Search results for "Biochemical Phenomena"
showing 10 items of 496 documents
Characterization of ESBL-producing enterobacteria from fruit bats in an unprotected area of Makokou, Gabon.
2020
In Gabon, terrestrial mammals of protected areas have been identified as a possible source of antibiotic-resistant bacteria. Some studies on antibiotic resistance in bats have already been carried out. The main goal of our study was to detect extended-spectrum beta-lactamases (ESBLs) that are produced by enterobacteria from bats in the Makokou region in Gabon. Sixty-eight fecal samples were obtained from 68 bats caught in the forests located 1 km from the little town of Makokou. After culture and isolation, 66 Gram-negative bacterial colonies were obtained. The double-disk diffusion test confirmed the presence of ESBLs in six (20.69%) Escherichia coli isolates, four (13.79%) Klebsiella pneu…
To B or Not to B: Comparative Genomics Suggests Arsenophonus as a Source of B Vitamins in Whiteflies
2018
Insect lineages feeding on nutritionally restricted diets such as phloem sap, xylem sap, or blood, were able to diversify by acquiring bacterial species that complement lacking nutrients. These bacteria, considered obligate/primary endosymbionts, share a long evolutionary history with their hosts. In some cases, however, these endosymbionts are not able to fulfill all of their host's nutritional requirements, driving the acquisition of additional symbiotic species. Phloem-feeding members of the insect family Aleyrodidae (whiteflies) established an obligate relationship with Candidatus Portiera aleyrodidarum, which provides its hots with essential amino acids and carotenoids. In addition, ma…
Molecular epidemiology of KPC-producing Klebsiella pneumoniae from invasive infections in Italy: Increasing diversity with predominance of the ST512 …
2016
Objectives The spread of carbapenem-resistant Enterobacteriaceae (CRE) represents one of the most worrisome problems for clinical medicine worldwide. In Italy, the Antibiotic-Resistance-Istituto Superiore di Sanita surveillance network, in collaboration with the Committee for Antimicrobial Agents of the Italian Society of Clinical Microbiologists, promoted a study to investigate the carbapenem-resistance mechanisms, clonal relatedness and capsular typing of a recent collection of carbapenem-resistant Klebsiella pneumoniae (CR-KP). Methods A total of 17 laboratories distributed across Italy collected all consecutive non-replicate CR-KP isolated from invasive infections during two different s…
Local adaptation in populations of Mycobacterium tuberculosis endemic to the Indian Ocean Rim
2021
24 páginas, 3 figuras, 1 tabla. The sequence data generated by this study has been deposited on SRA (https://www.ncbi.nlm.nih.gov/sra) under the accession number PRJNA670836. Extended data is available here: https://github.com/fmenardo/MTBC_L1_L3. DOI: https://doi.org/10.5281/zenodo.4609804 (Menardo, 2021).
In vitro study of antimicrobial activity on Klebsiella Pneumoniae biofilms in endotracheal tubes
2019
Effective treatment approaches for biofilms in endotracheal tubes (ETTs) are lacking. In this study, we evaluated the in vitro effects of five antimicrobials against biofilms formed by Klebsiella pneumoniae in ETTs. K. pneumoniae was added to minimal mucin medium prior to inoculation in microtiter plates containing ETT fragments. Biofilm susceptibility was assessed by crystal violet staining. At 24 h, the antimicrobials significantly reduced biofilm formation. At 48 h, all of the antimicrobial agents exhibited significant reductions in biofilm formation, even at concentrations above the minimum inhibitory concentration (MIC). Tigecycline and fosfomycin showed the greatest inhibition capacit…
Host Cell Calpains Can Cleave Structural Proteins from the Enterovirus Polyprotein
2019
Enteroviruses are small RNA viruses that cause diseases with various symptoms ranging from mild to severe. Enterovirus proteins are translated as a single polyprotein, which is cleaved by viral proteases to release capsid and nonstructural proteins. Here, we show that also cellular calpains have a potential role in the processing of the enteroviral polyprotein. Using purified calpains 1 and 2 in an in vitro assay, we show that addition of calpains leads to an increase in the release of VP1 and VP3 capsid proteins from P1 of enterovirus B species, detected by western blotting. This was prevented with a calpain inhibitor and was dependent on optimal calcium concentration, especially for calpa…
Reinventing the Wheel and Making It Round Again: Evolutionary Convergence in Buchnera-Serratia Symbiotic Consortia between the Distantly Related Lach…
2016
International audience; Virtually all aphids (Aphididae) harbor Buchnera aphidicola as an obligate endosymbiont to compensate nutritional deficiencies arising from their phloem diet. Many species within the Lachninae subfamily seem to be consistently associated also with Serratia symbiotica We have previously shown that both Cinara (Cinara) cedri and Cinara (Cupressobium) tujafilina (Lachninae: Eulachnini tribe) have indeed established co-obligate associations with both Buchnera and S. symbiotica However, while Buchnera genomes of both Cinara species are similar, genome degradation differs greatly between the two S. symbiotica strains. To gain insight into the essentiality and degree of int…
Snapshots of a shrinking partner: Genome reduction inSerratia symbiotica
2016
AbstractGenome reduction is pervasive among maternally-inherited endosymbiotic organisms, from bacteriocyte- to gut-associated ones. This genome erosion is a step-wise process in which once free-living organisms evolve to become obligate associates, thereby losing non-essential or redundant genes/functions. Serratia symbiotica (Gammaproteobacteria), a secondary endosymbiont present in many aphids (Hemiptera: Aphididae), displays various characteristics that make it a good model organism for studying genome reduction. While some strains are of facultative nature, others have established co-obligate associations with their respective aphid host and its primary endosymbiont (Buchnera). Further…
Tremblaya phenacola PPER: an evolutionary beta-gammaproteobacterium collage
2017
Many insects rely on bacterial endosymbionts to obtain nutrients that are scarce in their highly specialized diets. The most surprising example corresponds to the endosymbiotic system found in mealybugs from subfamily Pseudococcinae in which two bacteria, the betaproteobacterium 'Candidatus Tremblaya princeps' and a gammaproteobacterium, maintain a nested endosymbiotic consortium. In the sister subfamily Phenacoccinae, however, a single beta-endosymbiont, 'Candidatus Tremblaya phenacola', has been described. In a previous study, we detected a trpB gene of gammaproteobacterial origin in 'Ca. Tremblaya phenacola' from two Phenacoccus species, apparently indicating an unusual case of horizonta…
Evaluation of antimicrobial resistance and virulence of enterococci from equipment surfaces, raw materials and traditional cheeses
2016
Forty enterococci isolated along the production chains of three traditional cheeses (PDO Pecorino Siciliano, PDO Vastedda della Valle del Belìce, and Caciocavallo Palermitano) made in Sicily (southern Italy) were studied for the assessment of their antibiotic resistance and virulence by a combined phenotypic/genotypic approach. A total of 31 Enterococcus displayed resistance to at least one or more of the antimicrobials tested. The strains exhibited high percentages of resistance to erythromycin (52.5%), ciprofloxacin (35.0%), quinupristin–dalfopristin (20.0%), tetracycline (17.5%), and high-level streptomycin (5.0%). The presence of tet(M), cat(pC221), and aadE genes for resistance to tetr…