Methicillin-resistant Staphylococcus aureus Bacteremia With Splenic Abscess Masked by Epstein-Barr Virus-associated Hemophagocytic Lymphohistiocytosis.

Abstract

To the Editors: Splenic abscess, often associated with bacteremia, is a rare, potentially life-threatening disease that is sometimes reported in immunocompromised patients. It is characterized by prolonged fever and leukocytosis.1 Epstein–Barr virus-associated hemophagocytic lymphohistiocytosis (EBV-HLH) is also a potentially life-threatening hyperinflammatory disease triggered by EBV infection and characterized by high-grade fever and cytopenia.2 We present a case of methicillin-resistant Staphylococcus aureus (MRSA) bacteremia with splenic abscess masked by EBV-HLH. A previously healthy 7-year-old girl, with no family history of immunodeficiency or hematologic diseases, developed a fever, cough and rhinorrhea. She was treated for suspected bacterial pneumonia with clarithromycin followed by tosufloxacin. On day 4, blood examination showed bicytopenia (WBC 1690/μL, neutrophils 598/μL, platelets 92 × 103/μL) and a negative blood culture. On day 7, although the cough and rhinorrhea improved, the high-grade fever continued, and cracked lips, cervical lymphadenopathy and scattered erythema appeared. Blood examination showed hypercytokinemia (platelets 52 × 103/μL, C-reactive protein 13.63 mg/dL, fibrinogen 155 mg/dL, triglyceride 219 mg/dL, lactate dehydrogenase 5727 U/L). She was suspected to have HLH or Kawasaki disease and was referred to our hospital. We stopped antibiotic treatment and administered intravenous immunoglobulin 2 g/kg and prednisolone 2 mg/kg. Both ferritin (26,566 ng/dL) and soluble interleukin-2 receptor (4998/mL) were elevated, and along with fever, bicytopenia, and later-recognized splenomegaly, 5 of the 8 HLH 2004 diagnostic criteria were met.3 We did not perform bone marrow aspiration due to the invasiveness. Additionally, EBV-VCA IgM and EBV-VCA IgG were positive, and anti-EBNA was negative. The initial EBV infection was considered to be a trigger of the HLH. On day 8, bicytopenia and coagulopathy had improved, but C-reactive protein was further elevated. The blood culture and urine culture of day 7 were positive for gram-positive cocci, later identified as MRSA. On day 10, abdominal contrast-enhanced CT showed splenomegaly and multiple spleen abscesses (Fig. 1A–C). We administered intravenous vancomycin for 7 weeks (Figure, Supplemental Digital Content 1, https://links.lww.com/INF/E923). Repeated cardiac ultrasound showed no evidence of infective endocarditis. Since then, no relapse was documented.FIGURE 1.: Abdominal contrast-enhanced computed tomography on day 10. Splenomegaly, scattered nodular low-density areas (arrows) and multiple wedge-shaped low-density lesions (arrowheads) in the spleen (A, B, and C).No report has described bacteremia or splenic abscess after only 7 days following the onset of EBV-HLH. HLH causes severe neutropenia, which contributes to an immunosuppressed state.4 Splenic abscesses, sometimes with bacteremia, often occur in an immunosuppressed state.1,5 In our case, no etiology other than HLH, suggestive of immunodeficiency leading to a splenic abscess, was identified. HLH induces persistent high-grade fever and leukocytopenia.2,3 Furthermore, a study that reviewed 6 immunocompromised patients diagnosed with splenic abscesses reported that the five patients were febrile because of their splenic abscess and that none had leukocytosis.5 High-grade fever is the common characteristic of HLH and bacterial infection. Leukocytosis, one of the characteristics of bacterial infection, can be masked by leukopenia due to HLH, as in our case. In conclusion, a severe bacterial infection such as bacteremia with a splenic abscess may develop shortly after EBV-HLH. HLH induces persistent high-grade fever and leukocytopenia, and thus a diagnosis of concurrent bacterial infection may be challenging. Blood cultures and abdominal contrast-enhanced CT should be performed.