Infectious Sacroiliitis in a Patient With a History of IV Drug Use
Infectious sacroiliitis secondary to P aeruginosa, a gram-negative bacillus, is difficult to treat because of the glycocalyx and slime production that protects the pathogen from antibiotics, the development of multiple-antimicrobial resistance, and poor drug penetration into bones and abscesses.14 Antibiotic treatment should cover Staphylococcus aureus and may be broadened to cover gram-negative bacilli. The recommended duration of treatment is at least a 2-week course of IV antibiotics, followed by a 6-week course of oral antibiotics.2 Therapy also includes pain control and surgical intervention for abscesses, osteomyelitis, and refractory cases.7
Complications
Complications and long-term sequelae are common in ISI, often due to late diagnosis of the condition. Our case illustrates the delayed diagnosis of Pseudomonas ISI with candidemia in a young man with a history of IV drug use presenting with atraumatic low back pain. His clinical course was complicated by a thromboembolic event, likely secondary to immobility and a hypercoagulable state from infection and inflammation.15 Infectious sacroiliitis secondary to P aeruginosa is most commonly seen in patients with immunosuppression, hospitalization, and IV drug use.2
Summary
Infectious sacroiliitis remains a diagnostic challenge for physicians due to its rare incidence and nonspecific clinical manifestations. Our case illustrates the importance of maintaining a high level of clinical suspicion for infectious arthritis in young patients presenting with common MSK complaints in the presence of infectious risk factors. Emergency physicians should consider red flags, abnormal vital signs, and patient recidivism when deciding on the most appropriate workup.
