Staphylococcal pyomyositis in a temperate region: epidemiology and modern management

OBJECTIVES

To describe all cases of staphylococcal pyomyositis in the Geelong region of Victoria over 110 months, to estimate the incidence of this disease, and to describe the clinical outcomes and identify any predisposing factors.

DESIGN, PARTICIPANTS AND SETTING

A prospective case series identified by clinical features (local pain and fever) and magnetic resonance imaging (MRI) findings (hyperintense signal on T2-weighted scan), among patients presenting to Geelong Hospital, Victoria between 1 April 1998 and 1 June 2007.

MAIN OUTCOME MEASURES

Estimation of incidence, clinical course and identification of predisposing factors.

RESULTS

We estimate an annual incidence of 0.5 cases per 100 000 person-years, and propose a recent history of vigorous exercise (six of 11 patients) and underlying skin condition (five of 11 patients) as possible predisposing factors. MRI showed eight patients had osteomyelitis and one had septic arthritis. All patients had bacteraemia and one had mitral valve endocarditis. The duration of intravenous antibiotic therapy varied between 4 and 12 weeks, and all patients were completely cured.

CONCLUSION

Pyomyositis should be considered in patients presenting with local pain, fever, muscle tenderness, and a recent history of vigorous exercise or underlying skin condition. MRI may guide non-surgical management.

Infections in Systemic Connective Tissue Diseases: Systemic Lupus Erythematosus, Scleroderma, and Polymyositis/Dermatomyositis

In SLE, scleroderma, and PM/DM, infections are important causes of morbidity and mortality. This increased risk for developing infections is the result of immune abnormalities and of organ system manifestations associated with these diseases and their treatments. Common bacteria are responsible for most mild and lethal infections; however, opportunistic microorganisms cause death in some patients, particularly in those receiving high doses of corticosteroid and immunosuppressive therapy. Various viral and fungal infections also contribute to the morbidity and mortality associated with these diseases. Regardless of the cause of infections, adequate and prompt recognition and proper treatment of the infected patient are imperative. Patients who have these diseases, especially when receiving high doses of corticosteroids and immunosuppressive therapy, need to be monitored closely for these infections. This care and concern is necessary to ensure optimal patient outcomes, both in morbidity and mortality.

Nontropical pyomyositis in adults

Pyomyositis (PMS) is a primary infection of striated muscle. Recent scanty reports suggest that non-tropical PMS may differ from classical tropical PMS. To address this question, 12 cases of nontropical PMS seen at two hospitals between 1976 and 1992 were reviewed and an English-literature search of similar cases was conducted. Both the series and reported cases are pooled together and herein reported. The age distribution of the 97 patients showed 30-50 and 60-70-year peaks, with a 3:1 (male-female) ratio. Fever, high erythrocyte sedimentation rate, and muscle stiffness or inflammation were present in more than 75% of patients. Muscles of the thigh (54%), back (13%), buttock (11%), arm (9%), or chest wall (4%) were involved. Staphylococci (61%), gram-negative bacilli (16%), streptococci (12%), and fungi (2%) were isolated from muscle specimens. Human immunodeficiency virus infection, diabetes mellitus, hemopoietic disorders, and other conditions with defective neutrophil function were present in 64 patients (66%). Drainage of pus and antibiotic therapy were the standard treatments. The mortality rate reached 10%. Analysis of patients classified by the comorbid condition showed differences in age, causative microorganisms, clinical features, and death rate. It is concluded that several clinical presentations of nontropical PMS are at variance with that of tropical PMS.

Pyomyositis: early detection utilizing multiple imaging modalities

Pyomyositis represents 3% to 4% of surgical admissions in East Africa, however, there were no reported cases in the United States prior to 1971. Since, there have been numerous reports of this entity. Four recent cases are presented utilizing multiple imaging modalities including magnetic resonance. MR was very sensitive to early soft tissue inflammatory processes and demonstrated these focal abscesses with superior anatomic localization. MR is advocated in the initial evaluation of a focal process. In a systemic, nonfocal process, nuclear medicine WBC or Gallium Scans to localize areas for further MR scanning is recommended.