Case Presentation: A 70 year old male with psoriatic arthritis on infliximab, hypertension, and chronic low back pain complained of three weeks of intermittent fevers, headaches and worsening back pain after returning from the Dominican Republic. He reported contact with a box turtle and a non-traumatic bird bite but denied sick contacts. In addition to infliximab infusion every 8 weeks, home medications included lisinopril, hydrochlorothiazide, metoprolol, atorvastatin, methotrexate, and as needed tizanidine and hydrocodone. Upon return, he was originally treated for sinusitis in the outpatient setting with no relief; his back pain was believed chronic in nature. His symptoms acutely worsened after receiving an infliximab infusion. He was promptly sent to the Emergency Department for MRI spine that showed nonspecific edema. He was admitted for severe back pain preventing his ability to move. He was hemodynamically stable with white blood cell count 17, erythrocyte sedimentation rate 109, C-reactive protein 230. Urinalysis and chest x-ray were normal. He was started on broad spectrum antibiotics but continued to spike fevers to 39 degrees Celsius. Blood cultures grew salmonella sensitive to Ceftriaxone. MRI lumbar spine 1 week later showed discitis and osteomyelitis at L2-L3 and septic facet arthritis and myositis at L3-L4. Neurosurgery was consulted for spinal involvement. Decision was made to forgo surgery. At two months, patient had improvement in pain and mobility but repeat MRI showed continued infection. He underwent biopsy and aspirate grew salmonella. At that time, antibiotic course was extended to a 96 day course of ceftriaxone plus oral azithromycin, which he remains on at present day.
Discussion: This case demonstrates the rare risk of disseminated salmonella infection in patients, such as ours, on infliximab, an anti-tumor necrosis factor (TNF) agent. These patients are at risk for intracellular infections. The medication inhibits TLR-4 expression on dendritic cells, leading to decreased activation of interferon gamma which defends against intracellular and fungal pathogens. This pathway is also involved in bacterial adherence in the gut, affecting bacterial migration across the intestinal epithelium. Case reports describe unusual infections of soft tissue and septic arthritis, but literature is limited on spinal involvement in this population. Spinal osteomyelitis and discitis is an uncommon manifestation of salmonella. It generally develops from hematogenous spread and usually is associated with sickle cell disease or an immunocompromised state, as in our patient.Anti-TNF drugs are now one of the best-selling pharmaceutical drugs in the world. Over 1 million people are prescribed anti-TNF medications to treat chronic inflammatory conditions. Thus, the incidence of disseminated infection is likely to increase. Patients on these medications should be counseled to avoid risk factors. Reptiles are known to carry Salmonella, and turtles, birds, raw egg consumption should be avoided. Salmonella should be considered in these patients with persistent fevers, pain, travel to endemic regions, and no clear infectious source.
Conclusions: Understanding of susceptibility to disseminated salmonella infection with spinal involvement in patients on anti TNF medications is essential as these drugs become more widespread. Education and awareness can lead to timely diagnosis and treatment and may have mitigated complications in our patient.