Magnetic resonance imaging diagnosis of acute focal bacterial nephritis with MERS

Utility of MRI in diagnosis and treatment of acute focal bacterial nephritis with abscess formation in a paediatric patient

Contrast-enhanced CT is the gold standard for the diagnosis of acute focal bacterial nephritis (AFBN). However, owing to radiation exposure and the possibility of contrast agent-induced side effects, contrast-enhanced CT is not always recommended for children. A paediatric patient presenting with a 1-week history of fever was admitted to our hospital. After a urine culture detected Escherichia coli, antimicrobials were administered; however, the fever had not resolved by the third day of hospitalisation. Renal diffusion-weighted MRI was performed and showed multiple wedge-shaped areas of high signal intensity in the right kidney. Additionally, the same site showed an area of low signal intensity in the apparent diffusion coefficient, and a diagnosis of AFBN with abscess was made. A chronic-phase technetium-99m-labelled dimercaptosuccinic acid renal scintigraphy was performed, but there was no renal scarring. MRI may be a more suitable tool for diagnosing AFBN given no radiation exposure.

Clinical features of acute focal bacterial nephritis in adults

Acute focal bacterial nephritis (AFBN) is a localized bacterial infection of the kidneys presenting as an inflammatory mass that can develop into renal abscess. The current reports on AFBN mostly are among children and rarely described in adults. This study was aimed to analyze the clinical features of AFBN in adults and make a review for the disease to give the clinicians some clues to suspect and recognize it in adults. From January 2014 to December 2019, AFBN was diagnosed by contrast-enhanced computed tomography (CT) in 238 adults at the Department of Nephrology, the Second Hospital of Hebei Medical University, Shijiazhuang, China. We reviewed the clinical records of these patients and asked them about their post-discharge status via telephone follow-up. Of all the patients, 195 were female and 43 were male, the median age were 46.87 years. 86.13% presented with fever, 55.89% presented with lower urinary tract symptoms and 97.9% presented with pyuria. In renal ultrasonography, abdominal findings were seen only 22.69% patients. E.coli accounted for 74.73% of the isolated pathogen. After 4 weeks of treatment, the patients had no recurrence of symptoms. We recommend that when a patient presents clinically with acute pyelonephritis, but the fever persist longer after antimicrobial treatment (≥ 4 days in our study), AFBN should be suspected. For the diagnosis, contrast-enhanced CT is the “gold standard”, magnetic resonance imaging (MRI) may be a good option, but the ultrasonography is probably not satisfied. 3–4 weeks of antibiotic therapy may be appropriate for AFBN in adults.

Increased cytokines/chemokines and hyponatremia as a possible cause of clinically mild encephalitis/encephalopathy with a reversible splenial lesion associated with acute focal bacterial nephritis

OBJECTIVE

Clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS), the second most common encephalopathy syndrome in Japan, is most often associated with viral infection. Bacterial MERS has been rarely reported but is mostly associated with acute focal bacterial nephritis (AFBN) for an unknown reason. We examined cytokines and chemokines in four MERS patients with AFBN to determine if they play an important role in the pathogenesis.

METHODS

We examined the clinical charts and MRI results in four MERS patients with AFBN, and measured 10 cytokines and chemokines in serum and cerebrospinal fluid in the acute phase. These were analyzed using the Mann-Whitney U test, compared with the control group (cases with a non-inflammatory neurological disease). Longitudinal changes in the serum cytokine and chemokine levels were evaluated in two patients.

RESULTS

Hyponatremia was observed in all four patients with MERS associated with AFBN (128-134 mEq/L). CSF analysis revealed increased cytokines/chemokines associated with Th1 (CXCL10, TNF-α, IFN-γ), T reg (IL-10), Th17 (IL-6), and neutrophil (IL-8 and CXCL1). In serum, upregulation was observed in those associated with Th1 (CXCL10, TNF-α, IFN-γ), Th17 (IL-6), and inflammasome (IL-1ß). The increased serum cytokines/chemokines in the acute stage normalized within 2 weeks in patients 1 and 2, so examined, in accordance with their clinical improvement.

CONCLUSION

Increased cytokines/chemokines and hyponatremia may be factors that explain why AFBN is likely to cause MERS.

Diagnosis and Treatment for Acute Focal Bacterial Nephritis With Renal Abscess Based on Magnetic Resonance Imaging Evaluation

A 5-year-old boy was diagnosed with left acute focal bacterial nephritis (AFBN) complicated with renal abscess (RA) on magnetic resonance imaging (MRI). MRI is useful for diagnosing AFBN and RA complications. He was administered antibiotics for 3 weeks on evaluation of MRI findings. Evaluation of apparent diffusion coefficient values over time may be useful as an index of treatment of RA.