Klebsiella pneumoniae psoas abscess: Predominance in diabetic patients and grave prognosis in gas-forming cases

Seven cases of psoas abscess caused by Klebsiella pneumoniae were observed at the National Cheng Kung University Hospital within a period of 4.5 years. These cases constituted 25% of a total 28 episodes of non-tuberculous psoas abscess, ranking second to those caused by Staphylococcus aureus (8 cases). Eight cases of psoas abscess caused by K. pneumoniae were identified from Medline, and 5 of which were reported from Taiwan. Of these 8 cases, 1 neonatal case was excluded, and the remaining 7 adult cases were combined with the 7 cases in this series for analysis. The mean age was 53.8 years, and diabetes mellitus was the most common underlying disease. Fever and pain on the flank and back area were the common findings. The interval between the onset of symptoms and diagnosis ranged from 1 to 60 days. The most common sites of concurrent infection were the urinary tract (6 cases; 43%) and bone (3 cases; 21%). All patients received percutaneous or surgical drainage in addition to antibiotic treatment. Gas formation was present in 5 of the 12 patients recorded, and 4 of them died during hospitalization. Only 1 patient had a metastatic infection with osteomyelitis of the left radius and right humerus; he had experienced 5 episodes of recurrent K. pneumoniae infections in different sites. We concluded that K. pneumoniae should be considered as an important endemic pathogen of psoas abscess in diabetics in Taiwan. The high mortality rate in the gas-forming cases should also be highlighted. Early recognition, empiric antimicrobial coverage for K. pneumoniae, and aggressive drainage or debridement are indicated in these patients.