Staphylococcus aureus is a Gram-positive coccus that resides harmlessly on the skin and mucous membranes of healthy individuals. When the skin barrier is breached, it can shift from a commensal to an opportunistic pathogen. This transition is facilitated by surface adhesins, such as clumping factor B and S. aureus surface protein G (SasG), which bind to structural proteins, including loricrin and cytokeratin, in the damaged epidermis. Protein A, another key factor, binds the Fc region of...

Acne is a multifactorial skin condition primarily affecting adolescents and young adults, with a global prevalence estimated to exceed 75% in this demographic. The condition is characterized by the formation of comedones (blackheads and whiteheads), papules, pustules, nodules, and, in severe cases, cysts, particularly in areas rich in sebaceous glands such as the face, neck, chest, and back. The pathogenesis involves increased sebum production, follicular hyperkeratinization, colonization by...

Rheumatic heart disease or RHD is a chronic condition that results from rheumatic fever, causing permanent damage to the heart valves.Etiology and Risk FactorsIt primarily arises from rheumatic fever, an inflammatory disease that can develop after untreated or inadequately treated group A streptococcal (GAS) pharyngitis. Streptococcus spreads through direct contact with oral or respiratory secretions. While the bacteria are the causative agents, factors like malnutrition, overcrowding, poor...

Sweat glands or sudoriferous glands are one of the important accessory structures of the skin. They are small, coiled tubular structures located in the dermis, the middle layer of the skin. Sweat glands are responsible for producing and secreting sweat, a watery fluid that helps regulate body temperature and excrete waste products.
Sweat glands are classified as merocrine glands; that is, the secretions are excreted by exocytosis through a duct without affecting the cells of the gland. There...

Peripheral artery disease (PAD) predominantly results from atherosclerosis, which involves the accumulation of fatty deposits, or plaques, within the walls of arteries. This causes them to narrow and harden, significantly reducing blood flow. PAD predominantly affects the legs, particularly the arteries supplying the thighs and calves. In rare cases, it may involve other arteries, including those in the arms.Etiology of PAD:The principal cause of PAD is atherosclerosis, which results from fatty...

Pyelonephritis is a bacterial infection that primarily affects the renal parenchyma and collecting system, including the renal pelvis, tubules, and interstitial tissue of one or both kidneys. It can be classified as either acute—a sudden, severe infection—or chronic, which refers to long-term or recurrent kidney infections.The primary cause of acute pyelonephritis (APN) is bacterial infection, with Escherichia coli accounting for approximately 70-80% of cases. Other bacteria, such...