scholarly journals β-Lactamases as Major Mechanism of Resistance in Gram-Negative Bacteria

2012 ◽  
pp. 210-226
Keyword(s):  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Major Mechanism ◽  
Mechanism Of Resistance

scholarly journals Emergence and dissemination of a new mechanism of resistance to aminoglycosides in Gram-negative bacteria: 16S rRNA methylation

2005 ◽  
Vol 10 (4) ◽  
Author(s):  
M Galimand ◽  
T Lambert ◽  
P Courvalin
Keyword(s):  
16S Rrna ◽  
Severe Illness ◽  
Gram Negative Bacteria ◽  
Important Class ◽  
Gram Negative ◽  
Mechanism Of Resistance ◽  
Rrna Methylation

Despite the development of new ß-lactams and fluoroquinolones, aminoglycosides are still a very important class of antibacterials for the treatment of severe illness caused by a variety of pathogens

Bacterial production of methylglyoxal: a survival strategy or death by misadventure?

2003 ◽  
Vol 31 (6) ◽  
pp. 1406-1408 ◽  
Author(s):  
I.R. Booth ◽  
G.P. Ferguson ◽  
S. Miller ◽  
C. Li ◽  
B. Gunasekera ◽  
...  
Keyword(s):  
Bacterial Production ◽  
Survival Strategy ◽  
Gram Negative Bacteria ◽  
Bacterial Cells ◽  
Cytoplasmic Ph ◽  
Glyoxalase System ◽  
Loss Of Life ◽  
Gram Negative ◽  
Major Mechanism ◽  
Spontaneous Reaction

The production of MG (methylglyoxal) in bacterial cells must be maintained in balance with the capacity for detoxification and protection against this electrophile. Excessive production of MG leads to cell death. Survival of exposure to MG is best understood in the Gram-negative bacteria. The major mechanism of protection is the spontaneous reaction of MG with GSH to form hemithiolacetal, followed by detoxification by the glyoxalase system leading to the production of d-lactate. The KefB and KefC glutathione-gated K+ efflux systems are integrated with the activity of the glyoxalase system to regulate the cytoplasmic pH in response to exposure to electrophiles. Bacteria only produce MG when an imbalance occurs in metabolism. Operation of the MG bypass enables cells to adapt, such that balance is restored to metabolism. Excessive production of MG is an adaptive ploy, which, if it fails, has fatal consequences. On this basis one might define MG-induced loss of life as ‘death by misadventure’ rather than suicide!

Drown them in their own garbage: a new strategy to reverse polymyxin resistance?

2021 ◽  
Author(s):  
Kerrie L. May
Keyword(s):  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Major Mechanism ◽  
New Strategy ◽  
Key Factor ◽  
By Products

Purcell and colleagues offer new insights into a major mechanism of polymyxin resistance in Gram-negative bacteria. Inactivating a single lipid recycling enzyme causes accumulation of waste lipid by-products that inhibit a key factor responsible for polymyxin resistance.

Bacterial-Mucosal Cell Junctional Complexes

1974 ◽  
Vol 32 ◽  
pp. 144-145
Author(s):  
Roger C. Wagner
Keyword(s):  
Intestinal Wall ◽  
Rat Colon ◽  
Mucosal Cell ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Mucosal Cells ◽  
Mucosal Lining ◽  
Degenerative Alterations ◽  
Junctional Complexes ◽  
Intestinal Mucosal Cells

Bacteria exhibit the ability to adhere to the apical surfaces of intestinal mucosal cells. These attachments either precede invasion of the intestinal wall by the bacteria with accompanying inflammation and degeneration of the mucosa or represent permanent anchoring sites where the bacteria never totally penetrate the mucosal cells.Endemic gram negative bacteria were found attached to the surface of mucosal cells lining the walls of crypts in the rat colon. The bacteria did not intrude deeper than 0.5 urn into the mucosal cells and no degenerative alterations were detectable in the mucosal lining.

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.

Ultrastructure of periplasmic bodies in gram-negative bacteria

1990 ◽  
Vol 48 (3) ◽  
pp. 640-641
Author(s):  
Xie Nianming ◽  
Ding Shaoqing ◽  
Wang Luping ◽  
Yuan Zenglin ◽  
Zhan Guolai ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Campylobacter Jejuni ◽  
Proteus Mirabilis ◽  
Shigella Flexneri ◽  
Morphological Description ◽  
Gram Negative Bacteria ◽  
Periplasmic Space ◽  
Clostridium Tetani ◽  
Gram Negative ◽  
Brucella Canis

Perhaps the data about periplasmic enzymes are obtained through biochemical methods but lack of morphological description. We have proved the existence of periplasmic bodies by electron microscope and described their ultrastructures. We hope this report may draw the attention of biochemists and mrophologists to collaborate on researches in periplasmic enzymes or periplasmic bodies with each other.One or more independent bodies may be seen in the periplasmic space between outer and inner membranes of Gram-negative bacteria, which we called periplasmic bodies. The periplasmic bodies have been found in seven species of bacteria at least, including the Pseudomonas aeroginosa. Shigella flexneri, Echerichia coli. Yersinia pestis, Campylobacter jejuni, Proteus mirabilis, Clostridium tetani. Vibrio cholerae and Brucella canis.

Dual stain kit for the microscopic gram classification of ocular infection bacteria

1993 ◽  
Vol 51 ◽  
pp. 248-249
Author(s):  
Jacob S. Hanker ◽  
Dale N. Holdren ◽  
Kenneth L. Cohen ◽  
Beverly L. Giammara
Keyword(s):  
Contact Lenses ◽  
Ocular Infection ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Gram Staining ◽  
Ocular Infections ◽  
Different Types ◽  
Culture Positive ◽  
Increased Susceptibility

Keratitis and conjunctivitis (infections of the cornea or conjunctiva) are ocular infections caused by various bacteria, fungi, viruses or parasites; bacteria, however, are usually prominent. Systemic conditions such as alcoholism, diabetes, debilitating disease, AIDS and immunosuppressive therapy can lead to increased susceptibility but trauma and contact lens use are very important factors. Gram-negative bacteria are most frequently cultured in these situations and Pseudomonas aeruginosa is most usually isolated from culture-positive ulcers of patients using contact lenses. Smears for staining can be obtained with a special swab or spatula and Gram staining frequently guides choice of a therapeutic rinse prior to the report of the culture results upon which specific antibiotic therapy is based. In some cases staining of the direct smear may be diagnostic in situations where the culture will not grow. In these cases different types of stains occasionally assist in guiding therapy.

Neutrophil pseudoplatelets in subgingival plaque and crevicular fluid samples from periodontal diseased sites

1989 ◽  
Vol 47 ◽  
pp. 862-863 ◽  
Author(s):  
J Hanker ◽  
E.J. Burkes ◽  
G. Greco ◽  
R. Scruggs ◽  
B. Giammara
Keyword(s):  
Electron Microscopy ◽  
Bone Marrow ◽  
Peripheral Blood ◽  
Gingival Crevicular Fluid ◽  
Light And Electron Microscopy ◽  
Subgingival Plaque ◽  
Staining Reaction ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Crevicular Fluid

The mature neutrophil with a segmented nucleus (usually having 3 or 4 lobes) is generally considered to be the end-stage cell of the neutrophil series. It is usually found as such in the bone marrow and peripheral blood where it normally is the most abundant leukocyte. Neutrophils, however, must frequently leave the peripheral blood and migrate into areas of infection to combat microorganisms. It is in such areas that neutrophils were first observed to fragment to form platelet-size particles some of which have a nuclear lobe. These neutrophil pseudoplatelets (NPP) can readily be distinguished from true platelets because they stain for neutrophil myeloperoxidase. True platelets are not positive in this staining reaction because their peroxidase Is inhibited by glutaraldehyde. Neutrophil pseudoplatelets, as well as neutrophils budding to form NPP, could frequently be observed in peripheral blood or bone marrow samples of leukemia patients. They are much more prominent, however, in smears of inflammatory exudates that contain gram-negative bacteria and in gingival crevicular fluid samples from periodontal disease sites. In some of these samples macrophages ingesting, or which contained, pseudoplatelets could be observed. The myeloperoxidase in the ingested pseudoplatelets was frequently active. Despite these earlier observations we did not expect to find many NPP in subgingival plaque smears from diseased sites. They were first seen by light microscopy (Figs. 1, 3-5) in smears on coverslips stained with the PATS reaction, a variation of the PAS reaction which deposits silver for light and electron microscopy. After drying replicate PATS-stained coverslips with hexamethyldisilazane, they were sputter coated with gold and then examined by the SEI and BEI modes of scanning electron microscopy (Fig. 2). Unstained replicate coverslips were fixed, and stained for the demonstration of myeloperoxidase in budding neutrophils and NPP. Neutrophils, activated macrophages and spirochetes as well as other gram-negative bacteria were also prominent in the PATS stained samples. In replicate subgingival plaque smears stained with our procedure for granulocyte peroxidases only neutrophils, budding neutrophils or NPP were readily observed (Fig. 6).

Antimicrobial and cytotoxic activity of Macrophomina phaseolina isolated from gummosis infected citrus reticulata

2013 ◽  
pp. 125-133
Author(s):  
Rubal C Das ◽  
Rajib Banik ◽  
Robiul Hasan Bhuiyan ◽  
Md Golam Kabir
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Brine Shrimp ◽  
Inhibitory Concentration ◽  
Lethal Dose ◽  
Macrophomina Phaseolina ◽  
Chloroform Extract ◽  
Citrus Reticulata ◽  
Gram Negative Bacteria ◽  
Gram Negative

Macrophomina phaseolina is one of the pathogenic organisms of gummosis disease of orange tree (Citrus reticulata). The pathogen was identified from the observation of their colony size, shape, colour, mycelium, conidiophore, conidia, hyaline, spore, and appressoria in the PDA culture. The crude chloroform extracts from the organism showed antibacterial activity against a number of Gram positive and Gram-negative bacteria. The crude chloroform extract also showed promising antifungal activity against three species of the genus Aspergillus. The minimum inhibitory concentration (MIC) of the crude chloroform extract from M. phaseolina against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Shigella sonnie were 128 ?gm, 256 ?gm, 128 ?gm and 64 ?gm/ml respectively. The LD50 (lethal dose) values of the cytotoxicity assay over brine shrimp of the crude chloroform extract from M. phaseolina was found to be 51.79 ?gm/ml. DOI: http://dx.doi.org/10.3329/cujbs.v5i1.13378 The Chittagong Univ. J. B. Sci.,Vol. 5(1 &2):125-133, 2010

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