Fecal microbiota analysis of polycystic kidney disease patients according to renal function: A pilot study.

IMPACT STATEMENT: The heterogeneity of the renal disease, therapeutic interventions, and the original cause of the renal failure, all directly affect the microbiota. We delineate in this report the direct effect of decreased renal function on the bacterial composition following stringent criteria to eliminate the possibilities of other confounding factors and dissect the direct effects of the uremic milieu. We analyzed the microbiome following three different approaches to further evaluate the effects of mild, moderate and advanced renal insufficiency on the microbiome. We also present here a detailed functional analysis of the projected altered pathways secondary to changes in the microbiome composition.

Complete Sequence of pCY-CTX, a Plasmid Carrying a Phage-Like Region and an ISEcp1-Mediated Tn2 Element from Enterobacter cloacae.

A plasmid pCY-CTX carrying a phage-like backbone from an extensively drug-resistant Enterobacter cloacae strain Guangzhou-ECL001 (previously known as CY01) was identified in this study. By Illumina MiSeq 2 × 250-bp paired-end sequencing, de novo assembly, and PCR, full sequence of pCY-CTX was obtained. Plasmid pCY-CTX was a circular plasmid with a length of 116,700 bp, harboring 136 putative open reading frames with the average G + C content of 50.8%. The backbone of pCY-CTX showed high identity to previously reported phage-like plasmid pHCM2 and phage SSU5. In addition, pCY-CTX contained a distinctive ISEcp1-mediated Tn2 region with two resistance genes blaTEM-1 and blaCTX-M-3. Transposition unit "ISEcp1- blaCTX-M-3- orf477" was inserted into the Tn2 structure, dividing Tn2 into two parts. This represents the first identification of a plasmid carrying a phage-like backbone and a distinctive ISEcp1-mediated Tn2 region within blaTEM-1 and blaCTX-M-3 in clinical E. cloacae. The finding of phage-like regions located in plasmids provides a new perspective in gene transfer associated with antimicrobial resistance.

Biliary infection may exacerbate biliary cystogenesis through the induction of VEGF in cholangiocytes of the polycystic kidney (PCK) rat.

Cholangitis arising from biliary infection dominates the prognosis in Caroli's disease. To clarify the influences of bacterial infection on the biliary cystogenesis, in vivo and in vitro studies were performed using the polycystic kidney (PCK) rat as an animal model of Caroli's disease. Cholangitis became a frequent histological finding in aged PCK rats, and neovascularization around the bile ducts also increased in aged PCK rats. Immunohistochemistry revealed that expression of vascular endothelial growth factor (VEGF) was increased in PCK rat biliary epithelium. In vitro, PCK cholangiocytes overexpressed VEGF, and the supernatant of cultured PCK cholangiocytes significantly increased the proliferative activity, migration, and tube formation of cultured rat vascular endothelial cells. Stimulation with lipopolysaccharide (LPS) further induced VEGF expression in PCK cholangiocytes, which might be mediated by signaling pathways involving phosphatidylinositol 3-kinase (PI3K)-Akt and c-Jun N-terminal kinase (JNK). Both LPS and VEGF increased cell proliferative activity in PCK cholangiocytes, and siRNA against VEGF significantly reduced LPS-induced cell proliferation. Thus, LPS-induced overexpression of VEGF in the biliary epithelium may lead to hypervascularity around the bile ducts; concurrently, LPS and VEGF act as cell proliferation factors for cholangiocytes. Biliary infection may thus exacerbate biliary cystogenesis in PCK rats.

Renal tuberculosis in adult polycystic kidney disease: report of 2 cases and review of the literature.

Adult polycystic kidney disease (APKD) is a common and potentially fatal disease, leading to end-stage renal failure in 50% of cases. The disease is frequently complicated by arterial hypertension, bacterial pyelonephritis, and hematuria. The association between APKD and tuberculosis has rarely been reported and is related to a more unfavorable course since the infection becomes refractory to specific treatment. The authors report 2 cases of renal tuberculosis diagnosed in the native nephrectomy specimens of 2 patients with APKD after renal transplantation. Tuberculosis, although not common, must be recognized as a potential source of infection of native polycystic kidneys in immunocompromised transplant recipients.

Inhibition of nanobacteria by antimicrobial drugs as measured by a modified microdilution method.

Compounds from 16 classes of antimicrobial drugs were tested for their abilities to inhibit the in vitro multiplication of nanobacteria (NB), a newly discovered infectious agent found in human kidney stones and kidney cyst fluids from patients with polycystic kidney disease (PKD). Because NB form surface calcifications at physiologic levels of calcium and phosphate, they have been hypothesized to mediate the formation of tissue calcifications. We describe a modified microdilution inhibitory test that accommodates the unique growth conditions and long multiplication times of NB. This modified microdilution method included inoculation of 96-well plates and determination of inhibition by periodic measurement of the absorbance for 14 days in cell culture medium under cell culture conditions. Bactericidal or bacteriostatic drug effects were distinguished by subsequent subculture in drug-free media and monitoring for increasing absorbance. NB isolated from fetal bovine serum (FBS) were inhibited by tetracycline HCl, nitrofurantoin, trimethoprim, trimethoprim-sulfamethoxazole, and ampicillin at levels achievable in serum and urine; all drugs except ampicillin were cidal. Tetracycline also inhibited multiplication of isolates of NB from human kidney stones and kidney cyst fluids from patients with PKD. The other antibiotics tested against FBS-derived NB either had no effect or exhibited an inhibitory concentration above clinically achievable levels; the aminoglycosides and vancomycin were bacteriostatic. Antibiotic-induced morphological changes to NB were observed by electron microscopy. Bisphosphonates, aminocaproic acid, potassium citrate-citric acid solutions, and 5-fluorouracil also inhibited the multiplication of NB in a cidal manner. Insights into the nature of NB, the action(s) of these drugs, and the role of NB in calcifying diseases may be gained by exploiting this in vitro inhibition test system.

Laparoscopic retroperitoneal nephrectomy for Aspergillus-infected polycystic kidney.

BACKGROUND AND PURPOSE: The management of polycystic kidney disease is mostly restricted to conservative measures. However, nephrectomy may be indicated in particular cases, especially when there are infective complications. To decrease the morbidity of the procedure, the laparoscopic approach has become appealing. We present a laparoscopic retroperitoneal approach to complicated polycystic kidney disease in a high-risk patient. CASERESPORT: We performed right retroperitoneal laparoscopic nephrectomy in a 39-year-old man who had autosomal polycystic kidney disease and had undergone heart transplantation. The immunosuppressed patient presented with severe flank pain, generalized signs of infection, and acute renal insufficiency. With the patient in the right lateral decubitus position, the retroperitoneal space was entered by the open technique, and the posterior pararenal space was developed with finger dissection. Five trocars were used. After the renal vessels had been secured and divided, the cysts were successively punctured, gradually shrinking the operative specimen. The kidney was placed in an Endo-catch and removed after morcellation, with no need to enlarge the 2-cm lumbotomy. The operating time was 80 minutes, and the hospital stay was 4 days. Histologic examination revealed a polycystic kidney with Aspergillus infection. CONCLUSION: The laparoscopic approach is a less-invasive option for removing a polycystic kidney when nephrectomy is indicated. The retroperitoneal route has the advantage of minimizing infection risks because of the absence of peritoneal opening.

Nanobacteria: controversial pathogens in nephrolithiasis and polycystic kidney disease.

Nanobacteria are unconventional agents 100-fold smaller than common bacteria that can replicate apatite-forming units. Nanobacteria are powerful mediators of biogenic apatite nucleation (crystal form of calcium phosphate) and crystal growth under conditions simulating blood and urine. Apatite is found in the central nidus of most kidney stones and in mineral plaques (Randall's plaques) in renal papilla. The direct injection of nanobacteria into rat kidneys resulted in stone formation in the nanobacteria-injected kidney during one month follow-up, but not in the control kidney injected with vehicle. After intravenous administration in rats and rabbits, nanobacteria are rapidly excreted from the blood into the urine, as a major elimination route, and damage renal collecting tubuli. Nanobacteria are cytotoxic to fibroblasts in vitro. Human kidney cyst fluids contain nanobacteria. Nanobacteria thus appear to be potential provocateurs and initiators of kidney stones, tubular damage, and kidney cyst formation. It is hypothesized that nanobacteria are the initial nidi on which kidney stone is built up, at a rate dependent on the supersaturation status of the urine. Those individuals having both nanobacteria and diminished defences against stone formation (i.e. genetic factors, diet and drinking habits) could be at high risk. Kidney cyst formation is hypothesized to involve nanobacteria-induced tubular damage and defective tissue regeneration yielding cyst formation, the extent of which is dependent on genetic vulnerability.

Endotoxin and nanobacteria in polycystic kidney disease.

BACKGROUND: Microbes have been suspected as provocateurs of polycystic kidney disease (PKD), but attempts to isolate viable organisms have failed. Bacterial endotoxin is the most often reported microbial product found in PKD fluids. We assessed potential microbial origins of endotoxin in cyst fluids from 13 PKD patients and urines of PKD and control individuals. METHODS: Fluids were probed for endotoxin and nanobacteria, a new bacterium, by the differential Limulus Amebocyte Lysate assay (dLAL), genus-specific antilipopolysaccharide (LPS) antibodies, monoclonal antibodies to nanobacteria, and hyperimmune serum to Bartonella henselae (HS-Bh). Selected specimens were also assessed by transmission electron microscopy (TEM) and nanobacterial culture methods. RESULTS: LPS or its antigenic metabolites were found in more than 75% of cyst fluids tested. Nanobacteria were cultured from 11 of 13 PKD kidneys, visualized in 8 of 8 kidneys by TEM, and immunodetected in all 13 PKD kidneys. By immunodetection, nanobacterial antigens were found in urine from 7 of 7 PKD males, 1 of 7 PKD females, 3 of 10 normal males, and 1 of 10 normal females. "Nanobacterium sanguineum" was dLAL positive and cross-reactive with antichlamydial LPS and HS-Bh. Some cyst fluids were also positive for LPS antigens from Escherichia coli, Bacteroides fragilis and/or Chlamydia, and HS-Bh, as were liver cyst fluids from one patient. Tetracycline and citrate inhibited nanobacterial growth in vitro. CONCLUSION: Nanobacteria or its antigens were present in PKD kidney, liver, and urine. The identification of candidate microbial pathogens is the first step in ascertaining their contribution, if any, to human disease.

Retroperitoneoscopic management of infected cysts in adult polycystic kidney disease.

Conservative measures are the mainstay of therapy in adult polycystic kidney disease (APKD). Pain, infection and obstructive uropathy are the major indications for intervention. Chronic pain has been treated with narcotic analgesics, needle aspiration of dominant cysts, and open renal cyst decortication. Laparoscopic cyst decortication, by either transperitoneal or retroperitoneal access, is a new emerging option with similar efficacy to open surgery and less morbidity. Cyst infection in these patients responds poorly to commonly used antibiotics. Patients with refractory cyst infection may even require nephrectomy. Herein, we present 2 cases with APKD that were treated by retroperitoneoscopic decortication for painful and infected cysts. Both patients showed prompt and sustained improvement in symptoms, with minimal morbidity and short convalescence. This approach has not hitherto been described for infected cysts in APKD. The retroperitoneoscopic route should be preferred in the presence of infected cysts so as to prevent intraperitoneal contamination.

Mycobacterium tuberculosis infection of a native polycystic kidney following renal transplantation.

BACKGROUND: Tuberculosis is a recognized complication following renal transplantation. Patients with autosomal dominant polycystic kidney disease are increasingly being offered renal transplantation as an alternative to chronic hemodialysis. These patients are uniquely susceptible to serious upper urinary tract infections that are associated with significant morbidity and mortality. While involvement with gram-negative organisms is well described, mycobacterial infection of native polycystic kidneys after transplantation has not been addressed. METHODS: A case report of a renal transplant recipient who suffered an isolated Mycobacterium tuberculosis infection of a native polycystic kidney and a literature review. RESULTS: Despite appropriate drug therapy, the infection proved refractory, and the patient required nephrectomy. CONCLUSIONS: Mycobacterial tuberculosis, though not common, must be recognized as a potential source of infection of native polycystic kidneys in immunocompromised transplant recipients. Similar to the pattern observed with more common pathogens, these infections may be difficult to eradicate with standard antimicrobial drug regimens.

Polyomavirus replicates in differentiating but not in proliferating tubules of adult mouse polycystic kidneys.

Previous observations led us to propose that ongoing cellular differentiation, rather then proliferation, may be needed for high-level polyomavirus (Py) replication in permissive organs in vivo. We further tested this proposal by using the C57BL/6J-cpk/cpk mouse model for the autosomal recessive form of polycystic kidney disease (PKD) because both cellular proliferation and differentiation continue into the adult kidney in separate and distinct regions of the kidneys, whereas normal adult kidneys are quiescent and nonpermissive to Py. Adult PKD mice inoculated with Py were assayed for Py DNA replication by in situ hybridization and Southern analysis and for viral gene expression by immunofluorescence 5 days postinfection. The proliferation of collecting duct tubules of PKD kidneys was confirmed by in situ autoradiography for tritiated thymidine incorporation but were observed to be nonpermissive for Py gene expression or replication. Normal differentiated collecting ducts, however, are capable of supporting Py replication in non-PKD runted mice (Rochford et al., 1992). Py DNA, large T-Ag, and VP1, however, were detected in the nonproliferating distal and proximal tubules of the PKD parenchyma. The parenchymal tissues appear to be differentiating in a compensatory response to cyst growth. These results further support the view that in vivo Py replication may require ongoing cellular differentiation rather then mitosis.

Autosomal recessive polycystic kidney disease: characterization of human peritoneal and cystic kidney cells in vitro.

Renal cystic epithelia and peritoneal mesothelia from two humans with autosomal recessive polycystic kidney disease (ARPKD) were grown in culture. Cystic epithelial and mesothelial cells formed continuous monolayers in vitro. By electron microscopy, cystic renal cells exhibited a single apical cilium and numerous short, stubby microvilli, both in situ and in vitro. Mesothelial cells exhibited intra- and extracellular membrane-limited, lipid-filled vesicles and surface microvilli. Cystic kidney cells in vitro stained positive for lectins from Cancanavalia ensiformis (concanavalin A), Triticum vulgaris, Erythrina cristagalli, Ulex europeaus, and Arachis hypogaea. Immunocytochemical and lectin staining revealed the renal and peritoneal cells to be of collecting tubule and mesothelial origin, respectively. Both cell types showed large depositions of glycogen granules in the cytoplasm during propagation in certain culture media; in kidney cells, dibutyryl cyclic adenosine monophosphate (cAMP) abolished glycogen depositions. Glycogen deposition also was observed in liver tissue obtained by needle biopsy from one patient. No bacteria were cultured from nor endotoxin detected in the renal cyst fluid. Relative to serum, the cyst fluids contained low sodium, potassium, and chloride levels. Thus, cultured ARPKD cells demonstrate a number of characteristics that are different from cells derived from the autosomal dominant form of renal cystic disease (ADPKD).

[Chronic pyelonephritis in polycystic kidney]. / Kum problema za khronichniia pielonefrit pri bubrechna polikistoza.

The characteristics of chronic pyelonephritis are studied in 37 patients out of a total of 53 patients with proved renal polycystosis. A group of 71 patients with chronic pyelonephritis selected at random are used as a control group. The frequency of chronic pyelonephritis among the patients with renal polycystosis is 69.8%. The difference between the mean age of the patients with renal polycystosis and chronic pyelonephritis and the patients with renal polycystosis without chronic pyelonephritis is 8.6 years. A significant difference is established between these two groups of patients concerning the frequency of symptomatic hypertension--89.2% for the patients with renal polycystosis and chronic pyelonephritis and 45% for the patients with uncomplicated renal polycystosis. A similar difference is established also for the renal failure--respectively 64.9% and 37.5%. The frequency of hypertension and chronic renal failure is lower in the control group of patients. 59% of the patients with renal polycystosis and chronic pyelonephritis have significant bacteriuria, E. coli and Proteus being the most frequently isolated bacteria but Pseudomonas shows the highest drug resistance. The isolated bacteria are most sensitive to nitroxoline and aminoglycoside antibiotics.