Primary iliopsoas abscess due to Staphylococcus aureus bacteremia

A 17-year-old girl with poorly controlled type I diabetes mellitus presented with a 2-week history of fever and limping. She reported no history of previous trauma. On examination, there was reduced range of motion in the right hip and a positive psoas sign. The cardiovascular and lung examinations were unremarkable. Blood investigations showed leukocytosis (25 x 10³/uL). The chest radiograph and transthoracic echocardiography findings were normal. Because psoas abscess was suspected, CT of the abdomen and pelvis was performed, which revealed multiloculated rim-enhancing collection at the right iliopsoas muscle (Figure 1). She then underwent percutaneous drainage in which a copious amount of purulent material was drained. The blood culture revealed Staphylococcus aureus (sensitive to oxacillin and trimethoprim-sulfamethoxazole). In the ward, she was treated with intravenous cloxacillin 2 g every 4 hours for 2 weeks. One week later, the musculoskeletal ultrasonography showed a reduction in the size of the abscess. Her fever subsided, and the right hip pain started improving. Subsequently, she took oral trimethoprim-sulfamethoxazole for another 4 weeks, which had resulted in ultrasonographic resolution of the right iliopsoas abscess.

FIGURE 1:
Computed tomography (CT) of the abdomen and pelvis shows multiloculated rim-enhancing collections at the right iliopsoas muscle

Iliopsoas abscess can be classified as a primary or secondary abscess. The former occurs as a result of hematogenous spread of an infectious process from an occult source, while the latter occurs when there is a direct spread of infection from an adjacent structure¹. The presenting features of iliopsoas abscess were non-specific, and the classic Mynter’s triad of fever, pain, and limping is present in 30% of the patients^1,2. S. aureus and Escherichia coli are the most common causative organisms of primary and secondary iliopsoas abscesses, respectively³. Treatment of iliopsoas abscess involves the use of appropriate antibiotics along with abscess drainage¹. Iliopsoas abscess is a rare but serious complication of S. aureus bacteremia and should be suspected in patients presenting with fever and limping. Early diagnosis and prompt treatment are crucial to a successful outcome.

ACKNOWLEDGMENTS

We express our deepest gratitude to the staff at Sarawak General Hospital who were involved in the care of the patient.

REFERENCES

• ¹
  Mallick IH, Thoufeeq MH, Rajendran TP. Iliopsoas abscesses. Postgrad Med J. 2004;80(946):459-62.
• ²
  Chern CH, Hu SC, Kao WF, Tsai J, Yen D, Lee CH. Psoas abscess: making an early diagnosis in the ED. Am J Emerg Med. 1997;15(1):83-8.
• ³
  Lai YC, Lin PC, Wang WS, Lai JI. An update on Psoas muscle abscess: an 8-year experience and review of literature. Int J Gerontol. 2011;13(2):75.

Publication Dates

• Publication in this collection
  13 Nov 2020
• Date of issue
  2021

History

• Received
  06 May 2020
• Accepted
  21 May 2020