Alkaline-encrusted pyelitis and cystitis is a nosocomial urinary tract infection caused by Corynebacterium urealyticum.
We have selected the most representative cases in our hospital in order to define the typical features of the disease.
Clinical context
Clinical manifestations are non-specific and can be minimal for a prolonged period.
Patients present with flank pain,
dysuria,
suprapubic pain,
acute obstruction,
pyuria,
macroscopic hematuria with elimination of stones,...
Fever is not constant.
It may also develop loss of renal function.
Encrusted pyelitis has been reported particularly in renal transplant patients but also in native kidneys.
Special conditions are required to cause alkaline-encrusted cystitis or pyelitis such a long-period hospitalisation with prolonged broad-spectrum antibiotic therapy, immunosuppression,
a urologic procedure like manipulations of the urinary tract or prolonged bladder catheterisation,
or an inflammatory or neoplastic preexisting lesion of the urothelium.
Fig. 2: Calcifications of the calyces of two kidneys (red arrow) in a patient with bilateral nephrostomy (yellow arrow).
References: Servicio de Radiodiagnóstico, Hospital Clínico Universitario de Valencia. Spain
Fig. 3: Calcifications of the calyces of two kidneys in a patient with bilateral nephrostomy. Percutaneus nephrostomy tubes (white arrows).
References: Servicio de Radiodiagnóstico, Hospital Clínico Universitario de Valencia. Spain
The specific diagnosis of C.
urealyticum infection can be easily overlooked by a standard urine culture.
It requires a prolonged incubation for more than 48 hr on special media.
Urine analysis is characterized by alkaline pH,
pyuria,
hematuria,
and struvite crystals.
Imaging findings
Alkaline-encrusted pyelitis and cystitis is characterised by stone encrustation in the wall of the urinary tract .
Mucosal linear,
thin,
superficial and regular calcifications that covers the urothelium.
It may be sometimes associated with free stones.
Micro‐abscesses of the renal parenchyma may be present in contact with encrustations.
Fig. 7: Unenhanced CT scan shows thickening of bladder wall with encrusted calcification (blue arrow) associated with free stones in a patient with bladder-vaginal fistula (red arrow shows air bubble).
References: Servicio de Radiodiagnóstico, Hospital Clínico Universitario de Valencia. Spain
Calcification of encrusted pyelitis may be radiolucent.
Abdominal radiograph is often normal.
Fig. 6: Abdominal radiograph shows bilateral urothelial wall thin an regular calcifications in a patient with cystectomy and history of urologic diseases.
Calcification of encrusted pyelitis may be radiolucent, and abdominal radiograph may be normal.
References: Servicio de Radiodiagnóstico, Hospital Clínico Universitario de Valencia. Spain
Ultrasonography shows hyperechogenic images in contact with the collecting system of the involved kidney and regular hiperechogenic layer of bladder wall.
Fig. 4: Right kidney. Thin and regular calcifications that superficially covers calicial system in a patient with long medical history of urologic diseases.
References: Servicio de Radiodiagnóstico, Hospital Clínico Universitario de Valencia. Spain
Fig. 8: Sonogram of bladder reveals a superficial and hyperechogenic layer with acoustic shadowing that correspond to linear and thin calcifications that covers the urothelium.
References: Servicio de Radiodiagnóstico, Hospital Clínico Universitario de Valencia. Spain
The high sensitivity and specificity of CT scan makes it the best imaging technique for diagnosis and follow‐up after treatment.
Ultrasonography is not as specific as CT scan.
Fig. 1: Unenhanced CT scan shows bilateral hydronephrosis and thickening of urothelial wall with superficial encrustation in a man with chronicdebilitating diseases.
References: Servicio de Radiodiagnóstico, Hospital Clínico Universitario de Valencia. Spain
Urothelial wall encrustation,
particularly in the bladder,
can also be observed in schistosomiasis,
tuberculosis,
necrotic urothelial carcinoma,
leucoplakia,
or after intravesical instillations of cyclophosphamide or mitomycin.
In the upper urinary tract,
when calcification is bulky and lobed,
it could be mistaken for a staghorn calculus.
Fig. 9: Longitudinal sonogram of bladder shows hyperechogenic structures with acoustic shadowing that could correspond to encrustation or free stones.
References: Servicio de Radiodiagnóstico, Hospital Clínico Universitario de Valencia. Spain
Fig. 10: a) Unenhanced CT scan shows thickening of bladder wall with encrusted calcification.
References: Servicio de Radiodiagnóstico, Hospital Clínico Universitario de Valencia. Spain
Fig. 11: a) Abdominal radigraphy pre urination where we can see an urothelial wall encrustation in the bladder in a patient with schistosomiasis.
b) Abdominal radigraphy post urination where we see an empty bladder.
References: Servicio de Radiodiagnóstico. Hospital Clínico Universitario de Valencia. Spain.
Fig. 12: a) Abdominal radigraphy pre urination where we can see an urothelial wall encrustation in the bladder in a patient with schistosomiasis.
b) Abdominal radigraphy post urination where we see an empty bladder.
References: Servicio de Radiodiagnóstico. Hospital Clínico Universitario de Valencia. Spain.
Fig. 13: Curvilinear calcification in left vesicoureteral junction in a patient with longstanding TBC in the urinary tracts. We can also see grade IV hydronephrosis of the left kidney.
References: Servicio de Radiodiagnóstico. Hospital Clínico Universitario de Valencia. Spain.
The diagnosis is confirmed by showing a urea-splitting micro-organism on urine culture.
Standard urine culture is usually negative.
It requires a prolongued incubation (more than 48 hours) on special media.
When the infection is clinically and bacteriologically suspected,
direct visualization on imaging of encrusted plaques should confirm the diagnosis.
Medical history,
clinical context,
and urine analysis associated with radiologic findings are basic elements used in the diagnosis of encrusted cystitis or pyelitis.
Treatment is based on appropriate antibiotic therapy,
acidification of urine (oral or by percutaneus nephrostomy) and if it is required,
surgical removal of the encrustations,
however,
resection of encrustations is difficult and may be dangerous.
Repeated urine cultures,
urine pH measurement and follow-up CT scan should be performed at various intervals to assess treatment efficacy.