Final answer:
The mentioned diseases are caused by a bacterial infection, specifically Streptococcus pyogenes. Strep throat presents with fever and sore throat, while rheumatic fever and acute glomerulonephritis are its severe sequelae caused by autoimmune responses.
Step-by-step explanation:
The causes of strep sore throat, rheumatic fever, glomerulonephritis, scarlet fever (scarlatina), erysipelas, puerperal sepsis, and impetigo are all typically due to a bacterial infection. Specifically, these conditions are often caused by Streptococcus pyogenes, which belongs to the Lancefield group A, ß-hemolytic Streptococcus, often referred to as GAS or group A strep.
Symptoms of strep throat include fever, sore throat, inflammation of pharynx and tonsils, petechiae, swollen lymph nodes, and in the case of scarlet fever, a skin rash and strawberry tongue. The strain of S. pyogenes responsible for these infections produces various exoenzymes and exotoxins that lead to tissue damage. One of such toxins, the erythrogenic toxin, is responsible for the rash observed in scarlet fever.
Rheumatic fever and acute glomerulonephritis are serious sequelae of untreated or inadequately treated infections with certain strains of this bacterium. Rheumatic fever can lead to rheumatic heart disease and occurs due to an autoimmune response triggered by molecular mimicry between the M protein of the bacteria and heart tissue. Acute glomerulonephritis is an inflammation of the kidney glomeruli resulting from immune complex deposition, which is also an autoimmune response to the infection.