Objective: To describe the clinical, radiological and microbiological features of a series of patients diagnosed with pyomyositis in a tertiary care university-affiliated center over a 12-year period.
Patients and methods: The medical records of all patients diagnosed with pyomyositis between January 1992 and December 2003 were reviewed. The charts were retrieved from the hospital database. Data were extracted according to a standardized protocol and included clinical, radiological, laboratory and microbiological parameters.
Results: A total of 54 patients (mean age, 50 years, 61% men) had pyomyositis. The most frequent predisposing factors were diabetes mellitus (22%) and traumatic injury (20%), followed by neoplasms (9%). Primary pyomyositis was diagnosed in 25 patients (55%), and a contiguous source of infection was detected in the remainder, with skin infection being the most frequent (40%). The most common presentation was isolated inflammatory signs with or without other symptoms (94%). Isolated fever was documented in only one patient. Ultrasonography was the most common diagnostic procedure performed (32%), followed by CT scanning (18%). Forty-five patients underwent a drainage procedure combined with antibiotic therapy. Pyomyositis was monomicrobial in 20 cases, and polymicrobial in 12. The most frequent pathogen was Staphylococcus aureus followed by coagulase-negative staphylococci (6 cases). Sepsis developed in 4 patients, and recurrence was observed in 8 (15%). Mortality was 10% (5 patients).
Conclusions: Pyomyositis is a relatively uncommon infection in temperate climates, and is often considered late in the diagnostic workup. Physicians should bear this disease in mind to avoid diagnostic delays and initiate prompt therapy, in order to improve the prognosis of these patients.