Pathogenic bacteriaPathogenic bacteria are bacteria that can cause disease. This article focuses on the bacteria that are pathogenic to humans. Most species of bacteria are harmless and are often beneficial but others can cause infectious diseases. The number of these pathogenic species in humans is estimated to be fewer than a hundred. By contrast, several thousand species are part of the gut flora present in the digestive tract.
Nephritic syndromeNephritic syndrome is a syndrome comprising signs of nephritis, which is kidney disease involving inflammation. It often occurs in the glomerulus, where it is called glomerulonephritis. Glomerulonephritis is characterized by inflammation and thinning of the glomerular basement membrane and the occurrence of small pores in the podocytes of the glomerulus. These pores become large enough to permit both proteins and red blood cells to pass into the urine (yielding proteinuria and hematuria, respectively).
Urinary castUrinary casts are microscopic cylindrical structures produced by the kidney and present in the urine in certain disease states. They form in the distal convoluted tubule and collecting ducts of nephrons, then dislodge and pass into the urine, where they can be detected by microscopy. They form via precipitation of Tamm–Horsfall mucoprotein, which is secreted by renal tubule cells, and sometimes also by albumin in conditions of proteinuria. Cast formation is pronounced in environments favoring protein denaturation and precipitation (low flow, concentrated salts, low pH).
GlomerulonephritisGlomerulonephritis (GN) is a term used to refer to several kidney diseases (usually affecting both kidneys). Many of the diseases are characterised by inflammation either of the glomeruli or of the small blood vessels in the kidneys, hence the name, but not all diseases necessarily have an inflammatory component. As it is not strictly a single disease, its presentation depends on the specific disease entity: it may present with isolated hematuria and/or proteinuria (blood or protein in the urine); or as a nephrotic syndrome, a nephritic syndrome, acute kidney injury, or chronic kidney disease.
Renal biopsyRenal biopsy (also kidney biopsy) is a medical procedure in which a small piece of kidney is removed from the body for examination, usually under a microscope. Microscopic examination of the tissue can provide information needed to diagnose, monitor or treat problems of the kidney. A renal biopsy can be targeted to a particular lesion, for example a tumour arising from the kidney (targeted renal biopsy). More commonly, however, the biopsy is non-targeted as medical conditions affecting the kidney typically involve all kidney tissue indiscriminately.
Lupus nephritisLupus nephritis is an inflammation of the kidneys caused by systemic lupus erythematosus (SLE), an autoimmune disease. It is a type of glomerulonephritis in which the glomeruli become inflamed. Since it is a result of SLE, this type of glomerulonephritis is said to be secondary, and has a different pattern and outcome from conditions with a primary cause originating in the kidney. The diagnosis of lupus nephritis depends on blood tests, urinalysis, X-rays, ultrasound scans of the kidneys, and a kidney biopsy.
Streptococcus pyogenesStreptococcus pyogenes is a species of Gram-positive, aerotolerant bacteria in the genus Streptococcus. These bacteria are extracellular, and made up of non-motile and non-sporing cocci (round cells) that tend to link in chains. They are clinically important for humans, as they are an infrequent, but usually pathogenic, part of the skin microbiota that can cause Group A streptococcal infection. S. pyogenes is the predominant species harboring the Lancefield group A antigen, and is often called group A Streptococcus (GAS).
HematuriaHematuria or haematuria is defined as the presence of blood or red blood cells in the urine. "Gross hematuria" occurs when urine appears red, brown, or tea-colored due to the presence of blood. Hematuria may also be subtle and only detectable with a microscope or laboratory test. Blood that enters and mixes with the urine can come from any location within the urinary system, including the kidney, ureter, urinary bladder, urethra, and in men, the prostate.
Nephrotic syndromeNephrotic syndrome is a collection of symptoms due to kidney damage. This includes protein in the urine, low blood albumin levels, high blood lipids, and significant swelling. Other symptoms may include weight gain, feeling tired, and foamy urine. Complications may include blood clots, infections, and high blood pressure. Causes include a number of kidney diseases such as focal segmental glomerulosclerosis, membranous nephropathy, and minimal change disease. It may also occur as a complication of diabetes or lupus.
PharyngitisPharyngitis is inflammation of the back of the throat, known as the pharynx. It typically results in a sore throat and fever. Other symptoms may include a runny nose, cough, headache, difficulty swallowing, swollen lymph nodes, and a hoarse voice. Symptoms usually last 3–5 days, but can be longer depending on cause. Complications can include sinusitis and acute otitis media. Pharyngitis is a type of upper respiratory tract infection. Most cases are caused by a viral infection.
