MRSA Research - Methicillin-Resistant Staphylococcus Aureus, Hospitals, Infection, Antibiotic Resistance, Superbugs

MRSA Research Today is a free monthly online journal that collates and summarizes the latest research about MRSA, including details on methicillin-resistant staphylococcus aureus, hospitals, infection, antibiotic resistance, superbugs.


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Mutation in the C-Di-AMP Cyclase dacA Affects Fitness and Resistance of Methicillin Resistant Staphylococcus aureus.

Dengler V, McCallum N, Kiefer P, Christen P, Patrignani A, Vorholt JA, Berger-B├Ąchi B, Senn MM

Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland.

Faster growing and more virulent strains of methicillin resistant Staphylococcus aureus (MRSA) are increasingly displacing highly resistant MRSA. Elevated fitness in these MRSA is often accompanied by decreased and heterogeneous levels of methicillin resistance; however, the mechanisms for this phenomenon are not yet fully understood. Whole genome sequencing was used to investigate the genetic basis of this apparent correlation, in an isogenic MRSA strain pair that differed in methicillin resistance levels and fitness, with respect to growth rate. Sequencing revealed only one single nucleotide polymorphism (SNP) in the diadenylate cyclase gene dacA in the faster growing but less resistant strain. Diadenylate cyclases were recently discovered to synthesize the new second messenger cyclic diadenosine monophosphate (c-di-AMP). Introduction of this mutation into the highly resistant but slower growing strain reduced resistance and increased its growth rate, suggesting a direct connection between the dacA mutation and the phenotypic differences of these strains. Quantification of cellular c-di-AMP revealed that the dacA mutation decreased c-di-AMP levels resulting in reduced autolysis, increased salt tolerance and a reduction in the basal expression of the cell wall stress stimulon. These results indicate that c-di-AMP affects cell envelope-related signalling in S. aureus. The influence of c-di-AMP on growth rate and methicillin resistance in MRSA indicate that altering c-di-AMP levels could be a mechanism by which MRSA strains can increase their fitness levels by reducing their methicillin resistance levels.

Published 9 September 2013 in PLoS One, 8(8): e73512.
Full-text of this article is available online (may require subscription).


Articles on MRSA published 9 September 2013:

A selected screening programme was less effective in the detection of methicillin-resistant Staphylococcus aureus colonisation in an orthopaedic unit.   Int Orthop.

[Abstract] [Full-text]

The synthesis and SAR study of phenylalanine-derived (Z)-5-arylmethylidene rhodanines as anti-methicillin-resistant Staphylococcus aureus (MRSA) compounds.   Bioorg Med Chem Lett.

[Abstract] [Full-text]

Impact of Weight on Treatment Efficacy and Safety in Complicated Skin and Skin Structure Infections and Nosocomial Pneumonia Caused by Methicillin-Resistant Staphylococcus aureus.   Clin Ther.

[Abstract] [Full-text]

Sustained meticillin-resistant Staphylococcus aureus control in a hyper-endemic tertiary acute care hospital with infrastructure challenges in Singapore.   J Hosp Infect.

[Abstract] [Full-text]

Invasive Methicillin-Resistant Staphylococcus aureus Infections Among Patients on Chronic Dialysis in the United States, 2005-2011.   Clin Infect Dis.

[Abstract] [Full-text]

Panton-Valentine Leukocidin Facilitates the Escape of Staphylococcus aureus From Human Keratinocyte Endosomes and Induces Apoptosis.   J Infect Dis.

[Abstract] [Full-text]

Impact of Colonization Pressure and Strain Type on Methicillin-Resistant Staphylococcus aureus Transmission in Children.   Clin Infect Dis.

[Abstract] [Full-text]

Staphylococcal Enterotoxin B-Specific Monoclonal Antibody 20B1 Successfully Treats Diverse Staphylococcus aureus Infections.   J Infect Dis.

[Abstract] [Full-text]


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MRSA Books

Possible risk for re-colonization with methicillin-resistant Staphylococcus aureus (MRSA) by faecal transmission [An article from: International Journal of Hygiene and Environmental Health]

Possible risk for re-colonization with methicillin-resistant Staphylococcus aureus (MRSA) by faecal transmission [An article from: International Journal of Hygiene and Environmental Health]