Pielonefrite Flashcards
General findings
Urine pregnancy test in women of child-bearing age! Esegui CT scan se c’è il sospetto di ostruzione, ascesso o pielonefrite enfisematosa👓
Pyelonephritis is an infection of the renal pelvis and parenchyma that is usually associated with an ascending bacterial infection of the bladder. It occurs more commonly in women and risk factors include pregnancy and urinary tract obstruction. Patients typically present with flank pain, costovertebral angle tenderness, fever, and other features of cystitis (e.g., dysuria, frequency). Urinalysis shows pyuria and bacteriuria. Urine cultures should be taken in all patients before initiating treatment to identify the pathogen and possible antibiotic resistance. Early empiric antibiotic treatment is essential to avoid renal complications and urosepsis. Definitive treatment depends on the drug sensitivities of the causative pathogen and the patient’s clinical profile (e.g., possible comorbidities). See also urinary tract infections.
Risk factors
L’ostruzione delle vie urinarie, e quindi la calcolosi, sono tra le maggiori condizioni predisponenti una pielonefrite. La presenza di una nefrolitiasi o di una ostruzione rendono in automatico la pielonefrite in questione una forma complicata.
- Most common in women because they have shorter urethras
- Pregnancy
- Urinary tract obstruction
1. Foreign bodies (e.g., indwelling urinary catheters or other urologic instrumentation)
2. Anatomical abnormalities (e.g., benign prostatic hyperplasia, vesicoureteral reflux, nephrolithiasis, ureteral strictures) - Cystitis
- Recent administration of antibiotics (possible antibiotic resistance)
- Immunosuppression (e.g., HIV, diabetes mellitus)
- Acute kidney injury
Classification
1.Uncomplicated pyelonephritis: pyelonephritis in an immunocompetent, nonpregnant female with normal genitourinary anatomy and renal function
2.Complicated pyelonephritis: pyelonephritis associated with any of the following risk factors for complications:
-Failure of outpatient therapy
-Sepsis
-Male sex🧨
-Age > 60 years
-Urinary tract abnormalities (e.g., obstruction, indwelling catheter)
History of surgery to the urinary tract or kidneys
Hospital-acquired infection
Renal impairment
-History of nephrolithiasis
Immunosuppression and/or severe comorbidities (e.g., diabetes mellitus, chronic corticosteroid use)
Clinica
Fever 👓, chills
Flank pain
Costovertebral angle tenderness: pain upon percussion of the flank (usually unilateral, may be bilateral)
Dysuria as well as other symptoms of cystitis (e.g., frequency, urgency)
Weakness, nausea, vomiting (diarrhea may also be present)
Possible abdominal or pelvic pain
Analisi delle urine
Collect urine and blood cultures before administering empiric antibiotic therapy!👓
Nonspecific findings of UTI
- Pyuria (positive esterase on dipstick test)
- Leukocyturia (WBCs > 5/hpf)
- Bacteriuria
- Positive nitrites on dipstick test indicates infection with a urea-splitting organism.
- Hematuria (including microhematuria)
Other findings
-WBC casts: rare finding, but considered to be pathognomonic of pyelonephritis!!
-Urine pH of ≥ 7: associated with urea-splitting organisms.
-Epithelial cells > 5/hpf: suggests contamination.
Urine Gram stain: > 10/5 colony-forming units/mL suggests bacterial infection.
Urine culture
All patients!
Perform in all patients with suspected pyelonephritis to determine the pathogen and any associated drug resistance.
Blood colture
Attenzione: un aumento dell’azotemia o creatninemia può indicare AKI in atto o ostruzione!
Should be performed in all patients with suspected complicated pyelonephritis
Imaging: imaging is not routinely indicated in patients with suspected acute uncomplicated pyelonephritis.
CT abdomen with and without IV contrast💥GS in non pregnant women and others
Imaging serves to identify
- obstruction
- abscess
- emphysematous pyelonephritis
Consider in the following situations:
- Complicated pyelonephritis
- Sepsis or septic shock
- Known or suspected nephrolithiasis
- New decline in eGFR to < 40 (indica ostruzione)
- Recurrent pyelonephritis (To evaluate for underlying risk factors, e.g., congenital renal tract abnormalities or nephrolithiasis.)
- No response to therapy within 2 days
CT abdomen with and without IV contrast!
- Indications: Modality of choice in nonpregnant patients
- Findings supportive of pyelonephritis :
1. Renal parenchyma may appear normal (early) or edematous
2. Infected parenchyma may be visible as wedge-shaped areas of streaky contrast enhancement (striated nephrogram) (A healthy kidney has a homogeneous appearance on contrast-enhanced CT. However, in pyelonephritis, there is reduced or streaky enhancement, as obstruction of the tubules from edema, vasospasm, and inflammatory debris reduces the uptake of contrast.) - Findings supportive of urinary tract obstruction
1. Hydroureter, hydronephrosis
2. Nephrolithiasis, urolithiasis - Other findings that may be present
1. Congenital abnormalities of the renal tract
2. Abscess
3. Emphysematous pyelonephritis: presence of gas within the renal parenchyma, collecting system or perinephric space
4. Hemorrhage in the parenchyma
Ultrasound
Indications: patients with contraindications to CT scan (e.g., allergy to contrast)!
Findings supportive of pyelonephritis
- Renal enlargement
- Loss of corticomedullary differentiation
- Edema
- Hemorrhage in the parenchyma
- Abscess
Findings supportive of urinary tract obstruction
- Hydroureter, hydronephrosis
- Thickened bladder wall
- High bladder residual volume
- Prostate enlargement
Disadvantages: low sensitivity compared to CT, particularly in early acute infections
Pielonefrite acuta, interstiziale
Corticale renale! PMN
- Most commonly affects the cortex (spares glomeruli and vessels)
- Purulent inflammation of the interstitium with destruction of the parenchyma, the renal tubules, and, in some cases, the renal pelvis.
Histology
- Neutrophilic infiltration of the renal tubules and the interstitium
- Sparing of the glomeruli and intrarenal vessels
Chronic pyelonephritis, FIBROSI!💥
Giunzione cortico-midollare! EOSINOFILI
- Chronic inflammatory changes with rough, asymmetric scarring and fibrosis of the corticomedullary junction
- Blunted calyces from recurrent urinary reflux
Histology: eosinophilic casts in the tubules that resemble thyroid tissue with coloid (thyroidization of the kidney)
Xanthogranulomatous pyelonephritis
GRANULOMA, yellow, Proteus MIrabilis
- A rare form of chronic pyelonephritis characterized by chronic destructive granuloma formation
- Associated with Proteus mirabilis and Escherichia coli infections
- Large, irregular, yellow-orange masses on gross examination of the kidney (may be mistaken for a true renal neoplasm)
- Histology: granulomatous tissue with lipid-laden foamy macrophages and multinucleated giant cells
Principi di farmacologia
Antibiotic therapy, source control, and supportive care are the mainstays of treatment of pyelonephritis. The choice of empiric antibiotic regimen should be guided by the risk of infection with resistant organisms (i.e., complicated vs. uncomplicated pyelonephritis) and antibiotics should be tailored as soon as culture results become available. Consider specialist consultation in cases of complicated pyelonephritis, especially if urinary tract obstruction is suspected.
Pielonefrite non complicata
🧨Empiric antibiotic therapy for uncomplicated pyelonephritis
Most patients can be treated with an oral fluoroquinolone (e.g., ciprofloxacin, levofloxacin ) for 5–7 days!
Alternatives
- Trimethoprim-sulfamethoxazole, for 10–14 days (only recommended if susceptibility is known)
- Amoxicillin-clavulanate for 10–14 days
- Cefpodoxime for 10–14 days
Consider a single dose of a broad-spectrum parenteral antibiotic prior to the administration of oral antibiotics, especially when the local rates of drug-resistant E. coli are unknown or known to be > 10%.
- Ceftriaxone
- Gentamicin
Outpatient treatment is generally appropriate!
If there is no response within 48 hours of starting empiric antibiotic therapy:
- Consider imaging to evaluate for urinary tract obstruction or formation of renal abscess (see “Diagnostics”).
- Check urine culture results and adjust treatment accordingly (dopo la terapia empirica)
Repeat urine culture (i.e., “test for cure”) is not routinely indicated
Pielonefrite complicata
Patients with complicated acute pyelonephritis should be admitted to the hospital and started on parenteral empiric antibiotic therapy as soon as possible!🧨 ( to avoid renal complications and urosepsis)
Patients with concurrent urinary tract obstruction are at very high risk of clinical deterioration and require immediate intervention to remove the obstruction.🧨
1.Not severely ill and no risk factors for multidrug-resistant bacterial infection:
One of the following:
- Fluoroquinolone
- Ceftriaxone
- An extended-spectrum penicillin with a β-lactamase inhibitor (e.g., piperacillin-tazobactam )
Consider adding an aminoglycoside until culture results are available.
- Gentamicin
- Tobramycin
2.Severely ill (i.e., septic) and/or with risk factor(s) for multidrug-resistant gram-negative bacterial infection
One of the following: -A carbapenem Meropenem Doripenem Ertapenem
-An extended-spectrum penicillin with a β-lactamase inhibitor (e.g., piperacillin-tazobactam )
-Aztreonam
-An extended-spectrum cephalosporin
Ceftriaxone
Ceftazidime
Cefepime
-Consider adding an aminoglycoside until culture results are available.
Gentamicin
Tobramycin
Consider colistin if there is a known MDR organism with resistance to aminoglycosides and carbapenems.
3.MRSA suspected
-Consider adding vancomycin.
OR if there is concern for VRE, add one of the following:
-Daptomycin
-Linezolid
Duration of antibiotic therapy: 10–14 days
Antibiotic therapy should be adjusted once blood and urine culture sensitivity reports are available.
Consider repeat urine culture in pregnant women and those with recurrent pyelonephritis 2–4 days after completion of the antibiotic course.
Identify and treat the underlying cause.
