In pyelonephritis (PN) – colloquially called renal pelvic inflammation – (synonyms: Renal pelvic infection; Renal pelvic infection, acute; PN; Pyelitis, acute; ICD-10 N10: Acute tubulointerstitial nephritis) is a purulent infection of the renal pelvis involving the renal parenchyma (kidney tissue).
Pyelonephritis (= upper urinary tract infection, UTI) should be assumed if acute symptoms, e.g., flank pain, a palpitating renal bed and/or fever (> 38 °C) are found.
Pyelonephritis is one of the common infectious diseases and in most cases is caused by Escherichia coli (gram-negative rods from the intestinal flora). Cocci (gram-positive), Proteus and Klebsiella can also lead to pyelonephritis.
Urinary tract infections (UTI), Clostridioides difficile infections (CDI), pneumonia/pneumonia (HAP), primary bloodstream infections (BSI), and surgical infections (SSI) account for approximately 80% of all hospital infections (nosocomial infections).
The following forms of pyelonephritis (PN) are distinguished:
- Acute pyelonephritis (aPN).
- Chronic pyelonephritis (cPN) – chronic episodic inflammatory renal parenchymal destruction (destruction of kidney tissue); a precise definition of cPN does not exist.
Sex ratio: men to women is 1: 2. Since women have a shorter urethra (urethra), this favors the ascent of bacteria into the urinary bladder and from there into the renal pelvis.
Frequency peak: The disease often occurs in older men with benign prostatic hyperplasia (BPH, benign prostatic hyperplasia). Due to the enlarged prostate, residual urine remains in the bladder after urination, providing a good opportunity for germs to grow.In children, acute urinary tract infections (UTIs) occur in approximately 7% of girls and 2% of boys during the first 6 years of life. Furthermore, pyelonephritis occurs in 1-2% of pregnancies.
Epidemiologic studies in Holland indicate a 1-year prevalence (disease incidence) for pyelonephritis of 1.19 per 1,000 patients in the 65- to 74-year-old age group.
The incidence (frequency of new cases) in women is approximately 2.5 cases per 1,000 women per year and in men approximately 1 case per 1,000 men per year (in Germany).
Course and prognosis: Acute uncomplicated pyelonephritis (AUP) is one of the uncomplicated urinary tract infections (UTI). A UTI is classified as uncomplicated if there are no functional or anatomic abnormalities in the urinary tract, no renal dysfunction, and no concomitant diseases that favor the UTI. AUP is accompanied by high fever, severe flank pain (pain in the side), and nausea (nausea). It heals without sequelae with antibiotic therapy. Pyelonephritis may be recurrent (recurring). If urosepsis (blood poisoning caused by the kidneys) occurs, the disease is still potentially life-threatening despite modern antibiotic therapy. Rarely, acute pyelonephritis progresses to a chronic form.
