Infectious Kidney Stones Research Articles

#6056 NEPHROLOGIC INVOLVEMENT IN A SURGICAL COMPLICATION: WHEN TO SUSPECT A PYELO-DUODENAL FISTULA

Abstract Background and Aims Spontaneous pyeloduodenal fistula is a rare condition occurring primarily after urologic events, in most cases infected kidney stones, pyonephrosis, xanthogranulomatous pyelonephritis, renal tumors, and infected renal cysts, with nowadays 80 cases described. The close relationship between the kidney and the duodenum is a facilitating condition. Method We describe the case of a 78 yo woman admitted in April 2022 for Acute Kidney Injury associated with fever, vomiting, oliguria and metabolic alkalosis. Over the last two years the patient reported recurrent febrile episodes associated with abdominal tenderness and weight loss. Urine cultures showed recurrent bacterial growth and she received antibiotics for recurrent episodes of pyelonephritis and lower urinary tract infections (K. Pneumonie ESBL +, E. Faecalis, P. Mirabilis). She was under nephrologic follow-up with a renal function demonstrating eGFR CKD-EPI of 35-30 ml/min/1.73 m2. In past medical history she reported atrial fibrillation in DOAC, heart failure with preserved ejection fraction, hypertension, previous left occipito-parietal ischemic stroke and right parotid adenoma. On physical examination of the abdomen there was no tenderness, mild pain in the right hypochondrium, Giordano's maneuver mild positive on the right side. Because of the evidence of lithiasis in the right kidney on ultrasound with grade III hydroureteronephrosis, we performed a CT scan with contrast, finding imaging compatible with right pyelonephritis with associated grade IV hydronephrosis, in particular lithiasic formation localized at the level of the right pyelo-ureteral junction (2 × 1cm), with partial involvement of the proximal portion of the ureter, severe calico-pyelic dilatation with overall reduction of the cortico-medullary thickness; diffuse inhomogeneity of the middle and lower thirds of the renal parenchyma, with evidence of some bubbles in contextual areas and inhomogeneity of the perirenal adipose tissue. Reduced nephrographic effect in the post-contrastographic phases and lack of elimination of the contrast in the urographic phase (12 min) were reported. She was started on antibiotics piperacillin-tazobactam and underwent right percutaneous nephrostomy placement. During the procedure we evidenced a communication between the calyx of the right upper calyceal group and an intestinal loop, probably the duodenum (Fig. 1). Results The patient underwent elective laparotomic surgery for right nephrectomy (Fig. 2) and closure of the intestinal fistula with duodenoraffia and omental patch. She was admitted to a post-operative intensive care unit, given comorbidities and the complexity of the operation. She was discharged in 9 days without post-operative complications, with stable renal function. One month after discharge the patient died of pneumonia. Conclusion Pyeloduodenal fistula is an infrequent condition causing occasional or continuous passing of materials between the alimentary canal and urinary tract. The presence of gastrointestinal symptoms and urinary tract alterations may be misinterpreted when occurring. Management of this case required collaboration between several specialists, with particular skills on AKI and CKD, infective complications, interventional radiology and surgical procedures. The outcome was strongly affected by the patient's general condition and comorbidities, with a good short-term outcome but complications on the long-term follow-up. The occurrence of air in the urinary tract is strongly suggestive of communications across the renal pelvis and the gastrointestinal tract. In particular if occurring in the setting of recurrent infections and nephrolithiasis, the diagnosis of pyelo-intestinal fistula should be considered.

The Role of Urinary Modulators in the Development of Infectious Kidney Stones.

Introduction: The pathogenesis of infectious kidney stones is poorly understood. Bacteria have been implicated in promoting infectious stones via urease production; however, there is mounting evidence indicating the relationship is more complex. The aim of our study was to characterize suspected biotic and abiotic extrinsic factors that may modulate the formation of infectious stones. Materials and Methods: A high-throughput experimental model with Griffith's artificial urine was used to test a wide variety of urinary modulators and cytoplasmic enzymes present in crude cell-free extracts (CFEs) from bacterial strains to investigate how they impact struvite and calcium (Ca) phosphate crystal production. Crystal formation was evaluated with spectrophotometry and growth curve analysis. Light microscopy and scanning electron microscopy/X-ray diffraction was used for crystal structure and composition identification. Results: The acidic urinary modulators used in this study prevented crystal formation, whereas osteopontin had a significant inhibitory effect. Addition of CFEs from Proteus mirabilis 175A and 177A resulted in Ca phosphate and struvite crystals. Of interest, Klebsiella pneumoniae and Klebsiella oxytoca produced crystals including Ca phosphate and Ca oxalate, respectively. Pseudomonas aeruginosa had no urease production detected and produced Ca phosphate crystals. Discussion: Urinary modulators can have a wide variety of effects on infectious stone formation and the role of pH is important but does not guarantee robust crystal formation. Bacterial strains can produce Ca oxalate, Ca phosphate, and struvite stones with and without urease activity. Conclusion: Various urinary modulators appear to influence the process and are worthy of further evaluation as a potential therapeutic strategy to prevent infection-related urinary stone formation. Stones formed from urinary tract infections may be a result of multiple encoded metabolic pathways and discovering these would improve our understanding of the stone-bacterial relationship.

Chronic urine acidification by fludrocortisone to treat infectious kidney stones

Chronic urine acidification by fludrocortisone to treat infectious kidney stones

PD32-10 KIDNEY STONE ENDOTOXIN CONCENTRATION CORRELATES WITH POST-OPERATIVE SEPSIS FOLLOWING PERCUTANEOUS NEPHROLITHOTOMY

You have accessJournal of UrologyCME1 May 2022PD32-10 KIDNEY STONE ENDOTOXIN CONCENTRATION CORRELATES WITH POST-OPERATIVE SEPSIS FOLLOWING PERCUTANEOUS NEPHROLITHOTOMY David T. Tzou, Farhan Anwar, Ava C. Wong, David T. Harris, Thomas Chi, and Gayatri Vedantam David T. TzouDavid T. Tzou More articles by this author , Farhan AnwarFarhan Anwar More articles by this author , Ava C. WongAva C. Wong More articles by this author , David T. HarrisDavid T. Harris More articles by this author , Thomas ChiThomas Chi More articles by this author , and Gayatri VedantamGayatri Vedantam More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002583.10AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Patients with infected kidney stones are at risk for post-operative sepsis following surgical removal of their calculi. Of all the surgical approaches, percutaneous nephrolithotomy (PCNL) remains associated with the highest risk for experiencing post-operative SIRS (severe inflammatory response syndrome). Accurate prediction of patients at risk for SIRS after surgery would be of clinical value. While previous studies have demonstrated infected kidney stones contain variable levels of endotoxin concentrations, these were limited in their rigor and ability to correlate stone immunobiology with important clinical outcomes. The aim of this study was to quantitate endotoxin levels amongst PCNL patients who experienced and did not experience SIRS. METHODS: Between October 2020 and June 2021, urine & stone specimens from consecutive stone patients were prospectively collected as part of the Registry for Stones of the Kidneys and Ureter (ReSKU) at the University of Arizona. Clinical data including stone analyses and post-operative outcomes have been tracked. Equal weights of stones were uniformly broken using an easy-to-replicate ‘beat-beating’ homogenization approach, allowing for consistent measurement of stone endotoxin using a Pierce™ LAL Chromogenic Endotoxin Quantification Kit (ThermoFisher, Waltham, MA). Endotoxin levels from stones removed during PCNL were compared between patients who experienced and did not experience SIRS. Independent T-test was used to determine statistical significance. RESULTS: Endotoxin levels amongst 4 patients with infection calculi who experienced SIRS were compared to 16 patients who did not experience SIRS – 8 of which had infection calculi and 8 had non-infection calculi (Figure 1). In the SIRS group, the mean Endotoxin concentration was 1.084 endotoxin units (EU)/ml compared to 0.476 EU/ml in the non-SIRS group (p<0.01). CONCLUSIONS: Higher kidney stone bacterial endotoxin concentrations are present in patients who experienced SIRS after percutaneous stone removal compared to those who did not. Whether exceeding a threshold endotoxin level corresponds to patients experiencing SIRS warrants future study. Source of Funding: P30DK081943 – SUBK00015084 - NIH/NIDDK; University of Arizona Health Sciences Career Development Award © 2022 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 207Issue Supplement 5May 2022Page: e550 Advertisement Copyright & Permissions© 2022 by American Urological Association Education and Research, Inc.MetricsAuthor Information David T. Tzou More articles by this author Farhan Anwar More articles by this author Ava C. Wong More articles by this author David T. Harris More articles by this author Thomas Chi More articles by this author Gayatri Vedantam More articles by this author Expand All Advertisement PDF DownloadLoading ...

Photothermal nanoparticles for ablation of bacteria associated with kidney stones

Objective To determine whether photothermal polymer nanoparticles (NPs) can interface with bacteria associated with kidney stones, generate heat when stimulated with near infrared (NIR) light, and aid in reducing bacterial burden. Methods Two types of kidney stones, artificial, and those removed during percutaneous nephrolithotomy (PCNL), were inoculated with Escherichia coli (E. coli) and then incubated with NPs composed of FITC-labeled Poly[4,4-bis(2-ethylhexyl)-cyclopenta[2,1-b;3,4-b′]-dithiophene-2,6-diyl-alt-2,1,3-benzoselenadiazole-4,7-diyl] (PCPDTBSe). Association of the PCPDTBSe NPs was evaluated using fluorescence microscopy. Infected stones were incubated with NPs and exposed to 800 nm light to generate temperature increases from 25.4 to 68.6 °C on the stones. Following photothermal treatment, the stones were homogenized and the bacteria was enumerated via colony counting assays to evaluate the bactericidal effect. The photothermal effect was also evaluated using scanning electron microscopy of the treated biofilms. Results Both kidney stone types sequestered E. coli. Control stones and stones treated with laser only had growth of numerous bacterial colonies, while stones exposed to NPs and laser grew significantly less, or none (p = 0.02). Conclusions The polymer NPs interface with E. coli on artificial and patient-derived kidney stones, and they can impart a bactericidal effect, when stimulated with NIR to generate heat. This technique may possibly be extended to treating infected kidney stones in patients.

The biofilm-associated bacterial infections unrelated to indwelling devices.

Biofilms are microbial communities established in the self-produced extracellular substances that include up to 80% of associated microbial infections. During biofilm formation, bacterial cells shift from the planktonic forms to aggregated forms surrounded by an extracellular polymeric substance. The bacterial biofilm shows resistance against immune reactions as well as antibiotics and is potentially able to cause disorders by both device-related and nondevice-related infections. The nondevice-related bacterial biofilm infections include dental plaque, urinary tract infections, cystic fibrosis, otitis media, infective endocarditis, tonsillitis, periodontitis, necrotizing fasciitis, osteomyelitis, infectious kidney stones, and chronic inflammatory diseases. In this review, we will summarize and examine the literature about bacterial biofilm infections unrelated to indwelling devices.

The clinical observation of fifth generation EMS pneumatic lithotripsy combined with ultrasonic lithotripsy in the treatment of 22 cases of infectious kidney stones

目的 探讨使用第五代EMS气压弹道联合超声碎石清石术治疗感染性肾结石的临床效果观察。 方法 选取2015年4月至2018年3月在本院收治的22例感染性肾结石患者作为临床研究对象，所有患者均使用瑞士第五代EMS气压弹道联合超声清石系统进行治疗。 结果 所有患者均获成功，一期结石清除率达86.3%(19/22)；平均手术时间为58 min；住院时间为(8.5±2.3)d；术中平均估计失血量为150 mL，术后常规复查KUB，手术效果非常满意，术后2例出现高热，积极抗感染治疗后症状逐渐消失。其他患者未出现感染性休克、出血、损伤周围组织脏器等严重的并发症。 结论 对感染性肾结石患者采取瑞士第五代EMS超声联合气压弹道碎石清石系统进行治疗是安全有效的，能够有效提高结石清石率，减少手术时间，降低并发症，缩短住院时间，值得临床推广应用。

Лапароскопическая пиелолитотомия и ее роль в современной хирургии нефролитиаза

To determine the place of laparoscopic pyelolithotomy in surgical management of nephrolithiasis. We analyzed 16 laparoscopic pyelolithotomies performed in our clinic over the last few years for large and stag-horn stones of anomalous kidneys (n=8), the "giant" (>30-40 cc) monolithic stones of the large extrarenal pelvis (n=3), multiple stones of PCS with the stone burden of more or equal 40 cm (n=2) and large recurrent (after PCNL) kidney stones in patients at risk of bacteriotoxic complications of percutaneous nephroscopy (n=3). The age of the patients ranged from 39 to 72 years (mean age 51+/-8 years). The average density of stones was 1012 (160-1483) HU. There were no conversions to open surgery. The mean operating time of laparoscopic pyelolithotomy was 137 (96-255) minutes, flexible transabdominal pyelocalycoscopy 31.2 (12-110) min. The stone-free rate was 87%. Residual clinically insignificant stones were found in two (13%) patients with staghorn horseshoe kidney calculi and complex PCS. The preoperative hospital stay was 1 day, postoperative-from 2 to 18 (mean 6) days. We believe that laparoscopic pyelolithotomy supplemented by transabdominal flexible pyelocalycoscopy may be recommended for surgical management of patients with "giant", multiple and infected kidney stones, because the length of their percutaneous removal is beyond the recommended time intervals and it is accompanied by an increased risk of septic complications.

Riboswitches as Potential Targets for the Development of Anti-Biofilm Drugs.

In nature, bacteria can exist as single motile cells or as sessile cellular community, known as microbial biofilms. Bacteria within biofilms are embedded in a self-produced extracellular matrix that makes them more resistant to antibiotic treatment and responses of the host immune system. Microbial biofilms are very important in medicine since they are associated with several human diseases such as dental caries, periodontitis, otitis media, infective endocarditis, infectious kidney stones, osteomyelitis or prostatitis. In addition, biofilms formed on the surface of clinical devices such as pacemakers, implants and catheters are difficult to treat, which underlines the clinical relevance of biofilm formation. At the molecular level, the switch from the planktonic state to biofilm formation is regulated primarily by bis- (3'-5)-cyclic dimeric guanosine monophosphate (c-di-GMP). C-di-GMP performs its function by binding to a wide variety of proteins, but also to riboswitches. C-di-GMP riboswitches are RNA regulatory elements located in the 5'-untranslated regions (5'-UTRs) of RNA messengers (mRNA) from genes involved in virulence, motility and biofilm formation, which are regulated by changes in the intracellular concentration of c-di-GMP. This review discusses the role of c-di-GMP responsive riboswitches as potential targets for the design of anti-biofilm agents.

Chemical and morphological analysis of kidney stones: a double-blind comparative study

To compare chemical to morphological kidney stone composition analysis based on a sample of 50 stones retrieved from patients at a nephrology service. The chemical analysis was performed with a Bioclin® kit, while a 10-mm magnifying glass (10x; Prolabo, Paris, France) was employed in the morphological analysis. Findings obtained with the two methods were compared and classified as concordant (100% agreement), partly concordant (concordant for major components, discordant for minor components) or discordant (discordant for major components). In the chemical analysis, the most commonly observed major component was calcium (70%), followed by oxalate (66%), ammonium (56%), urate (28%) and carbonate (24%). In the morphological analysis, the most commonly observed major components were calcium phosphate and magnesium (32% each), followed by calcium oxalate monohydrate (24%), uric acid and urates (20% each), calcium oxalate dihydrate (18%) and cystine (6%). Infectious kidney stones were identified in 34% and 24% of cases by morphological and chemical analysis, respectively. Thirty-eight percent of the samples were classified as concordant, 52% were partly concordant and 10% were discordant. We suggest kidney stones be routinely submitted to both types of analysis for a better understanding of the mechanisms involved in lithogenesis.

Lithiase urinaire et sclérose en plaques

The aim of our study was to determine the nature of urinary stones and the main lithogenic process in patients with multiple sclerosis who developed secondary urolithiasis. This is a retrospective study of 60 urinary stones from 49 patients with lithiasis including 30 women and 19 men. The stones have been analyzed by optical microscopy and infrared spectroscopy. Our study clearly showed the net preponderance of phosphatic stones. Urinary stones were mainly located in the upper urinary tract (2/3 of cases). A particularly high frequency of struvite was observed among these stones (65% of cases in women and 45% of cases in men), thus suggesting the main lithogenic mechanism in multiple sclerosis patients was a urinary tract infection by urea splitting-bacteria. The second lithogenic process among these patients was metabolic. The high frequency of weddellite and brushite, especially in men, suggested that mainly hypercalciuria was involved in these metabolic stones. Urolithiasis in multiple sclerosis was mainly due to urinary tract infection, especially in women. Urinary tract infection related to bladder and sphincter disorders is extremely frequent and polymorphic in multiple sclerosis. Hence the importance of providing appropriate care to prevent complications of urinary tract infections and, especially, the ascending migration of microorganisms and the risk of pyelonephritis and of infectious kidney stones.

Managing Cyst Infections in ADPKD

Kidney and liver cyst complications are frequent in patients with autosomal dominant polycystic kidney disease (ADPKD). It has been estimated that 30 to 50% of patients with ADPKD experience some form of kidney infection during their lifetime (1,2). Patients may experience symptoms from cyst infections, cyst hemorrhage, or pain from ruptured or expanding cysts. The clinical determination of an infected kidney cyst may be difficult in a patient with ADPKD. The typical presentation of fever and abdominal pain carries a broad differential that includes pyelonephritis, infected kidney stones, perinephric or perihepatic abscess, cyst hemorrhage, or even intra-abdominal pathology unrelated to ADPKD. Conventional imaging with ultrasound, computed tomography, or magnetic resonance imaging scan may not be definitive in isolating the location of infection or even in differentiating cyst infection from cyst hemorrhage or pyelonephritis (3). A urine culture is often negative because kidney cysts become separated from their parent nephron, and one must rely more on blood cultures or cyst fluid aspiration when they can be obtained. The accurate diagnosis of cyst infection is of great importance, because it can influence the prompt initiation of antibiotics (particularly one that is widely known to penetrate cyst membranes), it can determine the need for extending the duration of antibiotic …

High power accelerator-based boron neutron capture with a liquid lithium target and new applications to treatment of infectious diseases

A new conceptual design for an accelerator-based boron neutron capture therapy (ABNCT) facility based on the high-current low-energy proton beam driven by the linear accelerator at SARAF (Soreq Applied Research Accelerator Facility) incident on a windowless forced-flow liquid-lithium target, is described. The liquid-lithium target, currently in construction at Soreq NRC, will produce a neutron field suitable for the BNCT treatment of deep-seated tumor tissues, through the reaction 7Li(p,n) 7Be. The liquid-lithium target is designed to overcome the major problem of solid lithium targets, namely to sustain and dissipate the power deposited by the high-intensity proton beam. Together with diseases conventionally targeted by BNCT, we propose to study the application of our setup to a novel approach in treatment of diseases associated with bacterial infections and biofilms, e.g. inflammations on implants and prosthetic devices, cystic fibrosis, infectious kidney stones. Feasibility experiments evaluating the boron neutron capture effectiveness on bacteria annihilation are taking place at the Soreq nuclear reactor.

Interaction of Shockwaves with Infected Kidney Stones: Is There a Bactericidal Effect?

Many calculi contain bacteria, which can remain active inside kidney stones and cause infection after lithotripsy. Reduction in renal infections after extracorporeal shockwave lithotripsy has been observed; however, results are controversial, and no information on the effect of shockwaves on bacteria inside kidney stones has been reported. The purpose of this research was to study whether bacteria inside kidney stones can be inactivated by shockwaves. A series of infected artificial kidney stones were exposed in vitro to either 90 or 400 shockwaves using a research electrohydraulic or a commercial piezoelectric lithotripter. Two types of stones (soft and hard) were manufactured by mixing gypsum cement and Vel-mix-stone with water. Half of the stones were inoculated with Salmonella typhimurium. The suspension containing stone powder and bacteria was inoculated on agar plates and incubated. Bactericidal action was defined as the logarithmic viability reduction. About 95% of the bacteria were inactivated with 400 shockwaves using the electrohydraulic lithotripter; however, most of the damage was associated with the electromagnetic emission (ultraviolet radiation and visible light) generated at the spark gap. After 2730 shockwaves to stones placed inside a black polypropylene bag, about 29% and 14% of all bacteria were inactivated with the piezoelectric and the electrohydraulic lithotripter, respectively. In this case, the electromagnetic radiation was blocked by the black bag. Bacteria inactivation is possible by in vitro shockwave application; however, according to our results, no significant bactericidal effect is expected during extracorporeal shockwave lithotripsy.

Inactivation of bacteria inoculated inside urinary stone-phantoms using intracorporeal lithotripters

Intracorporeal lithotripsy is used to treat a high percentage of urinary calculi. Urinary calculi may contain bacteria, which might cause septicemia after lithotripsy; however, little is known about the effects of lithotripters on the viability of microorganisms inside renal calculi. The objectives of this study were to evaluate the bactericidal effect, and the potential effect on intra-bacterial protein release of four different intracorporeal lithotripters on Escherichia coli (E. coli) inoculated inside artificial kidney stones. An electrohydraulic, a pneumatic, an ultrasonic, and a holmium-laser lithotripter were used to pulverize a set of infected kidney stones inside a test tube containing a saline solution. Two different energy levels were tested per lithotripter. The stones were manufactured by mixing gypsum cement and Vel-mix-stone with a suspension containing E. coli. Results were analyzed by analysis of variance. The release of intracellular protein was measured with a spectrophotometer. Bacteria inactivation was observed with all lithotripters. The highest percentage of inactivated bacteria was obtained with the electrohydraulic lithotripter. The smallest effect was observed using the holmium-laser lithotripter. A relatively high amount of intracellular protein was released into the saline solution after stone pulverization. Intracorporeal lithotripters inactivate a high percentage of bacteria during stone comminution; however, intracellular protein is released, increasing the probability of septicemia.

Chemical Countermeasures for the Control of Bacterial Biofilms: Effective Compounds and Promising Targets

The pathogenic nature of many infectious bacteria is enhanced by their ability to form surface-associated, protected communities known as "biofilms." Due to various factors, bacteria in biofilm communities display significantly greater resistance to traditional antimicrobial therapies than their planktonic brethren. This resistance complicates many common bacterial infections, resulting in recurrent ear infections, bacterial endocarditis, chronic lung infection in cystic fibrosis, infectious kidney stones, and surface infection of implanted medical devices. Owing to the serious nature of many biofilm-mediated infections and the near-complete dearth of effective strategies for treating them, efforts are underway to further understand the nature of bacterial infections involving biofilms and to discover and develop effective therapies to combat them. Particularly, several classes of chemical compounds have shown promise in combating biofilms when used in conjunction with traditional antimicrobials. The vast majority of these compounds exert their anti-biofilm properties through disruption of "quorum sensing," a common means of intercellular communication in bacterial communities that allows coordinated expression of virulence factors and facilitates formation of the oft-complex architecture of mature bacterial biofilms. Other new chemical entities are effective against biofilms without necessarily affecting quorum sensing. This review summarizes salient research in the development of effective chemical countermeasures for Gram-negative and Gram-positive bacterial infections involving biofilms.

Methods for the treatment and prevention of bacterial biofilms

Attachment of bacterial cells to host tissue is usually a prerequisite to colonisation and pathogenesis. Surface-associated bacteria often form tightly-packed, exopolysaccharide-encased colonies known as biofilms. Biofilms play a role in the pathogenesis of dental caries, periodontitis, infective endocarditis, cystic fibrosis pneumonia, prostatitis, osteomyelitis, otitis media, infectious kidney stones and other chronic infections. In addition, biofilms that form on indwelling catheters are responsible for a majority of hospital-acquired bloodstream, eye, ear, nose, throat and urinary tract infections; and biofilms that form on permanently implanted medical devices, such as artificial heart valves and prosthetic joints, are a major cause of device failure. Biofilms are notorious for their resistance to conventional antimicrobial agents. The role played by biofilms in human disease, combined with the importance of biofilms in industry, agriculture and biotechnology, has led to an exponential growth in the number of publications related to biofilms in recent years, and a concomitant growth in the number of biofilm-related patents. This review describes the current status of research on pathogenic biofilms with an emphasis on discoveries that have been the subjects of recent therapeutic patents.

Can the urinalysis predict urinary tract infection in patients with renal colic caused by kidney stones?

Study objectives: Patients who present with renal stones and an occult urinary tract infection may be difficult to detect and treat. Infected kidney stones are cited as an indication for admission by emergency medicine textbooks. Detection of infection by plain urinalysis can be complicated by gross hematuria, which can cause inaccurate readings. We hypothesize that standard plain urinalysis may not adequately detect occult infection. Methods: We performed a retrospective institutional review board–approved medical record review on all patients presenting with renal colic from July 2003 to October 2003 to a tertiary care emergency department with an annual census of 60,000. Patients were included if they presented with renal colic, confirmed radiographically, and had a urinalysis and urine culture performed. Patients were excluded if tests were performed improperly. Data were extracted in a standardized fashion by physician-investigators and included demographics and initial presenting data and radiology and laboratory reports. Predictive values and likelihood ratios were calculated. Results: Two hundred eighty-three consecutive patient charts were identified. Two charts were excluded because of technical difficulties during testing. Seven patients had a positive urine culture result, and 85 patients had negative urine culture results. Only 1 of the 7 patients presented with a fever. Positive predictive value of leukocyte esterase was 24%, with a negative predictive value of 97%, a positive likelihood ratio of 3.8, and a negative likelihood ratio of 0.35. Positive predictive value of nitrate was 17%, and negative predictive value was 93%, with a positive likelihood ratio of 2.41 and a negative likelihood ration of 0.90. Conclusion: In our retrospective study, plain urinalysis was able to adequately detect the presence of concomitant infection. Hematuria did not significantly alter the sensitivity and specificity of the urinalysis to detect infection.

Bacterial biofilms: an emerging link to disease pathogenesis.

The role of biofilms in the pathogenesis of some chronic human infections is now widely accepted. However, the criteria used to determine whether a given infection is caused by biofilms remain unclear. In this chapter we discuss three infections that are caused by biofilms--infectious kidney stones, bacterial endocarditis, and cystic fibrosis lung infections--and focus on the role of the biofilm in disease pathogenesis. Biofilms are also important as environmental reservoirs for pathogens, and the biofilm growth mode may provide organisms with survival advantages in natural environments and increase their virulence. The consequences of pathogens living in environmental biofilms and an analysis of some specific environmental biofilm systems are presented.

Observations of the Ultrastructure of Infected Kidney Stones

Struvite stones are formed as the result of urinary tract infection by urease-producing bacteria. Ultrastructural examination of calculi removed from a patient revealed bacteria incorporated throughout the stone matrix. Exopolysaccharide stained by ruthenium red was associated with most of the bacteria, but it represented only a small portion of the organic matrix in the stone. Localised deposits of calcium and phosphorus, components of carbonate-apatite, and magnesium, a struvite component, were detected in close proximity to the cells. Histochemical examinations revealed that several of the gram-negative bacteria within the stone matrix possessed high levels of urease activity. We propose that bacterial slime production, intimately involved in the initiation of stone matrix deposition, is less prominent in mature stones because of the increased incorporation of host-derived mucoproteins and mucopolysaccharides.