A comparison between septic bursitis caused by Staphylococcus aureus and those caused by other organisms.

Septic bursitis is an infection that usually involves olecranon and prepatellar bursae. Staphylococcus aureus is responsible for around 80% of cases. However, information regarding bursitis caused by non-Staphylococcus aureus microorganisms (NSAB) is scant. In this paper we describe the characteristics of NSAB and emphasise differences between these and Staphylococcus aureus bursitis (SAB). A retrospective study of all cases with septic bursitis seen between January 1991 and June 1998 at one university hospital was conducted. Only cases in which bursal fluid culture yielded growth of a microorganism were analysed. A literature review was conducted for completeness. Fifty-seven episodes of septic bursitis in 56 patients were studied: 47 of these were caused by Staphylococcus aureus and 11 by non-Staphylococcus aureus microorganisms. Forty-three SAB patients were male (91%). Mean age at diagnosis was 50 years (range 20-85 years). The presentation of bursitis had a seasonal trend, with a peak in the summer. Twenty-three patients (51%) had occupations involving frequent or sustained pressure on the bursae. Other risk factors were recent trauma in 11 (23%), alcoholism in six (13%), pre-existing bursal disease in five (11%), and chronic obstructive pulmonary disease in four (9%). There were 20 cases of olecranon bursitis (43%), 25 of prepatellar bursitis (53%) and two of first metatarsophalangeal bursitis. Characteristics of patients from the literature review were similar. Eight NSAB patients (73%) were male. Mean age at diagnosis was 46.9 (range 29-83 years). Two patients were plumbers and one a stonemason. Five (45%) had neither putative systemic nor local risk factors. There were five olecranon (45%), five prepatellar (45%), and one external malleolus bursitis. Infection by a mixed flora was common. Unlike SAB, the presentation of cases did not have a seasonal trend. The clinical spectrum of non-Staphylococcus aureus bursitis (NSAB) differs from that of Staphylococcus Aureus bursitis (SAB), and this should be considered in the initial diagnosis of septic bursitis.