scholarly journals STUDIES ON THE BACTERIOPHAGE OF D'HERELLE

1925 ◽  
Vol 42 (4) ◽  
pp. 483-497 ◽  
Author(s):  
Jacques J. Bronfenbrenner ◽  
Charles Korb
Keyword(s):  
Quantitative Evaluation ◽  
Bacterial Species ◽  
Relative Concentration ◽  
Serial Dilution ◽  
The Other ◽  
Resistant Bacteria ◽  
Dilution Method ◽  
High Concentration ◽  
Average Size ◽  
Broth Dilution

The experiments reported above confirm the fact that lytic principle is distributed in active solution in a state of indivisible units. This permits its quantitative evaluation by serial dilution, as well as by plating on agar. The latter method, however, often gives readings considerably lower than those obtained by the broth dilution method of titration. By varying the concentration of agar it has been possible to show that the discrepancy is due to adsorption of the lytic agent on agar. When the concentration of the latter is increased from 0.3 per cent to 2.5 per cent the number of plaques of lysis is reduced more than 100 times. At the same time the average size of the plaques also decreases approximately to one-tenth of the original. The size, as well as the number of plaques, has been found to depend also on the condition of the culture employed in titration. Thus, when the culture exposed to the action of lytic agent is composed of young susceptible bacteria, the greater the concentration of bacteria, the smaller the plaques. When the culture is composed partly of young and partly of old susceptible bacteria, both the size and the number of the plaques are diminished with the increase in the relative concentration of old bacteria. On the other hand, presence in the culture of resistant bacteria does not affect either the size or the number of the plaques so long as the relative concentration of susceptible bacteria in the culture is sufficient to allow formation of them. The plaques appearing in the presence of a high concentration of resistant variants in the culture are relatively indistinct owing to overgrowth. Under carefully controlled conditions the size of plaques is found to be determined by the character of the lytic filtrate. Thus in the case of lytic agents which act upon more than one bacterial species the size of the plaques remains constant, irrespective of the bacterial substratum used for the production of the active filtrate.

scholarly journals Amtimicrobial activity of essential oil of Melissa officinalis L, Lamiaceae

2005 ◽  
Vol 59 (9-10) ◽  
pp. 243-247 ◽  
Author(s):  
Nada Anicic ◽  
Suzana Dimitrijevic ◽  
Mihailo Ristic ◽  
Slobodan Petrovic ◽  
Slobodan Petrovic
Keyword(s):  
Antimicrobial Activity ◽  
Essential Oil ◽  
Bacterial Species ◽  
Antimicrobial Properties ◽  
Dilution Method ◽  
Melissa Officinalis ◽  
E Coli ◽  
Diffusion Technique ◽  
Main Components ◽  
Broth Dilution

The antimicrobial activity of the essential oil of Melissa officinalis was investigated in this paper. The essential oil was obtained by the principle of water and steam and analyzed by GC and GC-MS using FID and MSD. The main components of the oil of Melissa officinalis were geranial (17.30%), neral (14.70%) and citronellal (10.70%). The antimicrobial properties were tested against the following bacterial species: B subtilis, B.cereus Bifidobacterium sp., Corynobacterium sp., E. coli, Klebsiella sp., L. acidophilus, L. fermentum, L. plantarum, L. rhamnosus, Listeria monocytogenes, P. vulgaris, P. aerugenosa, S. enteritidis, Shigella sp., S. aureus, and fungi Candida albicans, Alternarija sp. and Aspergillus niger. The diffusion technique was used for testing: the antimicrobial activity, and the MIC was determined by the broth dilution method. The essential oil of M. officinalis showed high antimicrobial activity.

scholarly journals Synthesis of Gold Nanoparticles by using Batch Method and Study its Antibacterial Activity

2020 ◽  
Vol 17 (2(SI)) ◽  
pp. 0633
Author(s):  
Ahmed Mohammed et al.
Keyword(s):  
Gold Nanoparticles ◽  
Dilution Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
E Coli ◽  
Inhibition Concentration ◽  
Uv Visible ◽  
Average Size ◽  
Broth Dilution ◽  
Initial Heating

The research involves preparing gold nanoparticles (AuNPs) and studying the factors that influence the shape, sizes and distribution ratio of the prepared particles according to Turkevich method. These factors include (reaction temperature, initial heating, concentration of gold ions, concentration and quantity of added citrate, reaction time and order of reactant addition). Gold nanoparticles prepared were characterized by the following measurements: UV-Visible spectroscopy, X-ray diffraction and scanning electron microscopy. The average size of gold nanoparticles was formed in the range (20 -35) nm. The amount of added citrate was changed and studied. In addition, the concentration of added gold ions was changed and the calibration curve was calculated used to estimate Au ions in different samples. The effectiveness of gold nanoparticles prepared according to Turkevich method was studied as antibacterial agents against E. coli bacteria. The minimum inhibition concentration of gold nanoparticles that inhibit bacterial growth was calculated using the broth dilution method, which is based on several dilutions to determine the inhibition concentration.

Assessment of micro and macro nutrients in poultry feeds available in Dhaka city, Bangladesh.

2017 ◽  
Vol 1 ◽  
pp. 264
Author(s):  
Md Didarul Islam ◽  
Ashiqur Rahaman ◽  
Fahmida Jannat
Keyword(s):  
Heavy Metals ◽  
Adverse Effect ◽  
The Other ◽  
Nutrient Level ◽  
Dhaka City ◽  
Toxic Heavy Metals ◽  
High Concentration ◽  
Low Concentration ◽  
Feed Formulation ◽  
Macro Nutrients

This study was based on to determine the concentration of macro and micro nutrients as well as toxic and nontoxic heavy metals present in the chicken feed available in Dhaka city of Bangladesh. All macro nutrients, if present in the feed at high concentration have some adverse effect, at the same time if this nutrient present in the feed at low concentration this have some adverse effect too. So that this nutrient level should be maintained at a marginal level. On the other side toxic heavy metals if present in the feed at very low concentration those can contaminate the total environment of the ecosystem. In this study six brand samples (starter, grower, finisher and layer) which was collected from different renowned chicken feed formulation industry in Bangladesh. Those samples were prepared for analysis by wet ashing and then metals were determined by Atomic Absorption Spectroscopy. It was found that 27.7 to 68.4, 57.3 to 121.9, 0.21 to 4.1, 0.32 to 2.1, 0.11 to 1.58, 0.28 to 2.11 and 0.28 to 1.78 for zinc, iron, copper, mercury, cadmium, nickel and cobalt respectively. It was found that essential macro and micro nutrients were present in the feed in low concentration on the other side mercury was present in high concentration in the feed samples.

ANTIBACTERIAL, ANTIFUNGAL ACTIVITY OF COMPOSITE EDIBLE COATING INCORPORATED WITH CITRUS LIMON L. PEEL EXTRACT AND IT’S EFFECT ON FUJI APPLES.

2020 ◽  
Author(s):  
Renu Jaisinghani ◽  
Vishnu Vasant Dayare
Keyword(s):  
Shelf Life ◽  
Antimicrobial Properties ◽  
Edible Coating ◽  
Dilution Method ◽  
Citrus Limon ◽  
Edible Coatings ◽  
Lemon Peel ◽  
Fruit Shelf Life ◽  
Broth Dilution ◽  
Peel Extract

Edible film and coatings are been looked upon for preservation of fruits, vegetables and bakery products. Extended shelf life with preservation of natural properties of food is always been a challenge; by incorporation of bio-actives in edible coatings, the shelf life can be increased as they are known for their antioxidant and antimicrobial properties. With this view, present study was undertaken, where edible coatings were prepared from starch, gelatin and glycerol and incorporated with Lemon peel extracts and coated on apples for increased shelf life. Antimicrobial activity of Lemon peel extracts was studied on eight organisms by broth dilution method and were found to be effective at concentration 3mg/mL-9mg/mL for bacteria and 50mg/mL- 90mg/mL for fungi. Fuji apples coated with starch-gelatin based edible formulation containing lemon peel extracts were studied for the effect of coating on fruit shelf life during storage for 28 days. Incorporation of lemon peel extract into edible coating improved shelf life with reducing rate of browning of apples.

A study on the antifungal susceptibility pattern of dermatophytes isolated in a tertiary care hospital

2017 ◽  
Vol 6 (05) ◽  
pp. 5379
Author(s):  
Vanathi Sabtharishi* ◽  
Radhika Katragadda ◽  
Thyagarajan Ravinder
Keyword(s):  
Tertiary Care Hospital ◽  
Antifungal Susceptibility ◽  
Tertiary Care ◽  
Antifungal Drugs ◽  
Dilution Method ◽  
Care Hospital ◽  
Susceptibility Pattern ◽  
Superficial Mycosis ◽  
Broth Dilution ◽  
Common Infections

Recent years, due to increased usage of antifungal treatment worldwide, there is an increased chance of rising resistance among antifungal drugs too. Dermatophytic infections causes’ superficial mycosis and it affects skin, hair and nail. These infections are more common and antifungal drugs are used everywhere to treat those common infections. To conduct a study by determining the antifungal susceptibility pattern in dermatophytic isolates from patients attending dermatology OPD in a tertiary care hospital. A total of 217 samples like hair, nail and skin scrapings were obtained and isolation of dermatophytes was done. Antifungal susceptibility testing for dermatophytes was performed by micro broth dilution method. Antifungal drugs tested were Griseofulvin, Fluconazole, Itraconazole and Ketoconazole. Minimum inhibitory concentration for each drug for fungal isolates was tested and results studied. Fluconazole showed a higher MIC values in the range of 1-8µg/ml. Itraconazole showed the lowest MIC values by micro broth dilution method. Since there is limitation of standard guidelines and protocol, meticulous research must be conducted on effect of antifungals and derive at universally implementable guidelines.

scholarly journals Development of an Immunochromatographic Strip Using Conjugated Gold Nanoparticles for the Rapid Detection of Klebsiella pneumoniae Causing Neonatal Sepsis

Pharmaceutics ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1141
Author(s):  
Noha M. Elhosseiny ◽  
Tamer M. Samir ◽  
Aliaa A. Ali ◽  
Amani A. El-Kholy ◽  
Ahmed S. Attia
Keyword(s):  
Gold Nanoparticles ◽  
Klebsiella Pneumoniae ◽  
Causative Agent ◽  
Neonatal Sepsis ◽  
Bacterial Species ◽  
Resistant Bacteria ◽  
Immunochromatographic Strip ◽  
Amino Acid Peptide ◽  
Negative Results ◽  
Drug Resistant Bacteria

Neonatal sepsis is a leading cause of death among newborns and infants, especially in the developing world. The problem is compounded by the delays in pinpointing the causative agent of the infection. This is reflected in increasing mortality associated with these cases and the spread of multi-drug-resistant bacteria. In this work, we deployed bioinformatics and proteomics analyses to determine a promising target that could be used for the identification of a major neonatal sepsis causative agent, Klebsiella pneumoniae. A 19 amino acid peptide from a hypothetical outer membrane was found to be very specific to the species, well conserved among its strains, surface exposed, and expressed in conditions simulating infection. Antibodies against the selected peptide were conjugated to gold nanoparticles and incorporated into an immunochromatographic strip. The developed strip was able to detect as low as 105 CFU/mL of K. pneumoniae. Regarding specificity, it showed negative results with both Escherichia coli and Enterobacter cloacae. More importantly, in a pilot study using neonatal sepsis cases blood specimens, the developed strip selectively gave positive results within 20 min with those infected with K. pneumoniae without prior sample processing. However, it gave negative results in cases infected with other bacterial species.

scholarly journals Antimicrobial Resistance among Neonates with Bacterial Sepsis and Their Clinical Outcomes in a Tertiary Hospital in Kathmandu Valley, Nepal

2021 ◽  
Vol 6 (2) ◽  
pp. 56
Author(s):  
Bijendra Raj Raghubanshi ◽  
Karuna D. Sagili ◽  
Wai Wai Han ◽  
Henish Shakya ◽  
Priyanka Shrestha ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Neonatal Sepsis ◽  
Bacterial Culture ◽  
Bacterial Species ◽  
Antibiotic Sensitivity ◽  
College Teaching ◽  
Hospital Treatment ◽  
Resistant Bacteria ◽  
Coagulase Negative Staphylococcus ◽  
Cross Sectional

Globally, antibiotic resistance in bacteria isolated from neonatal sepsis is increasing. In this cross-sectional study conducted at a medical college teaching hospital in Nepal, we assessed the antibiotic resistance levels in bacteria cultured from neonates with sepsis and their in-hospital treatment outcomes. We extracted data of neonates with sepsis admitted for in-patient care from June 2018 to December 2019 by reviewing hospital records of the neonatal intensive care unit and microbiology department. A total of 308 neonates with sepsis were admitted of which, blood bacterial culture antibiotic sensitivity reports were available for 298 neonates. Twenty neonates (7%) had bacteriologic culture-confirmed neonatal sepsis. The most common bacterial species isolated were Staphylococcus aureus (8), followed by coagulase-negative Staphylococcus (5). Most of these bacteria were resistant to at least one first-line antibiotic used to manage neonatal sepsis. Overall, there were 7 (2%) deaths among the 308 neonates (none of them from the bacterial culture-positive group), and 53 (17%) neonates had left the hospital against medical advice (LAMA). Improving hospital procedures to isolate bacteria in neonates with sepsis, undertaking measures to prevent the spread of antibiotic-resistant bacteria, and addressing LAMA’s reasons are urgently needed.

scholarly journals Development of a Genoserotyping Method for Salmonella Infantis Detection on the Basis of Pangenome Analysis

2020 ◽  
Vol 9 (1) ◽  
pp. 67
Author(s):  
Seung-Min Yang ◽  
Jiwon Baek ◽  
Eiseul Kim ◽  
Hyeon-Be Kim ◽  
Seyoung Ko ◽  
...  
Keyword(s):  
Public Health ◽  
Polymerase Chain Reaction ◽  
Bacterial Species ◽  
Cost Effective ◽  
The Other ◽  
Gene Marker ◽  
Diagnostic Assay ◽  
Chain Reaction ◽  
Polymerase Chain ◽  
Substantial Economic Burden

In recent years, Salmonella Infantis has become a predominant serovariant in clinical and poultry isolates, thereby imposing a substantial economic burden on both public health and the livestock industry. With the aim of coping with the steep increase in serovar Infantis prevalence, a polymerase chain reaction (PCR)-based rapid and accurate diagnostic assay was developed in this study through pangenome profiling of 60 Salmonella serovars. A gene marker, SIN_02055, was identified, which is present in the S. Infantis genome but not in the pangenome of the other serovars. Primers specific to SIN_02055 were used to accurately detect serovar Infantis, and to successfully differentiate Infantis from the other 59 serovars in real-time PCR with a R2 of 0.999 and an efficiency of 95.76%. The developed method was applied to 54 Salmonella strains belonging to eight dominant serovars, and distinguished Infantis from the other seven serovars with an accuracy of 100%. The diagnostic primer set also did not show false positive amplification with 32 strains from eight non-Salmonella bacterial species. This cost-effective and rapid method can be considered an alternative to the classic serotyping using antisera.

scholarly journals Susceptibility to patterns of ciprofloxacin among nalidixic acid-resistant Salmonella isolates collected in Banepa, Nepal from enteric fever patients

2016 ◽  
Vol 89 (2) ◽  
Author(s):  
Girija Roka ◽  
Subash Pandaya ◽  
Md. Reyad-ul Ferdous ◽  
Manson Pandey ◽  
Naba Raj Pokhrel ◽  
...  
Keyword(s):  
Nalidixic Acid ◽  
Salmonella Enterica ◽  
Enteric Fever ◽  
Inhibitory Concentration ◽  
Acid Resistance ◽  
Dilution Method ◽  
Disc Diffusion ◽  
Antimicrobial Sensitivity ◽  
Broth Dilution ◽  
Nalidixic Acid Resistance

The present study determined the susceptibility to ciprofloxacin of nalidixic acid resistant <em>Salmonella</em> (NARS) isolated from enteric fever patients at Scheer Memorial Hospital, Banepa, Nepal, from June 2012 to December 2012. The antimicrobial sensitivity to nalidixic acid and ciprofloxacin was determined using modified Kirby-Bauer disc diffusion and broth dilution method according to the guidelines of the Clinical and Laboratory Standard Institute. <em>Salmonella</em> was isolated from 34 out of 992 (3.43%) blood cultures collected during the study period, and 10 (29.4%) isolates were identified as <em>Salmonella enterica</em> serotype Typhi, while 24 (70.6%) were identified as <em>Salmonella enterica</em> serotype Paratyphi. Out of the total isolates, 31 (91.2%) were nalidixic acid-resistant <em>Salmonella</em> (NARS). Among NARS, the minimum inhibitory concentration values for ciprofloxacin ranged from 0.25 to 2 mg/L and were constantly higher than those shown by the nalidixic acid-susceptible <em>Salmonella</em>. Therefore, in typhoid <em>Salmonella</em> nalidixic acid resistance may be the indicator of decreased susceptibility to ciprofloxacin.

scholarly journals Evaluation of Commercial Disinfectants against Staphylococcus lentus and Micrococcus spp. of Poultry Origin

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Otun Saha ◽  
Nadira Naznin Rakhi ◽  
Arif Istiaq ◽  
Israt Islam ◽  
Munawar Sultana ◽  
...  
Keyword(s):  
Micrococcus Luteus ◽  
Bacterial Species ◽  
16S Rrna Gene Sequencing ◽  
Average Diameter ◽  
Diffusion Method ◽  
Dilution Method ◽  
Rrna Gene ◽  
Poultry Farms ◽  
Rrna Gene Sequencing ◽  
Selection Of

Introduction. Effective sanitation strategies for poultry farms require an appropriate selection of the disinfectant based on the contaminants present and their sensitivity to the disinfectants. Aim. The current study investigated the prevalence of streptococci/micrococci in poultry farms of Bangladesh and the efficacy of commercial disinfectants (Savlon, Lysol, Quatovet, Virkon S, and Virocid) along with alcohol against these pathogens to adopt appropriate strategies. Materials and Methods. Conventional approaches and the 16S rRNA gene sequencing were performed to confirm the isolates at the species level along with microtiter biofilm assay to determine their biofilm-forming ability. Efficacy of the disinfectants was tested against those isolates using agar well diffusion and minimum inhibitory concentration (MIC) test by broth dilution method using different dilutions of the disinfectants. Results. Staphylococcus lentus (n = 32), Micrococcus luteus (n = 7), and Micrococcus aloeverae (n = 4) were confirmed among 102 presumptively screened streptococci/micrococci isolates from 43 samples. No single disinfectant showed equally high efficacy against all three bacterial species in agar well diffusion test, although Virocid showed the lowest MIC against all three of them. Lysol was least effective among the commercial disinfectants by both MIC and diffusion method, although each commercial disinfectant was more effective than alcohol. Considering both the average diameter of the inhibition zones and the MIC values, efficacy can be interpreted as Virocid > Quatovet > Savlon > Virkon S > Lysol. Although the efficacy decreased with decreasing concentration, the disinfectants retained a satisfactory level of efficacy at 50% concentration. Among test pathogens, M. aloeverae was the most sensitive to the disinfectants and the weakest biofilm producers, whereas 4/14 S. lentus and 1/5 M. luteus were strong biofilm producers, which may cause more reduction in the efficacy in environmental conditions. Conclusion. As no ideal disinfectant was found in the study, the efficacy of the disinfectants should be routinely evaluated and validated to ensure the sanitation standards in the poultry sector.

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