Analysis of virulence profiles in clinical isolates of Klebsiella pneumoniae from renal abscesses: clinical significance of hypervirulent isolates

Introduction

Klebsiella pneumoniae can cause a wide range of infections. Hypervirulent K. pneumoniae (hvKp), particularly associated with the K1 and K2 capsular types, is an increasingly significant microorganism with the potential to cause invasive infections, including renal abscesses. Despite the rising prevalence of hvKp infections, information on renal abscesses caused by K. pneumoniae is limited, and the clinical significance of hvKp associated with specific virulence genes remains elusive.

Methods

This study performed at a 1200-bed tertiary hospital sought to identify the clinical and microbiological characteristics of renal abscesses caused by K. pneumoniae, focusing on various virulence genes, including capsular serotypes and multilocus sequence typing (MLST).

Results

Over an 8-year period, 64 patients with suspected renal abscesses were reviewed. Ten patients diagnosed with K. pneumoniae-related renal abscesses were ultimately enrolled in the study. Among the isolates from the 10 patients, capsular serotype K2 was predominant (40.0%), followed by K1 (30.0%). The most common sequence type by MLST was 23 (40.0%). In particular, six patients (60.0%) harbored specific genes indicative of hvKp: iucA, peg-344, rmpA, and rmpA2.

Conclusions

Our findings highlight the importance of hvKp as a pathogen in renal abscesses. Although the nature of hvKp is relatively unknown, it is widely recognized as a highly virulent pathogen that can infect relatively healthy individuals of various ages and simultaneously cause infections at multiple anatomical sites. Therefore, when treating patients with K. pneumoniae-related renal abscesses, caution is necessary when considering the characteristics of hvKp, such as potential bacteremia, multi-organ abscess formation, and metastatic spread.

Renal abscess complicating acute pyelonephritis in children: Two cases report and literature review

RATIONALE

To describe the diagnostic and treatment approaches of renal abscesses complicated with acute pyelonephritis in children.

PATIENT CONCERNS

Two children presented with fever, vomiting, and abdominal pain with no typical manifestations, like frequent urination, urgency, dysuria, hematuria, foam urine, and lumbago. Renal abscess complicating acute pyelonephritis was diagnosed by B-ultrasound and computed tomography enhancement. Moreover, inflammatory markers were elevated significantly, but routine blood and urine cultures were repeatedly negative. The empirical anti-infection therapy had no obvious effect. A pathogenic diagnosis was confirmed in case two, and macro gene detection in blood and urine guided the follow-up treatment.

DIAGNOSES

Both children were diagnosed with acute gastroenteritis on admission, but renal abscess complicating acute pyelonephritis were diagnosed by imaging examination.

INTERVENTIONS

Both children were given anti-infection therapy of third-generation cephalosporin, which had no obvious effect. Routine blood and urine cultures were repeatedly negative. Case one was changed to piperacillin sodium tazobactam. We further carried out blood and urinary metagenomic next-generation sequencing detection for case two. Meanwhile, meropenem and linezolid anti-infection treatment was given. The results showed overlapping infection with Escherichia coli and Enterococcus faecalis. According to the genetic test results, amoxicillin clavulanate potassium combined with nitrofurantoin were prescribed after discharge.

OUTCOMES

Clinical symptoms of the 2 children disappeared, the infection was controlled, and imaging showed that renal abscess complicated with acute pyelonephritis disappeared.

LESSONS

The clinical spectrum of renal abscess complicating acute pyelonephritis is vague, with no specific manifestations, and can be easily misdiagnosed. B-ultrasound and computed tomography enhancement are helpful in making a definite diagnosis. Moreover, the sensitivity of routine culture is low, and metagenomic next-generation sequencing might be helpful to detect pathogenic microorganisms and guided treatment. Early treatment with broad-spectrum antibiotics might have favorable outcomes.

Renal Abscess Drainage Using a Novel Transgastric Endoscopic Approach: A Case Report

Renal and perinephric abscesses are rare purulent infections within or around renal parenchyma, typically treated with antibiotics or various procedural approaches depending on abscess size. In this case report, we describe the novel use of a transgastric endoscopic ultrasound (EUS)-guided technique with placement of a stent for drainage between a renal abscess and the stomach in a patient who had failed attempted percutaneous drainage twice and where an open surgical approach was deemed inappropriate. The patient presented with a chief complaint of left flank pain, with CT revealing a ~4 x 4 cm renal abscess in the upper pole of the left kidney. Urology, Infectious Disease, and Interventional Radiology were consulted. Following two failed attempts at percutaneous drain placement, the patient elected for EUS-guided transgastric stent placement for drainage. The stent was removed by postoperative day two after significant decompression of the abscess. He was advised to follow up outpatient with Urology to confirm full renal abscess resolution.

Mycotic Aneurysm of the Thoracoabdominal Aorta: A Diagnostic Challenge

Mycotic aortic aneurysms (MAAs) are a rare form of aortic aneurysms that are associated with catastrophic outcomes if not diagnosed and treated on time. However, MAAs are a diagnostic challenge owing to their often nonspecific presentation. In this study, we present a case of a 42-year-old female with a pertinent history of intravenous drug use who presented with generalized body pain for two weeks and was found to have a mycotic thoracoabdominal aortic aneurysm (TAAA) extensively involving adjacent structures, including lungs with pleural cavity and upper renal pole. Not only does this case highlight the difficulty in early diagnosis and complex pathology of a mycotic TAAA, but it also illustrates the multidisciplinary approach required to effectively treat them.

Acute Acalculous Cholecystitis Associated with Abscesses-An Unknown Dual Pathology

(1) Introduction and Aims: Little is known about the relationship between renal pathology and gallbladder pathology, although the two organs (the gallbladder and the right kidney) are in close proximity to one another. If a renal abscess disseminates, the gallbladder would be one of the secondary organs involved. As the bile provides a favorable environment for the development of pathogenic germs, it allows for the development of acute cholecystitis, even if calculi are absent, thus resulting in the development of acute acalculous cholecystitis. The aim of our study was to analyze the association between acute acalculous cholecystitis (AAC) and renal abscesses. (2) Methods: A department-wide retrospective cohort observational study including 67 patients with renal abscesses, with a mean age of 34.5+/-16.21 years and with five males and 62 females, was conducted. All of the patients were examined by an abdominal ultrasound. The lab tests included CBC with differential liver enzymes and serum bilirubin (in order to assess alterations in the liver function which can be associated with AAC) and serum creatinine (in order to assess the renal function). Blood culture and urine culture tests were also performed. (3) Results: Of the 67 patients with renal abscesses, eight (11.94%) were associated with acute cholecystitis: four cases (5.97%) of acalculous cholecystitis and four cases (5.97%) of calculous cholecystitis, two of which presented biliary sludge (acute micro-calculous cholecystitis). All four cases of acute acalculous cholecystitis presented with sepsis, and there was one case of septic shock at onset. We did not observe an impairment in renal function in the patients presenting with acute acalculous cholecystitis, and hepatic impairment was inconstant and moderate. All of the cases had a favorable outcome after a prompt initiation of intensive antibiotic therapy; both the renal abscess and the acute acalculous cholecystitis receded without further complications. (4) Conclusions: The association of acute acalculous cholecystitis with renal abscesses could be related to the possibility of germ dissemination from the infectious focus. In the case of a renal abscess, careful clinical, lab, and imaging exams of the gallbladder are recommended in order to ensure early therapeutic intervention in the event of an association with acute acalculous cholecystitis.

Case report: Sarcomatoid urothelial carcinoma of the renal pelvis masquerading as a renal abscess

Sarcomatoid urothelial carcinoma (SUC), a rare tumor of the urinary tract epithelium, exhibits a high degree of malignancy and therefore a poor prognosis. Due to the absence of specific clinical presentations and imaging findings, SUC of the renal pelvis masquerades as a renal abscess is frequently under-recognized or misdiagnosed as benign inflammatory disease, resulting in delayed or erroneous treatment. Here, we report a patient with SUC of the renal pelvis who presented with a renal abscess. Repeated anti-inflammatory treatment was ineffective. Unexpectedly, cancerous cells were detected in subsequent exfoliative cytology of nephrostomy drainage fluid. In accordance with this, radical surgery and postoperative chemotherapy were conducted. Fortunately, neither recurrence nor metastasis occurred during a one-year follow-up.

Clinical features, outcomes and predictors of drug resistance and complications in patients admitted with pyelonephritis

Drug resistance and the presence of structural complications have significant implications for the treatment of acute pyelonephritis. We aimed to examine the predictors of drug resistance and complications in a retrospective cohort of patients admitted with pyelonephritis. 188 patients were included in this study. Patients who had had a urinary catheterization in the previous month and who lived outside the district in which the hospital was located were more likely to have ESBL infections. Carbapenem resistance was associated with recent urinary catheterization, a positive urine nitrate test, hypotension requiring vasopressors and the need for intensive care. A history of flank pain, urea level >13.3 mmol/L, a differential neutrophil count >75% and a urinalysis with >1000 leucocytes per high power field was associated with an increased risk of complications. A score derived from these variables to predict structural complications of infection had a sensitivity of 77.8% and a specificity of 67.1.

A Case of Acute Focal Bacterial Nephritis With Negative Pyuria and Urine Culture Test Results

Acute focal bacterial nephritis (AFBN) is a radiologically diagnosed acute localized kidney infection that appears in the continuum between a perinephric abscess and renal abscess. We report an unusual case of AFBN presenting without pyuria or positive urine cultures. A 42-year-old woman with chronic lower back pain who regularly used nonsteroidal anti-inflammatory drugs was admitted to our hospital with right-sided abdominal distention, fever, chills, and pain extending from the right lower abdomen to the back since two days. The physical examination revealed no abdominal or costovertebral angle tenderness. Urinalysis was negative. Abdominal ultrasound was notable for an indistinct nodular shadow (32 × 25 mm) on the upper pole of the right kidney. Abdominal contrast-enhanced computed tomography revealed a wedge-shaped area with a minimal uptake of the contrast in the right kidney. The patient was admitted to the hospital, and antimicrobial therapy was started for AFBN. Antibiotics were administered intravenously for one week and orally for two weeks. No relapse of symptoms was observed during the four-month follow-up period. This case report suggests the importance of considering AFBN as a differential diagnosis for cases of idiopathic fever and lateral pain or back pain, even when pyuria and urine culture test results are negative.

Systemic Bacillus Calmette-Guérin (BCG) Infection With Renal Involvement: A Rare Complication of BCG Immunotherapy

Intravesical instillation of bacillus Calmette-Guérin (BCG) is the adjuvant therapy for superficial urothelial carcinoma of the bladder with the lowest recurrence rates and is well tolerated with minor and self-limiting adverse effects. Serious complications, such as systemic BCG infection, are uncommon as the diagnosis is difficult and, in the majority of cases, Mycobacterium bovis cannot be isolated. We describe a case of a man who presented with prolonged fever associated with polyuria, dysuria, anorexia, and significant weight loss, refractory to several courses of appropriate antibiotic therapy. After an exhaustive investigation, the underlying diagnosis of systemic BCG infection with renal involvement was considered. Antituberculosis treatment resulted in a marked clinical and radiological recovery, supporting this diagnosis.

Renal abscesses in children: an 11-year retrospective study and review of the literature

BACKGROUND

There is limited literature on renal abscesses in children and therefore no consensus on management. The objectives of this study were to describe renal abscesses in a contemporary paediatric Australian population and present a 20 year review of the literature.

METHODS

An 11 year retrospective comparative study was conducted of paediatric patients with renal abscesses. A literature review of all eight original articles on paediatric renal abscesses from January 2001 to December 2021 was performed.

RESULTS

Fourteen children with a mean age of 11 years were diagnosed with a renal abscess on ultrasound and/or computed tomography. The most common presenting symptoms were fever (n = 13, 93%) and flank or abdominal pain (n = 12, 86%). The most common causative organisms were Staphylococcus aureus (n = 7, 50%) and Escherichia coli (n = 4, 29%). All renal abscesses less than 3 cm were managed with antibiotics alone. Five out of nine abscesses 3-5 cm were managed with percutaenous drainage (56%). Two multi-loculated abscesses greater than 5 cm required open drainage in theatre (100%).

CONCLUSIONS

The most common causative organism in the North Queensland population was S. aureus, with a higher incidence of MRSA. This should be taken into consideration when prescribing empirical antibiotics. Most renal abscesses in children that are less than 3 cm in size can be managed with antibiotic therapy only. The evidence for management of larger abscesses is less clear, but where clinically appropriate conservative management with antibiotic therapy should be considered in the first instance, with percutaneous drainage in cases of antibiotic failure.

A case of Citrobacter koseri renal abscess and review of the literature

Citrobacter species are anaerobic gram-negative bacteria that are known to cause infections in immunocompromised hosts, particularly in hospital settings. Their opportunistic nature and tendency to develop antibiotic resistance make Citrobacter species challenging to treat. Renal or perinephric abscess formation as a result of Citrobacter infection is uncommon, having only previously been reported in four cases. We present a case of a 70-year-old man with diabetes and prostate cancer who was diagnosed with an 18 cm perinephric and a 10 cm perihepatic abscess caused by Citrobacter koseri. The patient required drains and re-positioning of the drains multiple times in addition to a prolonged course of antibiotics to achieve complete radiographic resolution. This case highlights the challenges in treating renal and perinephric abscess, as it required drain re-placements two additional times after the initial placement and an additional 4 weeks of antibiotics. Successful treatment for larger abscesses usually requires a two-arm approach, with antibiotics in combination with either percutaneous or surgical abscess drainage.

Xanthogranulomatous Pyelonephritis with Pyonephrosis and Renal Abscess in a Young Adult: A Consequence of Neglected Urinary Tract Infection Leading to Nephrectomy

Xanthogranulomatous pyelonephritis (XGP) is a rare form of chronic pyelonephritis, which is challenging to diagnose because its clinical presentation mimics other entities and is commonly associated with a history of urinary tract obstruction. We report a case of XGP in a young adult without nephrolithiasis and urinary tract obstruction. A 23-year-old woman presented with intermittent abdominal pain in the right upper quadrant persisting for the last ten months. The pain was dull, poorly localized, and started spreading to the right back, right shoulder, and right thigh in the last three months. Other complaints included fever, chills, pain during urination, and nausea. The patient had a history of infrequent urination, recurrent urinary tract infections (UTIs), and a low fluid intake. A physical examination revealed that the patient had right upper quadrant abdominal tenderness and right costovertebral angle tenderness. Laboratory findings showed leukocytosis and neutrophilia. The radiological examination revealed a round mass in the superior pole of the right kidney with mixed cystic and solid components, and a well-defined margin. It further enlarged from 4.5 cm to 10.6 cm in diameter in three months. The urologist performed a total right nephrectomy. The histopathological examination showed XGP with renal abscess. Proteus mirabilis was identified from the pus specimen culture. XGP should be considered in the diagnosis of patients having chronic UTI presented with or without the findings of urinary tract obstruction.

Ruptured Renal Abscess From Streptococcus agalactiae Invasion in a Postpartum Female

Streptococcus agalactiae (Group B Streptococcus or GBS)is an exceptionally rare causative organism of a ruptured renal abscess. We report a case of this normally commensal organism causing a large ruptured renal abscess in a 17-year-old postpartum female. Although S. agalactiae is known to cause postpartum neonatal morbidity and mortality, it has rarely caused invasive infections in the last 20 years in adults. While this diagnosis often presents with nonspecific findings that can easily be overlooked during the postpartum period, the patient responded well to the established treatment of broad-spectrum antibiotics and a percutaneous drain.

A Narrative Review on the Role of Staphylococcus aureus Bacteriuria in S. aureus Bacteremia

Staphylococcus aureus bacteriuria (SABU) can occur in patients with S. aureus bacteremia (SAB). However, little is known on the (molecular) pathomechanisms of the renal passage of S. aureus. This review discusses the epidemiology and pathogenesis of SABU in patients with SAB and identifies knowledge gaps. The literature search was restricted to the English language. The prevalence of SABU in patients with SAB is 7.8%-39% depending on the study design. The main risk factor for SABU is urinary tract catheterization. SABU in SAB patients is associated with increased mortality. Given present evidence, hematogenous seeding-as seen in animal models-and the development of micro-abscesses best describe the translocation of S. aureus from blood to urine. Virulence factors that might be involved are adhesion factors, sortase A, and coagulase, among others. Other potential routes of bacterial translocation (eg, transcytosis, paracytosis, translocation via "Trojan horses") were identified as knowledge gaps.

Diagnostic bias during the COVID-19 era: COVID-19 or renal abscess?

Introduction:

The Coronavirus disease-2019 (COVID-19) has been declared as a pandemic in March 2020 by the World Health Organization (WHO). Since then, this pandemic has dramatically affected the entire world, even radically influencing the way patients are framed at triage. Symptoms and tests in most cases lead to a correct diagnosis; however, error may be around the corner.

Case report:

A 60 years old patient was referred with weight loss, fatigue and mild fever for 3 weeks as he was working in a COVID-19 ward. After a positive swab and chest CT scan, he was admitted in the hospital and treated as mild COVID-19 patient. A CT scan performed after the patient was discharged revealed a renal lesion misidentified as a tumor then clarified to be an abscess which retrospectively appears to be the main cause of his symptoms.

Conclusion:

Clinicians should consider other life-threatening disease in the differential diagnosis of patients presenting with similar symptoms to minimize mistakes and avoid further unnecessary investigations.

Renal and perinephric abscesses involving Lactobacillus jensenii and Prevotella bivia in a young woman following ureteral stent procedure

 is a gram-positive bacillus in the female genital tract believed to be a commensal organism that inhibits the growth of more virulent pathogens. Prevotella bivia is a gram-negative bacillus species also typically commensal in the female genital tract. Lactobacillus as the primary causative agent in perinephric abscesses and bacteremia has been documented, albeit very uncommon and opportunistic. Prevotella bivia is not classically associated with perinephric abscesses but has been implicated in rare cases of pelvic inflammatory disease and tubo-ovarian abscesses. In this report, we present a 26-year-old immunocompetent woman with a recent history of nephrolithiasis treated with lithotripsy, ureteral stent placement and removal, and antibiotics who was admitted for fever and severe right flank pain. Imaging showed a right-sided renal and perinephric abscesses colonized by Lactobacillus jensenii and Prevotella bivia. Blood cultures were also positive for Lactobacillus species. Per literature review, intravenous ceftriaxone and metronidazole were administered with successful resolution of abscesses and negative repeat blood cultures. To our knowledge, this is the first case of simultaneous renal system abscesses caused by Lactobacillus and Prevotella species. Nephrolithiasis and prior antibiotics likely contributed to the opportunistic pathogenesis in this otherwise immunocompetent patient.

Acute Focal Bacterial Nephritis: Two Cases and Review of the Literature

Rationale:

Acute focal bacterial nephritis (AFBN) has mainly been reported in pediatrics. It may be an underdiagnosed condition in adults because it resembles acute pyelonephritis (APN) in its clinical presentation.

Presenting concerns of the patients:

Two young women (25 and 27 years old, respectively) presented with complaints compatible with a diagnosis of APN. However in both, fever was of high grade, persistent for several days in spite of antibiotic administration, and there was demonstrated worsening of the inflammatory biomarkers. A contrast-enhanced computed tomography (CECT) led to the diagnosis in both cases.

Diagnoses:

Contrast-enhanced computed tomography reveals the most sensitive and specific images of AFBN. This includes wedge-shaped lesions with decreased enhancement, which may be focal or multifocal.

Interventions (including prevention and lifestyle):

Antibiotic therapy for at least 3 weeks.

Outcomes:

Resolution of AFBN was obtained after 3 weeks of antibiotics.

Lessons learned:

Our 2 cases illustrate the importance of CECT imaging to confirm the diagnosis of AFBN. Interstitial bacterial inflammation may have a worse prognosis if not diagnosed early and efficiently treated. Unlike APN, the management of AFBN requires at least 3 weeks of antibiotics to prevent the development of renal scarring and renal abscess.

Invasive Ureaplasma Infection in Patients Receiving Rituximab and Other Humoral Immunodeficiencies-A Case Report and Review of the Literature

Ureaplasma species are small, fastidious bacteria that frequently colonize the lower reproductive tract of asymptomatic hosts. These organisms have been well described to cause chorioamnionitis, neonatal infection, and urethritis, and to a lesser degree surgical site infection and infection in transplant recipients. Outside of these settings, invasive Ureaplasma infections are rare. We describe the case of a young woman receiving rituximab for multiple sclerosis who presented with fever and bilateral renal abscesses due to Ureaplasma spp., which was successfully treated with oral doxycycline. We searched the literature for cases of invasive Ureaplasma infection and found a patient population that predominates with humoral immunodeficiency, either congenital or iatrogenic. Diagnostic and therapeutic interventions are discussed.

Emphysematous pyelonephritis: Case report and literature overview

INTRODUCTION

Emphysematous pyelonephritis is a rare necrotizing infection of the kidney with a poor prognosis. If it occurs in patients with a reduced general condition, this infection is life threatening. Early diagnosis is made by computed tomography. Treatment options are drainage and intensive care or immediate nephrectomy in severe cases.

CASE DESCRIPTION

A 73-year-old woman in a poor general condition presented with a fulminant urosepsis. Computed tomography revealed an impressive abscess formation of the right kidney with free air retro and intraperitoneal. The diagnosis of emphysematous pyelonephritis was made. Besides septicemia, she had a multiorgan failure including kidney and liver function deterioration. Nephrectomy was performed immediately. The postoperative course was successful with a complete stabilization of the kidney and liver function and reconvalescence of the patient.

DISCUSSION

The widespread availability of imaging techniques leads to early diagnosis and a reduction of mortality of renal and periphrenic abscesses and even of emphysematous pyelonephritis. However, severe cases have a poor outcome and require aggressive and immediate therapy. Besides systemic antibiotic therapy and percutaneous and surgical drainage, radical nephrectomy is a viable therapy option and should be performed immediately in patients with several risk factors, poor prognosis, and extensive findings.

CONCLUSION

Radical nephrectomy being performed immediately seems to be the optimal management in patients with acute emphysematous nephritis and urosepsis.

Klebsiella pneumoniae Renal Abscess and Peritonitis in a Peritoneal Dialysis Patient: A Novel Route of Infection

We present a peritoneal dialysis (PD) patient who had a renal biopsy performed during an episode of urosepsis and subsequently presented with a renal abscess at the biopsy site along with concurrent peritonitis. Microbiology from the PD effluent and from the renal abscess were both positive for Klebsiella pneumoniae We propose that the PD peritonitis was the result of seeding of the peritoneal cavity with bacteria from the renal abscess. Successful treatment was achieved through drainage of the abscess and intraperitoneal antibiotics.

Infected renal hematoma in a healthy adolescent with no renal structural anomaly

Renal abscesses are uncommon in otherwise healthy children and adolescents who have no underlying renal structural anomalies. A previously healthy, immunocompetent, 14-year-old male without a history of abdominal trauma or urinary tract infection (UTI) was found to have a renal hematoma that became infected and developed into a renal abscess. He presented with a 2-day history of nausea, vomiting, fever and 1-day history of abdominal pain that radiated to the right flank. Clinical examination, blood work, and initial imaging indicated likely infection; however, findings were normal on urinalysis and urine culture had no growth. Complete blood count (CBC) showed a leukocytosis with a left shift. Renal ultrasound showed a 4-cm mass-like area of liquefaction in the upper pole of the right kidney, confirmed by abdominal computed tomography (CT) scan with and without contrast. Intravenous ceftriaxone was started and the patient continued to improve. He was discharged on hospital day 6 after remaining afebrile for over 20 hours and inflammatory markers continued to decrease. Intravenous ceftriaxone was continued, and oral clindamycin was added. Both antibiotics were discontinued on day 24 since onset of illness.

Perihepatic, Pulmonary, and Renal Abscesses Due to Spilled Gallstones

BACKGROUND

Spilled gallstones are common during laparoscopic cholecystectomy; however, they rarely lead to postoperative complications. Perihepatic abscesses develop in < 0.1% of patients with spilled gallstones and are typically contained within the peritoneal cavity.

CASE REPORT

We present a 57-year-old man with history of cholecystectomy 2 years prior who presented with cough and flank pain and was discovered to have a perihepatic abscess invading his lung and kidney secondary to a spilled gallstone. WHY SHOULD EMERGENCY PHYSICIANS BE AWARE OF THIS?: Although most perihepatic abscesses can be treated with percutaneous drainage and antibiotics, abscesses secondary to spilled gallstones usually require open or laparoscopic surgery to drain the abscess and retrieve the gallstone. Prompt identification of spilled gallstones in patients with intra-abdominal and intrathoracic abscesses can thereby guide disposition and decrease morbidity and mortality.

Acacetin Protects Mice from Staphylococcus aureus Bloodstream Infection by Inhibiting the Activity of Sortase A

Staphylococcus aureus (S. aureus) is a major cause of infection in hospitals and communities. Widespread dissemination of multi-drug resistant S. aureus is a serious threat to the health of humans and animals. An anti-virulence strategy has been widely considered as an alternative therapeutic approach. Inhibitors of virulence factors are able to treat S. aureus infections without influencing the growth or viability of bacteria and rarely lead to bacterial resistance. Sortase A (SrtA) is a membrane-associated cysteine transpeptidase that catalyzes up to 25 surface proteins that covalently bind to cell wall peptidoglycans. In S. aureus, most of these surface proteins have been identified as important virulence factors that are vital in bacterial pathogenesis. In the present study, we show that acacetin, a natural flavonoid compound, inhibits the activity of SrtA in S. aureus (IC₅₀ = 36.46 ± 4.69 μg/mL, 128 μM) which affects the assembly of protein A (SpA) to cell walls and reduces the binding of S. aureus to fibrinogen (Fg). The mechanism of the interaction between acacetin and SrtA were preliminarily discussed using molecular dynamics simulations. The results suggested that acacetin adopted a compact conformation binding at the pocket of the SrtA via residues Arg-139 and Lys-140. By performing an animal infection model, we demonstrated that acacetin was able to protect mice from renal abscess formation induced by S. aureus and significantly increased survival rates. Taken together, these findings suggest that acacetin may be a promising candidate for the development of anti-S. aureus drugs.

Splenectomy and risk of renal and perinephric abscesses: A population-based cohort study in Taiwan

Little epidemiological research is available on the relationship between splenectomy and renal and perinephric abscesses. The purpose of the study was to examine this issue in Taiwan.We conducted a population-based retrospective cohort study using the hospitalization dataset of the Taiwan National Health Insurance Program. A total of 16,426 participants aged 20 and older who were newly diagnosed with splenectomy from 1998 to 2010 were assigned to the splenectomy group, whereas 65,653 sex-matched, age-matched, and comorbidity-matched, randomly selected participants without splenectomy were assigned to the nonsplenectomy group. The incidence of renal and perinephric abscesses at the end of 2011 was measured in both groups. The multivariable Cox proportional hazards regression model was used to measure the hazard ratio (HR) and 95% confidence interval (CI) for risk of renal and perinephric abscesses associated with splenectomy and other comorbidities including cystic kidney disease, diabetes mellitus, urinary tract infection, and urolithiasis.The overall incidence rate of renal and perinephric abscesses was 2.14-fold greater in the splenectomy group than that in the nonsplenectomy group (2.24 per 10,000 person-years vs 1.05 per 10,000 person-years, 95% CI 2.02, 2.28). After controlling for sex, age, cystic kidney disease, diabetes mellitus, urinary tract infection, and urolithiasis, the multivariable regression analysis demonstrated that the adjusted HR of renal and perinephric abscesses was 2.24 for the splenectomy group (95 % CI 1.30, 3.88), when compared with the nonsplenectomy group. In further analysis, the adjusted HR markedly increased to 7.69 for those comorbid with splenectomy and diabetes mellitus (95% CI 3.31, 17.9).Splenectomy is associated with renal and perinephric abscesses, particularly comorbid with diabetes mellitus. In view of its potential morbidity and mortality, clinicians should consider the possibility of renal and perinephric abscesses when patients with splenectomy present with fever of unknown origin.

The therapeutic effect of chlorogenic acid against Staphylococcus aureus infection through sortase A inhibition

The emergence and wide spread of multi-drug resistant Staphylococcus aureus (S. aureus) requires the development of new therapeutic agents with alternative modes of action. Anti-virulence strategies are hoped to meet that need. Sortase A (SrtA) has attracted great interest as a potential drug target to treat infections caused by S. aureus, as many of the surface proteins displayed by SrtA function as virulence factors by mediating bacterial adhesion to specific organ tissues, invasion of host cells, and evasion of the host-immune responses. It has been suggested that inhibitors of SrtA might be promising candidates for the treatment and/or prevention of S. aureus infections. In this study, we report that chlorogenic acid (CHA), a natural compound that lacks significant anti-S. aureus activity, inhibit the activity of SrtA in vitro (IC50 = 33.86 ± 5.55 μg/ml) and the binding of S. aureus to fibrinogen (Fg). Using molecular dynamics simulations and mutagenesis assays, we further demonstrate that CHA binds to the binding sites of C184 and G192 in the SrtA. In vivo studies demonstrated that CHA prevent mice from S. aureus-induced renal abscess, resulting in a significant survival advantage. These findings indicate that CHA is a promising therapeutic compound against SrtA during S. aureus infections.

Renal Abscess Caused by Salmonella Typhi

Salmonella typhi is a true pathogen, which is capable of causing both intestinal and extraintestinal infections. Unusual presentations of Salmonella should always be kept in mind as this organism can cause disease in almost any organ of the body. S. typhi has been reported to cause the life-threatening infections such as meningitis, endocarditis, myocarditis, empyema, and hepatic abscess. Renal involvement by S. typhi is a relatively rare presentation. We report a case of renal abscess caused by S. typhi in an afebrile, 10-year-old child who did not have any clinical history of enteric fever. To our knowledge, this is the first reported case of isolation of S. typhi from the renal abscess, and interestingly this isolate was found to be resistant to quinolones.

A coagulase-negative and non-haemolytic strain of Staphylococcus aureus for investigating the roles of SrtA in a murine model of bloodstream infection

Sortase A (SrtA) is a cysteine transpeptidase and virulence factor from Staphylococcus aureus (S. aureus) that catalyses the attachment and display of surface proteins on the cell wall, thereby mediating bacterial adhesion to host tissues, host-cell entry and evasion of the immune response. As a result, SrtA has become an important target in the development of therapies for S. aureus infections. In this study, we used the new reference strain S. aureus Newman D2C to investigate the role of SrtA in a murine model of bloodstream infection, when the impact of coagulase and haemolysin is excluded. The results suggested that deletion of SrtA reduced the bacterial burden on the heart, liver and kidneys by blunting the host proinflammatory cytokine response at an early point in infection. Kidneys, but not heart or liver, formed abscesses on the sixth day following non-lethal infection, and this effect was diminished by SrtA mutation. These findings indicate that SrtA is a determining virulence factor in lethality and formation of renal abscesses in mice followed by S. aureus bloodstream infection. We have thus established a convenient in vitro and mouse model for developing SrtA-targeted therapeutic strategies.

Role of diffusion-weighted MRI in acute pyelonephritis: a prospective study

BACKGROUND

Imaging is vital in diagnosis of complicated pyelonephritis and has been traditionally performed by computed tomography (CT). However, CT with contrast agents cannot be performed in patients with renal failure. Diffusion-weighted (DW) magnetic resonance imaging (MRI) has the potential to overcome this disadvantage.

PURPOSE

To prospectively evaluate the accuracy of quantitative apparent diffusion coefficient (ADC) values to differentiate nephritis from renal abscesses in patients with pyelonephritis.

MATERIAL AND METHODS

Forty-two patients with clinical and laboratory diagnosis of pyelonephritis underwent CT and DW MRI examinations. Diffusion images were obtained by using a non-breath-hold, single-shot echo-planar sequence with b values of 0, 600, and 1000 s/mm(2). Circular regions of interest were places on areas of nephritis, normal renal parenchyma, and renal abscesses as localized by CT and DW MRI images to obtain the ADC values of each of these regions. The ADC values of these three different tissue types were statistically compared using the one-way analysis of variance test for statistical significance. A P value <0.05 was considered to be statistically significant.

RESULTS

For the diagnosis of pyelonephritis, DW MRI had a higher sensitivity of 95.3% as compared to that of non-contrast CT (66.7%) and contrast-enhanced CT (88.1%). Areas of nephritis had significantly lower ADC values (P < 0.001) than the normal renal cortical parenchyma. Also, renal abscesses had significantly lower ADC values (P < 0.001) than areas of nephritis. However, CT is more useful for the diagnosis of renal calculi and emphysematous pyelonephritis.

CONCLUSION

ADC values derived from the diffusion sequence have significantly lower values in renal abscesses than in areas of nephritis.

Primary adenocarcinoma of the renal pelvis: histologic features of a stepwise process from intestinal hyperplasia to dysplasia in a patient with chronic renal abscess

Pure adenocarcinomas of the urothelium are very rare and their location in the pelvis is uncommon. Although their pathogenesis is not well defined, adenocarcinomas are likely to originate from neoplastic transformation of the glandular cells of the urothelial intestinal metaplasia usually arising in response to chronic irritating stimuli, such as long-duration inflammation, urolithiasis, and hydronephrosis. We report a case of an 81-year-old woman who underwent right nephrectomy for relapsing renal abscess due to a staghorn calculus. Histological examination disclosed an infiltrating adenocarcinoma arising from a tubulovillous adenoma with the surrounding pelvic mucosa showing a sequence of intestinal metaplasia, low- and high-grade villous adenoma, and invasive adenocarcinoma, supporting the hypothesis of cancer progression due to chronic inflammation from the urothelium through the metaplasia step.

Complicated urinary tract infections associated with diabetes mellitus: Pathogenesis, diagnosis and management

Diabetes mellitus has a number of long-term effects on the genitourinary system. These effects predispose to bacterial urinary tract infections (UTIs) in the patient with diabetes mellitus. Complicated UTIs are also common and potentially life-threatening conditions. They include emphysematous pyelonephritis, emphysematous pyelitis/cystitis, xanthogranulomatous pyelonephritis, renal/perirenal abscess, and renal papillary necrosis. Improved outcomes of these entities may be achieved by early diagnosis, knowledge of common predisposing factors, appropriate clinical and radiological assessment, and prompt management. Herein we review complicated UTIs associated with diabetes mellitus in terms of pathogenesis, clinical manifestations, radiological features, and current management options.

Effect of diabetes on mortality and length of hospital stay in patients with renal or perinephric abscess

OBJECTIVES

We compared the risk of in-hospital mortality and the length of hospital stay between diabetic and non-diabetic patients hospitalized for renal or perinephric abscess.

METHOD

The data analyzed in this study were retrieved from Taiwan's National Health Insurance claims. The risk of in-hospital mortality and the length of hospital stay were compared between 1,715 diabetic patients, hospitalized because of renal or perinephric abscess in Taiwan between 1997 and 2007, and a random sample of 477 non-diabetes patients with renal or perinephric abscess.

RESULTS

The in-hospital mortality rates from renal or perinephric abscess for the diabetic patients and the non-diabetic patients were not different, at 2.3% and 3.4%, respectively. However, diabetes was significantly associated with a longer length of hospital stay among patients with renal abscess, by 3.38 days (95% confidence interval [CI]: 1.59-5.17).

CONCLUSIONS

Diabetes does not increase the risk of in-hospital mortality from renal or perinephric abscess. Nevertheless, appropriate management of patients with diabetes and concurrent renal or perinephric abscess is essential to reduce the length of hospital stay.