2022 Volume 82 Issue 4 Pages 307-313
Pyomyositis is common in the tropics but rare in Japan. Obturator muscle pyomyositis, particularly, is a rare pyomyositis with difficult pathogen identification due to its deep location in the trunk. A healthy 4-year-old boy developed gastroenteritis a few days before hospitalization after eating grilled meat. He was then referred to our hospital with a fever and right hip pain. He was unable to walk due to pain, and a blood test revealed an elevated C-reactive protein level. He was diagnosed with obturator muscle pyomyositis after a T2-weighted magnetic resonance imaging revealed a high-intensity lesion in the right obturator muscle. He was first given cefazolin, but his clinical symptoms did not improve. The cefazolin was then replaced with meropenem and vancomycin, which significantly alleviated his symptoms. Because the lesion was so deep in the trunk, blood culture yielded negative results, and puncture fluid could not be collected for culture. However, Salmonella enterica, a bacterium responsive to meropenem in vitro, was detected in the stool culture, and thus, a single-agent treatment was also enough to improve the patient’s clinical findings. The patient received antibiotic therapy for six weeks and had no recurrence afterward. He was successfully treated with no complications, such as a limited joint range of motion. Although identifying the pathogen causing obturator muscle pyomyositis is challenging, significant organisms can be detected in stool culture. Therefore, stool culture results may be beneficial in the treatment of obturator muscle pyomyositis.
