A simple UTI doesn't respond

A 15-year-old schoolgirl presented to urgent care with nausea and lower abdominal pain that began overnight. The pain was sharp, continuous, and located in the lower abdomen. She also reported urinary frequency but no dysuria. There was no fever or rigors. There was no flank or back pain. She had no past surgical history.

On examination she appeared well. Her vital signs were stable with a temperature of 37.4 °C, heart rate 104, and blood pressure 118/83. Her abdomen was soft and non-tender. A urine dipstick showed leukocytes 2+, protein 3+, blood 3+, and nitrites negative. Urine bhcg was negative. The working diagnosis at this stage was a simple urinary tract infection. She was started on nitrofurantoin and paracetamol for pain relief. Urine culture later grew Klebsiella pneumoniae complex, which was sensitive to nitrofurantoin.

Six days later she re-presented to urgent care feeling significantly worse. She initially went to the local ED that day but left after being told about the wait time. The lower abdominal pain persisted, she was unable to eat or drink, and she was passing only small amounts of urine. She had developed vomiting, weakness, and difficulty standing, and this time she was febrile. On assessment her temperature was 39.2 °C, heart rate 150, and blood pressure 90/47, although her abdominal examination remained unremarkable. The working diagnosis was evolving urosepsis. She was given one litre of IV fluids and IV Augmentin before being referred urgently to the local emergency department.

In the emergency department, blood tests revealed a CRP of 386, white cell count of 9, and creatinine of 155. CT abdomen and pelvis demonstrated a left pelvi-ureteric junction obstruction with gross pelvicalyceal dilatation, no hydroureter, and a horseshoe kidney with fusion of the poles. The following day, she underwent insertion of a left nephrostomy. Five days later a left ureteric stent was placed, and a retrograde pyelogram demonstrated a very high insertion of the left ureter, consistent with the horseshoe kidney configuration. She recovered well and was discharged home a week later, with plans for urology follow-up and a pyeloplasty.

Learning Nuggets

*Horseshoe kidney:¹

• most common type of renal fusion anomaly.
• occurring in about 1:500 adults/ M:F ratio approx 2:1
• associated with several syndromes e.g Down's and Fanconi syndrome.
• most patients remain asymptomatic, with the diagnosis made on incidental imaging.
• several important complications: hydronephrosis, usually secondary to pelvi-ureteric junction obstruction, renal calculi which(60%), renovascular hypertension, malignancy, and increased susceptibility to trauma.

*Ureteropelvic junction obstruction/Pelvi-ureteric junction obstruction:^2,3,4

• well studied in paediatrics and is one of the leading causes of hydronephrosis in children.
• estimated incidence of 1: 1000 to 1500 live births however, the incidence  and causes are not well-defined in adults.
• adults with UPJO more commonly report hematuria and chronic loin pain- can be triggered by fluid intake or caffeine beverages.
• children and adolescents present with: periodic abdominal or loin pain, vomiting, recurrent pyelonephritis, fever, abdominal mass or hematuria.
• complications of UPJO can be severe: Recurrent urinary tract infection is common. Chronic loin pain and secondary stone formation occur due to urinary stasis. With prolonged obstruction, patients risk partial or complete loss of renal function. 
• Dietl’s crisis: episodic crampy upper abdominal pain, nausea, and vomiting associated with intermittent obstruction at the ureteropelvic junction.³
• extrinsic compression secondary to crossing vessels is the most commonly reported cause of PUJO in adults, present in greater than 50% of cases.⁴

*Klebsiella pneumonia species complex:^5,6

• Klebsiella pneumoniae has developed a concerning capacity worldwide for antibiotic resistance, causing the WHO to classify it as a “critical” priority pathogen.
• Klebsiella pneumoniae is the second most common causative organism of pyelonephritis(after E.coli).

References

1. Kirkpatrick JJ, Leslie SW. Horseshoe kidney. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025. Available from: http://www.ncbi.nlm.nih.gov/books/NBK431105/
2. Al Aaraj MS, Badreldin AM. Ureteropelvic junction obstruction. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025. Available from: http://www.ncbi.nlm.nih.gov/books/NBK560740/
3. Cadogan M. Józef Dietl. Life in the Fast Lane • LITFL [Internet]. 2025. Available from: https://litfl.com/jozef-dietl/
4. O’Sullivan NJ, Anderson S. Pelviureteric junction obstruction in adults: a systematic review of the literature. Curr Urol. 2023;17(2):86–91. Available from: https://doi.org/10.1097/CU9.0000000000000154
5. Hetta HF, Alanazi FE, Ali MAS, Alatawi AD, Aljohani HM, Ahmed R, et al. Hypervirulent Klebsiella pneumoniae: insights into virulence, antibiotic resistance, and fight strategies against a superbug. Pharmaceuticals. 2025;18(5):724. Available from: https://doi.org/10.3390/ph18050724
6. Belyayeva M, Leslie SW, Jeong JM. Acute pyelonephritis. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025. Available from: http://www.ncbi.nlm.nih.gov/books/NBK519537/