NDT Advance Access originally published online on May 8, 2008
Nephrology Dialysis Transplantation 2008 23(8):2685-2687; doi:10.1093/ndt/gfn243
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Encrusted cystitis by Corynebacterium urealyticum: a case report with novel insights into bladder lesions
1 Nephrology Unit and Kidney Histomorphology and Molecular Biology Laboratory, Department of Medical and Surgical Sciences 2 Urology Unit 3 Histology, Microbiology and Medical Biotechnology Department 4 Department of Medical-Diagnostic Sciences, Institute of Pathological Anatomy, University of Padova, Padova, Italy
Correspondence and offprint requests to: Dorella Del Prete, Nephrology Unit, Department of Medical and Surgical Sciences, University of Padova, via Giustiniani 2, 35128 Padova, Italy. Tel: +39-049-8212146; Fax: +39-049-8212151; E-mail: dorella.delprete{at}unipd.it
Keywords: Corynebacterium urealyticum; cystitis; encrustation; osteogenic markers
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Background |
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 Top Background Case reportDiscussionReferences |
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Corynebacterium urealyticum (CU) (formerly Corynebacterium group D2) is a gram-positive bacillus with a strong urease activity that can infect the lower (acute or chronic cystitis) and upper (pyelonephritis and encrusted pyelitis) urinary tract [1]. CU is a commensal skin organism that an estimated 12% of healthy individuals carry and it has been isolated in 30% of hospitalized patients. CU converts urea into ammonia, creating alkaline urine, which precipitates struvite and calcium phosphate crystals, forming stones and encrustations on the infected mucosa [2].
Prolonged vesical and ureteral catheterization is considered the most important risk factor for developing encrusted cystitis (EC) and encrusted pyelitis (EP); these procedures not only carry CU or other urea-splitting micro-organisms into the urinary tract, but may also create conditions, e.g. urothelial trauma, that increase the risk of simple urinary tract infections turning into EC or EP [3]. Bladder wall histology following resection of calcified encrustations reveals three distinct zones: a necrotic layer containing calcified encrustations revealed by Von Kossa stain; an inflammatory layer containing bacterial colonies, lymphocytes and polymorphonuclear cells; and normal tissue [4].
A recent study on systemic inflammatory disease associated with pathological calcifications found osteonectin, osteopontin and bone sialoprotein in calcified deposits, suggesting that crystal formation is a protein-mediated regulatory process involving the damaged tissue and an attempted healing mechanism [5]. Osteonectin is a protein that binds calcium, hydroxyapatite and collagen, abundantly expressed in growth and occurring in high levels in bone, possibly linking the organic and mineral phases of bone tissue [6]. Osteocalcin is a vitamin-K-dependent, calcium-binding bone protein and the most abundant non-collagenous bone protein secreted by osteoblastic cells and deposited in the bone matrix [7]. Osteopontin is a phosphorylated acidic glycoprotein expressed in the bone matrix and strongly upregulated in many organs following different types of tissue injury [8].
In a patient with EC, we investigated whether the calcification might be an active process regulated by osteogenic proteins using immunohistochemical studies to analyse osteonectin, osteopontin and osteocalcin deposition in encrusted bladder tissue.
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Case report |
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TopBackgroundCase reportDiscussionReferences |
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A 67-year-old woman was admitted for recurrent cystitis following bladder catheterization for orthopaedic surgery despite prolonged non-specific and differentiated antibiotic therapy. Many calcium-oxalate and struvite ‘stones’ were expelled daily in urine with an alkaline pH (pH 8–9), and severe bladder incontinence limited the patient's social life.
On admission, renal function was normal and standard urine culture negative. Sonography showed a right kidney with an unevenly reduced parenchymal thickness. Excretory urography showed moderate hydronephrosis, more evident on the right. CT scan showed thickening and calcification of the bladder wall.
Cystoscopy identified a low bladder capacity and solid neoformations coated by calcifications on the trigone, side walls and neck. Bladder biopsies showed necrotic tissue with oedema and intense mononuclear leukocyte infiltration with focal calcified encrustations on the bladder wall (Figure 1A, B), prompting a diagnosis of EC.
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Specific urine and resected tissue culture for CU revealed a few copies of the bacillus in the former (
103 cfu/ml) and many in the latter (
105 cfu/g), suggesting that urine cultures may be positive for CU infection at a lower cfu/ml level than according to the Kass’ criterion of 105 cfu/ml. To confirm the species identification, PCR and sequencing was performed on the 18S ribosomal gene DNA of the bacterial isolate. High sequence homology was found on BLAST, NCBI. CU responded to Vancomycin administered iv 1000 mg for 23 days along with bladder irrigations with Suby's solution G 100.
After treatment, urine culture was negative and symptoms had improved with no further incontinence, a situation confirmed by sonography, urofluxometric test, cystoscopy and bladder biopsy.
The chance to obtain bladder biopsies before and after the treatment enabled immunohistochemical analyses on the bladder lesions and calcified encrustations to seek osteogenic markers, identify the gram-positive bacillus, test for calcium deposition by von Kossa staining and analyse the encrustations under the scanning electron microscope (SEM) and by X-ray microanalysis.
Immunohistochemistry was performed on formalin-fixed, paraffin-embedded sections of bladder tissue biopsied before and after treatment (method details given in legend of Figure 2).
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With Haematoxylin and eosin staining (H&E) the bladder tissue revealed ulcerative necrotic tissue with a major inflammatory infiltrate (Figure 1A) and bladder wall calcification (Figure 1B). The bladder tissue contained calcified encrustations revealed by von Kossa staining (Figure 1C) that became increasingly numerous and compact towards the surface. Small calcium deposits were also found scattered in the wall.
By SEM and X-ray microanalysis, the encrustations revealed calcium and phosphate. Histology on the biopsy taken after treatment showed a normal morphology on both H&E and Von Kossa staining.
Immunohistochemical staining was semi-quantitatively assessed, recording the percentage of granular staining as borderline (<5%), intermediate (5–25%), moderate (25–50%) or strong (50–75%).
The biopsy taken before treatment was strongly positive for osteocalcin (Figure 2A) in endothelial, fibroblast and inflammatory mononuclear cells (Figure 2B), focally and moderately so for osteonectin in interstitial cells and borderline for osteopontin at the site of inflammation in inflammatory mononuclear cells. All osteogenic markers were negative in the biopsy taken after treatment (Figure 2C).
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Discussion |
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TopBackgroundCase reportDiscussionReferences |
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Encrusted cystitis was described by Francois in 1914 [9]. Hager and Magath [10] related this disease to implanted urea-splitting micro-organisms in a bladder already harbouring inflammation or tumour. Since its first description, CU has been detected almost exclusively in EC and EP, and is considered their most common causative agent.
Our patient had all the clinical and histological features of CU infection as well as severe bladder incontinence, which promptly regressed after treatment.
The urinary bladder may have a complex array of reactions to various harmful stimuli, one being prolonged inflammation, like that caused by CU. Finding calcium in the bladder wall made us investigate the possibility of a bio-active calcification process.
Several cells, e.g. smooth muscle cells, myofibroblasts, calcifying vascular cells and microvascular pericytes, may exhibit interchangeable phenotypes under certain pathological conditions, such as prolonged inflammation [11]. We hypothesized that bladder cells may differentiate towards an osteogenic lineage, triggering the synthesis of typical bone osteoid proteins. Our finding, positive staining for osteocalcin, osteonectin and osteopontin in the biopsy taken before treatment, suggested an active osteogenic process, probably induced by CU infection. To our knowledge, this is the first demonstration of the activation of osteoid proteins following CU infection.
We speculate that a strongly alkaline pH and the presence of cellular fragments derived from apoptotic cells constitute environmental conditions favouring calcium phosphate precipitation. Similar to the vascular calcification process, high calcium and phosphate concentration along with cytokines and growth factors produced by activated inflammatory cells may induce the transdifferentiation of resident cells towards the osteogenic lineage.
Negative staining for osteogenic markers in biopsies taken after treatment demonstrated that this active osteogenic process is reversible, probably by changing the tissue's environmental conditions (reducing inflammation and eradicating infection), therefore suggesting that CU infection can be considered the ‘primum movens’ of pathogenic mechanisms behind bladder tissue calcification.
Conflict of interest statement. None declared.
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References |
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TopBackgroundCase reportDiscussionReferences |
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- Garcia-Bravo M, Aguado JM, Morales JM, et al. Influence of external factors in resistance of Corynebacterium urealyticum to antimicrobial agents. Antimicrob Agents Chemother (1996) 40:497–499.[Abstract]
- Chung SY, Davies BJ, O’Donnell WF. Mortality from grossly encrusted bilateral pyelitis, ureteritis, and cystitis by Corynebacterium group D2. Urology (2003) 61:463.[Medline]
- Giannakopoulos S, Alivizatos G, Deliveliotis C, et al. Encrusted cystitis and pyelitis. Eur Urol (2001) 39:446–448.[CrossRef][Web of Science][Medline]
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- Pachman LM, Veis A, Stock S, et al. Composition of calcifications in children with juvenile dermatomyositis: association with chronic cutaneous inflammation. Arthritis Rheum (2006) 54:3345–3350.[CrossRef][Web of Science][Medline]
- Mansergh FC, Wells T, Elford C, et al. Osteopenia in Sparc (osteonectin)-deficient mice: characterization of phenotypic determinants of femoral strength and changes in gene expression. Physiol Genomics (2007) 32:64–73.
[Abstract/Free Full Text] - Shimonishi M, Hatakeyama J, Sasano Y, et al. Mutual induction of noncollagenous bone proteins at the interface between epithelial cells and fibroblasts from human periodontal ligament. J Periodontal Res (2008) 43:64–75.[Web of Science][Medline]
- Obermüller N, Gassler N, Gretz N, et al. Distinct immunohistochemical expression of osteopontin in the adult rat major salivary glands. J Mol Histol (2006) 37:53–60.[CrossRef][Web of Science][Medline]
- Francois JJ. La cystite incrustée. J Urol Méd Chir (1914) 5:35–52.
- Hager BH, Magath TB. The etiology of incrusted cystitis with alkaline urine. JAMA (1925) 85:1353–1355.
- Jono S, Shioi A, Ikari Y, et al. Vascular calcification in chronic kidney disease. J Bone Miner Metab (2006) 24:176–181.[CrossRef][Web of Science][Medline]
Accepted in revised form: 8. 4.08
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