Identification of vaccine and drug targets in Shigella dysenteriae sd197 using reverse vaccinology approach

Shigellosis is characterized as diarrheal disease that causes a high mortality rate especially in children, elderly and immunocompromised patients. More recently, the World Health Organization advised safe vaccine designing against shigellosis due to the emergence of Shigella dysenteriae resistant strains. Therefore, the aim of this study is to identify novel drug targets as well as the design of the potential vaccine candidates and chimeric vaccine models against Shigella dysenteriae. A computational based Reverse Vaccinology along with subtractive genomics analysis is one of the robust approaches used for the prioritization of drug targets and vaccine candidates through direct screening of genome sequence assemblies. Herein, a successfully designed peptide-based novel highly antigenic chimeric vaccine candidate against Shigella dysenteriae sd197 strain is proposed. The study resulted in six epitopes from outer membrane WP_000188255.1 (Fe (3+) dicitrate transport protein FecA) that ultimately leads to the construction of twelve vaccine models. Moreover, V9 construct was found to be highly immunogenic, non-toxic, non-allergenic, highly antigenic, and most stable in terms of molecular docking and simulation studies against six HLAs and TLRS/MD complex. So far, this protein and multiepitope have never been characterized as vaccine targets against Shigella dysenteriae. The current study proposed that V9 could be a significant vaccine candidate against shigellosis and to ascertain that further experiments may be applied by the scientific community focused on shigellosis.

Aspergillus niger Culture Filtrate (ACF) Mediated Biocontrol of Enteric Pathogens in Wastewater

Robust control of pathogens in sewage facilitates safe reuse of wastewater rich in valuable nutrients for potential valorization through biological means. Aspergillus niger is widely reported in bioremediation of wastewater but studies on control of enteric pathogens in sewage are very sparse. So, this study aimed at exploring the antibacterial and nematicidal activity of A. niger culture filtrate (ACF). Antibacterial activity of ACF on enteric pathogens (Klebsiella pneumoniae, Pseudomonas aeruginosa, Vibrio cholerae, Salmonella enterica, Shigella dysenteriae, Escherichia coli, Staphylococcus aureus, Klebsiella variicola) was determined by spectrophotometric growth analysis, resazurin based viability assay and biofilm formation assay. ACF showed inhibition against all enteric pathogens except Pseudomonas aeruginosa. Nematicidal studies on Caenorhabditis elegans showed 85% egg hatch inhibition and 52% mortality of L1 larvae. Sewage treatment with ACF at 1:1 (v/v) showed 2–3 log reduction in coliforms, Klebsiella, Shigella, Salmonella, S. aureus and Vibrio except Pseudomonas, indicating significant alteration of complex microbial dynamics in wastewater. Application of ACF can potentially be used as a robust biocontrol strategy against infectious microbes in wastewater and subsequent valorization by cultivating beneficial Pseudomonas.

Chemical Composition and Antibacterial Activity of Extracts of Cymbopogon Citratus (Lemon Grass) and Phyllantus Amarus (Stone Breaker) Leaves

This study described the chemical composition, antioxidant and antibacterial activities of the ethanol and aqueous extracts of fresh and dried leaves of Phyllantus amarus (PA) (Stone breaker), Cymbopogon citratus (CC) (Lemon grass) and combination of stone breaker and lemon grass (PA/CC and DL/DP) using standard methods. The proximate and mineral results showed that both fresh and dried samples of Phyllantus amarus and Cymbopogon citratus were rich in crude fibre (18.53%, 14.65%), ash (16.27%, 2.29%), potassium (95.56 mg/100g, 54.04 mg/100g), calcium (58.57 mg/100g, 7.05 mg/100g), and sodium (15.23 mg/100g, 9.84 mg/100g) respectively. The ability of the extracts to scavenge 2, 2 diphenyl -2- picryl-hydrazyl (DPPH) radical showed that the fresh PA had the highest scavenging activity of 91.12 mg/g, followed (PA/CC) 90.93 mg/g and dried PA (85.61mg/g). The phytochemical composition of the extracts also revealed that they contain high content of cardiac glycoside (11.62 mg/g - 64.81 mg/g), terpenoid (14.56 mg/g - 69.66 mg/g), phenol (14.73 mg/g - 53.93 mg/g), saponin (22.61 mg/g - 30.47mg/g). Dried lemon and dried Phyllantus amarus (DL/DP) was found to be rich in Vitamin A (22.22 mg/g), while the lowest value of Vitamin E (0.36 mg/g) was obtained from fresh lemon grass (0.36mg/g). Antibacterial assay carried out on the two leaves extracts showed that they produced mild antibacterial activity against some foodborne pathogen (Bacillus cereus, Shigella dysenteriae, Escherichia coli, Salmonella spp, Staphylococcus aureus, Pseudomonas spp). with zones of inhibition of 4.3 mm -9.1mm. Further studies should be carried out to investigate the employment of the leaves in production of functional food

Shigellosis and Development of Multiple Antimicrobial Resistance Mechanisms of Shigella spp.

Shigellosis is a serious public health issue. Millions of people suffer from this deadly food and water borne disease each year. The main manifestations of affected persons are bloody diarrhea with excessive dehydration. The causative agent of this disease is the bacteria Shigella spp. which has four serogroups. Though Shigella flexneri and Shigella dysenteriae are the dominant serogroups in developing countries, reports of other serogroups, namely Shigella boydii and Shigella sonnei, in the food contaminations are available. There are seasonal variations of Shigella infection throughout the world. In Asian subcontinent, monsoon and post monsoon times are the ideal for infection. The transmission of the bacteria in human is usually caused by feco-oral route or by contaminated food and water. There are several groups of antibiotics like foscomycin, macrolide, amiglycoside, tetracycline etc. which were used before. But they are now become useless as Shigella spp. is getting resistant against those drugs. The quinolone groups of antibiotics like ciprofloxacin, ofloxacin, norflxacin, ceftriaxone etc. are the important drugs for the cure of the disease shigellosis but prevalence of drug resistant strains of Shigella spp. against those drugs are a great concern nowadays. The occurrence of plasmid mediated quinolone resistance genes (PMQR), efflux pump proteins and effective mutations at drug binding region of gyrA etc. are the major mechanisms for the development of drug resistance.

Microwave assisted extraction, phytochemical and antimicrobial evaluation of ethyl acetate extracts of stem bark of Ficus exasperata (Vahl)

Stem bark of Ficus exasperata was extracted using ethyl acetate by microwave-assisted solvent extraction. Phytochemical screening and antimicrobial evaluation were carried out on the extract. Phytochemical screening revealed the presence of cardiac glycosides, tannins, flavonoids, triterpenes and steroids. Antimicrobial evaluation revealed that the extract is active against Methicillin – resistant Staphylococcus aureus (MRSA), Staphylococcus aureus, Streptococcus pneumoniae, Salmonella typhi, Proteus mirabilis, Shigella dysenteriae, Candida stellatoidea and Candida tropicalis. The zones of inhibition (mm) for the test organisms were (24 - 31) mm. Minimum inhibition concentrations (mg/L) of extract against MRSA, Staphylococcus aureus, Streptococcus pneumonia, Salmonella typhi, Proteus mirabilis, Shigella dysenteriae, Candida stellatoidea and Candida tropicalis were 2.5, 1.25,1.25, 2.5, 1.25, 1.25, 1.25 and 2.5 respectively. Minimum bactericidal concentrations (mg/L) of extract against Methicillin – resistant Staphylococcus aureus (MRSA), Staphylococcus aureus, Streptococcus pneumonia, Salmonella typhi, Proteus mirabilis Shigella dysenteriae Candida stellatoidea and Candida tropicalis were 5, 2.5, 2.5, 5, 5, 2.5,2.5 and 5 respectively. The extract showed high inhibition against MRSA and Candida tropicalis.

Phytochemical Analysis, Antimicrobial and Antioxidant Properties of Thymus zygis L. and Thymus willdenowii Boiss. Essential Oils

Essential oils (EOs) are chemical products produced by odoriferous glands from a variety of plants. These essential oils have many health benefits: antiseptic, anti-inflammatory and antimicrobial activities. So due to these medicinal properties, the present study was designed to analyze essential oils of Thymus zygis L. and Thymus willdenowii Boiss. for their chemical composition and biological activities. These two thyme species were collected from the region of Ifrane, Middle Atlas of Morocco. The EO was obtained by hydrodistillation, and the yields were 5.25% for T. zygis and 3.00% for T. willdenowii. The chemical composition of the EOs was analyzed by gas chromatography coupled with mass spectrometry (GC-MS), and the results showed that T. zygis EO is dominated by carvacrol (52.5%), o-cymene (23.14%), and thymol (9.68%), while the EO of T. willdenowii contains germacrene D (16.51%), carvacrol (16.19%), and geranyl acetate (8.35%) as major compounds. The antioxidant activity assessed by Diphenylpicrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays revealed that both EOs have excellent antioxidant activities; by DPPH it resulted in IC50 = 6.13 ± 0.11 for T. zygis and 6.78 ± 0.3 µg/mL for T. willdenowii, while the one by FRAP yielded EC50 = 2.46 ± 0.01 (T. zygis) and 5.17 ± 0.2 (T. willdenowii) µg/mL. The antimicrobial activity of the two essential oils was evaluated against six bacterial strains and five fungal strains by the disk diffusion method to determine the Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC) and Minimum Fungicidal Concentration (MFC). The EOs revealed variable antimicrobial activities against the different tested microbial strains and showed strong antimicrobial activities, even against strains known as multi-resistant to antibiotics (Acinetobacter baumannii) at low concentrations (2 µL/mL). T. zygis EO showed the most powerful activity against all the studied bacteria, while that of T. willdenowii recorded moderate activity when tested against Shigella dysenteriae and Salmonella Typhi. With inhibition diameters that vary between 75 mm and 84 mm for concentrations of 2 µL/mL up to 12 µL/mL, S. aureus was shown to be the most sensitive to T. zygis EO. For the antifungal activity test, T. zygis EO showed the best inhibition diameters compared to T. willdenowii EO. These results showed that T. zygis EO has more powerful antioxidant and antimicrobial activities than T. willdenowii EO, therefore, we deduce that thyme EOs are excellent antioxidants, they have strong antimicrobial properties, and may in the future represent new sources of natural antiseptics that can be used in pharmaceutical and food industry.

Evaluation of Antioxidant and Antibacterial Activities of White Mulberry (Morus alba L.) Fruit Extracts

The fruit of mulberry trees (Morus sp.), mulberries, are traditionally utilised as a nutritional food and provide health benefits as well as skin nourishment in Thailand. White mulberries (Morus alba L.) from Chiang Mai and Mae Hong Son provinces were evaluated for their antioxidant and antibacterial activities. The antioxidant activities as well as the total phenolic, flavonoid and anthocyanin content of the aqueous and ethanolic extracts were determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azinobis-(3-ethylbenzothiazolin-6-sulfonic acid) (ABTS) and ferric reducing antioxidant power (FRAP) assays. The aqueous extracts of mulberries exhibited the highest antioxidant activity, which was associated with a higher phenolic and anthocyanin content. In testing the potent antibacterial activity against Escherichia coli, Salmonella Typhi, Shigella dysenteriae, Staphylococcus aureus and Vibrio cholerae, the mulberry extracts proved to be quite efficient, especially following water extraction. Time-kill and antibacterial adhesion assays further indicated that aqueous mulberry extracts could inhibit bacterial growth and prevent adhesions of pathogenic enteric bacteria on intestinal epithelial cells. It thus appears that mulberries can potentially be consumed as a good source of antioxidants, containing antimicrobial properties against some pathogenic bacteria which cause gastrointestinal tract infections.

Aktivitas Antibakteri Ekstrak Metanol Kulit Buah Kawista (Limonia acidissima) terhadap Shigella dysenteriae dan Salmonella thypi

Shigella dysenteriae dan Salmonella thypi merupakan bakteri yang dapat menyebabkan infeksi pada saluran cerna. Kawista banyak ditemui di Indonesia dan dapat dijadikan terapi alternatif untuk mengatasi diare. Kandungan kimia yang terdapat pada kulit buah kawista diduga dapat berkhasiat sebagai antibakteri. Tujuan dari penelitian ini adalah untuk mengetahui aktivitas antibakteri ekstrak kulit buah kawista (Limonia acidissima) terhadap bakteri Shigella dysenteriae dan Salmonella thypi. Tahap penelitian diawali dengan proses ekstrasi kulit buah kawista melalui metode maserasi, menggunakan pelarut metanol. Selanjutnya, dilakukan penapisan fitokimia dan pengujian aktivitas antibakteri. Pengujian aktivitas antibakteri ekstrak kulit buah kawista menggunakan metode difusi cakram dalam berbagai konsentrasi, yaitu 5%, 10%, 20%, 40% dan 80% ekstrak. Uji aktivitas antibakteri diukur berdasarkan diameter daerah hambat (DDH) yang dihasilkan. Hasil penelitian menunjukkan bahwa semakin tinggi konsentrasi ekstrak kulit buah kawista, semakin kuat aktivitas antibakteri yang diberikan. Pada konsentrasi 5%, rata-rata DDH untuk bakteri Shigella dysenteriae dan Salmonella thypi masing-masing adalah 7,91 mm dan 7,73 mm. Pada konsentrasi 80%, ekstrak memiliki aktivitas antibakteri yang paling kuat dengan rata-rata DDH 21,42 mm pada Shigella dysenteriae dan 20,93 mm pada Salmonella thypi. Ekstrak kulit buah kawista (Limonia acidissima) memiliki aktivitas antibakteri terhadap Shigella dysenteriae dan Salmonella thypi.

Bacteriostatic and bactericidal activities of Acalypha indica L. plant leave extracts on bacteria shigella disenteriae type 1 in vitro

This study aimed to analyze the bacteriostatic and bactericidal activity of Acalypha indica L. extract against Shigella dysenteriae type 1 bacteria in vitro. This research is a laboratory experimental study consisting of six concentration treatments, namely: (K = 0/ml, P1 = 100/ml, P2 = 200/ml, P3 = 400/ml, P4 = 800/ml, P5 = 1600 mg/ml ), and five replications each. The results showed that the herbal extract of Acalypha indica L. was bacteriostatic (inhibiting) at a concentration of 400 mg/mm, and bactericidal (killing) the bacteria Shigella dysenteriae type 1, which was tested in vitro at a concentration of at least 800 mg/ml. It is necessary to study the effect of Acalypha indica L. herbal extract from Timor in the serum of Rattus norwegicus against bacteria that cause bloody diarrhea (EHEC O157:H7, and Shigella dysenteriae type 1), MRSA bacteria, and other pathogenic bacteria.