Pyelonephritis
Encyclopedia
Pyelonephritis is an ascending urinary tract infection
that has reached the pyelum or pelvis of the kidney. It is a form of nephritis
that is also referred to as pyelitis. Severe cases of pyelonephritis can lead to pyonephrosis
(pus accumulation around the kidney), urosepsis
(a systemic inflammatory response
of the body to infection), kidney failure and even death.
Pyelonephritis presents with fever
, accelerated heart rate
, painful urination
, abdominal pain radiating to the back
, nausea
, and tenderness at the costovertebral angle
on the affected side. Pyelonephritis that has progressed to urosepsis may be accompanied by signs
of septic shock
, including rapid breathing
, decreased blood pressure
, violent shivering, and occasionally delirium
. Pyelonephritis requires antibiotic therapy, and sometimes surgical intervention such as ureteroscopy
, percutaneous
nephrostomy
or percutaneous nephrolithotomy
, as well as treatment of any underlying causes to prevent its recurrence. Xanthogranulomatous pyelonephritis is a rare form of chronic
pyelonephritis in which nephrectomy
(removal of the kidney) is usually necessary for definitive treatment.
.
Chronic pyelonephritis causes persistent flank or abdominal pain, signs of infection (fever, unintentional weight loss, malaise
, decreased appetite
), lower urinary tract symptoms
and blood in the urine
. Chronic pyelonephritis can in addition cause fever of unknown origin
. Furthermore, inflammation-related proteins can accumulate in organs and cause the condition AA amyloidosis
.
Physical examination may reveal fever and tenderness at the costovertebral angle on the affected side.
(70–80%) and Enterococcus faecalis
. Hospital-acquired infections
may be due to coliform bacteria
and enterococci, as well as other organisms uncommon in the community (e.g. Pseudomonas aeruginosa
and various species of Klebsiella
). Most cases of pyelonephritis start off as lower urinary tract infections, mainly cystitis
and prostatitis
. E. coli can invade the superficial umbrella cells of the bladder to form intracellular bacterial communities (IBCs), which can mature into biofilm
s. These biofilm-producing E. coli are resistant to antibiotic therapy and immune system responses, and present a possible explanation for recurrent urinary tract infections, including pyelonephritis. Risk is increased in the following situations:
may show signs of urinary tract infection. Specifically, the presence of nitrite
and white blood cell
s on a urine test strip
in patients with typical symptoms are sufficient for the diagnosis of pyelonephritis, and are an indication for empirical treatment
. Blood test
s such as a complete blood count
may show neutrophilia
. Microbiological culture
of the urine, with or without blood culture
s and antibiotic sensitivity testing
are useful for establishing a formal diagnosis.
or the presence of a disproportionate amount of blood in the urine), a kidneys, ureters, and bladder x-ray (KUB film) may assist in identifying radioopaque
stones. Where available, a noncontrast helical CT scan
with 5 millimeter sections is the diagnostic modality of choice in the radiographic evaluation of suspected nephrolithiasis. All stones are detectable on CT scans except very rare stones composed of certain drug residues in the urine. In patients with recurrent ascending urinary tract infections, it may be necessary to exclude an anatomical abnormality, such as vesicoureteral reflux or polycystic kidney disease
. Investigations used in this setting include ultrasonography
of the kidneys or voiding cystourethrography
. CT scan or abdominal ultrasonography is useful in the diagnosis of xanthogranulomatous pyelonephritis; serial imaging may be useful for differentiating this condition from kidney cancer.
purulent
localized inflammation
of the renal pelvis
(collecting system) and kidney. The renal parenchyma
presents in the interstitium abscesses (suppurative necrosis
), consisting in purulent exudate (pus): neutrophils, fibrin, cell debris and central germ colonies (hematoxylinophils). Tubules are damaged by exudate and may contain neutrophil casts. In the early stages, the glomerulus
and vessels are normal. Gross pathology often reveals pathognomonic radiations of bleeding
and suppuration
through the renal pelvis to the renal cortex
.
of the renal parenchyma and impaired function, especially in the setting of obstruction. A perinephric abscess
(infection around the kidney) and/or pyonephrosis may develop in severe cases of pyelonephritis.
tous abscess
formation, severe kidney destruction, and a clinical picture that may resemble renal cell carcinoma
and other inflammatory renal parenchymal
diseases. Most patients present with recurrent fevers and urosepsis, anemia
, and a painful renal mass. Other common manifestations include kidney stones and loss of function of the affected kidney. Bacterial cultures of renal tissue are almost always positive. Microscopically
, there are granulomas and lipid
-laden macrophage
s (hence the term xantho-, which means yellow in ancient Greek
). It is found in roughly 20% of specimens from surgically managed cases of pyelonephritis.
test is performed, and initial therapy is tailored on the basis of the infecting organism. As most cases of pyelonephritis are due to bacterial infections, antibiotics are the mainstay of treatment. The choice of antibiotic depends on the species and antibiotic sensitivity profile of the infecting organism, and may include fluoroquinolones
, cephalosporin
s, aminoglycoside
s, or trimethoprim/sulfamethoxazole, either alone or in combination.
In patients not requiring hospitalization where there is a low prevalence of antibiotic-resistant
bacteria, an oral fluoroquinolone such as ciprofloxacin
or levofloxacin
is an appropriate initial choice for therapy. In areas where there is a higher prevalence of fluoroquinolone resistance, it is useful to initiate treatment with a single intravenous dose of a long-acting antibiotic such as ceftriaxone
or an aminoglycoside, and then continuing treatment with an oral fluoroquinolone. Oral trimethoprim/sulfamethoxazole is an appropriate choice for therapy if the uropathogen is known to be susceptible. If trimethoprim/sulfamethoxazole is used when the susceptibility is not known, it is useful to initiate treatment with a single intravenous dose of a long-acting antibiotic such as ceftriaxone or an aminoglycoside. Oral beta-lactam antibiotic
s are less effective than other available agents for treatment of pyelonephritis.
People with acute pyelonephritis that is accompanied by high fever and leukocytosis
are typically admitted to the hospital for intravenous hydration and intravenous antibiotic treatment. Treatment is typically initiated with an intravenous fluoroquinolone, an aminoglycoside, an extended-spectrum penicillin
or cephalosporin, or a carbapenem
. Combination antibiotic therapy is often used in such situations. The treatment regimen is selected based on local resistance data and the susceptibility profile of the specific infecting organism(s).
During the course of antibiotic treatment, serial white blood cell count and temperature are closely monitored. Typically, the intravenous antibiotics are continued until the patient is afebrile for at least 24 to 48 hours, then equivalent oral antibiotic agents can be given for a total of 2–week duration of treatment. Intravenous fluids may be administered to compensate for the reduced oral intake, insensible losses (due to the raised temperature) and vasodilation
and to optimize urine output. Percutaneous nephrostomy
or ureteral stent placement may be indicated to relieve obstruction caused by a stone. Children with acute pyelonephritis can be treated effectively with oral antibiotics (cefixime
, ceftibuten
and amoxycillin/clavulanic acid) or with short courses (2 to 4 days) of intravenous therapy followed by oral therapy. If intravenous therapy is chosen, single daily dosing with aminoglycosides is safe and effective.
Treatment of xanthogranulomatous pyelonephritis involves antibiotics as well as surgery. Nephrectomy is the best surgical treatment in the overwhelming majority of cases, although polar resection (partial nephrectomy) has been effective for some people with localized disease. Watchful waiting
with serial imaging may be appropriate in rare circumstances.
(prophylactic) treatment with antibiotics, either daily or after sexual activity. In children at risk for recurrent urinary tract infections, meta-analysis
of the existing literature indicates that not enough studies have been performed to conclude prescription of long-term antibiotics have a net positive benefit. Ingestion of cranberry juice
has been studied as a prophylactic measure; while studies are inconclusive, many suggest a benefit. Increasing fluid intake, consuming cranberry juice, blueberry
juice, and fermented milk products containing probiotic
bacteria have all been shown to inhibit adherence of bacteria to the epithelial cells
of the urinary tract, and may reduce the recurrence rate of urinary tract infections.
of pyelonephritis is roughly 12–13 cases annually per 10,000 population in women receiving outpatient treatment and 3–4 requiring admission. In men, 2–3 per 10,000 are treated as outpatients and 1–2/10,000 require admission. Young women are most often affected, probably reflecting sexual activity in that age group. Infants and the elderly are also at increased risk, reflecting anatomical changes and hormonal status. Xanthogranulomatous pyelonephritis is most common in middle-aged women. It can present somewhat differently in children, in whom it may be mistaken for Wilms' tumor
.
Urinary tract infection
A urinary tract infection is a bacterial infection that affects any part of the urinary tract. Symptoms include frequent feeling and/or need to urinate, pain during urination, and cloudy urine. The main causal agent is Escherichia coli...
that has reached the pyelum or pelvis of the kidney. It is a form of nephritis
Nephritis
Nephritis is inflammation of the nephrons in the kidneys. The word "nephritis" was imported from Latin, which took it from Greek: νεφρίτιδα. The word comes from the Greek νεφρός - nephro- meaning "of the kidney" and -itis meaning "inflammation"....
that is also referred to as pyelitis. Severe cases of pyelonephritis can lead to pyonephrosis
Pyonephrosis
Pyonephrosis is an infection of the renal collecting system. Pus collects in the renal pelvis and causes distension of the kidney.It can cause kidney failure.-Causes:...
(pus accumulation around the kidney), urosepsis
Sepsis
Sepsis is a potentially deadly medical condition that is characterized by a whole-body inflammatory state and the presence of a known or suspected infection. The body may develop this inflammatory response by the immune system to microbes in the blood, urine, lungs, skin, or other tissues...
(a systemic inflammatory response
Systemic inflammatory response syndrome
Systemic inflammatory response syndrome is an inflammatory state affecting the whole body, frequently a response of the immune system to infection, but not necessarily so...
of the body to infection), kidney failure and even death.
Pyelonephritis presents with fever
Fever
Fever is a common medical sign characterized by an elevation of temperature above the normal range of due to an increase in the body temperature regulatory set-point. This increase in set-point triggers increased muscle tone and shivering.As a person's temperature increases, there is, in...
, accelerated heart rate
Tachycardia
Tachycardia comes from the Greek words tachys and kardia . Tachycardia typically refers to a heart rate that exceeds the normal range for a resting heart rate...
, painful urination
Dysuria
In medicine, specifically urology, dysuria refers to painful urination.Difficult urination is also sometimes described as dysuria.It is one of a constellation of irritative bladder symptoms, which includes urinary frequency and haematuria....
, abdominal pain radiating to the back
Renal colic
Renal colic is a type of abdominal pain commonly caused by kidney stones.-Presentation:The pain typically begins in the abdomen and often radiates to the hypochondrium or the groin. The pain is often colicky due to ureteric peristalsis, but may be constant...
, nausea
Nausea
Nausea , is a sensation of unease and discomfort in the upper stomach with an involuntary urge to vomit. It often, but not always, precedes vomiting...
, and tenderness at the costovertebral angle
Murphy's punch sign
Kidney punch or CVA Tenderness is elicited when gently tapping the area of the back overlying the kidneyproducing pain in people with an infection around the kidney or pyelonephritis or renal stone...
on the affected side. Pyelonephritis that has progressed to urosepsis may be accompanied by signs
Medical sign
A medical sign is an objective indication of some medical fact or characteristic that may be detected by a physician during a physical examination of a patient....
of septic shock
Septic shock
Septic shock is a medical emergency caused by decreased tissue perfusion and oxygen delivery as a result of severe infection and sepsis, though the microbe may be systemic or localized to a particular site. It can cause multiple organ dysfunction syndrome and death...
, including rapid breathing
Tachypnea
Tachypnea means rapid breathing. Any rate between 12-20 breaths per minute is normal. Tachypnea is a respiration rate greater than 20 breaths per minute. - Distinction from other breathing terms :...
, decreased blood pressure
Hypotension
In physiology and medicine, hypotension is abnormally low blood pressure, especially in the arteries of the systemic circulation. It is best understood as a physiologic state, rather than a disease. It is often associated with shock, though not necessarily indicative of it. Hypotension is the...
, violent shivering, and occasionally delirium
Delirium
Delirium or acute confusional state is a common and severe neuropsychiatric syndrome with core features of acute onset and fluctuating course, attentional deficits and generalized severe disorganization of behavior...
. Pyelonephritis requires antibiotic therapy, and sometimes surgical intervention such as ureteroscopy
Ureteroscopy
Ureteroscopy is an examination of the upper urinary tract, usually performed with an endoscope that is passed through the urethra, bladder, and then directly into the ureter...
, percutaneous
Percutaneous
In surgery, percutaneous pertains to any medical procedure where access to inner organs or other tissue is done via needle-puncture of the skin, rather than by using an "open" approach where inner organs or tissue are exposed .The percutaneous approach is commonly used in vascular procedures...
nephrostomy
Nephrostomy
A nephrostomy is an artificial opening created between the kidney and the skin which allows for the urinary diversion directly from the upper part of the urinary system ....
or percutaneous nephrolithotomy
Percutaneous nephrolithotomy
Percutaneous nephrolithotomy is a surgical procedure to remove stones from the kidney by a small puncture wound through the skin. It is most suitable to remove stones of more than 2 cm in size. It is usually done under general anesthesia or spinal anesthesia.- Procedure :A Retrograde pyelogram is...
, as well as treatment of any underlying causes to prevent its recurrence. Xanthogranulomatous pyelonephritis is a rare form of chronic
Chronic (medicine)
A chronic disease is a disease or other human health condition that is persistent or long-lasting in nature. The term chronic is usually applied when the course of the disease lasts for more than three months. Common chronic diseases include asthma, cancer, diabetes and HIV/AIDS.In medicine, the...
pyelonephritis in which nephrectomy
Nephrectomy
Nephrectomy is the surgical removal of a kidney.-History:The first successful nephrectomy was performed by the German surgeon Gustav Simon on August 2, 1869 in Heidelberg. Simon practiced the operation beforehand in animal experiments...
(removal of the kidney) is usually necessary for definitive treatment.
Signs and symptoms
Symptoms of acute pyelonephritis generally develop rapidly over a few hours or a day. It can cause high fever, pain on passing urine, and abdominal pain that radiates along the flank towards the back. There is often associated vomitingVomiting
Vomiting is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose...
.
Chronic pyelonephritis causes persistent flank or abdominal pain, signs of infection (fever, unintentional weight loss, malaise
Malaise
Malaise is a feeling of general discomfort or uneasiness, of being "out of sorts", often the first indication of an infection or other disease. Malaise is often defined in medicinal research as a "general feeling of being unwell"...
, decreased appetite
Anorexia (symptom)
Anorexia is the decreased sensation of appetite...
), lower urinary tract symptoms
Lower urinary tract symptoms
Lower urinary tract symptoms are a common problem affecting approximately 40% of older men. LUTS is a recent term for what used to be known as prostatism.-Voiding or obstructive symptoms:*Poor stream*Hesitancy*Terminal dribbling...
and blood in the urine
Hematuria
In medicine, hematuria, or haematuria, is the presence of red blood cells in the urine. It may be idiopathic and/or benign, or it can be a sign that there is a kidney stone or a tumor in the urinary tract , ranging from trivial to lethal...
. Chronic pyelonephritis can in addition cause fever of unknown origin
Fever of unknown origin
Fever of unknown origin , pyrexia of unknown origin or febris e causa ignota refers to a condition in which the patient has an elevated temperature but despite investigations by a physician no explanation has been found....
. Furthermore, inflammation-related proteins can accumulate in organs and cause the condition AA amyloidosis
AA amyloidosis
AA amyloidosis is a form of amyloidosis associated with serum amyloid A protein , an acute-phase protein. It causes reactive systemic amyloidosis, as a "reaction" to inflammation, but also familial Mediterranean fever, which is an inheritable condition.-Presentation:The common feature to conditions...
.
Physical examination may reveal fever and tenderness at the costovertebral angle on the affected side.
Causes
Most cases of "community-acquired" pyelonephritis are due to bowel organisms that enter the urinary tract. Common organisms are E. coliEscherichia coli
Escherichia coli is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms . Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans, and are occasionally responsible for product recalls...
(70–80%) and Enterococcus faecalis
Enterococcus faecalis
Enterococcus faecalis – formerly classified as part of the Group D Streptococcus system – is a Gram-positive, commensal bacterium inhabiting the gastrointestinal tracts of humans and other mammals. It is among the main constituents of some probiotic food supplements. Like other species in the genus...
. Hospital-acquired infections
Nosocomial infection
A nosocomial infection , also known as a hospital-acquired infection or HAI, is an infection whose development is favoured by a hospital environment, such as one acquired by a patient during a hospital visit or one developing among hospital staff...
may be due to coliform bacteria
Coliform bacteria
Coliform bacteria are a commonly used bacterial indicator of sanitary quality of foods and water. They are defined as rod-shaped Gram-negative non-spore forming bacteria which can ferment lactose with the production of acid and gas when incubated at 35-37°C...
and enterococci, as well as other organisms uncommon in the community (e.g. Pseudomonas aeruginosa
Pseudomonas aeruginosa
Pseudomonas aeruginosa is a common bacterium that can cause disease in animals, including humans. It is found in soil, water, skin flora, and most man-made environments throughout the world. It thrives not only in normal atmospheres, but also in hypoxic atmospheres, and has, thus, colonized many...
and various species of Klebsiella
Klebsiella
Klebsiella is a genus of non-motile, Gram-negative, oxidase-negative, rod-shaped bacteria with a prominent polysaccharide-based capsule. It is named after the German microbiologist Edwin Klebs...
). Most cases of pyelonephritis start off as lower urinary tract infections, mainly cystitis
Cystitis
Cystitis is a term that refers to urinary bladder inflammation that results from any one of a number of distinct syndromes. It is most commonly caused by a bacterial infection in which case it is referred to as a urinary tract infection.-Signs and symptoms:...
and prostatitis
Prostatitis
Prostatitis is an inflammation of the prostate gland, in men. A prostatitis diagnosis is assigned at 8% of all urologist and 1% of all primary care physician visits in the United States.-Classification:...
. E. coli can invade the superficial umbrella cells of the bladder to form intracellular bacterial communities (IBCs), which can mature into biofilm
Biofilm
A biofilm is an aggregate of microorganisms in which cells adhere to each other on a surface. These adherent cells are frequently embedded within a self-produced matrix of extracellular polymeric substance...
s. These biofilm-producing E. coli are resistant to antibiotic therapy and immune system responses, and present a possible explanation for recurrent urinary tract infections, including pyelonephritis. Risk is increased in the following situations:
- Mechanical: any structural abnormalities in the urinary tract, vesicoureteral refluxVesicoureteral refluxVesicoureteral reflux is an abnormal movement of urine from the bladder into ureters or kidneys. Urine normally travels from the kidneys via the ureters to the bladder...
(urine from the bladder flowing back into the ureterUreterIn human anatomy, the ureters are muscular tubes that propel urine from the kidneys to the urinary bladder. In the adult, the ureters are usually long and ~3-4 mm in diameter....
), kidney stoneKidney stoneA kidney stone, also known as a renal calculus is a solid concretion or crystal aggregation formed in the kidneys from dietary minerals in the urine...
s, urinary tract catheterizationUrinary catheterizationIn urinary catheterization , a latex, polyurethane or silicone tube known as a urinary catheter is inserted into a patient's bladder via his or her urethra. Catheterization allows the patient's urine to drain freely from the bladder for collection. It may be used to inject liquids used for...
, ureteral stentsUreteric stentA ureteral stent, sometimes as well called ureteric stent, is a thin tube inserted into the ureter to prevent or treat obstruction of the urine flow from the kidney. The length of the stents used in adult patients varies between 24 to 30 cm. Additionally, stents come in differing diameters or...
or drainage procedures (e.g. nephrostomyNephrostomyA nephrostomy is an artificial opening created between the kidney and the skin which allows for the urinary diversion directly from the upper part of the urinary system ....
), pregnancyPregnancyPregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...
, neurogenic bladderNeurogenic bladderNeurogenic bladder refers to dysfunction of the urinary bladder due to disease of the central nervous system or peripheral nerves involved in the control of micturition .-Causes:...
(e.g. due to spinal cord damage, spina bifidaSpina bifidaSpina bifida is a developmental congenital disorder caused by the incomplete closing of the embryonic neural tube. Some vertebrae overlying the spinal cord are not fully formed and remain unfused and open. If the opening is large enough, this allows a portion of the spinal cord to protrude through...
or multiple sclerosisMultiple sclerosisMultiple sclerosis is an inflammatory disease in which the fatty myelin sheaths around the axons of the brain and spinal cord are damaged, leading to demyelination and scarring as well as a broad spectrum of signs and symptoms...
) and prostateProstateThe prostate is a compound tubuloalveolar exocrine gland of the male reproductive system in most mammals....
disease (e.g. benign prostatic hyperplasiaBenign prostatic hyperplasiaBenign prostatic hyperplasia also known as benign prostatic hypertrophy , benign enlargement of the prostate , and adenofibromyomatous hyperplasia, refers to the increase in size of the prostate....
) in men - Constitutional: diabetes mellitusDiabetes mellitusDiabetes mellitus, often simply referred to as diabetes, is a group of metabolic diseases in which a person has high blood sugar, either because the body does not produce enough insulin, or because cells do not respond to the insulin that is produced...
, immunocompromisedImmunodeficiencyImmunodeficiency is a state in which the immune system's ability to fight infectious disease is compromised or entirely absent. Immunodeficiency may also decrease cancer immunosurveillance. Most cases of immunodeficiency are acquired but some people are born with defects in their immune system,...
states - Behavioral: change in sexual partner within the last year, spermicideSpermicideSpermicide is a contraceptive substance that eradicates sperm, inserted vaginally prior to intercourse to prevent pregnancy. As a contraceptive, spermicide may be used alone. However, the pregnancy rate experienced by couples using only spermicide is higher than that of couples using other methods...
use - Positive family historyFamily historyFamily history is the systematic narrative and research of past events relating to a specific family, or specific families.- Introduction :...
(close family members with frequent urinary tract infections)
Laboratory examination
UrinalysisUrinalysis
A urinalysis , also known as Routine and Microscopy , is an array of tests performed on urine, and one of the most common methods of medical diagnosis...
may show signs of urinary tract infection. Specifically, the presence of nitrite
Nitrite test
A nitrite test is a chemical test used to determine the presence of nitrite ion in solution.-Chemical method:A common nitrite test can be performed by adding 4 M sulfuric acid to the sample until acidic, and then adding 0.1 M iron sulfate to the solution...
and white blood cell
White blood cell
White blood cells, or leukocytes , are cells of the immune system involved in defending the body against both infectious disease and foreign materials. Five different and diverse types of leukocytes exist, but they are all produced and derived from a multipotent cell in the bone marrow known as a...
s on a urine test strip
Urine test strip
A urine test strip or dipstick is a basic diagnostic instrument used to determine pathological changes in the urine in standard urinalysis. A standard urine test strip may comprise up to 10 different chemical pads or reagents which react when immersed in, and then removed from, a urine sample....
in patients with typical symptoms are sufficient for the diagnosis of pyelonephritis, and are an indication for empirical treatment
Empirical treatment
Empirical treatment is a medical treatment not derived from the scientific method, but derived from observation, survey or common use.In the medical profession, the term is also used when treatment is started before a diagnosis is confirmed The most common reason is that investigations are...
. Blood test
Blood test
A blood test is a laboratory analysis performed on a blood sample that is usually extracted from a vein in the arm using a needle, or via fingerprick....
s such as a complete blood count
Complete blood count
A complete blood count , also known as full blood count or full blood exam or blood panel, is a test panel requested by a doctor or other medical professional that gives information about the cells in a patient's blood...
may show neutrophilia
Neutrophilia
Neutrophilia is a condition where a person has a high number of neutrophil granulocytes in their blood.-Causes:...
. Microbiological culture
Microbiological culture
A microbiological culture, or microbial culture, is a method of multiplying microbial organisms by letting them reproduce in predetermined culture media under controlled laboratory conditions. Microbial cultures are used to determine the type of organism, its abundance in the sample being tested,...
of the urine, with or without blood culture
Blood culture
Blood culture is a microbiological culture of blood. It is employed to detect infections that are spreading through the bloodstream...
s and antibiotic sensitivity testing
Kirby-Bauer antibiotic testing
Kirby-Bauer antibiotic testing is a test which uses antibiotic-impregnated wafers to test whether particular bacteria are susceptible to specific antibiotics. A known quantity of bacteria are grown on agar plates in the presence of thin wafers containing relevant antibiotics...
are useful for establishing a formal diagnosis.
Imaging studies
If a kidney stone is suspected (e.g. on the basis of characteristic colicky painRenal colic
Renal colic is a type of abdominal pain commonly caused by kidney stones.-Presentation:The pain typically begins in the abdomen and often radiates to the hypochondrium or the groin. The pain is often colicky due to ureteric peristalsis, but may be constant...
or the presence of a disproportionate amount of blood in the urine), a kidneys, ureters, and bladder x-ray (KUB film) may assist in identifying radioopaque
Radiodensity
Radiodensity refers to the relative inability of electromagnetic radiation, particularly X-rays, to pass through a particular material. Radiolucency indicates greater transparency or "transradiancy" to X-ray photons...
stones. Where available, a noncontrast helical CT scan
Helical cone beam computed tomography
Spiral computed tomography is a computed tomography, technology involving movement in a spiral pattern for the purpose of increasing resolution...
with 5 millimeter sections is the diagnostic modality of choice in the radiographic evaluation of suspected nephrolithiasis. All stones are detectable on CT scans except very rare stones composed of certain drug residues in the urine. In patients with recurrent ascending urinary tract infections, it may be necessary to exclude an anatomical abnormality, such as vesicoureteral reflux or polycystic kidney disease
Polycystic kidney disease
Autosomal dominant polycystic kidney disease is an inherited systemic disorder that predominantly affects the kidneys, but may affect other organs including the liver, pancreas, brain, and arterial blood vessels...
. Investigations used in this setting include ultrasonography
Abdominal ultrasonography
Abdominal ultrasonography is a form of medical ultrasonography to visualise abdominal anatomical structures...
of the kidneys or voiding cystourethrography
Voiding cystourethrogram
In urology, a voiding cystourethrogram , also micturating cystourethrogram , is a technique for watching a person's urethra and urinary bladder while the person urinates . The technique consists of catheterizing the person in order to fill the bladder with a radiocontrast agent, typically cystografin...
. CT scan or abdominal ultrasonography is useful in the diagnosis of xanthogranulomatous pyelonephritis; serial imaging may be useful for differentiating this condition from kidney cancer.
Acute pyelonephritis
Acute pyelonephritis is an exudativeExudate
An exudate is any fluid that filters from the circulatory system into lesions or areas of inflammation. It can apply to plants as well as animals. Its composition varies but generally includes water and the dissolved solutes of the main circulatory fluid such as sap or blood...
purulent
Pus
Pus is a viscous exudate, typically whitish-yellow, yellow, or yellow-brown, formed at the site of inflammatory during infection. An accumulation of pus in an enclosed tissue space is known as an abscess, whereas a visible collection of pus within or beneath the epidermis is known as a pustule or...
localized inflammation
Inflammation
Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...
of the renal pelvis
Renal pelvis
The renal pelvis or pyelum is the funnel-like dilated proximal part of the ureter in the kidney.In humans, the renal pelvis is the point of convergence of two or three major calyces...
(collecting system) and kidney. The renal parenchyma
Nephron
The renal tubule is the portion of the nephron containing the tubular fluid filtered through the glomerulus. After passing through the renal tubule, the filtrate continues to the collecting duct system, which is not part of the nephron....
presents in the interstitium abscesses (suppurative necrosis
Necrosis
Necrosis is the premature death of cells in living tissue. Necrosis is caused by factors external to the cell or tissue, such as infection, toxins, or trauma. This is in contrast to apoptosis, which is a naturally occurring cause of cellular death...
), consisting in purulent exudate (pus): neutrophils, fibrin, cell debris and central germ colonies (hematoxylinophils). Tubules are damaged by exudate and may contain neutrophil casts. In the early stages, the glomerulus
Glomerulus
A glomerulus is a capillary tuft that is involved in the first step of filtering blood to form urine.A glomerulus is surrounded by Bowman's capsule, the beginning component of nephrons in the vertebrate kidney. A glomerulus receives its blood supply from an afferent arteriole of the renal...
and vessels are normal. Gross pathology often reveals pathognomonic radiations of bleeding
Bleeding
Bleeding, technically known as hemorrhaging or haemorrhaging is the loss of blood or blood escape from the circulatory system...
and suppuration
Pus
Pus is a viscous exudate, typically whitish-yellow, yellow, or yellow-brown, formed at the site of inflammatory during infection. An accumulation of pus in an enclosed tissue space is known as an abscess, whereas a visible collection of pus within or beneath the epidermis is known as a pustule or...
through the renal pelvis to the renal cortex
Renal cortex
The renal cortex is the outer portion of the kidney between the renal capsule and the renal medulla. In the adult, it forms a continuous smooth outer zone with a number of projections that extend down between the pyramids. It contains the renal corpuscles and the renal tubules except for parts of...
.
Chronic pyelonephritis
Chronic pyelonephritis implies recurrent kidney infections, and can result in scarringFibrosis
Fibrosis is the formation of excess fibrous connective tissue in an organ or tissue in a reparative or reactive process. This is as opposed to formation of fibrous tissue as a normal constituent of an organ or tissue...
of the renal parenchyma and impaired function, especially in the setting of obstruction. A perinephric abscess
Abscess
An abscess is a collection of pus that has accumulated in a cavity formed by the tissue in which the pus resides due to an infectious process or other foreign materials...
(infection around the kidney) and/or pyonephrosis may develop in severe cases of pyelonephritis.
Xanthogranulomatous pyelonephritis
Xanthogranulomatous pyelonephritis is an unusual form of chronic pyelonephritis characterized by granulomaGranuloma
Granuloma is a medical term for a tiny collection of immune cells known as macrophages. Granulomas form when the immune system attempts to wall off substances that it perceives as foreign but is unable to eliminate. Such substances include infectious organisms such as bacteria and fungi as well as...
tous abscess
Abscess
An abscess is a collection of pus that has accumulated in a cavity formed by the tissue in which the pus resides due to an infectious process or other foreign materials...
formation, severe kidney destruction, and a clinical picture that may resemble renal cell carcinoma
Renal cell carcinoma
Renal cell carcinoma is a kidney cancer that originates in the lining of the proximal convoluted tubule, the very small tubes in the kidney that filter the blood and remove waste products. RCC is the most common type of kidney cancer in adults, responsible for approximately 80% of cases...
and other inflammatory renal parenchymal
Nephron
The renal tubule is the portion of the nephron containing the tubular fluid filtered through the glomerulus. After passing through the renal tubule, the filtrate continues to the collecting duct system, which is not part of the nephron....
diseases. Most patients present with recurrent fevers and urosepsis, anemia
Anemia
Anemia is a decrease in number of red blood cells or less than the normal quantity of hemoglobin in the blood. However, it can include decreased oxygen-binding ability of each hemoglobin molecule due to deformity or lack in numerical development as in some other types of hemoglobin...
, and a painful renal mass. Other common manifestations include kidney stones and loss of function of the affected kidney. Bacterial cultures of renal tissue are almost always positive. Microscopically
Histopathology
Histopathology refers to the microscopic examination of tissue in order to study the manifestations of disease...
, there are granulomas and lipid
Lipid
Lipids constitute a broad group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins , monoglycerides, diglycerides, triglycerides, phospholipids, and others...
-laden macrophage
Macrophage
Macrophages are cells produced by the differentiation of monocytes in tissues. Human macrophages are about in diameter. Monocytes and macrophages are phagocytes. Macrophages function in both non-specific defense as well as help initiate specific defense mechanisms of vertebrate animals...
s (hence the term xantho-, which means yellow in ancient Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
). It is found in roughly 20% of specimens from surgically managed cases of pyelonephritis.
Management
In patients suspected of having pyelonephritis, a urine culture and antibiotic sensitivityAntibiotic sensitivity
Antibiotic sensitivity is a term used to describe the susceptibility of bacteria to antibiotics. Antibiotic susceptibility testing is usually carried out to determine which antibiotic will be most successful in treating a bacterial infection in vivo. Testing for antibiotic sensitivity is often...
test is performed, and initial therapy is tailored on the basis of the infecting organism. As most cases of pyelonephritis are due to bacterial infections, antibiotics are the mainstay of treatment. The choice of antibiotic depends on the species and antibiotic sensitivity profile of the infecting organism, and may include fluoroquinolones
Quinolone
The quinolones are a family of synthetic broad-spectrum antibiotics. The term quinolone refers to potent synthetic chemotherapeutic antibacterials....
, cephalosporin
Cephalosporin
The cephalosporins are a class of β-lactam antibiotics originally derived from Acremonium, which was previously known as "Cephalosporium".Together with cephamycins they constitute a subgroup of β-lactam antibiotics called cephems.-Medical use:...
s, aminoglycoside
Aminoglycoside
An aminoglycoside is a molecule or a portion of a molecule composed of amino-modifiedsugars.Several aminoglycosides function as antibiotics that are effective against certain types of bacteria...
s, or trimethoprim/sulfamethoxazole, either alone or in combination.
In patients not requiring hospitalization where there is a low prevalence of antibiotic-resistant
Antibiotic resistance
Antibiotic resistance is a type of drug resistance where a microorganism is able to survive exposure to an antibiotic. While a spontaneous or induced genetic mutation in bacteria may confer resistance to antimicrobial drugs, genes that confer resistance can be transferred between bacteria in a...
bacteria, an oral fluoroquinolone such as ciprofloxacin
Ciprofloxacin
Ciprofloxacin is a synthetic chemotherapeutic antibiotic of the fluoroquinolone drug class.It is a second-generation fluoroquinolone antibacterial. It kills bacteria by interfering with the enzymes that cause DNA to rewind after being copied, which stops synthesis of DNA and of...
or levofloxacin
Levofloxacin
Levofloxacin is a synthetic chemotherapeutic antibiotic of the fluoroquinolone drug class and is used to treat severe or life-threatening bacterial infections or bacterial infections that have failed to respond to other antibiotic classes. It is sold under various brand names, such as Levaquin and...
is an appropriate initial choice for therapy. In areas where there is a higher prevalence of fluoroquinolone resistance, it is useful to initiate treatment with a single intravenous dose of a long-acting antibiotic such as ceftriaxone
Ceftriaxone
Ceftriaxone is a third-generation cephalosporin antibiotic. Like other third-generation cephalosporins, it has broad spectrum activity against Gram-positive and Gram-negative bacteria. In most cases, it is considered to be equivalent to cefotaxime in terms of safety and efficacy...
or an aminoglycoside, and then continuing treatment with an oral fluoroquinolone. Oral trimethoprim/sulfamethoxazole is an appropriate choice for therapy if the uropathogen is known to be susceptible. If trimethoprim/sulfamethoxazole is used when the susceptibility is not known, it is useful to initiate treatment with a single intravenous dose of a long-acting antibiotic such as ceftriaxone or an aminoglycoside. Oral beta-lactam antibiotic
Beta-lactam antibiotic
β-Lactam antibiotics are a broad class of antibiotics, consisting of all antibiotic agents that contains a β-lactam nucleus in its molecular structure. This includes penicillin derivatives , cephalosporins , monobactams, and carbapenems...
s are less effective than other available agents for treatment of pyelonephritis.
People with acute pyelonephritis that is accompanied by high fever and leukocytosis
Leukocytosis
Leukocytosis is a raised white blood cell count above the normal range in the blood. It is frequently a sign of an inflammatory response, most commonly the result of infection, and is observed in certain parasitic infections...
are typically admitted to the hospital for intravenous hydration and intravenous antibiotic treatment. Treatment is typically initiated with an intravenous fluoroquinolone, an aminoglycoside, an extended-spectrum penicillin
Extended-spectrum penicillin
Extended-spectrum penicillin is a group of antibiotics that has the widest antibacterial spectrum of all penicillins. It is also called antipseudomonal penicillins...
or cephalosporin, or a carbapenem
Carbapenem
Carbapenems are a class of β-lactam antibiotics with a broad spectrum of antibacterial activity. They have a structure that renders them highly resistant to most β-lactamases...
. Combination antibiotic therapy is often used in such situations. The treatment regimen is selected based on local resistance data and the susceptibility profile of the specific infecting organism(s).
During the course of antibiotic treatment, serial white blood cell count and temperature are closely monitored. Typically, the intravenous antibiotics are continued until the patient is afebrile for at least 24 to 48 hours, then equivalent oral antibiotic agents can be given for a total of 2–week duration of treatment. Intravenous fluids may be administered to compensate for the reduced oral intake, insensible losses (due to the raised temperature) and vasodilation
Vasodilation
Vasodilation refers to the widening of blood vessels resulting from relaxation of smooth muscle cells within the vessel walls, particularly in the large arteries, smaller arterioles and large veins. The process is essentially the opposite of vasoconstriction, or the narrowing of blood vessels. When...
and to optimize urine output. Percutaneous nephrostomy
Percutaneous nephrostomy
Percutaneous nephrostomy is a surgical procedure in which the renal pelvis is punctured whilst using imaging as guidance. Images are obtained once an antegrade pyelogram , with a fine needle, has been performed. This contrast is used to show calcifications at the renal pelvis. A nephrostomy tube...
or ureteral stent placement may be indicated to relieve obstruction caused by a stone. Children with acute pyelonephritis can be treated effectively with oral antibiotics (cefixime
Cefixime
Cefixime is an oral third generation cephalosporin antibiotic. Cefixime is a cephalosporin antibiotic used to treat infections caused by bacteria such as pneumonia; bronchitis; gonorrhea; and ear, lung, throat, and urinary tract infections...
, ceftibuten
Ceftibuten
Ceftibuten is a third-generation cephalosporin antibiotic. It is an orally-administered agent, with 2 dosage forms, capsule or oral suspension. It is marketed by Pernix Therapeutics under the trade name Cedax....
and amoxycillin/clavulanic acid) or with short courses (2 to 4 days) of intravenous therapy followed by oral therapy. If intravenous therapy is chosen, single daily dosing with aminoglycosides is safe and effective.
Treatment of xanthogranulomatous pyelonephritis involves antibiotics as well as surgery. Nephrectomy is the best surgical treatment in the overwhelming majority of cases, although polar resection (partial nephrectomy) has been effective for some people with localized disease. Watchful waiting
Watchful waiting
Watchful waiting is an approach to a medical problem in which time is allowed to pass before medical intervention or therapy is used. During this time, repeated testing may be performed....
with serial imaging may be appropriate in rare circumstances.
Prevention
In people who experience recurrent urinary tract infections, additional investigations may identify an underlying abnormality. Occasionally, surgical intervention is necessary to reduce the likelihood of recurrence. If no abnormality is identified, some studies suggest long-term preventivePreventive medicine
Preventive medicine or preventive care refers to measures taken to prevent diseases, rather than curing them or treating their symptoms...
(prophylactic) treatment with antibiotics, either daily or after sexual activity. In children at risk for recurrent urinary tract infections, meta-analysis
Meta-analysis
In statistics, a meta-analysis combines the results of several studies that address a set of related research hypotheses. In its simplest form, this is normally by identification of a common measure of effect size, for which a weighted average might be the output of a meta-analyses. Here the...
of the existing literature indicates that not enough studies have been performed to conclude prescription of long-term antibiotics have a net positive benefit. Ingestion of cranberry juice
Cranberry juice
Cranberry juice is the juice of the cranberry. Commercially, it is sold in either as a pure juice, which is quite tart, or, more commonly, as cranberry juice "cocktail" or "drink" , in blends with other juices, such as apple or grape, or mixed with water and corn syrup, sugar, or an artificial...
has been studied as a prophylactic measure; while studies are inconclusive, many suggest a benefit. Increasing fluid intake, consuming cranberry juice, blueberry
Blueberry
Blueberries are flowering plants of the genus Vaccinium with dark-blue berries and are perennial...
juice, and fermented milk products containing probiotic
Probiotic
Probiotics are live microorganisms thought to be beneficial to the host organism. According to the currently adopted definition by FAO/WHO, probiotics are: "Live microorganisms which when administered in adequate amounts confer a health benefit on the host"...
bacteria have all been shown to inhibit adherence of bacteria to the epithelial cells
Urothelium
The urothelium is a form of transitional epithelial tissue layer that lines much of the urinary tract, including the renal pelvis, the ureters, the bladder, and parts of the urethra.-Structure and function:...
of the urinary tract, and may reduce the recurrence rate of urinary tract infections.
Epidemiology
The incidenceIncidence (epidemiology)
Incidence is a measure of the risk of developing some new condition within a specified period of time. Although sometimes loosely expressed simply as the number of new cases during some time period, it is better expressed as a proportion or a rate with a denominator.Incidence proportion is the...
of pyelonephritis is roughly 12–13 cases annually per 10,000 population in women receiving outpatient treatment and 3–4 requiring admission. In men, 2–3 per 10,000 are treated as outpatients and 1–2/10,000 require admission. Young women are most often affected, probably reflecting sexual activity in that age group. Infants and the elderly are also at increased risk, reflecting anatomical changes and hormonal status. Xanthogranulomatous pyelonephritis is most common in middle-aged women. It can present somewhat differently in children, in whom it may be mistaken for Wilms' tumor
Wilms' tumor
Wilms' tumor or nephroblastoma is cancer of the kidneys that typically occurs in children, rarely in adults.Its common name is an eponym, referring to Dr. Max Wilms, the German surgeon who first described this kind of tumor....
.