A 52-year-old female was admitted to our emergency department with fever, sore throat, acute severe right shoulder pain with a burning sensation, redness and swelling. She had a medical history of hypertension, hyperlipemia, renal lithiasis, and hydronephrosis, for which she was daily prescribed with levamlodipine besylate and atorvastatin calcium. She was not found with any common risk factors of septic arthritis such as immunosuppression, diabetes, recent trauma or surgery. Six years ago, she felt chronic pain at the right shoulder and limited movement without inducement. About a month before the acute episode, she was administered with right deltoid muscle injections of triamcinolone acetonide in a local clinic five times to relieve the recently worsened pain, after which the symptoms relieved temporarily while recurrent fevers occurred. Two days after the last dose, she experienced severe pain on her shoulder joint with minimal passive movement, local skin temperature increased with redness, and had a sore throat. X-ray films of the right shoulder joint were examined, where degenerative change of the right shoulder joint was observed. Her body temperature was 38.3 °C, the blood test showed increased level of WBC at 12.70 × 109/L (normal range 4.0–10.0 × 109cells/L, and Erythrocyte Sedimentation Rate (ESR) of 65 mm/h (normal range 0–20 mm/h) and C-Reactive Protein (CRP) level substantially increased to 41.2 mg/dL (normal range < 0.8-8 mg/dL). Based on the blood test results and her symptoms, she was diagnosed with a frozen shoulder associated with upper respiratory tract infection. After taking the anti-inflammatory painkiller Celecoxib for 8 days, her condition had no improvement. For systemic treatment, she was referred to the orthopedic department. MRI results showed a shoulder joint abscess. A total of 26 mL (normal range 0.1-2 mL) red gross pus was drawn from her joint for analysis. In total,46,000 cells/mm3 (normal range 200–700 cells/mm3) WBCs, 97% (normal range < 25%) polymorphonuclear (PMN) leukocytes and E. cloacae on culture were identified, whereas the fungal culture test was negative. The results of the antibiotic sensitivity test of the cultured pathogen are shown in Table. Based on these physical, clinical, radiological findings, and laboratory tests, a diagnosis of septic arthritis was made, and a surgical treatment plan, including arthroscopic debridement and irrigation, was administered. Through the arthroscopy, a synovial proliferation of glenohumeral joint, sporadic faint yellow floccule, and a massive rotator cuff tear was observed. In consideration of the shoulder joint infection, rotator cuff tear repair was not performed immediately, nevertheless, the intra-articular space was sufficiently irrigated. Based on the result of the antimicrobial susceptibility test, intravenous injection of levofloxacin (300 mg, q12h) was administered to the patient from the day of surgery. After 5 days, her shoulder pain was significantly relieved and her body temperature normalized. After discharge, she orally took levofloxacin antibiotics (0.5 g, qd). Unfortunately, the symptoms including increasing pain, joint swelling, and increased local skin temperature recurred after 12 days. Her body temperature increased to 38.1 °C, the WBC level was 11.72 × 109/L, ESR increased to 75 mm/h, and the CRP level rose to 69.1 mg/L. As a result, 6.5 mL red gross pus was drawn from the joint which showed 60,764 cells/mm3 WBCs with 96% PMN leukocytes and negative culture. Given that the wound left by her last surgery had not entirely healed, an intravenous injection of Levofloxacin (300 mg, q12h) was again administered instead of the surgical debridement and irrigation. Her condition gradually improved during re-hospitalization. After 19 days, her symptoms significantly relieved, i.e., the WBC level decreased to 8.66 × 109/L, ESR decreased to 19 mm/h, and CRP decreased to 3.53 mg/L. As a consequence, the intravenous injection was changed to oral administration. On the 24th day of re-hospitalization, she was discharged and orally prescribed with levofloxacin (0.5 g, qd) for 2 weeks. After discharge, the patient was followed-up by telephone for2 years. Although she refused to undergo the operation of rotator cuff tear repair, follow-up data revealed that she did not suffer from shoulder swelling and severe pain anymore, however, the mild pain and movement restriction persisted.