A 41-year-old male was admitted to the hospital with symptoms of diarrhea, fever, dyspnea and right pleural effusion. The illness began in the latter part of August 2008, initially presenting with diarrhea and fever. He was an MSM and the serology for HIV antibody was positive. He had no history of traveling abroad, alcoholism, any medication or intravenous drug use. His vital signs on admission were; conscious, blood pressure 95/60 mmHg, pulse late 146 beats/min, respiration, 45 breaths/min, saturation O2 (room air), 88% and body temperature 39 C. The notable findings of a physical examination included emaciation (BMI 16.1), oral candidasis and decreased breath sounds on the right side of his chest. A chest radiograph and computed tomography (CT) of the chest showed a large amount of right pleural effusion (Figure 1). A CT scan of the abdomen detected large liver abscess (Figure 2). The laboratory data included a leukocyte count of 10,320/muL with 89% neutrophils, 8% lymphocytes, 3% monocytes, hemoglobin 8.8 g/dL, C-reactive protein 23.6 mg/dL, aspirate aminotransferase 95 U/L, alanine aminotransferase 74 U/L, alkaline phosphatase 478 U/L, gamma-glutamyl transpeptidase 134 U/L, albumin 2.1 g/dL, total cholesterol 57 mg/dL, blood urea nitrogen 18.4 mg/dL, creatine 0.57 mg/dL and hyponatremia (123 mEq/L). The findings of human immunodeficiency virus type 1 antibody tests were positive for enzyme immunoassays (EIA) and also based on the Western blot method. Thoracentesis revealed milk chocolate or cafe au lait colored pleural fluid (Figure 3). In an examination of the pleural fluid, cytology, bacterial culture, smear and polymerase chain reaction to detect Mycobacterium tuberculosis DNA were negative, the adenosine deaminase activity was 240 IU/L. The pleural fluid showed a cell count of 40125/mL (74.3% neutrocytes, 25.7% monocytes). Other examinations of the laboratory findings detected cysts of Entamoeba histolytica in the patient's stool. The CD4 lymphocyte count in the peripheral blood was 179/muL (repeated counts for CD4 lymphocytes ranged from 286 to 359/muL) and the amount of HIV-RNA was 3700 copies/muL (repeated counts for HIV-RNA ranged from 43,000 to 90,000 copies/mL). Although E. histolytica was not identified from the pleural fluid, antibodies (fluorescence antibody technique) against E. histolytica were demonstrated in the serum (200x). The patient was thus diagnosed to have amoebic colitis, amoebic liver abscess and amoebic empyema complicated with an HIV infection. The right side pleural effusion was drained using a chest tube and he was administered metronidazole (2250 mg/day) orally for 28 days in total. A large volume of pus was drained from the right thoracic space. A small volume remained. The right lung was re-expanded. His fever, dyspnea and general condition significantly improved thereafter. The patient was therefore administered trimethoprim-sulfamethoxazole to prevent pneumocystis pneumonia and itraconazole to prevent fungal infections. However, he developed agranulocytosis 22 days after administration. The absolute neutrophil count was 0/muL. Agranulocytosis in this case was therefore considered to have been caused by the administration of trimethoprim-sulfamethoxazole. After the discontinuation of trimethoprim-sulfamethoxazole, the recombinant human granulocyte colony-stimulating factor (G-CSF) drug filgrastim was administered daily at a dose of 200 mug/m2 intravenously. Following 4 days of treatment with G-CSF, the patient's absolute neutrophil count was above 9/muL, while after 7 days of treatment it was 2990/muL (white blood cell count 4600/muL, neutrophils 65%). The patient did not demonstrate any further infection during the clinical course. He was discharged 45 days after admission.