Staphylococcus aureus is a Gram-positive, round-shaped bacterium that is a member of the Firmicutes, and it is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin. It is often positive for catalase and nitrate reduction and is a facultative anaerobe that can grow without the need for oxygen. Although S. aureus usually acts as a commensal of the human microbiota it can also become an opportunistic pathogen, being a common cause of skin infections including abscesses, respiratory infections such as sinusitis, and food poisoning. Pathogenic strains often promote infections by producing virulence factors such as potent protein toxins, and the expression of a cell-surface protein that binds and inactivates antibodies. The emergence of antibiotic-resistant strains of S. aureus such as methicillin-resistant S. aureus (MRSA) is a worldwide problem in clinical medicine. Despite much research and development, no vaccine for S. aureus has been approved.
Methicillin-resistant Staphylococcus aureus (MRSA) refers to a group of Gram-positive bacteria that are genetically distinct from other strains of Staphylococcus aureus. MRSA is responsible for several difficult-to-treat infections in humans. MRSA is any strain of S. aureus that has developed, through horizontal gene transfer and natural selection, multiple drug resistance to beta-lactam antibiotics. β-lactam antibiotics are a broad-spectrum group that include some penams and cephems such as the cephalosporins. Strains unable to resist these antibiotics are classified as methicillin-susceptible S. aureus, or MSSA.
Aspergillus fumigatus is a species of fungus in the genus Aspergillus, and is one of the most common Aspergillus species to cause disease in individuals with an immunodeficiency.
Staphylococcus epidermidis is a Gram-positive bacterium, and one of over 40 species belonging to the genus Staphylococcus. It is part of the normal human flora, typically the skin flora, and less commonly the mucosal flora. It is a facultative anaerobic bacteria. Although S. epidermidis is not usually pathogenic, patients with compromised immune systems are at risk of developing infection. These infections are generally hospital-acquired. S. epidermidis is a particular concern for people with catheters or other surgical implants because it is known to form biofilms that grow on these devices. Being part of the normal skin flora, S. epidermidis is a frequent contaminant of specimens sent to the diagnostic laboratory.
Sultamicillin, sold under the brand name Unasyn among others, is an oral form of the antibiotic combination ampicillin/sulbactam. It contains esterified ampicillin and sulbactam.
Panton–Valentine leukocidin (PVL) is a cytotoxin—one of the β-pore-forming toxins. The presence of PVL is associated with increased virulence of certain strains (isolates) of Staphylococcus aureus. It is present in the majority of community-associated Methicillin-resistant Staphylococcus aureus (CA-MRSA) isolates studied and is the cause of necrotic lesions involving the skin or mucosa, including necrotic hemorrhagic pneumonia. PVL creates pores in the membranes of infected cells. PVL is produced from the genetic material of a bacteriophage that infects Staphylococcus aureus, making it more virulent.
Alpha-toxin, also known as alpha-hemolysin (Hla), is the major cytotoxic agent released by bacterium Staphylococcus aureus and the first identified member of the pore forming beta-barrel toxin family. This toxin consists mostly of beta-sheets (68%) with only about 10% alpha-helices. The hly gene on the S. aureus chromosome encodes the 293 residue protein monomer, which forms heptameric units on the cellular membrane to form a complete beta-barrel pore. This structure allows the toxin to perform its major function, development of pores in the cellular membrane, eventually causing cell death.
A staphylococcus infection or staph infection is an infection caused by members of the Staphylococcus genus of bacteria. These bacteria commonly inhabit the skin and nose where they are innocuous, but may enter the body through cuts or abrasions which may be nearly invisible. Once inside the body, the bacterium may spread to a number of body systems and organs, including the heart, where the toxins produced by the bacterium may cause cardiac arrest. Once the bacterium has been identified as the cause of the illness, treatment is often in the form of antibiotics and, where possible, drainage of the infected area. However, many strains of this bacterium have become antibiotic resistant; for those suffering these kinds of infection, the body's own immune system is the only defense against the disease. If that system is weakened or compromised, the disease may progress rapidly. Anyone can contract Staph; but, pregnant women, children, people with chronic diseases or are immune-deficient are often more susceptible to contracting an infection.
'Staphylococcus aureus delta toxin is a toxin produced by Staphylococcus aureus. It has a wide spectrum of cytolytic activity.
Microbial toxins are toxins produced by micro-organisms, including bacteria and fungi. Microbial toxins promote infection and disease by directly damaging host tissues and by disabling the immune system. Some bacterial toxins, such as Botulinum neurotoxins, are the most potent natural toxins known. However, microbial toxins also have important uses in medical science and research. Potential applications of toxin research include combating microbial virulence, the development of novel anticancer drugs and other medicines, and the use of toxins as tools in neurobiology and cellular biology.
Victor Nizet, M.D. is a Distinguished Professor of pediatrics and physician-scientist who as of 2018 was Professor and Vice Chair of Basic Research in the Department of Pediatrics at the University of California, San Diego (UCSD) School of Medicine and Professor at UCSD Skaggs School of Pharmacy and Pharmaceutical Sciences in La Jolla, California. He is known for research in the areas of molecular microbiology and the innate immune system, with a particular focus on infectious diseases caused by common Gram-positive bacterial pathogens such as Group A Streptococcus, Group B Streptococcus and Staphylococcus aureus.
In molecular biology SprD is a non-coding RNA expressed on pathogenicity islands in Staphylococcus aureus. It was identified in silico along with a number of other sRNAs (SprA-G) through microarray analysis which were confirmed using a Northern blot. SprD has been found to significantly contribute to causing disease in an animal model.
The alpha-D-phosphohexomutases are a large superfamily of enzymes, with members in all three domains of life. Enzymes from this superfamily are ubiquitous in organisms from E. Coli to humans, and catalyze a phosphoryl transfer reaction on a phosphosugar substrate. Four well studied subgroups in the superfamily are:
- Phosphoglucomutase (PGM)
- Phosphoglucomutase/Phosphomannomutase (PGM/PMM)
- Phosphoglucosamine mutase (PNGM)
- Phosphoaceytlglucosamine mutase (PAGM)
4,4'-diapophytoene synthase is an enzyme with systematic name farnesyl-diphosphate:farnesyl-diphosphate farnesyltransferase . This enzyme catalyses the following chemical reaction
Glutamyl endopeptidase is an extracellular bacterial serine protease of the glutamyl endopeptidase I family that was initially isolated from the Staphylococcus aureus strain V8. The protease is, hence, commonly referred to as "V8 protease", or alternatively SspA from its corresponding gene.
Aureolysin is an extracellular metalloprotease expressed by Staphylococcus aureus. This protease is a major contributor to the bacterium's virulence, or ability to cause disease, by cleaving host factors of the innate immune system as well as regulating S. aureus secreted toxins and cell wall proteins. To catalyze its enzymatic activities, aureolysin requires zinc and calcium which it obtains from the extracellular environment within the host.
Teg49 is a non-coding RNA present in the extended promoter region of the staphylococcal accessory regulator sarA. It was identified by RNA-seq and confirmed by Northern blot. It is modulated by sigB and cshA and it most likely contributes to virulence of S. aureus by modulating SarA expression.
Staphopain A is a secreted cysteine protease produced by Staphylococcus aureus. It was first identified in the S. aureus V8 strain as a papain-like cysteine protease. The protease distinguishes itself from the other major proteases of S. aureus in its very broad specificity and its ability to degrade elastin.
ESKAPE is an acronym encompassing the names of six bacterial pathogens commonly associated with antimicrobial resistance: ESKAPE is an acronym for their names and a reference to their ability to escape the effects of commonly used antibiotics through evolutionarily developed mechanisms, and also because it is an acronym made from the first letters of their scientific names:
