Table 2 Brief clinical reports of ST398 CA-MRSA cases

CA-MRSA-1

A 35-year-old previously healthy woman presented with 4 days of fever, productive cough, and right-sided pleuritic chest pain. On presentation, she was found to be febrile (38.8 °C), dyspneic, and tachypneic (RR 31 breaths/minute). Laboratory examination revealed peripheral leukocytosis with neutrophil predominance, and a chest radiograph showed diffuse patchy infiltrates. A bronchoscopy was performed and the bronchoalveolar lavage culture grew MRSA, which was subsequently identified as ST398. The patient was diagnosed with community-acquired staphylococcal pneumonia, and was treated with vancomycin, fosfomycin, and rifampicin for 21 days, and recovered

CA-MRSA-2

A 48-year-old healthy man presented with 1 week of fever, chills, productive cough, and chest discomfort. On examination, the patient was found to be febrile (38.7 °C), hypotensive (95/61 mmHg), and tachypneic (RR 28 breaths/minute). Laboratory examination revealed peripheral leukocytosis (white blood cells, WBC 13 × 10⁹/L), 78% of which were neutrophils. A chest radiograph demonstrated right middle lobe and bilateral lower lobe infiltrates. A bronchoscopy was performed and the bronchoalveolar lavage culture grew MRSA, which was identified as ST398. The patient was treated with vancomycin for 30 days and experienced recurrence of his staphylococcal pneumonia

CA-MRSA-3

A 54-year-old man presented with 2 days of productive cough, shortness of breath, and hemoptysis 12 h before admission. On examination, he was found to be febrile (39.5 °C), hypotensive (68/34 mmHg), tachycardic (136 beats/minute), and tachypneic (RR 46 breaths/minute). The patient was intubated and admitted to the intensive care unit. Laboratory examination revealed peripheral leukocytosis with neutrophil predominance, and a chest radiograph showed a large right lung infiltrate. Blood culture grew MRSA, typed as ST398. One week after admission, systemic infection occurred, signs of renal failure appeared, and MRSA ST398 could be detected in the peritoneal dialysate. The patient was treated with vancomycin, fosfomycin, and rifampicin. However, 2 weeks later, the patient expired due to sepsis and multiorgan failure

CA-MRSA-4

A 65-year-old man presented with 4 days of productive cough, nausea, vomiting, and diarrhea. On examination, the patient was found to be febrile (39.1 °C), hypotensive (78/45 mmHg), tachycardic (123 beats/minute), and tachypneic (RR 37 breaths/minute). Laboratory examination revealed leukocytosis with a left shift, and a chest radiograph demonstrated empyema. Sputum and blood cultures grew MRSA ST398. The patient was treated with vancomycin and linezolid for 3 weeks and recovered

CA-MRSA-5

A 2-year-old healthy boy presented with a purulent draining skin and soft tissue lesion on his back. On examination he had an elevated body temperature (37.9 °C). Culture was obtained from the drainage and grew MRSA, which was later identified as ST398. He was treated with clindamycin and linezolid for 1 week and recovered

CA-MRSA-6

A 3-year-old girl with rubella presented with a skin abscess on her left arm, and vomiting. On presentation, she was found to be febrile (39.7 °C). Laboratory examination revealed peripheral leukocytosis (WBC 13 × 10⁹/L, 84.6% of which were neutrophils), anemia (Hb 11.9 g/dL), and thrombocytopenia (platelets 55 × 10⁹/L). MRSA ST398 was isolated from the skin abscess as well as the blood stream. The patient was continuously treated with vancomycin, but subsequently developed infective endocarditis and a brain abscess and died 17 days after admission

CA-MRSA-7

A 21-year-old healthy woman presented with multiple purulent skin and soft tissue lesions on her back that developed over the course of 2 days. On examination, she was found to have a temperature of 38.0 °C. Laboratory examination showed peripheral leukocytosis (WBC 9.2 × 10⁹/L). MRSA later identified as ST398 was isolated from skin lesions. She underwent drainage of the soft tissue lesions and was treated with trimethoprim/sulfamethoxazole and clindamycin for 2 weeks with resolution of the skin abscesses

CA-MRSA-8 (not further investigated)

A 57-year-old healthy man presented with fever (40 °C), chills, chest pain, and petechial rash of 1 month in duration. On examination, he was found to have a 5+/6 apical systolic murmur that radiated to the axilla. A chest radiograph revealed bilateral pleural effusions. A transesophageal ultrasound showed mitral valve vegetations and mitral valve prolapse. MRSA identified as ST398 was isolated from the blood stream as well as the pleural fluid. The patient was treated with vancomycin, fosfomycin, and rifampicin and underwent mitral valve replacement surgery. He was discharged 2 weeks after his valve replacement surgery. The patient was readmitted to another hospital 4 months after discharge with an intracerebral abscess. MRSA was detected in the cerebrospinal fluid, which was not genotyped. The patient received vancomycin, fosfomycin, and rifampicin for 1 month, and was discharged.