Lack of host epecificity in gut colonization ability of human and chicken Escherichia coli isolates.

The aim of this study was to investigate the possible existence of E. coli ecotypes specifically adapted to mammalian and avian intestines. E. coli isolates from chickens and humans were subjected to growth in lactose minimal media and allowed to colonize chicken’s intestines. Human isolates grew significantly faster (p=0.0188*) in lactose minimal medium; however, no differences were observed when one human and one chicken isolate colonized the chicken intestines. Results of this research showed that chicken isolates grew slowly comparing with human isolates, likely because the first were not exposed to milk as the second one. In addition, apparently chicken and human E. coli can equally colonize different host intestines which sign out the adaptability of this bacteria to different environments.El objetivo de este estudio fue investigar la posible existencia de ecotipos de E. coli específicamente adaptados a los intestinos de mamíferos y aves. Los aislados de E. coli de pollos y humanos fueron sometidos a crecimiento en medio mínimo lactosado y se les permitió colonizar los intestinos de pollos. Los aislados humanos crecieron significativamente más rápido en el medio mínimo lactosado (p=0.0188*); sin embargo, no se observaron diferencias cuando un aislado humano y un aislado de pollo colonizaron el intestino de los pollos. Los resultados de esta investigación muestran que los aislados de pollo crecen menos que los aislados humanos en un medio lactosado presumiblemente debido a que los primeros no han sido expuestos a leche como los segundos. Adicionalmente, parecería que las E. coli de pollos y humanos pueden colonizar indistintamente el intestino de uno u otro hospedero lo cual resalta la adaptabilidad de esta bacteria a diferentes ambientes

Unexpected distribution of the fluoroquinolone-resistance gene qnrB in Escherichia coli isolates from different human and poultry origins in Ecuador

Fluoroquinolone resistance can be conferred through chromosomal mutations or by the acquisition of plasmids carrying genes such as the quinolone resistance gene (qnr). In this study, 3,309 strains of commensal Escherichia coli were isolated in Ecuador from: (i) humans and chickens in a rural northern coastal area (n = 2368, 71.5%) and (ii) chickens from an industrial poultry operation (n = 827, 25%). In addition, 114 fluoroquinolone-resistant strains from patients with urinary tract infections who were treated at three urban hospitals in Quito, Ecuador were analyzed. All of the isolates were subjected to antibiotic susceptibility screening. Fluoroquinolone-resistant isolates (FRIs) were then screened for the presence of qnrB genes. A significantly higher phenotypic resistance to fluoroquinolones was determined in E. coli strains from chickens in both the rural area (22%) and the industrial operation (10%) than in strains isolated from humans in the rural communities (3%). However, the rates of qnrB genes in E. coli isolates from healthy humans in the rural communities (11 of 35 isolates, 31%) was higher than in chickens from either the industrial operations (3 of 81 isolates, 6%) or the rural communities (7 of 251 isolates, 2.8%). The occurrence of qnrB genes in human FRIs obtained from urban hospitals was low (1 of 114 isolates, 0.9%). These results suggested that the qnrB gene is more widely distributed in rural settings, where antibiotic usage is low, than in urban hospitals and industrial poultry operations. The role of qnrB in clinical resistance to fluoroquinolones is thus far unknown. [Int Microbiol 2015; 18(2):85-90]Keywords: Escherichia coli · gene qnrB · quinolone resistance · urban hospitals · industral poultry operation

Novel Kazal-type Protease inhibitors from the skin secretion of the Splendid leaf frog, Cruziohyla calcarifer

Peptidase inhibitors have an important role controlling a variety of biological processes. Here, we employed a peptidomic approach including molecular cloning, tandem mass spectrometry and enzymatic assays to reveal 7 Kazal-type proteinase inhibitors (CCKPs) (18 variants) in the skin secretion of the unexplored frog, Cruziohyla calcarifer. All 18 proteins shared the Kazal pattern C-X(7)-C-X(6,7)-C-X(6,7)-Y-X(3)-C-X(2)-C-X(15-21)-C and 3 disulphide bridges. Based on structural comparative analysis, we deemed trypsin and chymotrypsin inhibitory activity in CCKP-1, 4 and CCKP 2, 5, 7, respectively. These peptidase inhibitors presumably play a role to control the balance between other functional peptides produced in the amphibian skin secretions

Dual antibacterial mechanism of [K4K15]CZS-1 against Salmonella Typhimurium: a membrane active and intracellular-targeting antimicrobial peptide

Salmonella genus is a leading cause of food-borne infections with strong public health impact and economic ramifications. The development of antimicrobial resistance added complexity to this scenario and turned the antibiotic drug discovery into a highly important challenge. The screening of peptides has served as a successful discovery platform to design new antibiotic candidates. Motivated by this, the antimicrobial and cytotoxic properties of three cruzioseptins against Salmonella Typhimurium and RAW 264.7 murine macrophage cells, respectively, were investigated. [K4K15]CZS-1 was the most potent antimicrobial peptide identified in the screening step with a minimum inhibitory concentration (MIC) of 16 μg/mL (7.26 μM) and moderate cytotoxicity. From a structural point of view, in vitro and in silico techniques evidenced that [K4K15]CZS-1 is a α-helical cationic antimicrobial peptide. In order to capture mechanistic details and fully decipher their antibacterial action, we adopted a multidimensional approach, including spectroscopy, electron microscopy and omics analysis. In general lines, [K4K15]CZS-1 caused membrane damage, intracellular alterations in Salmonella and modulated metabolic pathways, such as the tricarboxylic acid (TCA) cycle, fatty acid biosynthesis, and lipid metabolism. Overall, these findings provide deeper insights into the antibacterial properties and multidimensional mode of action of [K4K15]CZS-1 against Salmonella Typhimurium. In summary, this study represents a first step toward the screening of membrane-acting and intracellular-targeting peptides as potential bio-preservatives to prevent foodborne outbreaks caused by Salmonella

Antibacterial and antiviral properties of Chenopodin-derived synthetic peptides

Antimicrobial peptides have been developed based on plant-derived molecular scaffolds for the treatment of infectious diseases. Chenopodin is an abundant seed storage protein in quinoa, an An-dean plant with high nutritional and therapeutic properties. Here, we used computer- and physico-chemical-based strategies and designed four peptides derived from the primary structure of Che-nopodin. Two peptides reproduce natural fragments of 14 amino acids from Chenopodin, named Chen1 and Chen2 and two engineered peptides of the same length were designed based on the Chen1 sequence. The two amino acids of Chen1 containing amide side chains were replaced by ar-ginine (ChenR) or tryptophan (ChenW) to generate engineered cationic and hydrophobic peptides. The evaluation of these 14-mer peptides on Staphylococcus aureus and Escherichia coli showed that Chen1 does not have antibacterial activity up to 512 µM against these strains, while other peptides exhibited antibacterial effects at lower concentrations. The chemical substitutions of glutamine and asparagine by amino acids with cationic or aromatic side chains significantly favoured their antibacterial effects. These peptides did not show significant hemolytic activity. Fluorescence mi-croscopy analysis highlighted the membranolytic nature of Chenopodin-derived peptides. Using molecular dynamic simulations, we found that a pore is formed when multiple peptides are as-sembled in the membrane. Whereas some of them form secondary structures when interacting with the membrane, allowing water translocations during the simulations. Finally, Chen2 and ChenR significantly reduced SARS-CoV-2 infection. These findings demonstrate that Chenopodin is a highly useful template for design, engineering, and manufacturing of non-toxic, antibacterial, and antiviral peptides

Bothrops atrox from ecuadorian amazon: initial analyses of venoms from individuals

Bothrops atrox is the most clinically relevant snake species within the Amazon region, which includes Ecuadorian territories. It comprises a large distribution, which could contribute to the genetic and venomic variation identified in the species. The high variability and protein isoform diversity of its venom are of medical interest, since it can influence the clinical manifestations caused by envenomation and its treatment. However, in Ecuador there is insufficient information on the diversity of venomic phenotypes, even of relevant species such as B. atrox. Here, we characterized the biochemical and toxicological profiles of the venom of six B. atrox individuals from the Ecuadorian Amazon. Differences in catalytic activities of toxins, elution profiles in liquid chromatography, electrophoretic patterns, and toxic effects among the analyzed samples were identified. Nonetheless, in the preclinical testing of antivenom, two samples from Mera (Pastaza) required a higher dose to achieve total neutralization of lethality and hemorrhage. Taken together, these data highlight the importance of analyzing individual venoms in studies focused on the outcomes of envenomin

Modelamiento molecular de la dermaseptina SP2 extraída de Agalychnis spurrelli

In this research, we present a computational study of Dermaseptine SP2 (DRS-SP2) extracted from the skin of the frog Agalychnis spurrelli. Experimental assays allowed extracting, purifying and obtaining the amino acid sequence of this peptide. Furthermore, they have demonstrated its antimicrobial properties against Escherichia coli, Staphylococcus aureus and Candida albicans. With the sequence, a computational study of the structure was carried out, obtaining its physical-chemical properties, its secondary structure and its similarity with other known peptides. Also, a molecular docking study of this peptide was performed against cell membrane and several enzymes known to kill these microorganisms. Results showed that DRS-SP2 is an α-helical cationic peptide with an isoelectric point of 10.68 and a positive charge +3 at physiological pH. It was determined that its structure is different to all dermaseptines found in databases reaching a maximum identity of 80 %. Molecular docking studies suggest the mechanism of action of this peptide is not given by the inhibition of a vital enzymatic pathway, but by destruction of the microorganism by cell lysis.En esta investigación se presenta un estudio computacional de la dermaseptina SP2 (DRS-SP2) extraída de exudado de la piel de la rana Agalychnis spurrelli. Ensayos experimentales han permitido extraer, purificar y obtener la secuencia de aminoácidos de este péptido, además de demostrar sus propiedades antimicrobianas contra Escherichia coli, Staphylococcus aureus y Candida albicans. Con la secuencia dilucidada, se realizó un estudio computacional de la estructura obteniéndose sus propiedades físico-químicas, su estructura secundaria y su similitud con otros péptidos conocidos. Además, se realizó el acoplamiento molecular de este péptido con la membrana celular y varias enzimas conocidas para suprimir a estos microorganismos. Los resultados muestran que la DRS-SP2 es un péptido catiónico α-helicoidal con un punto isoeléctrico de 10,68 y carga positiva +3 a pH fisiológico. Se determinó que su estructura es diferente a todas las dermaseptinas que se encuentran en bases de datos llegando a un porcentaje de identidad máximo del 80 %. Estudios de acoplamiento molecular sugieren que el mecanismo de acción de este péptido no se da por la inhibición de vías enzimáticas vitales para el microorganismo, sino por lisis celular

Unravelling the Skin Secretion Peptides of the Gliding Leaf Frog, Agalychnis spurrelli (Hylidae)

Frog skin secretions contain medically-valuable molecules, which are useful for the discovery of new biopharmaceuticals. The peptide profile of the skin secretion of Agalychnis spurrelli has not been investigated; therefore, the structural and biological characterization of its compounds signify an inestimable opportunity to acquire new biologically-active chemical scaffolds. In this work, skin secretion from this amphibian was analysed by molecular cloning and tandem mass spectrometry. Although the extent of this work was not exhaustive, eleven skin secretion peptides belonging to five peptide families were identified. Among these, we report the occurrence of two phyllokinins, and one medusin-SP which were previously reported in other related species. In addition, eight novel peptides were identified, including four dermaseptins, DRS-SP2 to DRS-SP5, one phylloseptin-SP1, and three orphan peptides. Phylloseptin-SP1 and dermaseptins-SP2 were identified in HPLC fractions based on their molecular masses determined by MALDI-TOF MS. Among the antimicrobial peptides, dermaseptin-SP2 was the most potent, inhibiting Escherichia coli, Staphylococcus aureus, and ORSA with a minimum inhibitory concentration (MIC) of 2.68 μM, and Candida albicans with an MIC of 10.71 μM, without haemolytic effects. The peptides described in this study represent but a superficial glance at the considerable structural diversity of bioactive peptides produced in the skin secretion of A. spurrelli