Infectious and inflammatory diseases of the kidney

Siderophore production as a biomarker for Klebsiella pneumoniae strains that cause sepsis: A pilot study

BACKGROUND/PURPOSE

Klebsiella pneumoniae bacteremia-induced sepsis is a clinically important condition with a high mortality rate and various known virulence factors. However, studies on the association of these virulence factors with the occurrence of K. pneumoniae bacteremia-induced sepsis are scarce. We aimed to investigate clinical variables and virulence factors in patients with K. pneumoniae bacteremia-induced sepsis.

METHODS

We retrospectively reviewed the medical records of 76 patients with K. pneumoniae bacteremia between January 2012 and July 2017. Patients were divided into sepsis (n = 25) and non-sepsis (n = 51) groups. Patient background characteristics, antimicrobial regimens, and prognosis were evaluated. We assessed the distribution of virulence factors related to K. pneumoniae, such as mucoviscosity, capsular polysaccharide, and siderophores. Siderophore production levels were determined by measuring the orange halo zone on chrome azurol S agar plate assay.

RESULTS

There were no intergroup differences in male-to-female ratio and age. Multivariable analysis revealed that siderophore production level (p < 0.01) was an independent predictor of K. pneumoniae bacteremia-induced sepsis. Furthermore, the optimal cut-off point of siderophore production to predict sepsis was 9.6 mm (sensitivity, 86%; specificity, 76%; AUC, 0.81).

CONCLUSION

Siderophore production was an independent predictor of sepsis caused by K. pneumoniae bacteremia. The optimal cut-off point for siderophore production for sepsis occurrence prediction was 9.6 mm. To improve outcomes, patients with K. pneumoniae bacteremia-induced sepsis with high siderophore production levels should be managed prudently.

Local antifungal immunity in the kidney in disseminated candidiasis

Disseminated candidiasis is a hospital-acquired infection that results in high degree of mortality despite antifungal treatment. Autopsy studies revealed that kidneys are the major target organs in disseminated candidiasis and death due to kidney damage is a frequent outcome in these patients. Thus, the need for effective therapeutic strategies to mitigate kidney damage in disseminated candidiasis is compelling. Recent studies have highlighted the essential contribution of kidney-specific immune response in host defense against systemic infection. Crosstalk between kidney-resident and infiltrating immune cells aid in the clearance of fungi and prevent tissue damage in disseminated candidiasis. In this review, we provide our recent understanding on antifungal immunity in the kidney with an emphasis on IL-17-mediated renal defense in disseminated candidiasis.

Blood culture reports by infectious disease physicians can improve prognosis of bacteremia, including weekend-onset cases

OBJECTIVES

Cases of positive blood cultures were previously reported by a microbiological technologist (MT) to an attending physician (AP), and the Antimicrobial Stewardship team provided medical assistance by grasping the situation at the morning meeting the next day. Since April 2018, MTs have reported positive blood cultures to an infectious disease physician (IDP), who proposes the management approach to the AP and provides weekend support. This study assessed the effectiveness of blood culture reports provided by IDPs to APs on outcomes of bacteremia, including weekend-onset cases.

METHODS

Patient characteristics and prognoses before (October 2017 to March 2018) and after intervention (April to September 2018) were compared.

RESULTS

The pre-intervention and post-intervention groups comprised 134 and 161 patients, respectively. Patients were more likely to be older (>65 years) in the post-intervention group (p < 0.05). There were no significant between-group differences in infection severity. The rate of de-escalation significantly increased from 38.1%-57.8% (p = 0.001). The rates of 28-day and in-hospital mortality reduced following the intervention (21.3% vs. 8.2% and 32.8% vs. 10.6%; p = 0.004 and p < 0.001, respectively). In-hospital mortality for weekend-onset cases also reduced following the intervention (33.3% vs. 12.9%, p = 0.01). Sepsis was a poor prognostic factor (OR 8.070, 95% CI 3.320-19.600, p < 0.001) and intervention was a good prognostic factor (OR 0.311, 95% CI 0.142-0.680, p = 0.003) affecting 28-day mortality in multivariate analysis.

CONCLUSIONS

Changes to blood culture result reporting protocols can improve outcomes of bacteremia, including weekend-onset cases.

CT imaging of acute and chronic pyelonephritis: a practical guide for emergency radiologists

Contrast-enhanced CT is not routinely indicated in uncomplicated urinary infections, but it may be necessary in patients with specific risk factors (i.e., diabetes, immunocompromised patients, history of stones, or prior renal surgery) or in patients not responding to antibiotics and in detecting complications of pyelonephritis. CT is the gold standard for imaging assessment of pyelonephritis severity. Imaging appearance of acute pyelonephritis, including focal (i.e., wedge-shaped zones of decreased attenuation or hypodense mass) and diffuse (i.e., global enlargement, poor parenchymal enhancement, lack of excretion of contrast, fat stranding) forms, needs to be differentiated from renal infarction, renal lymphoma, and interstitial nephritis. Chronic pyelonephritis-which appears as focal polar scars with underlying calyceal distortion, global atrophy, and hypertrophy of residual tissue-may mimic at imaging lobar infarcts. This pictorial essay reviews the CT imaging appearance of acute and chronic pyelonephritis, their uncommon subtypes, and their complications, with key features for early diagnosis. Their knowledge is crucial for emergency and abdominal radiologists to avoid misdiagnosis with malignancy and to guide the clinician towards the appropriate medical or surgical treatment.

Clinical and virulence factors related to the 30-day mortality of Klebsiella pneumoniae bacteremia at a tertiary hospital: a case-control study

Klebsiella pneumoniae bacteremia is a critical clinical presentation that is associated with high mortality. However, extremely few studies have investigated the virulence factors related to mortality of K. pneumoniae bacteremia in patients. The present study elucidated clinical and virulence factors associated with the 30-day mortality of K. pneumoniae bacteremia at a tertiary hospital. The medical records of 129 patients with K. pneumoniae bacteremia admitted to Osaka City University Hospital between January 2012 and December 2018 were retrospectively reviewed. Patient background characteristics, antimicrobial regimens, and prognosis were evaluated. Additionally, virulence factors were assessed using multiplex polymerase chain reaction to elucidate their association with K. pneumoniae. The 30-day mortality was 10.9% in patients with K. pneumoniae bacteremia. The male-to-female ratio, age, and underlying disease did not differ between the non-survivor and survivor groups. Multivariate analysis showed that sepsis (odds ratio (OR), 7.46; p = 0.005) and iutA (OR, 4.47; p = 0.046) were independent predictors associated with the 30-day mortality of K. pneumoniae bacteremia. Despite the relatively low 30-day mortality of patients with K. pneumoniae bacteremia, the treatment of those with sepsis and those infected with K. pneumoniae harboring iutA may require careful management for improving their outcomes.

Sonographic Evaluation of Genitourinary Inflammatory Pseudotumors and Its Mimics

Inflammatory pseudotumor is a relatively rare, nonneoplastic lesion composed of inflammatory cells and myofibroblastic spindle cells that can be identified on sonographic evaluation of the genitourinary system. These lesions are thought to be an inflammatory response to insults such as surgery, trauma, infection, or malignancy. Such lesions need to be distinguished from true neoplasms and other benign lesions, including inflammatory responses and infectious processes. Identification of inflammatory pseudotumors and its mimics is important for radiologists to guide patient treatment and follow-up. This pictorial essay presents sonographic features of inflammatory pseudotumors of the genitourinary tract and its mimics with cross-sectional imaging and histopathology, where available.

Clinical characteristics of bacteremia caused by hypermucoviscous Klebsiella pneumoniae at a tertiary hospital

This study aimed to assess the predictive factors of bacteremia due to hypermucoviscous Klebsiella pneumoniae (hvKP), as well as the mortality. The medical records of 114 patients with K. pneumoniae bacteremia who were divided into the hvKP (n = 24) and non-hvKP (n = 90) groups and were retrospectively reviewed. The male-to-female ratio, age, and underlying disease did not differ between the 2 groups. Mortality was higher among patients in the hvKP bacteremia group than in the non-hvKP bacteremia group (29.2% vs 6.7%). Multivariate analysis showed that the independent predictors associated with hvKP bacteremia were abscess (P = 0.01) and no antibiotic exposure (P = 0.02); thus, early assessment of these conditions is important. For patients with a history of abscess and no antibiotic exposure, it is necessary to administer treatment while keeping the risk of hvKP in mind.

EVALUATION OF THE THERAPEUTIC AND PREVENTIVE POTENTIAL OF THE MEDICINAL PRODUCT CANEPHRON N IN THE TREATMENT OF GESTATIONAL PYELONEPHRITIS IN PREGNANT WOMEN

Background: Gestational pyelonephritis (GP) is one of the most common and serious diseases of the middle and second half of pregnancy, which complicates approximately 6 % of pregnancies, and is one of the leading causes of non-obstetric pre-delivery hospitalization. Methods. The paper provides data from the open, multicentre, prospective, comparative (parallel group) study in 60 pregnant women diagnosed with gestational pyelonephritis, which were divided into two groups 30 subjects each. Patients in the treatment group received antibacterial therapy for 7 days + treatment with standard dosage of medicinal product Canephron N for 3 months. Patients in the control group received antibiotic therapy alone for 7 days. Results. The average age of pregnant women at the time of diagnosing was 23±6.23 years; it was the first pregnancy for 39 women (65 %). The most common complaints at admission to the in-patient department were as follows: lumbar pain (96.2 %), dysuria (70.2 %), rise in temperature above 38°C (64.4 %). Leukocyturia and bacteriuria were detected in 100 % of cases with prevalence of E. coli in 84.2 % (101 of 120) of cases. By 30 day in GP patients in the treatment group bacteriuria was detected in 2/30 (6.67 %) patients, and in the control group – in 5/30 (16.7 %) patients (p 1: 2 <0.05), by 60 day in the treatment group – 2/30 (6.67 %), in the control group – 8/30 (26.7 %) (p 1: 2 <0.05), respectively, by 90 day – 3/30 (10 %) and 10 (33.3 %), respectively (p 1: 2 <0.05). The disease relapsed in 1 of 30 (3.33 %) GP patients in the treatment group and 3/30 (10 %) patients in the control group (p 1: 2 <0.05) and 3/30 (10 %) patients in the treatment group with CP, and 7/30 (23.3 %) patients in the control group during the follow-up period (p 1: 2 <0.05). The use of the herbal medicinal product Canephron N in pregnant women with gestational pyelonephritis and in the acute exacerbations of chronic pyelonephritis has shown its high efficacy and undoubted therapeutic and prophylactic effect, good tolerability and decrease in the frequency of relapses of pyelonephritis.

Pictorial review: Renal ultrasound

Ultrasound (US) is the first-line imaging modality for evaluating azotemic patients for urinary obstruction and renal size. US is also valuable for distinguishing congenital variants and simple cystic lesions from renal masses. Doppler US is effective in detection of renal calculi and evaluation of vascular pathology. Unfortunately, renal US is limited in distinguishing causes of medical renal disease. The kidneys have a complex internal architecture with a highly variable appearance on US. This article illustrates non-neoplastic renal conditions, including normal and embryological variants, parenchymal, cystic, and vascular diseases. Renal infections, calcifications, and trauma and fluid collections are also discussed, with an emphasis on distinguishing US features and pathophysiology.

CT Imaging of Emergent Renal Conditions

The kidneys are paired intra-abdominal organs which provide essential functions and maintain homeostasis throughout the human body. Numerous disease processes affect the kidneys and cause acute renal dysfunction or other potentially catastrophic complications. These conditions can be broadly categorized into obstructive, infectious, hemorrhagic, traumatic, and vascular diseases. Imaging plays a vital role in the work-up and diagnosis of acute and emergent renal conditions. Evaluation of emergent renal conditions with a focus on CT imaging is discussed.

Perirenal fat stranding is not a powerful diagnostic tool for acute pyelonephritis

Purpose

Pyelonephritis, an upper urinary tract infection, is a serious infection that often requires hospitalization. However, the accurate diagnosis of acute pyelonephritis can be difficult, especially among older individuals who can present with unusual symptoms. Imaging with computed tomography (CT) is not unusual in the diagnosis of pyelonephritis, with some clinicians regarding perirenal fat stranding (PFS) as a characteristic finding. However, the sensitivity and specificity of PFS in diagnosing pyelonephritis are currently unknown. We therefore sought to clarify the relevance of PFS in diagnosing acute pyelonephritis.

Patients and methods

We conducted a case-controlled retrospective analysis of medical records. The pyelonephritis group included 89 patients who had been diagnosed with acute pyelonephritis, while the control group included 319 patients who had undergone percutaneous renal biopsy. CT findings were available for both groups. The frequency of PFS and its sensitivity and specificity for the diagnosis of acute pyelonephritis were investigated.

Results

The mean ages of the pyelonephritis and control groups were 74±15 years and 63±16 years, respectively. A total of 28% of men were in the pyelonephritis group vs 61% of men in the control group. The frequency of PFS was 72% in the pyelonephritis group vs 39% in the control group. Age and renal dysfunction were associated with an increased frequency of PFS. After adjusting for age, sex, and renal function using a propensity score analysis, the sensitivity, specificity, and positive likelihood ratio of PFS for diagnosing acute pyelonephritis were 72%, 58%, and 1.7, respectively.

Conclusion

The presence of PFS was not useful in diagnosing acute pyelonephritis.

Clinical Characteristics of Bacteremia Caused by Extended-spectrum Beta-lactamase-producing Escherichia coli at a Tertiary Hospital

Objective In recent years, infection caused by extended-spectrum beta-lactamase (ESBL)-producing organisms has become an important issue. However, comparative studies of the bacteremia caused by ESBL Enterobacteriaceae and non-ESBL Enterobacteriaceae are extremely rare in Japan. This study aimed to assess the risk factors and prognosis of patients with bacteremia due to ESBL Escherichia coli (E. coli). Methods The medical records of 31 patients with ESBL E. coli bacteremia and 98 patients with non-ESBL E. coli bacteremia who had been admitted to Osaka City University Hospital between January 2011 and June 2015 were retrospectively reviewed. The patient backgrounds, risk factors for infection, and prognosis were evaluated. Results The male-to-female ratio, mean age, underlying disease, leukocyte count, and C-reactive protein (CRP) level did not differ between the patients in the ESBL E. coli bacteremia and non-ESBL E. coli bacteremia groups. The mean Sequential Organ Failure Assessment (SOFA) score for patients with ESBL and non-ESBL E. coli bacteremia were 3.6 and 3.8, respectively. Further, the mortality did not differ between the two groups (9.7% vs 9.2%). However, the independent predictors associated with ESBL E. coli bacteremia according to a multivariate analysis were the use of immunosuppressive drugs or corticosteroids (p=0.048) and quinolones (p=0.005) prior to isolation. The mortality did not differ between the carbapenem and tazobactam/piperacillin (TAZ/PIPC) or cefmetazole (CMZ) groups for the patients with ESBL E. coli bacteremia. Conclusion Whenever we encountered patients with a history of immunosuppressive drug, corticosteroid, quinolone administration, it was necessary to perform antibiotic therapy while keeping the risk of ESBL E. coli in mind.

The Kallikrein-Kinin System: A Novel Mediator of IL-17-Driven Anti-Candida Immunity in the Kidney

The incidence of life-threatening disseminated Candida albicans infections is increasing in hospitalized patients, with fatalities as high as 60%. Death from disseminated candidiasis in a significant percentage of cases is due to fungal invasion of the kidney, leading to renal failure. Treatment of candidiasis is hampered by drug toxicity, the emergence of antifungal drug resistance and lack of vaccines against fungal pathogens. IL-17 is a key mediator of defense against candidiasis. The underlying mechanisms of IL-17-mediated renal immunity have so far been assumed to occur solely through the regulation of antimicrobial mechanisms, particularly activation of neutrophils. Here, we identify an unexpected role for IL-17 in inducing the Kallikrein (Klk)-Kinin System (KKS) in C. albicans-infected kidney, and we show that the KKS provides significant renal protection in candidiasis. Microarray data indicated that Klk1 was upregulated in infected kidney in an IL-17-dependent manner. Overexpression of Klk1 or treatment with bradykinin rescued IL-17RA-/- mice from candidiasis. Therapeutic manipulation of IL-17-KKS pathways restored renal function and prolonged survival by preventing apoptosis of renal cells following C. albicans infection. Furthermore, combining a minimally effective dose of fluconazole with bradykinin markedly improved survival compared to either drug alone. These results indicate that IL-17 not only limits fungal growth in the kidney, but also prevents renal tissue damage and preserves kidney function during disseminated candidiasis through the KKS. Since drugs targeting the KKS are approved clinically, these findings offer potential avenues for the treatment of this fatal nosocomial infection.

Multidetector Computed Tomography and MR Imaging Findings in Mycotic Infections

Fungal infections constitute a diverse spectrum of infections with variable clinical and imaging features. They are commonly opportunistic infections that affect immunocompromised individuals secondary to inherited or acquired disorders. Fungal infections may affect multiple organ systems and contribute to significant morbidity and mortality. Although the imaging features of some fungal infections are characteristic and permit their diagnosis, many mycotic infections manifest nonspecific findings. Definitive diagnosis often depends on histopathological analysis. Early diagnosis requires both clinical suspicion and supporting radiological evidence. Early treatment results in reduced morbidity and mortality. This article reviews the imaging findings in opportunistic and endemic fungal infections.

Acute Urinary Tract Disorders

Acute urinary tract disorders often manifest as flank pain and are a common complaint of patients who present to the emergency department. The pain is often a vague, poorly localized sensation that may have a variety of causes. Laboratory and clinical findings, such as hematuria, are neither sensitive nor specific for determining the cause of the flank pain. Accordingly, imaging is an important tool in determining a diagnosis and management plan. Patients with acute urinary tract disorders who present with pain include those with calculi as well as renal infection, vascular disorders, and hemorrhage.

Multimodality imaging of renal inflammatory lesions

Spectrum of acute renal infections includes acute pyelonephritis, renal and perirenal abscesses, pyonephrosis, emphysematous pyelonephritis and emphysematous cystitis. The chronic renal infections that we routinely encounter encompass chronic pyelonephritis, xanthogranulomatous pyelonephritis, and eosinophilic cystitis. Patients with diabetes, malignancy and leukaemia are frequently immunocompromised and more prone to fungal infections viz. angioinvasive aspergillus, candida and mucor. Tuberculosis and parasitic infestation of the kidney is common in tropical countries. Imaging is not routinely indicated in uncomplicated renal infections as clinical findings and laboratory data are generally sufficient for making a diagnosis. However, imaging plays a crucial role under specific situations like immunocompromised patients, treatment non-responders, equivocal clinical diagnosis, congenital anomaly evaluation, transplant imaging and for evaluating extent of disease. We aim to review in this article the varied imaging spectrum of renal inflammatory lesions.