Escherichia coli - Marauding masquerading microbe.

BACKGROUND: Escherichia coli is a rare cause of monoarticular septic arthritis, but is an even rarer cause of polyarticular septic arthritis. CASE DESCRIPTION: We report an unusual case of polyarticular septic arthritis with an atypical presentation caused by E. coli, the source of which was a left pyelonephritis. Our patient developed E coli sepsis resulting in polyarticular septic arthritis (PASA) in the absence of typical risk factors except for pre-existing osteoarthritis. The joints involved were the hip, ankle, sternoclavicular and L5/S1 joints. Of interest, ankle pain was not reported or evident until correlated with nuclear medicine scans. Furthermore, sternoclavicular joint involvement presented as left shoulder pain, resulting in an initial misdiagnosis of left shoulder septic arthritis. The patient was treated with surgical washout and antibiotic therapy. He was subsequently discharged from rehabilitation having returned to his baseline level of mobility. Future consideration will be given to total hip arthroplasty. LITERATURE REVIEW: There are no reported cases of E. coli PASA involving more than three joints in the absence of any recognized risk factors for septic arthritis. PURPOSE AND CLINICAL RELEVANCE: Asymptomatic involvement of joints can occur in polyarticular septic arthritis and should be considered in all cases of monoarticular septic arthritis (MASA). We believe that clinical suspicion is the key to early and comprehensive diagnosis of polyarticular septic arthritis particularly when presenting in an atypical fashion with an atypical pathogen. Strong consideration should be given to performing nuclear imaging in cases of monoarticular septic arthritis where polyarticular involvement cannot be definitively ruled out.