Bilateral Gluteal Pyomyositis Caused by Citrobacter Species: A Case Report from Sudan

Abstract Background: Pyomyositis is a bacterial infection of skeletal muscle that most commonly affects tropical populations and is usually caused by Staphylococcus aureus . Gram-negative organisms are uncommon causes, and Citrobacter species are rarely reported. Case presentation: A 27-year-old Sudanese man with no known chronic medical illness presented with an 8-day history of high-grade fever followed by severe bilateral hip pain and gluteal swelling. Initial investigations showed leukopenia, thrombocytopenia, and a positive typhoid IgM test, and ceftriaxone was initiated. During hospitalization, he developed progressive bilateral gluteal swelling, severe pain, and restricted hip movement. Magnetic resonance imaging demonstrated bilateral gluteal and peri-hip muscle inflammation with large intramuscular fluid collections consistent with pyomyositis. Image-guided aspiration yielded purulent material, from which Citrobacter species was isolated. Surgical drainage was recommended but declined by the patient. He was subsequently treated with repeated image-guided aspiration and two weeks of intravenous ciprofloxacin according to susceptibility testing, with marked clinical improvement and restoration of full hip movement. At three-week follow-up, he remained asymptomatic without clinical evidence of recurrence. Conclusion: Bilateral gram-negative pyomyositis caused by Citrobacter species is an unusual presentation in a previously healthy young adult. MRI and microbiological examination of aspirated material were important for diagnosis and targeted therapy. This case also illustrates that repeated percutaneous aspiration combined with appropriate antimicrobial therapy may provide an alternative source-control strategy when operative drainage is declined, although surgical or percutaneous drainage remains the recommended approach for established intramuscular abscesses.