scholarly journals The Phosphorus-containing Compounds of Gram-positive and Gram-negative Organisms in Relation to the Gram Staining Reaction

1958 ◽  
Vol 18 (3) ◽  
pp. 597-606 ◽  
Author(s):  
A. S. JONES ◽  
S. B. H. RIZVI ◽  
M. STACEY
Keyword(s):  
Staining Reaction ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Staining ◽  
Phosphorus Containing ◽  
Gram Negative Organisms

BACTERIAL LIPIDS AND THE GRAM STAINING REACTION

1964 ◽  
Vol 42 (8) ◽  
pp. 1141-1151 ◽  
Author(s):  
A. K. Bergh ◽  
S. J. Webb ◽  
C. S. McArthur
Keyword(s):  
Staphylococcus Epidermidis ◽  
Staining Reaction ◽  
Bacterial Cells ◽  
Polar Solvents ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Staining ◽  
A Cell ◽  
Gram Negative Organisms ◽  
High Polarity

In this study, no correlation was found between the Gram staining reaction of bacterial cells and the kinds of fatty acids in the lipids. The polar solvent (usually alcohol) used to wash out the stain from Gram-negative organisms removes much more lipid from these than from Gram-positive forms. The extractability of lipids from cells of Staphylococcus epidermidis increased when they became Gram-negative through aging. The infrared spectrum of the lipids extracted from these Gram-negative Staphylococci remained the same as that of the Gram-positive cells. It was further noted that high polarity characteristics and mutual miscibility in aqueous and lipid solvents are requirements of the decolorizing solvent.The Gram staining reaction of a cell appears to be related to the manner in which some of its lipids are bound to other components of the cell and the ease or difficulty with which the lipids are separated from lipoprotein and other complexes by certain polar solvents.

Gram staining v1

2021 ◽  
Author(s):  
lydiariver not provided
Keyword(s):  
Cell Walls ◽  
Group B Streptococcus ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Staining ◽  
Acetone Treatment ◽  
Gram Negative Organisms ◽  
Group B ◽  
Gram Positive Cocci

Gram staining is one of the first techniques used for the identification of group B Streptococcus agalactiae and one would expect to see gram-positive cocci under the microscope. The technique consists of applying a series of colorants and bleaches (acetone), which interact with the lipids of the membranes of gram-positive and gram-negative bacteria. The cell walls of gram-positive organisms retain the dye after acetone treatment and appear purple in color, whereas gram-negative organisms become discolored after acetone treatment and appear pink.

scholarly journals Assessing Gram-stain error rates within the pharmaceutical microbiology laboratory

2020 ◽  
Author(s):  
Tim Sandle
Keyword(s):  
Error Rates ◽  
Microbiology Laboratory ◽  
Gram Stain ◽  
Clinical Context ◽  
Determinative Bacteriology ◽  
Gram Positive ◽  
Gram Negative ◽  
Microbial Identification ◽  
Gram Staining ◽  
Gram Negative Organisms

Gram-staining remains the fundamental method for determinative bacteriology, dividing bacteria into Gram-positive and Gram-negative organisms. This test provides information as to the origin of any contamination and is a pre-requisite for many microbial identification methods. Despite the longevity of the test, the test is highly reliant upon analyst technique and therefore errors occur. While there are a few studies looking at errors in the clinical context, research has not been extended to the pharmaceutical microbiology laboratory context. In this study, we present a review of over 6,000 Gram-stains and establish an error rate of around 3%, with the most common reason for error being an over-decolourisation step resulting in organisms that should be Gram-positive appearing as Gram-negative. The analysis enables others to benchmark their facilities against.

scholarly journals Linearized esculentin-2EM shows pH dependent antibacterial activity with an alkaline optimum

2021 ◽  
Author(s):  
Erum Malik ◽  
David A. Phoenix ◽  
Timothy J. Snape ◽  
Frederick Harris ◽  
Jaipaul Singh ◽  
...  
Keyword(s):  
Helical Structure ◽  
Food Preservation ◽  
Forming Process ◽  
Gram Positive ◽  
Gram Negative ◽  
Bacterial Membranes ◽  
Gram Positive Bacteria ◽  
Alkaline Conditions ◽  
Ph Dependent ◽  
Gram Negative Organisms

AbstractHere the hypothesis that linearized esculentin 2EM (E2EM-lin) from Glandirana emeljanovi possesses pH dependent activity is investigated. The peptide showed weak activity against Gram-negative bacteria (MLCs ≥ 75.0 μM) but potent efficacy towards Gram-positive bacteria (MLCs ≤ 6.25 μM). E2EM-lin adopted an α-helical structure in the presence of bacterial membranes that increased as pH was increased from 6 to 8 (↑ 15.5–26.9%), whilst similar increases in pH enhanced the ability of the peptide to penetrate (↑ 2.3–5.1 mN m−1) and lyse (↑ 15.1–32.5%) these membranes. Theoretical analysis predicted that this membranolytic mechanism involved a tilted segment, that increased along the α-helical long axis of E2EM-lin (1–23) in the N → C direction, with −  < µH > increasing overall from circa − 0.8 to − 0.3. In combination, these data showed that E2EM-lin killed bacteria via novel mechanisms that were enhanced by alkaline conditions and involved the formation of tilted and membranolytic, α-helical structure. The preference of E2EM-lin for Gram-positive bacteria over Gram-negative organisms was primarily driven by the superior ability of phosphatidylglycerol to induce α-helical structure in the peptide as compared to phosphatidylethanolamine. These data were used to generate a novel pore-forming model for the membranolytic activity of E2EM-lin, which would appear to be the first, major reported instance of pH dependent AMPs with alkaline optima using tilted structure to drive a pore-forming process. It is proposed that E2EM-lin has the potential for development to serve purposes ranging from therapeutic usage, such as chronic wound disinfection, to food preservation by killing food spoilage organisms.

scholarly journals 1554. Epidemiology of Adult Bacterial Hand Infections at Two Urban Hospitals

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S777-S778
Author(s):  
Arsheena Yassin ◽  
Christine Stavropoulos ◽  
Krystina L Woods ◽  
Jiashan Xu ◽  
Justin Carale ◽  
...  
Keyword(s):  
New York ◽  
Staphylococcus Aureus ◽  
Antibiotic Regimen ◽  
Gram Positive ◽  
Gram Negative ◽  
Streptococcus Species ◽  
Urban Hospitals ◽  
Haemophilus Parainfluenzae ◽  
Empiric Antibiotic ◽  
Gram Negative Organisms

Abstract Background Hand infections represent a major source of morbidity, which can result in hand stiffness and amputation. Early appropriate empiric antibiotic regimen may reduce the associated morbidity, hence the importance to examine local epidemiology. The aim of this study was to define the current epidemiology of adult hand infections at two urban hospitals in New York City. Methods We performed a double center, retrospective study of adult patients hospitalized from March 2018 to May 2020. Patients with positive cultures associated with the hand infections were included. Retrospectively, 100 patients were reviewed. Data on baseline demographic, clinical, surgical, microbiology, and treatment parameters were collected. Results Of the 100 patients, 76% were male, with median age of 47.5 years (35, 58.25) and average C-reactive protein (CRP) of 50.66 mg/L (± 64.64) on admission (see Table 1). Previous hospitalization within 1 year (38%), previous surgical procedures (39%) and recent IV medication use (26%) were common. 130 bacterial isolates were identified (see Table 2). The most frequent organisms were Gram-positive, with Methicillin susceptible Staphylococcus aureus (MSSA, 25.38%), Streptococcus species (20.08%), and Methicillin resistant Staphylococcus aureus (MRSA, 15.38%) being the most common. Gram-negative organisms were infrequent, with Haemophilus parainfluenzae (3.85%), Enterobacter cloacae (3.85) and Pseudomonas aeruginosa (3.08%) being the most prevalent. Of the 100 patients, 27% had polymicrobial infections, associated with trauma (6%), illicit IV use (6%) and unknown (7%) etiologies. Table 1: Baseline demographics and co-morbid conditions Table 2: Types and numbers of organisms in relation to etiologies Conclusion Within our population, the most common organisms associated with hand infections were Gram-positive, with Staphylococcus aureus and Streptococcus species being the most prevalent. Gram-negative pathogens were infrequently isolated. The results within this study can provide guidance to clinicians on assessing the appropriate empiric antibiotic regimen in patients with hand infections, and can serve as a basis for further studies identifying risk factors associated with isolation of organisms associated with hand infections. Disclosures All Authors: No reported disclosures

scholarly journals Evaluation of MicroScan Bacterial Identification Panels for Low-Resource Settings

Diagnostics ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 349
Author(s):  
Sien Ombelet ◽  
Alessandra Natale ◽  
Jean-Baptiste Ronat ◽  
Olivier Vandenberg ◽  
Liselotte Hardy ◽  
...  
Keyword(s):  
Bacterial Species ◽  
Ease Of Use ◽  
Bacterial Identification ◽  
Gram Positive ◽  
Gram Negative ◽  
Low Resource Settings ◽  
Low Resource ◽  
Bacillus Spp ◽  
Gram Negative Organisms ◽  
Instructions For Use

Bacterial identification is challenging in low-resource settings (LRS). We evaluated the MicroScan identification panels (Beckman Coulter, Brea, CA, USA) as part of Médecins Sans Frontières’ Mini-lab Project. The MicroScan Dried Overnight Positive ID Type 3 (PID3) panels for Gram-positive organisms and Dried Overnight Negative ID Type 2 (NID2) panels for Gram-negative organisms were assessed with 367 clinical isolates from LRS. Robustness was studied by inoculating Gram-negative species on the Gram-positive panel and vice versa. The ease of use of the panels and readability of the instructions for use (IFU) were evaluated. Of species represented in the MicroScan database, 94.6% (185/195) of Gram-negative and 85.9% (110/128) of Gram-positive isolates were correctly identified up to species level. Of species not represented in the database (e.g., Streptococcus suis and Bacillus spp.), 53.1% out of 49 isolates were incorrectly identified as non-related bacterial species. Testing of Gram-positive isolates on Gram-negative panels and vice versa (n = 144) resulted in incorrect identifications for 38.2% of tested isolates. The readability level of the IFU was considered too high for LRS. Inoculation of the panels was favorably evaluated, whereas the visual reading of the panels was considered error-prone. In conclusion, the accuracy of the MicroScan identification panels was excellent for Gram-negative species and good for Gram-positive species. Improvements in stability, robustness, and ease of use have been identified to assure adaptation to LRS constraints.

scholarly journals THE AUTOLYTIC SYSTEM OF PNEUMOCOCCI

1937 ◽  
Vol 65 (6) ◽  
pp. 873-883 ◽  
Author(s):  
René J. Dubos
Keyword(s):  
Cell Suspension ◽  
Cellular Structure ◽  
Enzyme Preparation ◽  
Reducing Sugars ◽  
Proteolytic Enzymes ◽  
Bacterial Suspension ◽  
Staining Reaction ◽  
Gram Negative ◽  
Gram Staining ◽  
Original Weight

1. Living pneumococcus cells contain a group of enzymes, the bacteriolytic system, capable of causing the lysis of heat-killed pneumococci (R and S variants irrespective of type derivation). This lysis expresses itself by a loss of the Gram staining reaction, a disintegration of the cell body, and a clearing of the bacterial suspension. 2. Under certain conditions of treatment with the bacteriolytic complex, it is possible to render the cocci Gram-negative without changing their characteristic morphology, or causing any appreciable clearing of the cell suspension. 3. The enzyme responsible for this change has been partially purified, and some of its properties described. 4. The cellular structure which is responsible for the Gram-positive reaction of pneumococci is resistant to proteolytic enzymes, and is still present when tryptic digestion has reduced the heat-killed cell to a body which has lost 75 per cent of its original weight, and contains only 8 per cent nitrogen. 5. The same enzyme preparation which attacks pneumococci is also capable of liberating reducing sugars from some acetyl amino glucose glucuronides of animal and bacterial origin. The possibility is considered, and discussed, that one and the same enzyme in the autolytic complex is capable of attacking both types of substrates.

scholarly journals Morphological characterization of gram-positive and gram-negative bacteria from treated latex processing wastewater

2021 ◽  
Vol 1 (2) ◽  
pp. 32-36
Author(s):  
Farrah Aini Dahalan ◽  
Nor Azizah Parmin
Keyword(s):  
Oxygen Demand ◽  
Morphological Characterization ◽  
The Other ◽  
Morphological Properties ◽  
Morphological Observation ◽  
Gram Positive ◽  
Bacterial Colony ◽  
Gram Negative ◽  
Gram Staining

A preliminary morphological screening and isolation of bacterial colony from latex industrial wastewater was carried out. Bacteria colonies from latex processing wastewater were isolated from a local latex processing industry. It was found that 17 bacterial isolates had been purified grown on nutrient agar under 35˚C. The colonies were then purified and morphologically indicated via Gram staining and motility test. After morphological observation, it was identified that out of 17 isolates, 9 isolates were Gram positive and 8 isolates were Gram negative. There are 11 out of 17 colonies were rod-shaped bacterial colonies, while the other 6 colonies were cocci-shaped bacteria. There were 11 colonies of gliding bacteria, three colonies were non-motile bacteria and the other three colonies were flagellated bacteria. This study is only limited to morphological observation as the main aim of this study was to investigate the potential occurrence of viable growth in treated latex processing wastewater. The bacterial colonies were classified base on their morphological properties shown. This study has classified several genera such as Staphylococcus, Escherichia, Thiobacillus, Arthrobacter and other Genus. The growth curve of 17 isolates studied and the chemical oxygen demand were determined.

A 10-YEAR REVIEW OF COMPARISON BETWEEN GRAM-POSITIVE AND GRAM-NEGATIVE ORGANISMS IN ACUTE THORACIC EMPYEMA

CHEST Journal ◽  
2009 ◽  
Vol 136 (4) ◽  
pp. 45S
Author(s):  
Abhijit Duggal ◽  
Konstantinos Marmagkiolis ◽  
Lawrence Goldstein
Keyword(s):  
Gram Positive ◽  
Gram Negative ◽  
Thoracic Empyema ◽  
Gram Negative Organisms
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