Microbiology and Outcome of Iliopsoas Abscess in 124 Patients

Abstract

To describe the microbiology and outcome of iliopsoas abscess (IPA) in a large case series, we analyzed 124 cases of IPA collected from 1990 through 2004 in 11 hospitals in Spain. Twenty-seven (21.8%) patients had primary and 97 (78.2%) had secondary IPA. The main sources of infection were bone (50.5%), gastrointestinal tract (24.7%), and urinary tract (17.5%). A definitive microbial diagnosis was achieved in 93 (75%) cases. Abscess culture was the most frequent procedure leading to microbial diagnosis, followed by blood cultures. Staphylococcus aureus, Escherichia coli, and Bacteroides species were the most frequent microbial causes: S. aureus was the most common organism in patients with primary abscesses (42.9%) and with abscesses of skeletal origin (35.2%), whereas E. coli was the leading organism in those with abscesses of urinary (61.5%) and gastrointestinal (42.1%) tracts. Mycobacterium tuberculosis was found in 15 patients, 4 of them associated with human immunodeficiency virus (HIV) infection. Twenty (21.5%) cases had polymicrobial infections; these were more common among patients with abscesses of gastrointestinal origin. Information on clinical outcome was available for 120 patients; 19 (15.8%) had a relapse and 6 (5%) died due to complications related to the IPA. Patients who died were older and more likely to have bacteremia and E. coli isolated from cultures. In conclusion, secondary IPA is more prevalent than primary IPA. Among those with secondary IPA, most abscesses are secondary to a skeletal source. A bacterial etiology can be identified in most cases. The overall prognosis of patients with this condition is good.

A late diagnosis of Pott’s disease in an adolescent with psoas abscess

“…Microscopy and culture of the infected material sampled by the aid of either ultrasound or CT-guided percutaneous catheter drainage, which is also therapeutic or needle aspiration is the gold standard for the diagnosis of tuberculous PA. When microbiologic techniques remain negative, TB may also be diagnosed by compatible clinical findings and favorable response to empiric antituberculous treatment [9]. In the present case, gram staining of purulent abscess material revealed profuse polymorphonuclear leukocytes and acid fast staining was negative.…”

“…Because, it may come out with a long term subclinical presentation, nonspecific symptomatology, chronic and relatively less aggressive clinical course than other types of secondary PA. In the study from Spain mentioned above the delay between onset of symptoms and diagnosis was found to be significantly greater in tuberculous PA than that found in other types of PA (61 days vs. 21 days; p=0.03) [9].. Similarly, frequency of fever and leukocytosis was reported to be significantly less in patients with tuberculous PA.…”

“…Truly incidence of PA remains unknown but it has probably increased, especially secondary ones, due to improvement in diagnostic modalities and recurrence of tuberculosis in industrialized countries [8]. Frequency of secondary psoas abscess has been reported to be 78% in a cohort of 124 patients from Spain source of infection being tuberculosis in 12% of patients, and majority were of skeletal origin [9]. This rate would be expected higher in tuberculous endemic countries.…”

“…Psoas abscess may be treated mostly by antimicrobial therapy plus percutaneous drainage, antimicrobial therapy alone, especially when small size of PA is the concern, or antimicrobial therapy plus surgery, in occurrence of chambered or multiloculated abscesses [9,12]. Adjuvant surgical treatment may be needed in cases of spinal TB with spinal cord compression, spinal instability or neurologic deficits [14].…”

“…Risk factors have been defined both for spinal TB and PA [9][10][11], like immunosuppression, HIV infection and exposure history to TB. There was no underlying disease causing immunosuppression in our patient.…”