A case of Salmonella Potsdam osteomyelitis treated successfully with levofloxacin and ceftazidime

21 July, 2018

An extremely rare case of Salmonella Potsdam lumbar vertebral osteomyelitis was treated successfully with intravenous levofloxacin and ceftazidime with symptom improvement and no neurological deficits.

An immunocompetent, 29-year old female with no past medical history or any predisposing factors presented with serious lower back pain and severe limitation of motion for 50 days with no obvious inducements. The patient was misdiagnosed as having tuberculosis (TB) lumbar spondylitis empirically on her first admission based on her clinical presentation: magnetic resonance imaging (MRI) demonstrating spondylitis of the fourth and the fifth lumbar vertebrae as well as destruction of intervertebral disk between them, well-defined paraspinal abnormal signal and paraspinal abscess with thin and smooth walls. An anti-TB therapy with oral rifampicin for one month led to no improvement.

Subsequent culture of tissue and abscess contents obtained from the patient during surgery confirmed infection by Salmonella serovar Potsdam. She was eventually diagnosed as having a lumbar interstitial infection and was treated with intravenous levofloxacin and ceftazidime for 3 weeks followed by oral antibiotics for another 3 weeks. She also underwent anterior lateral approach debridement to remove lesions and percutaneous minimal invasively posterior instrumentation for better stabilisation. At 4-month follow-up after treatment, her symptoms had improved: her previous back pain had almost disappeared, soft tissue swelling had subsided and improvements were shown in laboratory tests and radiologic characteristics.

Salmonella infections are known to cause enteric fever, acute gastroenteritis, bacteraemia – with or without metastatic infections – and the asymptomatic carrier state; but it is an uncommon cause of osteomyelitis (representing only 0.5–2.0% of all osteomyelitis cases), especially Salmonella vertebrae osteomyelitis (SVO).^1-3

Susceptibility to SVO increases in immunocompromised patients, those with haemoglobinopathies, and those on steroids.⁴ As with other vertebral osteomyelitis, the cardinal symptoms of SVO are fever and back or neck pain, which are too common to lead to delayed diagnosis or misdiagnosis – particularly in patients without predisposing factors – as was noted in this case report.

Laboratory markers including elevated white blood cell (WBC) count, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) are sensitive but non-specific indicators for the early detection of Salmonella spinal infection.^4,5 The key to identifying the causative agent of spinal infection is to focus on specimens rather than blood or urine culture.⁵

SVO is typically treated with chloramphenicol, third-generation cephalosporins, and fluoroquinolones for at least 6 weeks. External immobilization is recommended for at least 3 months to alleviate pain and prevent deformity and exacerbation of neurological deficits; surgical treatment is only indicated in cases of neurologic complications, failure of conservative treatment and mechanical instability of the spine.⁴

The authors recommended special attention to be given to SVO – particularly when patients are presented with the corresponding risks and symptoms similar to that observed in this case report, and that conservative treatments such as levofloxacin and ceftazidime is appropriate in the absence of neurologic complications.