Search results for "Virulence"
showing 10 items of 457 documents
Phenotypic and genotypic study on antibiotic resistance and pathogenic factors of Staphylococcus aureus isolates from small ruminant mastitis milk in…
2021
Staphyloccoccus aureus is the major cause of mastitis in small ruminants in the Mediterranean farms causing severe losses to dairy industry. Antibiotic treatment has been the most common approach to control these infections. Aim of this study was to investigate antimicrobial resistance (AMR), virulence factors and biofilm-related genes of 84 Sicilian strains of S. aureus isolated from sheep and goats milk during two different periods δT1 (2006-2009) and δT2 (2013-2015). Kirby Bauer method and Polymerase Chain Reaction (PCR) were utilized to monitor AMR and related genes (mecA, tetK, tetM, ermA, ermC). Moreover, toxin genes (tsst-1, sea-see, seg-sej, and sep) and biofilm genes (bap, ica, sas…
Asymmetric Disulfanylbenzamides as Irreversible and Selective Inhibitors of Staphylococcus aureus Sortase A
2020
Abstract Staphylococcus aureus is one of the most frequent causes of nosocomial and community‐acquired infections, with drug‐resistant strains being responsible for tens of thousands of deaths per year. S. aureus sortase A inhibitors are designed to interfere with virulence determinants. We have identified disulfanylbenzamides as a new class of potent inhibitors against sortase A that act by covalent modification of the active‐site cysteine. A broad series of derivatives were synthesized to derive structure‐activity relationships (SAR). In vitro and in silico methods allowed the experimentally observed binding affinities and selectivities to be rationalized. The most active compounds were f…
Cellular, physiological, and molecular adaptive responses of Erwinia amylovora to starvation.
2013
Erwinia amylovora causes fire blight, a destructive disease of rosaceous plants distributed worldwide. This bacterium is a nonobligate pathogen able to survive outside the host under starvation conditions, allowing its spread by various means such as rainwater. We studied E. amylovora responses to starvation using water microcosms to mimic natural oligotrophy. Initially, survivability under optimal (28 °C) and suboptimal (20 °C) growth temperatures was compared. Starvation induced a loss of culturability much more pronounced at 28 °C than at 20 °C. Natural water microcosms at 20 °C were then used to characterize cellular, physiological, and molecular starvation responses of E. amylovora. Ch…
Streptococcus Mutans sortāzes A ekspresija, attīrīšana un raksturošana zāļu vielu skrīningam
2019
Slimības, ko izraisa patogēni, īpaši multirezistenti, piemēram, Streptococcus mutans, ir nepieciešams apkarot. Multirezistentu grampozitīvu patogēnu baktēriju transpeptidāzes - sortāzes A - mērķproteīna inhibēšana mazina patogēnu saistīšanās spēju - virulenci - un līdz ar to arī rezistenci. Bakalaura darbā Streptococcus mutans sortāze A tiek izmantota kā instruments, lai pārbaudītu novatoriskus ķīmiskus savienojumus, kam piemīt spēja inhibēt sortāzi A. Mērķis bija, izmantojot zāļu vielu skrīninga metodi, atlasīt ķīmiskas vielas, kam piemīt sortāzes A inhibēšana un kuras varētu izmantot, lai apkarotu multirezistentu grampozitīvu patogēnu izraistītas slimības. Streptococcus mutans sortāzes A …
No klīniskajiem paraugiem izdalīto Streptococcus pneumoniae virulences faktori un rezistence pret antibakteriālajiem līdzekļiem
2020
Ievads: Latvijā un Pasaulē aktuāla problēma ir Streptococcus pneumoniae baktērijas rezistence, kas izveidojusies pret antibakteriālajiem līdzekļiem. Rezistento Streptococcus pneumoniae celmu skaits palielinās ar katru gadu. Preventīvie pasākumi, kas samazinātu rezistences incidenci ir svarīga atbildīga un piesardzīga antibakteriālo līdzekļu izmantošana cilvēku veselības uzlabošanai un pacientu informētība, izpratne par Streptococcus pneumoniae rezistenci. Darba mērķi: Noteikt Streptecoccus pneumoniae jutību pret antibakteriālajiem līdzekļiem, kas iegūti no klīniskā materiāla paraugiem. Materiāli un metodes: Pētījums veikts RAKUS stacionārs ‘’Tuberkulozes un plaušu slimību centrs’’ klīnikas …
A Superantigen as Virulence Factor in an Acute Bacterial Infection
1994
This study addresses the role of a bacterial superantigen as a potential virulence factor during an acute systemic infection. BALB/c mice were intravenously infected with a recombinant Staphylococcus aureus strain capable of producing plasmid-encoded staphylococcal enterotoxin B (SEB) or with the SEB plasmid-deficient parental strain. Infection with SEB-producing bacteria resulted in an initial expansion and subsequent decrease of circulating V beta 8+ T lymphocytes. This numeric decrease was accompanied by a SEB-specific state of hyporesponsiveness of splenic T cells. In parallel with SEB-triggered unresponsiveness of a large proportion of T lymphocytes, a weakening of the overall T cell r…
Effects of salinity and temperature on long-term survival of the eel pathogen Vibrio vulnificus biotype 2 (serovar E)
1999
ABSTRACT Vibrio vulnificus biotype 2 (serovar E) is a primary eel pathogen. In this study, we performed long-term survival experiments to investigate whether the aquatic ecosystem can be a reservoir for this bacterium. We have used microcosms containing water of different salinities (ranging from 0.3 to 3.8%) maintained at three temperatures (12, 25, and 30°C). Temperature and salinity significantly affected long-term survival: (i) the optimal salinity for survival was 1.5%; (ii) lower salinities reduced survival, although they were nonlethal; and (ii) the optimal temperature for survival was dependent on the salinity (25°C for microcosms at 0.3 and 0.5% and 12°C for microcosms at 1.5 to 3.…
IMMUNOGENICITY OF AN ACELLULAR PERTUSSIS VACCINE COMPOSED OF GENETICALLY INACTIVATED PERTUSSIS TOXIN COMBINED WITH FILAMENTOUS HEMAGGLUTININ AND PERT…
1993
We studied the immunogenicity of an acellular pertussis vaccine composed of genetically detoxified pertussis toxin (PT-9K/129G), filamentous haemagglutinin, and a 69-kilodalton protein, pertactin, in 30 children aged 12 to 24 months and in 80 infants aged 2 to 4 months. A significant increase of the neutralizing titer and of the titers against pertussis toxin, filamentous hemagglutinin, and pertactin, as determined by enzyme-linked immunosorbent assay, was achieved after three doses of vaccine in all the children; a significant increase of these antibody titers was obtained in 100%, 96.1%, 93.5%, and 98.7% of the infants, respectively.
Use of a Genetically Engineered Strain To Evaluate the Pathogenic Potential of Yeast Cell and Filamentous Forms duringCandida albicansSystemic Infect…
2007
ABSTRACTThe pathogenesis ofCandida albicanssystemic infection is complex and results from the balance between its intrinsic virulence attributes and the host immune responses. Morphogenetic transitions between yeast cell and filamentous forms are considered one of the main virulence attributes inC. albicans. We have examined the pathogenesis of a genetically engineeredC. albicansstrain in which morphogenetic conversions can be externally manipulated in immunodeficient mice; these included B-cell deficient, nude (T cell deficient), SCID (lacking both functional T and B cells), and DBA/2N (C5 deficient with impaired neutrophil activity) mice. We also tested mice severely immunosuppressed by c…
Effect of priming with diphtheria and tetanus toxoids combined with whole-cell pertussis vaccine or with acellular pertussis vaccine on the safety an…
1995
Objective: To evaluate the safety and the immunogenicity of a booster dose of recombinant acellular pertussis vaccine combined with diphtheria and tetanus toxoids (DTaP, Biocine SpA) in 15- to 21-month-old children primed in infancy with either whole-cell diphtheria-tetanus-pertussis (DTwP) vaccine or DTaP vaccine. Design: Open-label second phase of a double-masked, controlled trail, with masked analysis of serum samples. Participants and setting: Three hundred fifty children, 15 to 21 months of age, who had been primed at 2, 4, and 6 months of age with either three doses of DTaP vaccine (n = 173) or DTwP vaccine (n = 177). The children were enrolled in eight vaccination centers in Italy. I…