The patient was a 6-year-old girl without a personal or family history of immunodeficiency, who had a left anklebone fracture due to trauma and was treated with plaster fixation and wasn’t hospitalized on January 14, 2019. The girl suffered no skin damage. Two days later, she developed a febrile illness with temperature of 38.0 °C and had left ankle swelling and was unable to walk. The girl still had fever, cough, dyspnea, chest tightness, headache, and pain in the left foot necessitating her to a local hospital on January 21, 2019. Physical examination: poor mental health, wet rales can be heard in both lungs, heart rate 164 beats per minute, reduced cardiac sounds, plaster fixation in the left lower limb, and no others abnormalities were seen. On admission, she was treated with intravenous meropenem and vancomycin before blood sample was sent for culture. Echocardiography showed moderate amounts of hydropericardium. To relieve this, the girl was performed pericardiocentesis and hydropericardium sample was sent for culture on January 22, 2019. The child had also been having high fever with a temperature of 40 °C and headache, and cerebrospinal fluid (CSF) investigation on January 23, 2019 showed CSF findings of 1233 × 106 leukocytes/L, glucose of 1.1 mmol/L, and protein of 1470 mg/L in keeping with a diagnosis of purulent meningitis. Blood and hydropericardium cultures were positive for MRSA on January 24, 2019. The isolate was resistant to penicillin, oxacillin, clindamycin and erythromycin and sensitive to gentamicin, ciprofloxacin, linezolid, vancomycin, rifampicin, cotrimoxazole, tigecycline and tetracycline. However, her condition gradually deteriorated necessitating her transfer to our hospital for further treatment in the pediatric ICU on January 24, 2019.
On admission, she was treated with intravenous vancomycin before blood sample was sent for culture. Further examination revealed reduced cardiac sounds, while echocardiography showed moderate amounts of hydropericardium and cardiac insufficiency. To relieve this, we performed pericardiocentesis on January 24, 2019 and drained approximately 100 mL yellowish pericardial fluid with flocs daily during the first 2 weeks, following which the volume decreased gradually and the pericardial drainage tube was removed on the 26th day. She also had severe respiratory distress and chest Computed tomography (CT) revealed bilateral pneumonia, with a large pleural effusion and hydropericardium (Fig. 1a, b). Therefore, closed thoracostomy drainage was performed on January 26, 2019. The chest tube was removed after 7 days. Pleural and pericardial fluid specimens were sent for culture.
After admission to our hospital, CSF investigation on January 27, 2019 showed 12.0 × 106 leukocytes/L, glucose of 2.5 mmol/L, and protein of 500 mg/L indicating marked improvement. CSF culture showed absence of bacteria or fungi, but next-generation sequencing (NGS) analysis revealed presence of S. aureus (Additional file 1). However, central nervous system examination at this time did not show any obvious abnormalities, and magnetic resonance imaging (MRI) of the cranium was normal. The other laboratory findings include a high peripheral white blood cell count of 13.9 × 109/L, with 78.3% neutrophils and an increased C-reactive protein (CRP) of 111 mg/L on the other hand indicated an ongoing acute infection. MRI of the left leg showed osteomyelitis (Fig. 1c, d). We did bone marrow biopsy, and the sample was sent for culture on January 28, 2019.
Eight days into hospitalization, she remained febrile, the inflammatory indices including CRP and procalcitonin (PCT) remained significantly elevated, and there were obvious signs of acute inflammation involving the left foot and knee with localized swelling, warmth, tenderness and restriction of movement. There the orthopedic surgical team performed debridement of the left ankle (Fig. 3a–d) and left knee, retained drainage after the surgery (Fig. 1d), and changed the dressing regularly. After the operation, however, the child still had a high fever and elevated WBC of 16.5 × 109/L and CRP of 122 mg/L, indicating that the infection was not yet under control even on day 11 of antibiotic treatment. Vancomycin trough was less than 7.4 µg/mL, which is below the effective range, hence according to the guidelines of Infectious Diseases Society of America (IDSA) of 2011, it was substituted with linezolid and rifampicin on February 6, 2019 (Fig. 2b). She was treated for 45 days with intravenous linezolid and rifampicin during which her condition gradually improved and the WBC count and CRP level returned to normal (Fig. 3a) while the chest CT showed resolution of the bilateral pneumonia, pleural effusion, and hydropericardium (Fig. 1c, d). However, MRI of the left leg showed only partial improvement and still had a high T2WI signal intensity (Fig. 1g, h). Eventually, the patient was discharged on the 57th day of admission. The child’s guardian provided written consent for reporting of this case.
Cultures of the bone marrow, blood, pleural effusion, and hydropericardium confirmed infection with MRSA, resistance to penicillin, oxacillin, clindamycin and erythromycin and sensitive to gentamicin, ofloxacin, linezolid, vancomycin, rifampicin, cotrimoxazole and minocycline. Multi-locus sequence typing (MLST) and S. aureus-specific staphylococcal protein A (spa) typing identified the strain, as sequence type (ST) 59, and spa type was t437 while Staphylococcal cassette chromosome mec (SCCmec) typing and MRSA toxin identification showed it to be, SCCmec type IV, positive for panton-valentine leukocidin (PVL) and staphylococcal enterotoxin genes, including seb, sek, and seq.