Salmonella enterica Serotype Choleraesuis Infection of the Knee and Femur in a Nonbacteremic Diabetic Patient

Osteoarticular infections caused by Salmonella are rare. The rates of osteomyelitis and septic arthritis due to Salmonella are estimated to be less than 1% and 0.1%-0.2%, respectively (Kato et al., 2012). Salmonella enterica serotype Choleraesuis is a nontyphoidal Salmonella, highly pathogenic in humans, usually causing septicemic disease with little or no intestinal involvement. Serotype Choleraesuis accounts for a small percentage of published studies of Salmonella infections in the United States. It is not commonly reported in joint fluid and bones in contrast to serotype Enteritidis and Typhi, where a considerable number of cases have been published. Chen et al. in Taiwan found that 21% of bacteremic patients with this infection subsequently develop focal infections such as septic arthritis, pneumonia, peritonitis, and cutaneous abscess (Chen et al., 1999, Chiu et al., 2004). In contrast, our patient presented with localized osteoarticular infection with Salmonella enterica serotype Cholerasuis, but without evidence of bacteremia. 1. Case A 48-year-old male from Gambia with a known history of noninsulin dependent diabetes presented with two weeks of pain and swelling over the lateral aspect of the right knee, later extending to the lateral aspect of the right thigh accompanied by fever and chills. The pain and swelling worsened so he decided to go to the emergency room. On his way, he developed five episodes of nonbloody, nonmucoid watery stools but denied nausea, vomiting, and abdominal pain. He denied use of intravenous drugs and history of trauma or surgeries. He works as a cab driver, is in a monogamous marriage, and has lived in New York City for more than ten years. He has not traveled and has not been exposed to animals or pets. Initial vitals showed blood pressure of 140/90, tachycardic at 115 beats per minute, tachypneic at 24 breaths per minute, and febrile at 38.1°C. Examination of the right lower extremity showed effusion of the knee with limitation in range of motion. There were swelling, tenderness, erythema, and fluctuance in the area of anterolateral aspect of the distal femur extending down to the anterior aspect of proximal tibia. Complete blood count revealed white blood cells of 18,000/uL with 83% polymorphonuclear cells. Glucose was 449？mg/dL, hemoglobin A1c was 12.1%, bicarbonate was 11？mmol/L, creatinine was 1.5？mg/dL, alkaline phosphatase was 265？U/L, serum ketone was large, and blood pH was 7.163. His erythrocyte sedimentation rate was 150？mm/hr, and C-reactive protein was 96.60？mg/L. The rest of the blood work-up was