Mechanisms of resistance to membrane-disrupting antibiotics in Gram-positive and Gram-negative bacteria

Cationic amphiphiles derived from trehalose have been synthesized; trehalose analogues substituted withn-pentyl orn-hexyl ethers exhibited membrane disrupting activities against clinically important Gram positive and Gram negative bacteria and fungi.

Download Full-text

Dermcidin-Derived Peptides Show a Different Mode of Action than the Cathelicidin LL-37 against Staphylococcus aureus

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01679-08 ◽

2009 ◽

Vol 53 (6) ◽

pp. 2499-2509 ◽

Cited By ~ 44

Author(s):

Ilknur Senyürek ◽

Maren Paulmann ◽

Tobias Sinnberg ◽

Hubert Kalbacher ◽

Martin Deeg ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Antimicrobial Activity ◽

Mode Of Action ◽

Cell Envelope ◽

Proteolytic Processing ◽

Bacterial Membrane ◽

Gram Negative Bacteria ◽

Binding Studies ◽

Gram Positive ◽

Gram Negative

ABSTRACT Dermcidin (DCD) is an antimicrobial peptide which is constitutively expressed in eccrine sweat glands. By postsecretory proteolytic processing in sweat, the DCD protein gives rise to anionic and cationic DCD peptides with a broad spectrum of antimicrobial activity. Many antimicrobial peptides induce membrane permeabilization as part of their killing mechanism, which is accompanied by a loss of the bacterial membrane potential. In this study we show that there is a time-dependent bactericidal activity of anionic and cationic DCD-derived peptides which is followed by bacterial membrane depolarization. However, DCD-derived peptides do not induce pore formation in the membranes of gram-negative and gram-positive bacteria. This is in contrast to the mode of action of the cathelicidin LL-37. Interestingly, LL-37 as well as DCD-derived peptides inhibit bacterial macromolecular synthesis, especially RNA and protein synthesis, without binding to microbial DNA or RNA. Binding studies with components of the cell envelope of gram-positive and gram-negative bacteria and with model membranes indicated that DCD-derived peptides bind to the bacterial envelope but show only a weak binding to lipopolysaccharide (LPS) from gram-negative bacteria or to peptidoglycan, lipoteichoic acid, and wall teichoic acid, isolated from Staphylococcus aureus. In contrast, LL-37 binds strongly in a dose-dependent fashion to these components. Altogether, these data indicate that the mode of action of DCD-derived peptides is different from that of the cathelicidin LL-37 and that components of the bacterial cell envelope play a role in the antimicrobial activity of DCD.

Download Full-text

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

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100123830 ◽

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.

Download Full-text

In-vitro Antioxidant and Antibacterial Activity of Methanolic Extract of Shorea robusta Gaertn. F. Resin

International Journal of Pharmaceutical and Phytopharmacological Research ◽

10.24896/eijppr.2016641 ◽

2016 ◽

Vol 6 (4) ◽

pp. 68

Author(s):

Sushma Vashisht ◽

Manish Pal Singh ◽

Viney Chawla

Keyword(s):

Antibacterial Activity ◽

Methanolic Extract ◽

Diffusion Method ◽

Gram Negative Bacteria ◽

Disc Diffusion ◽

Gram Positive ◽

Gram Negative ◽

Shorea Robusta ◽

Dose Dependent ◽

Resin Extract

The methanolic extract of the resin of Shorea robusta was subjected to investigate its antioxidant and antibacterial properties its utility in free radical mediated diseases including diabetic, cardiovascular, cancer etc. The methanol extract of the resin was tested for antioxidant activity using scavenging activity of DPPH (1,1-diphenyl-2-picrylhydrazil) radical method, reducing power by FeCl3 and antibacterial activity against gram positive and gram negative bacteria using disc diffusion method. The phytochemical screening considered the presence of triterpenoids, tannins and flavoniods. Overall, the plant extract is a source of natural antioxidants which might be helpful in preventing the progress of various oxidative stress mediated diseases including aging. The half inhibition concentration (IC50) of resin extract of Shorea robusta and ascorbic acid were 35.60 µg/ml and 31.91 µg/ml respectively. The resin extract exhibit a significant dose dependent inhibition of DPPH activity. Antibacterial activity was observed against gram positive and gram negative bacteria in dose dependent manner.Key Words: Shorea robusta, antioxidant, antibacterial, Disc-diffusion, DPPH.

Download Full-text

Antibacterial activity of magnesium oxide nanoparticles prepared by Calcination method

International Journal of Pharmaceutical Quality Assurance ◽

10.25258/ijpqa.10.3.25 ◽

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.

Download Full-text

Antimicrobial Activity of Iron-Halide Complexes Against Gram-Positive and Gram-Negative Bacteria

10.26434/chemrxiv.11864934.v1 ◽

2020 ◽

Author(s):

Nusrat Abedin ◽

Abdullah Hamed A Alshehri ◽

Ali M A Almughrbi ◽

Olivia Moore ◽

Sheikh Alyza ◽

...

Keyword(s):

Antimicrobial Activity ◽

Antimicrobial Resistance ◽

Extracellular Dna ◽

Antibiofilm Activity ◽

Gram Negative Bacteria ◽

Bacterial Strains ◽

Gram Positive ◽

Gram Negative ◽

Antimicrobial Substances ◽

Mammalian Cell Lines

Antimicrobial resistance (AMR) has become one of the more serious threats to the global health. The emergence of bacteria resistant to antimicrobial substances decreases the potencies of current antibiotics. Consequently, there is an urgent and growing need for the developing of new classes of antibiotics. Three prepared novel iron complexes have a broad-spectrum antimicrobial activity with minimum bactericidal concentration (MBC) values ranging from 3.5 to 10 mM and 3.5 to 40 mM against Gram-positive and Gram-negative bacteria with antimicrobial resistance phenotype, respectively. Time-kill studies and quantification of the extracellular DNA confirmed the bacteriolytic mode of action of the iron-halide compounds. Additionally, the novel complexes showed significant antibiofilm activity against the tested pathogenic bacterial strains at concentrations lower than the MBC. The cytotoxic effect of the complexes on different mammalian cell lines show sub-cytotoxic values at concentrations lower than the minimum bactericidal concentrations.

Download Full-text

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

JURNAL PESISIR DAN LAUT TROPIS ◽

10.35800/jplt.8.1.2020.28110 ◽

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

Download Full-text