A rare lumbar pyogenic spondylodiscitis caused by staphylococcus caprae with initial misdiagnosis: case report and literature review

Abstract

Background: Staphylococcus caprae (Sc) is an uncommon causative organism for human. Lumbar pyogenic spondylodiscitis (LPS) of Sc is extremely rare and only a few cases have been reported. As far as we know, there is no specific literature on the diagnosis and treatment for LPS of Sc with L5 nerve root irritation.

Case presentation: A 65-year-old male patient complained of chronic low back pain for 10 years, acute worsening with radiating pain to left lower extremity over a month. Physical examination revealed tenderness point on his low back, 3/5 dorsiflexor strength in his left 1st toe and decreased sensation of pin prick over the left lateral shank and medial dorsal foot. The individual was initially misdiagnosed with lumbar disc herniation (LDH) without further examination in outpatient, which was then found to be LPS of Sc with L5 nerve root irritation after admission to our hospital. Magnetic resonance images (MRI) of lumbar spine exhibited inflammation signal at L4-L5 level of the vertebral body and disc with hypointense on T1-weighted images (T1-WI) and hyperintense on T2-weighted images (T2-WI). The causative organism was confirmed by the culture of irrigation fluid obtained from L5 vertebrae by needle puncture. After systemic conservative treatment including using sensitive antimicrobial agents and immobilization, the rare infection was finally cured. The patient also showed a satisfactory recovery during the 36-month follow-up period.

Conclusions: Confirming the diagnosis and identifying the causative organism as soon as possible is the key point for the treatment of LPS. LPS of Sc causing nerve root irritation is rare but curable with early diagnosis and proper therapy. The culture of irrigation fluid obtained from vertebrae by needle puncture may be an effective and sensitive attempt for potential infection of spine to identify the causative organism at early stage of the disease.

Keywords: Case report; Pyogenic lumbar spondylodiscitis; Staphylococcus caprae; Vertebral needle biopsy.

Fig. 1

Radiological findings before treatment. Notes: (a and b) X-ray before treatment showed degeneration of lumbar spine, hyperplasia of vertebrae, no significant narrowing of L4–5 inter-vertebral space. (c and d) CT showed vertebral worm-eaten-like damages (arrow), the formation of sequestrum, hyperplasia of vertebrae. (e and f) MRI showed hypointense on T1-WI and heterogeneous hyperintense on T2-WI (arrow) in L4–5 level of vertebrae and disc. (g) PET-CT showed the significant uptake of the radioactive FDG in L4–5 level, high suspicion of infection

Fig. 2

Pictures during the operation and pathological report of L5 bony tissue biopsy. Notes: (a and b) X-ray pictures of fluoroscopy during operation, L5 vertebrae was punctured from left pedicle by needle. (c) bony tissue was obtained from L5. (d and e) Sterile saline solution was irrigated through needle into L5 by syringe and collected for aerobic and anaerobic bacteria culture and drug susceptibility test. (f) Pathological report showed diffused distribution of plenty of lymphocytes without the gathering of epithelioid cell granulomas, granular necrosis and Langerhans giant cells

Fig. 3

Radiological findings after 6 weeks treatment. Notes: (a and b) X-ray after treatment showed degeneration of lumbar spine, hyperplasia of vertebrae, no significant narrowing of L4–5 inter-vertebral space. (c) CT showed the area of vertebral worm-eaten-like damages were reducing and limited, the bone sclerosis appeared around the lesion (arrow).(d and e) MRI after 6 weeks treatment showed the area of inflammatory signal (hypointense on T1-WI and heterogeneous hyperintense on T2-WI) was significantly reducing (arrow)

Fig. 4

Radiological findings at the 12th month after treatment. Notes: (a and b) X-ray showed degeneration of lumbar spine, hyperplasia of vertebrae, no significant narrowing of L4–5 inter-vertebral space. (c) CT showed the area of vertebral destruction was almost recovered and the bone sclerosis around the lesion (arrow). (d and e) MRI showed the area of inflammatory signal (hypointense on T1-W images and heterogeneous hyperintense on T2-W images) almost disappeared (arrow)

Fig. 5

Radiological findings at the 36th month after treatment. Notes: (a) CT showed just hyperplasia and deterioration of L5 and no recurrence of vertebral destruction (arrow). (b and c) MRI showed there was no indication of inflammatory signal (hypointense on T1-WI and heterogeneous hyperintense on T2-WI) (arrow) compared with the images before