Gram staining v1

Author(s):  
lydiariver not provided

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.

2009 ◽  
Vol 55 (5) ◽  
pp. 627-632 ◽  
Author(s):  
Thomas Candela ◽  
Marie Moya ◽  
Michel Haustant ◽  
Agnès Fouet

Poly-γ-glutamate has been described in many Gram-positive organisms. When anchored to the surface, it is a capsule and as such a virulence factor. Based on sequence similarities, few Gram-negative organisms have been suggested to synthesize poly-γ-glutamate. For the first time, a Gram-negative bacterium, Fusobacterium nucleatum , is shown to produce and secrete poly-γ-glutamate. Putative poly-γ-glutamate-synthesizing genes from Gram-negative organisms have been compared with their Gram-positive homologs by in silico analysis, i.e., gene sequence and phylogenetic analysis. Clusters of three instead of four genes were highlighted by our screen. The products of the first two genes display similarity with their Gram-positive equivalents, yet the sequences from the Gram-negative organisms can be distinguished from those of the Gram-positives. Interestingly, the sequence of the predicted product of the third gene is conserved among Gram-negative bacteria but displays no similarity to that of either the third or fourth gene of the Gram-positive operons. It is suggested that, like for Gram-positive bacteria, poly-γ-glutamate has a role in virulence for pathogens and one in survival for other Gram-negative bacteria.


2013 ◽  
Vol 12 (1) ◽  
pp. 63-68 ◽  
Author(s):  
Javier Aragón-Sánchez ◽  
Benjamin A. Lipsky ◽  
Jose L. Lázaro-Martínez

Osteomyelitis frequently complicates infections in the feet of patients with diabetes. Gram-positive cocci, especially Staphylococcus aureus, are the most commonly isolated pathogens, but gram-negative bacteria also cause some cases of diabetic foot osteomyelitis (DFO). These gram-negatives require different antibiotic regimens than those commonly directed at gram-positives. There are, however, few data on factors related to their presence and how they influence the clinical picture. We conducted a retrospective study to determine the variables associated with the isolation of gram-negative bacteria from bone samples in cases of DFO and the clinical presentation of these infections. Among 341 cases of DFO, 150 had a gram-negative isolate (alone or combined with a gram-positive isolate) comprising 44.0% of all patients and 50.8% of those with a positive bone culture. Compared with gram-positive infections, wounds with gram-negative organisms more often had a fetid odor, necrotic tissue, signs of soft tissue infection accompanying osteomyelitis, and clinically severe infection. By multivariate analysis, the predictive variables related to an increased likelihood of isolating gram-negatives from bone samples were glycated hemoglobin <7% (odds ratio [OR] = 2.0, 95% confidence interval [CI] = 1.1-3.5) and a wound caused by traumatic injury (OR = 2.0, 95% CI = 1.0-3.9). Overall, patients whose bone samples contained gram-negatives had a statistically significantly higher prevalence of leukocytosis and higher white blood cell counts than those without gram-negatives. In conclusion, gram-negative organisms were isolated in nearly half of our cases of DFO and were associated with more severe infections, higher white blood cell counts, lower glycated hemoglobin levels, and wounds of traumatic etiology.


Author(s):  
Manpreet Kaur Bhatha Loveena Oberoi ◽  
Sapna Soneja Anuradha Malhotra ◽  
Kamaldeep Singh

Urinary tract infection(UTI) is one of the most commonest bacterial infection encountered in the pediatric age group. Early diagnosis is of utmost importance to preserve renal function and reduce long term complications such as renal scarring. The objective of this study was to determine the prevalence of UTI in pediatric population, identify the common uropathogens and study the antibiotic susceptibility pattern of bacterial isolates. Materials and Methods: A retrospective study was carried out in Department of Microbiology, GMC Amritsar for a period of 6 months from 1 Jan 2021 till 30 June 2021 amongst the pediatric patients (1 month-12 years age group) with clinically suspected UTI including both indoor and outdoor patients. Clean catch midstream urine samples received in the laboratory were processed as per the standard microbiological guidelines. Antibiotic susceptibility testing was done using Kirby-Bauer disc diffusion method as per CLSI guidelines. Results: A total of 549 samples were received and processed during study period from which 164(29.87%) were culture positive. Culture positivity was more prevalent in females (61.58%) than males (38.41%). Gram negative organisms were predominant (74.4%) followed by gram positive cocci (22.56%) and Candida (3.05%). Among gram negative organisms Escherichia coli was most predominant followed by Klebsiella spp., Pseudomonas spp., Acinetobacter spp., Proteus spp. and Citrobacter spp. Among gram positive cocci Staphylococcus aureus was most predominant followed by Coagulase negative Staphylococci and Enterococcus spp. Majority of gram negative bacilli were resistant to fluroquinolones, 3rd generation cephalosporins and co-trimoxazole while nitrofurantoin, piperacillin-tazobactam and gentamicin were most sensitive drugs. Among Staphylococcus aureus, methicillin resistance was seen in 17% isolates. High sensitivity was seen to linezolid and vancomycin in gram positive cocci. Conclusion: This study highlights increased prevalence of MDR uropathogens in pediatric population which indicates that antibiotic selection should be based on knowledge of local prevalence of bacterial organisms and their antibiotic sensitivities with rational use of antibiotics.


2020 ◽  
Vol 24 (3) ◽  
pp. 219-224
Author(s):  
Saba Mushtaq ◽  
Sohail Ashraf ◽  
Lubna Ghazal ◽  
Rida Zahid ◽  
Basharat Hussain ◽  
...  

Introduction: Neonatal sepsis is a clinical syndrome characterized by multiple symptoms and signs of infection during the first month of life. The objective of this study is to determine the frequency of commonly isolated bacteria from patients of neonatal sepsis and their susceptibility patterns in POF hospital at Wah. Methods: This cross-sectional study was carried out in POF Hospital Neonatal intensive care unit and Microbiology laboratory from January 2018 to December 2019. The blood samples of patients suspected with neonatal sepsis were processed as per standard methodology. Results: Out of ninety blood samples, fifty-one (56.7%) yielded the growth of Gram-negative rods and thirty-nine (43.3%) yielded Gram-positive cocci. Among Gram-positive bacteria, coagulase-negative staphylococci were the most common pathogen isolated from 53.8% cases followed by methicillin-resistant Staphylococcus aureus (15.3%). Among Gram-negative bacteria, Klebsiella pneumoniae (54.90%) was the most frequently identified bacteria followed by Serratia marcescens (27.45%). The Gram-positive cocci were the most susceptible to linezolid (100%) followed by vancomycin (87.2%). The Gram-negative rods depict remarkable resistance to ciprofloxacin (92.2%), gentamicin (100%), and meropenem (54.9%). Conclusions: The study concluded a predominance of Gram-negative bacteria as a causative agent of neonatal sepsis in our setup. The bacterial isolates are highly resistant to commonly prescribed oral as well as injectable antibiotics. Implementation of infection control policies is a dire need to combat the grave situation of increasing antibiotic resistance.


2019 ◽  
Vol 25 (5) ◽  
pp. 502-507 ◽  
Author(s):  
Zenith Khashim ◽  
Seán Fitzgerald ◽  
Ramanathan Kadirvel ◽  
Daying Dai ◽  
Karen M Doyle ◽  
...  

Background Bacteria and bacterial components have been associated with the activation of coagulation factors and initiating the blood clot formation. The aim of this study was to investigate whether bacterial populations are present in clots retrieved from patients that have suffered a large vessel occlusion acute ischemic stroke (AIS). Materials and methods Clot samples were collected from 20 AIS patients who underwent clot retrieval with mechanical thrombectomy. Patient clinical demographic details were noted. Expression of bacterial 16S rDNA was analyzed by standard and real-time polymerase chain reaction (PCR). Gram staining was performed to identify Gram-positive and Gram-negative bacteria. Results Both the real-time and standard PCR demonstrated no expression of 16S rDNA in any of the 20 clots samples from AIS patients. Gram staining results showed no expression of Gram-positive or Gram-negative bacteria present in the clot samples. Conclusion Our current study found no bacteria populations in the clots of AIS patients.


2018 ◽  
Vol 19 (4) ◽  
Author(s):  
Anna Kędzia ◽  
Andrzej W. Kędzia ◽  
Henry O. Meissner ◽  
Joanna Wiśniewska

Introduction. Sweet majoram (Origanum majorana L.), green plant from family Lamiaceae is common used in traditional medicine. Herba majoranae containing from 1 to 3.5% essential oil. The main components of the oil depend on the geographic origin of the plant and include: terpinen-4-ol, α-terpineol, terpinene, γ-terpinene, cis-sabinene hydrate, p-cymene, triterpenic acid, phenolic acid, flavonoids glycosides, tanins, diterpenoids and triterpenoids. The oil is used for treatment of lung diseases, spleen, kidneys, hepatitis, alimentary tract and headaches. It has antiemetic, anticancer, antioxidant and antimicrobial properties. Aim. The aim of the study was to determine the susceptibility of anaerobic bacteria isolated from oral cavity to majoram oil. Material and methods. A total of 57 anaerobic bacteria belonging to the genus of Porphyromonas (4 strains), Prevotella (9), Bacteroides (11), Parabacteroides (1), Tannerella (2), Fusobacterium (7), 11 strains of Gram-positive cocci, 12 strains of Gram-positive rods and 6 reference strains were tested. Investigation was carried out using the plate dilution technique in Brucella agar supplemented with 5% defibrynated sheep blood, menadione and hemine. Inoculum containing 106 CFU per spot was seeded with Steers replicator upon the agar with various oil concentrations as well as upon that no majoram oil (Semifarm, Elbląg). The concentrations oil were: 0.06, 0.12, 0.25, 0.5, 1.0 and 2.0 mg/ml. The plate were incubated in anaerobic conditions, in anaerobic jars for 48 hours in 37°C. Minimum inhibitory concentration (MIC) was interpreted as the lowest concentrations oil inhibiting the growth of strains of anaerobes. Results and discussion. The results of investigations indicated that the from Gram-negative bacteria belonging to the genus of Bacteroides uniformis, Tannerella forsythia and Bacteroides vulgatus were the most susceptible to the essential oil (MIC <0.06-0.5 mg/ml). But the 89% strains from genus of Prevotella was sensitive to 2.0 mg/ml and more. Tested oil was less active against the strains from genera of Fusobacterium. MIC of the strains were in ranges 1.0-> 2.0 mg/ml. The rods from the genera Prevotella bivia, Prevotella buccalis, Prevotella loescheii, Bacteroides fragilis, Parabacteroides distasonis and Fusobacterium nucleatum were the lowest sensitive (MIC > 2.0 mg/ml). The oil was very active vs. Gram-positive cocci. MIC for 50% this strains was in ranges < 0.06-0.25 mg/ml. But the Gram-positive rods were less sensitive. The growth of the strains were inhibited by concentrations in ranges 1.0-> 2.0 mg/ml (without Actinomyces viscosus – MIC 1.0 mg/ml). It appears that Gram-positive anaerobic bacteria were more susceptible to majoram oil than Gram-negative rods. Conclusions. The most susceptible to majoram oil from Gram-negative bacteria were rods of Bacteroides uniformis, Tannerella forsythia and Bacteroides vulgatus. The oil was very active against Gram-positive cocci and rods. The Gram-negative anaerobes were less susceptible to majoram oil than Gram-positive anaerobes.


1980 ◽  
Vol 8 (2) ◽  
pp. 112-117 ◽  
Author(s):  
J F Donald ◽  
D M D Rimmer

One hundred and eighty-four women, with acute uncomplicated cystitis, received a 3-day course of pivmecillinam comprising an initial 400 mg (two tablets) dose, followed by 200 mg every 8 hours; a total of ten tablets. A satisfactory clinical response was achieved in 91% of patients. Bacteriological success was observed in 94% of sixty-eight patients with a proven infection. Side-effects were reported in sixteen patients (8.4%). Two patients ceased therapy prematurely. Pivmecillinam did not select out resistant Gram-negative organisms. A trend towards reinfection with Gram-positive cocci was observed. The possible significance of reinfection with different organisms is discussed.


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