis Triyulianti ◽  
Nuryani Widagti ◽  
Suciadi Catur Nugroho ◽  
Yuli Pancawati
Keyword(s):  
Scleractinian Coral ◽  
Gram Negative Bacteria ◽  
Hard Coral ◽  
Field Sampling ◽  
Bacterial Isolation ◽  
Gram Positive ◽  
Coral Mucus ◽  
Gram Negative ◽  
Gram Positive Bacteria

Research on hard coral (Scleractinian coral) contaminated with bacteria is still not much done, especially in Indonesian waters. This study took samples of coral mucus in 2010 at 3 (three) different locations, namely Bunaken (May); Morotai (September) and Raja Ampat (November), which focused on the analysis of Research on hard coral (Scleractinian coral) contaminated with bacteria is still not much done, especially in Indonesian waters. This study took samples of coral mucus in 2010 at 3 (three) different locations, namely Bunaken (May); Morotai (September) and Raja Ampat (November), which focused on the analysis of gram-positive and gram-negative bacteria. The method used for field sampling is time swim, which is by diving at a depth of 5-10 meters for ± 30 minutes and randomly taking samples of coral mucus using siring or by taking directly on corals (reef branching). Mucus samples were analyzed by bacterial isolation in the laboratory. The result shows that there were differences between gram-positive and gram-negative bacteria in the three research sites and that gram-positive bacteria were higher or dominant. Further research that can identify the bacteria species and explain its relationship to the ecosystem is highly recommended.Keywords: Bacteria, Scleractinian coral, gram-positive and -negative, Bunaken, Morotai, Raja Ampat  AbstrakPenelitian tentang karang keras (Scleractinian coral) yang terkontaminasi bakteri masih belum banyak dilakukan, terutama di perairan Indonesia. Penelitian ini mengambil sampel mucus karang pada tahun 2010 di 3 (tiga) lokasi berbeda, yakni Bunaken (Mei); Morotai (September) dan Raja Ampat (November), yang difokuskan pada analisis bakteri gram postif dan gram negatif. Metode yang digunakan untuk pengambilan sampel di lapangan adalah time swim, yaitu dengan penyelaman pada kedalaman 5-10 meter selama ±30 menit dan mengambil sampel mucus karang secara acak menggunakan siring atau dengan mengambil langsung pada karang (fraksi cabang). Sampel mucus dianalisis dengan cara isolasi bakteri di laboratorium. Hasil analisis menunjukkan bahwa ada perbedaan antara bakteri gram positif dan gram negative di tiga lokasi survei dan bakteri gram positif lebih tinggi atau dominan. Penelitian lebih lanjut yang dapat menentukan jenis bakteri serta menjelaskan hubungannya dengan ekosistem sangat disarankan untuk dilakukan.Kata Kunci : Bakteri, Scleractinian coral, gram positif dan negatif, Bunaken, Morotai, Raja Ampat

scholarly journals N-Doped Carbon Quantum Dots as Fluorescent Bioimaging Agents

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 789
Author(s):  
Shih-Fu Ou ◽  
Ya-Yun Zheng ◽  
Sin-Jen Lee ◽  
Shyi-Tien Chen ◽  
Chien-Hui Wu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Carbon Nanomaterials ◽  
Graphene Quantum Dots ◽  
Carbon Quantum Dots ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Fluorescence Characteristics ◽  
And Staphylococcus Aureus

Graphene quantum dots, carbon nanomaterials with excellent fluorescence characteristics, are advantageous for use in biological systems owing to their small size, non-toxicity, and biocompatibility. We used the hydrothermal method to prepare functional N-doped carbon quantum dots (N-CQDs) from 1,3,6-trinitropyrene and analyzed their ability to fluorescently stain various bacteria. Our results showed that N-CQDs stain the cell septa and membrane of the Gram-negative bacteria Escherichia coli, Salmonellaenteritidis, and Vibrio parahaemolyticus and the Gram-positive bacteria Bacillus subtilis, Listeria monocytogenes, and Staphylococcus aureus. The optimal concentration of N-CQDs was approximately 500 ppm for Gram-negative bacteria and 1000 ppm for Gram-positive bacteria, and the exposure times varied with bacteria. N-Doped carbon quantum dots have better light stability and higher photobleaching resistance than the commercially available FM4-64. When excited at two different wavelengths, N-CQDs can emit light of both red and green wavelengths, making them ideal for bioimaging. They can also specifically stain Gram-positive and Gram-negative bacterial cell membranes. We developed an inexpensive, relatively easy, and bio-friendly method to synthesize an N-CQD composite. Additionally, they can serve as a universal bacterial membrane-staining dye, with better photobleaching resistance than commercial dyes.

Sign in / Sign up

Export Citation Format

Share Document