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284scopic nasogallbladder drainage (ENGBD) on the first day and was treated with 3 g/day cefmetazole (CMZ) for three days. The bile sample obtained during ENGBD was negative for bacterial culture, but his AST/ALT was elevated. Endoscopic sphincterotomy (EST) was performed on the third day, and he was treated with 1.5 g/day meropenem (MEPM) for three days, followed by 3 g/day CMZ for three days. His symptoms disappeared and the patient was not administered any antimicrobial agents after day 10. He underwent cholecystec-tomy on day 59. Gross examination of the resected gallbladder showed the hemorrhagic mucosa with marked wall thickness (Figure 1A). Microscopic examination showed diffuse infiltration of foam cells along with multinucleated giant cells, lympho-cytes, and cholesterol deposit (Figure 1B, C). No bacterial colonies or neutrophilic reactions were evident histologically. The patient was pathologically diagnosed with chronic phase XGC. A. baumannii was isolated from the bile sample obtained from Patient 1 during the operation. This isolate was susceptible to all drugs tested (Table 2). Metage-nomic analysis of the bile sample from Patient 1 Figure 1　Pathological view of the 2 cases of gallbladder with xanthogranulomatous cholecystitis1A-C: Patient 1. A: Grossly, a thickened black gallbladder is seen. B and C: Microscopically, diffuse infiltration of foam cells and lymphocytes are observed along with bile and cholesterol deposits. 1D-F. Patient 2. D. Grossly, a thickened gallbladder with coarse mucosa at the fundus (Arrows) is seen. E and F: Microscopically, diffuse infiltration of foam cells with bile pigment is seen.showed bacterial DNA derived from seven genera, with the genus Acinetobacter being predominant. Filtering of the data sets to include OTUs present in > 0.5% of the samples revealed bacterial DNA from four phyla, Actinobacteria (0.8%), Bacteroi︲detes (1%), Firmicutes (10%) and Proteobacteria (88%) (Figure 2).Patient 2 was a 58-year-old Japanese man with no previous medical history. He presented with abdominal pain and was diagnosed with acute cholecystitis. He underwent endoscopic retrograde biliary drainage (ERGBD) on the first day, and was treated with 6 g/day CMZ for two days, followed by 18 g/day piperacillin-tazobactam (PIPC/TAZ) for five days. His symptoms improved, but acute cholecystitis became exacerbated on day 53. The patient was treated with 1 g/day ceftri-axone (CTRX) for one day, followed by 0.5 g/day levofloxacin (LVFX) for seven days. His symptoms disappeared and the patient was not administered any antimicrobial agents after day 60. We adjusted the waiting period for a month to improve the inflammation, and he underwent cholecystectomy on day 88. Gross examination of the resected gall-