80 research outputs found
Staphylococcal cassette chromosome mec typing and meca sequencing in methicillin-resistant staphylococci from Algeria: A highly diversified element with new mutations in mecA
Genetic mechanisms of methicillin resistance are still relevant in staphylococci. The aims of this study are to assess the possible exchanges of staphylococcal cassette chromosome mec (SCCmec) among isolates of methicillin-resistant staphylococci (MRS) and to check for known or new mutations in mecA DNA. A total of 35 MRS non-repetitive isolates were recovered, including 20 Staphylococcus haemolyticus, 7 Staphylococcus aureus, 4 Staphylococcus sciuri, 2 Staphylococcus saprophyticus and 1 isolate each of Staphylococcus xylosus and Staphylococcus lentus. Only 16 of the 35 strains were assigned to known SCCmec types: 7 SCCmec VII, 6 SCCmec IV and 3 SCCmec III, with possible horizontal transfer of the SCCmec VII from methicillin-resistant S. haemolyticus to methicillin-susceptible S. aureus. mecA gene sequencing in ten selected isolates allowed description of nine punctual mutations, seven of which were reported for the first time. The most frequent mutation was G246E, identified in isolates of methicillin-resistant S. aureus, S. sciuri, S. saprophyticus and S. lentus. These results emphasized the high degree of genetic diversity of SCCmec element in MRS and describe new missense mutations in mecA, which might be important in understanding the evolution of methicillin and new b-lactam resistance
Descriptive Epidemiology of Nasal Carriage of Staphylococcus aureus and Methicillin-Resistant Staphylococcus aureus Among Patients Admitted to Two Healthcare Facilities in Algeria
Aim: To evaluate nasal carriage rate and variables associated with Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA) in patients admitted in two healthcare facilities. Results: S. aureus was isolated from 159 (26%) of the enrolled patients. Methicillin-susceptible S. aureus was isolated from 150 (24.5%) patients, and MRSA was isolated from 9 (1.5%). Cancer and previous hospitalization were associated with a significantly higher frequency of nasal S. aureus carriage among the patients admitted to the general hospital and the nephrology department, respectively. MRSA isolates were heterogeneous with respect to their staphylococcal cassette chromosome mec element (SCCmec) type, sequence type (ST), and toxin genes (pvl and tst1) content. Four isolates were attributed with the ST80-MRSA-IV clone, which is known to be predominant in Algeria. Conclusions: This is the first assessment of S. aureus and MRSA nasal carriage and associated variables in Algeria. Our findings provide also a picture of the MRSA strains circulating in the community in this geographic area. They can be useful as a guide for implementing screening and control procedures against S. aureus/MRSA in the Algerian healthcare facilities
Hyaluronic Acid Scaffolds for Loco-Regional Therapy in Nervous System Related Disorders
Hyaluronic acid (HA) is a Glycosaminoglycan made of disaccharide units containing N-acetyl-D-glucosamine and glucuronic acid. Its molecular mass can reach 10 MDa and its physiological properties depend on its polymeric property, polyelectrolyte feature and viscous nature. HA is a ubiquitous compound found in almost all biological tissues and fluids. So far, HA grades are produced by biotechnology processes, while in the human organism it is a major component of the extracellular matrix (ECM) in brain tissue, synovial fluid, vitreous humor, cartilage and skin. Indeed, HA is capable of forming hydrogels, polymer crosslinked networks that are very hygroscopic. Based on these considerations, we propose an overview of HA-based scaffolds developed for brain cancer treatment, central and peripheral nervous systems, discuss their relevance and identify the most successful developed systems
Panton-Valentine leukocidin positive sequence type 80 methicillin-resistant Staphylococcus aureus carrying a staphylococcal cassette chromosome mec type IVc is dominant in neonates and children in an Algiers hospital
Methicillin-resistant Staphylococcus aureus (MRSA) is a major antimicrobial
drug-resistant pathogen causing serious infections. It was first detected in
healthcare settings, but in recent years it has also become disseminated in the
community. Children and young adults are most susceptible to infection by
community-acquired (CA) MRSA strains. In this study 25 MRSA isolates implicated
in infections of neonates and children admitted to an Algiers hospital during an
18 month period were characterized by molecular methods including staphylococcal
cassette chromosome (SCC) mec typing, PCR amplification of pvl genes, pulsed
field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Fifteen
out of 25 isolates were from hospital-acquired infections. Twenty-four isolates
carried SCCmec type IVc and belonged to the sequence type (ST) 80, one isolate
carried SCCmec type II and was ST 39. Twenty-two out of 24 ST80-MRSA-IVc isolates carried pvl genes. Our results suggest that the Panton-Valentine leukocidin positive ST80- MRSA-IVc is the dominant MRSA clone causing disease in neonates and children in Algiers
Do About Half the Top Quarks at FNAL Come From Gluino Decays?
We argue that it is possible to make a consistent picture of FNAL data
including the production and decay of gluinos and squarks. The additional cross
section is several pb, about the size of that for Standard Model (SM) top quark
pair production. If the stop squark mass is small enough, about half of the top
quarks decay to stop squarks, and the loss of SM top quark pair production rate
is compensated by the supersymmetric processes. This behavior is consistent
with the reported top quark decay rates in various modes and other aspects of
the data, and suggests several other possible decay signatures. This picture
can be tested easily with more data, perhaps even with the data in hand, and
demonstrates the potential power of a hadron collider to determine
supersymmetric parameters. It also has implications for the top mass
measurement and the interpretation of the LEP excess.Comment: 18 pages, including 4 Postscript figures, uses epsf.tex, also
available at http://www.hep.anl.gov/theory/mrenna
Analysis of the dust evolution in the circumstellar disks of TTauri stars
We present a compositional analysis of 8-13um spectra of 32 young stellar
objects (YSOs). Our sample consists of 5 intermediate-mass stars and 27
low-mass stars. While the spectra and first scientific results have already
been published by Przygodda et al. (2003) and Kessler-Silacci et al. (2004) we
perform a more detailed analysis of the 10um silicate feature. In our analysis
we assume that this emission feature can be represented by a linear
superposition of the wavelength-dependent opacity
describing the optical properties of silicate grains with different chemical
composition, structure, and grain size. The determination of an adequate
fitting equation is another goal of this study. Using a restricted number of
fitting parameters we investigate which silicate species are necessary for the
compositional fitting. Particles with radii of 0.1um- and 1.5um consisting of
amorphous olivine and pyroxene, forsterite, enstatite, and quartz have been
considered. Only compact, homogeneous dust grains have been used in the
presented fitting procedures. In this context we show that acceptable fitting
results can also be achieved if emission properties of porous silicate grains
are considered instead. Although some previous studies give reasons for the
similarity between the dust in circumstellar disks of TTauri stars and Herbig
Ae/Be stars, a quantitative comparison has been missing, so far. Therefore, we
conclude with a discussion of the results of a 10um spectroscopic survey of van
Boekel et al. (2005) who focus on Herbig Ae/Be stars, the higher mass
counterparts of T Tauri stars and draw comparisons to this and other studies.
We find that the results of our study of T Tauri systems partly agree with
previous studies of Herbig Ae/Be stars.Comment: 17 pages, 6 figure
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