Infective discitis with concurrent calcific discitis masquerading as renal colic

A 76‐year‐old man with a history of ureteric nephrolithiasis presented with dysuria and sharp, severe right flank pain with radiation to the inguinal region. He was febrile to a temperature of 39°C, tender over the right costovertebral angle, lumbar spine, right iliac fossa, and suprapubic regions with no focal neurology. Clinically, he was diagnosed with ureteric nephrolithiasis and sent for imaging. Computed tomography (CT) scan of the abdomen and pelvis revealed non‐specific right retroperitoneal inflammation (Box 1) associated with calcific material at the anterolateral L4–L5 disc space (Box 2, A and B) without evidence of appendicitis or ureteric stones. Immediate magnetic resonance imaging (MRI) scan of the spine demonstrated L4/L5 calcific material extruded anterolaterally and paraspinal inflammation (Box 3, A and B), with a diagnosis of acute calcific discitis and the caveat that this is exceedingly rare and infection is a differential. Biochemistry revealed creatinine level 138 µmol/L (reference interval [RI], 60–110 µmol/L), C‐reactive protein 342.3 mg/L (RI, 0–8.0 mg/L), white cell count 13.8 × 10⁹/L (RI, 4–11 × 10⁹/L), and unremarkable urine microscopy, culture and sensitivity analysis. On day 2, blood cultures returned positive for methicillin‐sensitive Staphylococcus aureus (MSSA), creatinine was 338 µmol/L and C‐reactive protein was 432 mg/L. He was managed with intravenous cephazolin 500 mg every 12 hours, the dose was adjusted for acute renal failure, presumed secondary to MSSA bacteraemia. Echocardiogram was normal, and nuclear medicine renal scan did not reveal cortical infarction. Four days after the initial presentation, the patient developed new L4/L5 hyperesthesia and MRI scan of the spine demonstrated severe canal stenosis secondary to an epidural abscess (Box 4, A and B). He underwent posterior decompression with tissue cultures positive for S. aureus. The renal failure resolved with source control for sepsis. The patient completed 12 weeks of antibiotic therapy in total; 6 weeks of intravenous cephazolin, and 6 weeks of oral clindamycin 450 mg three times a day. Six‐month follow‐up revealed the patient had no recurrence or neurological deficit.