![]() ![]() ![]() The combination of temperature and humidity is measured by the heat index. Heat waves are more dangerous when combined with high humidity. The National Climate Assessment estimates 20-30 more days over 90 degrees F in most areas by mid-century. If greenhouse gas emissions are not significantly curtailed, daily high and low temperatures will increase by at least 5 degrees F in most areas by mid-century, rising to 10 degrees F by late century. West, although in some parts of the country the 1930s still holds the record for number of heat waves (primarily related to the Dust Bowl, which was exacerbated by the conversion of prairie to farmland).” Heat waves are becoming more common, and intense heat waves are more frequent in the U.S. Over the past decade, daily record high temperatures have occurred twice as often as record lows across the continental United States, up from a near 1:1 ratio in the 1950s. In July 2023, Earth broke or tied its record for the hottest day on record, four days in a row. aureus strains to form biofilms as well as communicate using quorum sensing in a bacterial cell density-dependent manner.Across the globe, hot days are getting hotter and more frequent, while we’re experiencing fewer cold days. Pneumonia infections are associated with the bacterial production of PVL (Panton-Valentine leukocidin), Protein A, and alpha-hemolysin, and infections are more common following influenza virus infection as well as a diagnosis of Cystic Fibrosis. Prosthetic device infections are often mediated by the ability of S. Also, Staphylococcal superantigens (TSST-1 or toxic shock syndrome toxin 1) are important virulence factors in infectious endocarditis, sepsis, as well as toxic shock syndrome. Binding of the bacteria to extracellular matrix proteins and fibronectin in infectious endocarditis is mediated by bacterial cell wall-associated proteins such as fibrinogen-binding proteins, clumping factors, and teichoic acids. Mechanisms for evasion of the host immune response include the production of an antiphagocytic capsule, sequestering of host antibodies or antigen masking by Protein A, biofilm formation, intracellular survival, and blocking chemotaxis of leukocytes. The pathophysiology varies greatly depending on the type of S. ![]() Depending on the strains involved and the site of infection, these bacteria can cause invasive infections and/or toxin-mediated diseases. aureus are one the most common bacterial infections in humans and are the causative agents of multiple human infections, including bacteremia, infective endocarditis, skin and soft tissue infections (e.g., impetigo, folliculitis, furuncles, carbuncles, cellulitis, scalded skin syndrome, and others), osteomyelitis, septic arthritis, prosthetic device infections, pulmonary infections (e.g., pneumonia and empyema), gastroenteritis, meningitis, toxic shock syndrome, and urinary tract infections. MRSA strains tend to be resistant to methicillin, nafcillin, oxacillin, and cephalosporins. aureus strains that synthesize PBP-2A can grow in the presence of many antibiotics, and these MRSA strains are resistant to many antibiotics. PBP-2A has a lower affinity to bind to beta-lactams (and other penicillin-derived antibiotics) when compared to other PBPs, so PBP-2A continues to catalyze the synthesis of the bacterial cell wall even in the presence of many antibiotics. PBP-2a is a penicillin-binding protein (PBP), or essential bacterial cell wall enzyme that catalyzes the production of the peptidoglycan in the bacterial cell wall. The mec gene encodes the protein PBP-2a (penicillin-binding protein 2a). MRSA strains carry a mec gene on the bacterial chromosome, which is a component of the larger Staphylococcal chromosomal cassette mec (SCC mec) region, conferring resistance to multiple antibiotics depending on the SCC mec type. ![]() Typical biochemical identification tests include catalase positive (all pathogenic Staphylococcus species), coagulase positive (to distinguish Staphylococcus aureus from other Staphylococcus species), novobiocin sensitive (to distinguish from Staphylococcus saprophyticus), and mannitol fermentation positive (to distinguish from Staphylococcus epidermidis). These organisms can grow aerobically or anaerobically (facultative) and at temperatures between 18 C and 40 C. Staphylococcus aureus is Gram-positive bacteria (stain purple by Gram stain) that are cocci-shaped and tend to be arranged in clusters that are described as “grape-like.” On media, these organisms can grow in up to 10% salt, and colonies are often golden or yellow (aureus means golden or yellow). ![]()
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