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.