scholarly journals Aqueous extracts of Flacourtia indica, Swartzia madagascariensis and Ximenia caffra are strong antibacterial agents against Shigella spp., Salmonella typhi and Escherichia coli O157

2020 ◽  
Vol 128 ◽  
pp. 119-127 ◽  
Author(s):  
Constance Chingwaru ◽  
Tanja Bagar ◽  
Walter Chingwaru
Keyword(s):  
Escherichia Coli ◽  
Antibacterial Agents ◽  
Salmonella Typhi ◽  
Escherichia Coli O157 ◽  
Aqueous Extracts ◽  
Shigella Spp

Microbiological Quality of Retail Imported Unprepared Whole Lettuces: A PHLS Food Working Group Study

1999 ◽  
Vol 62 (4) ◽  
pp. 325-328 ◽  
Author(s):  
C. LITTLE ◽  
D. ROBERTS ◽  
E. YOUNGS ◽  
J. de LOUVOIS
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Microbiological Quality ◽  
Escherichia Coli O157 ◽  
Salmonella Spp ◽  
Shigella Spp ◽  
Natural Microflora ◽  
Production Practices ◽  
Campylobacter Spp

A study of imported unprepared whole lettuces sampled from supermarkets, greengrocers, shops, and market stalls found that all were of acceptable microbiological quality. Twenty-seven out of 151 (18%) imported lettuce samples had Enterobacteriaceae levels of 104 CFU/g or more. However, these bacteria that constitute part of the natural microflora of unprepared vegetables may also be derived from the soil and/or by poor handling. The pathogens, Salmonella spp., Shigella spp., Campylobacter spp., Escherichia coli O157:H7, Vibrio cholerae, Listeria monocytogenes, and also Escherichia coli, an indicator of fecal contamination, were not detected in any imported lettuces, indicating that hygiene, harvesting, and production practices were good. Imported lettuces with Enterobacteriaceae levels of 104 CFU/g or more varied with type of retail premises and the temperature at which the lettuces were displayed. Samples from greengrocers, shops, and market stalls were more likely to contain Enterobacteriaceae at levels in excess of 104 CFU/g than those from supermarkets.

scholarly journals The Structure and Function of Modular Escherichia coli O157:H7 Bacteriophage FTBEc1 endolysin, LysT84: Defining a New Endolysin Catalytic Subfamily

2021 ◽  
Author(s):  
Michael Love ◽  
David Coombes ◽  
Salim Ismail ◽  
Craig Billington ◽  
Renwick CJ Dobson
Keyword(s):  
Crystal Structure ◽  
Escherichia Coli ◽  
Antibacterial Agents ◽  
Analytical Ultracentrifugation ◽  
Structural Data ◽  
Scattering Data ◽  
Structural Basis ◽  
Escherichia Coli O157 ◽  
Dynamic Simulations ◽  
Enzymatic Function

Bacteriophage endolysins degrade peptidoglycan and have been identified as antibacterial candidates to combat antimicrobial resistance. Considering the catalytic and structural diversity of endolysins, there is a paucity of structural data to inform how these enzymes work at the molecular level—key data that is needed to realize the potential of endolysin-based antibacterial agents. Here, we determine the atomic structure and define the enzymatic function of Escherichia coli O157:H7 phage FTEBc1 endolysin, LysT84. Bioinformatic analysis reveals that LysT84 is a modular endolysin, which is unusual for Gram-negative endolysins, comprising a peptidoglycan binding domain and an enzymatic domain. The crystal structure of LysT84 (2.99 Å) revealed a mostly α-helical protein with two domains connected by a linker region but packed together. LysT84 was determined to be a monomer in solution using analytical ultracentrifugation. Small-angle X-ray scattering data revealed that LysT84 is a flexible protein but does not have the expected bimodal P(r) function of a multidomain protein, suggesting that the domains of LysT84 pack closely creating a globular protein as seen in the crystal structure. Structural analysis reveals two key glutamate residues positioned on either side of the active site cavity; mutagenesis demonstrating these residues are critical for peptidoglycan degradation. Molecular dynamic simulations suggest that the enzymatically active domain is dynamic, allowing the appropriate positioning of these catalytic residues for hydrolysis of the β(1–4) bond. Overall, our study defines the structural basis for peptidoglycan degradation by LysT84 which supports rational engineering of related endolysins into effective antibacterial agents.

scholarly journals Screening of the Dichloromethane: Methanolic Extract of Centella asiatica for Antibacterial Activities against Salmonella typhi, Escherichia coli, Shigella sonnei, Bacillus subtilis, and Staphylococcus aureus

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Berick Moturi Sieberi ◽  
George Isanda Omwenga ◽  
Rachael Kitondo Wambua ◽  
Judith Chemutai Samoei ◽  
Mathew Piero Ngugi
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Bacillus Subtilis ◽  
Bacterial Infections ◽  
Antibacterial Agents ◽  
Methanolic Extract ◽  
Centella Asiatica ◽  
Salmonella Typhi ◽  
Phytochemical Screening ◽  
Time Kill

Bacterial infections are responsible for a large number of deaths every year worldwide. On average, 80% of the African population cannot afford conventional drugs. Moreover, many synthetic antibiotics are associated with side effects and progressive increase in antimicrobial resistance. Currently, there is growing interest in discovering new antibacterial agents from ethnomedicinal plants. About 60% of the population living in developing countries depends on herbal drugs for healthcare needs. This study involved the screening of Centella asiatica commonly used by herbal medicine practitioners in Kisii County to treat symptoms related to bacterial infections. Standard bioassay methods were applied throughout the study. They included preliminary screening of dichloromethane: methanolic extract of Centella asiatica against human pathogenic bacteria including Salmonella typhi ATCC 19430, Escherichia coli ATCC 25922, Shigella sonnei ATCC 25931, Bacillus subtilis ATCC 21332, and Staphylococcus aureus ATCC 25923 using agar disc diffusion, broth microdilution method, and time-kill kinetics with tetracycline as a positive control. Phytochemical screening was carried out to determine the different classes of compounds in the crude extracts. Data were analyzed using one way ANOVA and means separated by Tukey’s test. Dichloromethane: methanolic extract of Centella asiatica was screened against the selected bacterial strains. Time-kill kinetic studies of the extracts showed dose- and time-dependent kinetics of antibacterial properties. Phytochemical screening of the DCM-MeOH extract revealed the presence of alkaloids, flavonoids, phenolics, terpenoids, cardiac glycosides, saponins, steroids, and tannins. The present study indicates that the tested plant can be an important source of antibacterial agents and recommends that the active phytoconstituents be isolated, identified, and screened individually for activities and also subjected further for in vivo and toxicological studies.

Antimicrobial Activity of Hibiscus sabdariffa Aqueous Extracts against Escherichia coli O157:H7 and Staphylococcus aureus in a Microbiological Medium and Milk of Various Fat Concentrations

2014 ◽  
Vol 77 (2) ◽  
pp. 262-268 ◽  
Author(s):  
KRISTEN L. HIGGINBOTHAM ◽  
KELLIE P. BURRIS ◽  
SVETLANA ZIVANOVIC ◽  
P. MICHAEL DAVIDSON ◽  
C. NEAL STEWART
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Antimicrobial Activity ◽  
Membrane Filtration ◽  
Anthocyanin Content ◽  
Escherichia Coli O157 ◽  
Hibiscus Sabdariffa ◽  
Aqueous Extracts ◽  
E Coli ◽  
And Staphylococcus Aureus

Hibiscus sabdariffa L. calyces are widely used in the preparation of beverages. The calyces contain compounds that exhibit antimicrobial activity, yet little research has been conducted on their possible use in food systems as antimicrobials. Aqueous extracts prepared from the brand “Mi Costenita” were sterilized by membrane filtration (0.22-μm pore size) or autoclaving (121°C, 30 min) and tested for antimicrobial activity against the foodborne pathogens Escherichia coli O157:H7 strains ATCC 43894 and Cider and Staphylococcus aureus strains SA113 and ATCC 27708 in a microbiological medium and ultrahigh-temperature-processed milk with various fat percentages. Extracts heated by autoclaving exhibited greater activity than did filtered extracts in a microbiological medium. Against E. coli, results of 20 mg/ml filtered extract were not different from those of the control, whereas autoclaved extracts reduced viable cells ca. 3 to 4 log CFU/ml. At 60 mg/ml, both extracts inactivated cells after 24 h. There were reduced populations of both strains of S. aureus (ca. 2.7 and 3 log CFU/ml, respectively) after 24 h of incubation in 40 mg/ml filtered extracts. When grown in autoclaved extracts at 40 mg/ml, both strains of S. aureus were inactivated after 9 h. Autoclaved extracts had decreased anthocyanin content (2.63 mg/liter) compared with filtered extracts (14.27 mg/liter), whereas the phenolic content (48.7 and 53.8 mg/g) remained similar for both treatments. Autoclaved extracts were then tested for activity in milk at various fat concentrations (skim [<0.5%], 1%, 2%, and whole [>3.25%]) against a 1:1 mixture of the two strains of E. coli O157:H7 and a 1:1 mixture of the two strains of S. aureus. Extracts at 40 mg/ml inactivated S. aureus after 168 h in skim and whole milk, and E. coli was inactivated after 96 h in 60 mg/ml extract in all fat levels. These findings show the potential use of Hibiscus extracts to prevent the growth of pathogens in foods and beverages.

scholarly journals Antimicrobial activity of aqueous extracts of pomegranate, sumac, sage, anise, hand bull tongue, thyme, cloves, lemon and mint against some food-borne pathogens

2010 ◽  
Vol 34 (2) ◽  
pp. 85-94
Author(s):  
Maha A. Mahmood
Keyword(s):  
Escherichia Coli ◽  
Candida Albicans ◽  
Inhibition Zone ◽  
Salmonella Typhi ◽  
Antimicrobial Activities ◽  
Inhibitory Effect ◽  
The Other ◽  
Aqueous Extracts ◽  
Food Borne Pathogens ◽  
Food Borne

The increasing rate of resistance development for commonly used antibiotics have led to search for newer, more effective, affordable and easily available medicine. Medicinal plants have revived as a consequence of current problems associated with the use of antibiotics. Aqueous extracts of nine plants (pomegranate, sumac, sage, anise, hand bull tongue, thyme, cloves, lemon and mint) were qualitatively and quantitatively examined against twenty microbial isolates, mostly food borne including pathogens. (E.coli, Salmonella typhi and Candida albicans) antimicrobial screening was done by agar diffusion (well diffusion) and minimal inhibitory concentration (MIC) methods. Among the screened plants, cloves were the most inhibitor against isolates of Escherichia coli, Salmonella typhi and Candida albicans followed by the inhibitory effect of sumac against (E.coli, Salmonella typhi and Candida albicans). On the other hand, pomegranate, sage and lemon showed varied inhibitory effect against the tested food borne isolates, whereas the extracts of anise, hand bull tongue, thyme and mint showed no antimicrobial activities against most of the tested isolates. Regarding the inhibition zone and MIC results, the present study certified that Candida albicans was the most sensitive pathogen as compared with the other food borne pathogens tested (Escherichia coli and Salmonella typhi).

scholarly journals Hoàn thiện quy trình phát hiện đồng thời 14 vi khuẩn gây bệnh đường ruột bằng kĩ thuật PCR-Reverse Dot Blot (PCR-RDB)

2020 ◽  
Vol 13 (1) ◽  
pp. 66-80
Author(s):  
Hồ Thị Thanh Thủy ◽  
Nguyễn Văn Trường ◽  
Nguyễn Bảo Toàn ◽  
Lao Đức Thuận ◽  
Trương Kim Phượng ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Campylobacter Jejuni ◽  
Yersinia Enterocolitica ◽  
Vibrio Parahaemolyticus ◽  
Clostridium Botulinum ◽  
Escherichia Coli O157 ◽  
Dot Blot ◽  
Salmonella Spp ◽  
Shigella Spp ◽  
Reverse Dot Blot

Ngộ độc thực phẩm, với một trong những nguyên nhân chính do nhiễm khuẩn vẫn luôn là mối lo ngại, mang tính toàn cầu, được Tổ chức Sức khỏe Thế giới rất quan tâm. Việc xác định chính xác đối tượng vi khuẩn nhiễm vẫn luôn là một nhu cầu cấp thiết của các labo lâm sàng. Nghiên cứu trước đây của chúng tôi đã được công bố với việc thành công bước đầu trong việc xây dựng một quy trình dựa trên kĩ thuật PCR-Reverse Dot Blot (PCR-RDB) nhằm xác định đồng thời 12 vi khuẩn gây bệnh đường ruột ch yếu, bao gồm Bacillus cereus, Clostridium botulinum, Clostridium perfringen, Staphylococcus aureus, Listeria monocytogenes, Escherichia coli O157:H7, Salmonella spp., Shigella spp.., Vibrio cholerae, Vibrio parahaemolyticus, Yersinia enterocolitica và Brucella spp. Chúng tôi tiếp tục phát triển nghiên cứu này nhằm hoàn thiện quy trình PCR-RDB bằng việc thiết kế bổ sung trên màng các loại mẫu dò nhằm làm chứng dương, chứng âm, chứng màu và chứng kiểm tra tín hiệu nền. Bên cạnh đó, xét nhu cầu lâm sàng, việc bổ sung hai loại mẫu dò đề dò hai vi khuẩn Campylobacter jejuni và Yersinia enterocolitica O:8 gây bệnh đường ruột chủ yếu ở trẻ em, là cần thiết. Quy trình PCR-RDB được hoàn thiện trong nghiên cứu này vì vậy có khả năng phát hiện đồng thời 14 vi khuẩn gây bệnh đường ruột, một cách đặc hiệu, với độ nhạy đạt 10^2 bản sao/ml, đã được thử nghiệm trên 30 mẫu phân, ghi nhận kết quả hoàn toàn khớp với kít thương mại PowerCheckTM 20 Pathogen Multiplex Real-time PCR Kit (Korea).

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