An 81-year-old Asian man presented to our department with complaints of fever since the preceding day. Abdominal computed tomography revealed the presence of a low-density mass in the right iliopsoas muscle indicative of a psoas abscess. Computed tomography-guided percutaneous drainage of the psoas abscess was performed. Results of organism cultures of the abscess and blood were positive for P. micra. However, our patient had no known primary focus of infection. On the basis of these findings, a primary psoas abscess caused by P. Micra was diagnosed, and treatment with ampicillin/sulbactam 1.5 g, administered intravenously every 8 h, was initiated. By day 7, the patient’s white blood cell count normalized. By day 20, his C-reactive protein level was decreased to 0.35 mg/dl.
An 81-year-old Asian man presented to our department complaining of fever since the preceding day. The patient had been under treatment for the previous 3 years for chronic heart failure and chronic renal failure. He did not have a history of malignancy, diabetes mellitus, cytotoxic therapy, or corticosteroid use, and no foreign bodies had been implanted. The patient’s family history was unremarkable. Physical examination revealed a heart rate of 101 beats/min, blood pressure of 87/48 mmHg, respiratory rate of 20 breaths/min, the temperature of 37.0 °C, and oxygen saturation of 87% on room air. He had no caries or periodontitis. Results of respiratory, cardiac, and abdominal examinations were unremarkable. Limb examination demonstrated mild edema of both legs. Abdominal computed tomography (CT) showed a low-density mass in the right iliopsoas muscle indicative of an iliopsoas abscess.
The patient’s white blood cell count, C-reactive protein (CRP), and procalcitonin levels were 19,400/μl, 13.35 mg/dl, and 3.950 ng/ml, respectively. Serum blood urea nitrogen and creatinine were elevated at 77.2 mg/dl and 3.69 mg/dl, respectively. CT-guided percutaneous drainage of the psoas abscess was performed, and an indwelling catheter was placed. Gram staining of the drained fluid revealed many neutrophils and Gram-positive streptococci. On the basis of these findings, a presumptive diagnosis of iliopsoas abscess caused by Streptococcus species was made, and treatment with ampicillin/sulbactam (ABPC/SBT) 1.5 g, administered intravenously every 8 h, was initiated.
Results of organism cultures of the abscess and blood were positive, and P. micra was identified by using the API ZYM system (Sysmex-bioMérieux Co. Ltd., Tokyo, Japan), with the organism exhibiting susceptibility to penicillin G, ampicillin, clindamycin, and meropenem. By day 7, the patient’s white blood cell count normalized. By day 20, his CRP level was decreased to 0.35 mg/dl. Therefore, the pigtail catheter was removed. The patient died of peritonitis due to colon diverticulum perforation after 5 weeks of treatment. An autopsy revealed no right iliopsoas abscess at the time of death.