It is the acute infection of the renal pelvis or parenchyma.
Acute or chronic pyelonephritis usually occurs due to ascending infection; in uncomplicated cases, the aggressor organism is usually Escherichia coli (75%).
Severe variants of pyelonephritis are observed when there are factors that cause complications or stasis, calculations, alterations of immunity, structural defect, or diabetes, which are also known as complicated pyelonephritis.
Patients with chronic pyelonephritis have severe tissue infection and are at risk of bacteremia; these patients deserve admission for consultation and intensive parenteral antimicrobial treatment.
Patients with uncomplicated pyelonephritis can be treated as outpatients with 14 days of antibiotics to be given orally.
Patients with complicated pyelonephritis need urgent hospital treatment (i.e., people with coexisting diabetes, calculi, anterior pyelonephritis, known renal damage, known renal anatomical abnormalities, and pregnancy, these conditions are indications of hospitalization)
Causes of chronic pyelonephritis
Urinary tract infections ascending: 75% of cases of pyelonephritis are due to E. Coli bacteria, 10% and 15% are caused by other Gram-negative bacilli, Klebsiella, Proteus, Enterobacter, while others include Pseudomonas, Serratia, and Citrobacter.
Gram-positive agents include Enterococcus faecalis and, less frequently, anaerobes Staphylococcus aureus,
Agents such as fungi, especially Candida spp, are seen in immunocompromised patients and patients with diabetes.