Imaging of Group B Streptococcus infection in pyonephrosis: a case report

Abstract

Introduction: Pyonephrosis is hydronephrosis accompanied by a bacterial infection in the kidney, causing suppurative destruction of the renal parenchyma; this condition is an emergency and usually associated with stones or chronic urinary tract infections. Urinalysis is typically inaccurate for establishing the diagnosis, as bacteriuria may not manifest due to ureteral obstruction. Case report: We reported a 55-year-old male patient with flanks pain and an account of stone expulsion. Based on history taking, physical examination, radiology examinations, and percutaneous nephrotomy, we concluded a diagnosis of pyonephrosis causing by Streptococcus agalactiae as known as Group B Streptococcus. Discussion: While both US and CT scan guided the early diagnosis, CT was more accurate as it is able to capture the renal function and the underlying cause of obstruction. Pyonephrosis was described as having a pus collection in the pelvicalyceal system, cortex thinning, and the appearance of stones. Conclusion: Pyonephrosis is a rare emergency, and many clinicians find it challenging to recognize since the presentations are frequently nonspecific. In order to prevent renal failure and the spread of bacteremia that entails life-threatening urosepsis, acquiring imaging knowledge (sonography and CT) and other findings are indispensable in determining this entity.

Keywords: GBS; Pyonephrosis; Streptococcus agalactiae, Imaging.

Fig. 1

Abdominal X-ray showed ground-glass opacity at the left upper-lower quadrant abdomen accompanied by two oval-shaped opaque shadows at the level of 2nd – 3rd lumbar vertebrae.

Fig. 2

(A and B) Right pelvicalyceal ectasis with (C) proximal ureter dilatation.

Fig. 3

(A and B) sagittal and transverse views of the left kidney suggested severe hydronephrosis with layers of echogenic material and prominent fluid-fluid level at renal pelvic.

Fig. 4

Normal prostate with a urinary catheter.

Fig. 5

CT scan images depicted the stones (Asterix) at the proximal right ureter, causing dilatation of the structures above. Right hydronephrosis equivalent to 2nd – 3rd grade and right hydroureter were also visible.

Fig. 6

A renal stone (Asterix) in the left proximal ureter caused left proximal ureter dilatation. The presence of thick fluid in the left pelvicalyceal system and thinning of the renal cortex suggested left pyonephrosis with severe hydronephrosis and left hydroureter.

Fig. 7

Streptococcus agalactiae, also known as Group B Streptococcus (GBS), was isolated after a percutaneous nephrostomy catheter was placed.