A Case of Septic Arthritis Caused by Staphylococcus schleiferi

Abstract

Septic arthritis leads to significant hospital burden in the United States adult patient population. Bacteria are the leading cause of septic arthritis with Staphylococcus aureus being the most common. Of the staphylococcal species, Staphylococcus ​​​​​​​schleiferi, primarily found in carnivores, rarely causes septic arthritis. We here report the presentation, diagnosis, treatment, and discharge of a 39-year-old male with S. schleiferi septic arthritis. Due to biochemical similarities, S. schleiferi are commonly misidentified as S. aureus, and correct identification is increasingly relevant for the selection of appropriate therapy due to the rise in cases of multidrug-resistant microorganisms.

Keywords: case report; misdiagnosed staphylococcal aureus; septic arthritis; septic emboli; staphylococcal schleiferi.

Figure 1. CT abdomen and pelvis showing enlargement and heterogeneity of the left seminal vesicles, with soft tissue fullness and obliteration of the fat planes between the rectum, prostate gland, and seminal vesicles(shown by orange arrow). These findings are concerning for gas-forming infectious process.

Figure 2. CT of the right shoulder showing a hypodense intramuscular collection (yellow lines marking length and breadth of the collection) with no signs of gas, concerning for intramuscular hematoma versus infection specifically in the infraspinatus muscle.

Figure 3. CT of left shoulder joint showing a hypodense collection (yellow lines showing dimensions, length and breadth of the collection) with multiple foci of air concerning for intramuscular hematoma/abscess which measures 8.0 x 3.8 cm in the anterior left shoulder, specifically the musculature of the anterior deltoid and pectoralis major/minor.

Figure 4. MRI of right shoulder: Moderate of fluid (as shown by the red arrows) within the subacromial-subdeltoid bursae as well as within the joint which represents septic arthritis. Diffuse edema especially within the infraspinatus muscle may represent infectious myositis or reactive changes.

Figure 5. CT pulmonary angiography with septic embolus in the right lung as shown by the red arrow.