Primary Staphylococcus aureus meningitis in an infant

Abstract

suggestive of a¯uid collection (Figure 1). Repeat ultrasound of the swelling disclosed that the left paravertebral muscles were bulky and more echogenic than previously, with a suspicion of an echogenic area adjacent to the L3 spinous process. Immunological investigations showed a normal nitroblue tetrazolium test, negative antistaphylococcal and antinuclease antibodies and normal total immunoglobulin levels. Initial IgG2 level was low (1.14 g/L, reference range 1.4±4.5) but normal on repeat testing two weeks later. After six weeks of antibiotic treatment the swelling had disappeared and radiological images and in¯ammatory markers were normal. COMMENT Pyomyositis is very rare in temperate climates. S. aureus is responsible for about 90% of cases, other pathogens being streptococci and anaerobic bacteria. In tropical climates there are two peaks in prevalenceÐearly childhood (age 2±5) and middle age (35±40). The aetiology is uncertain. Previous trauma has sometimes been noted but other reported associations are concurrent skin or respiratory infections, muscle injury through exercise, diabetes mellitus, AIDS, steroid use and induction therapy for acute lymphocytic leukaemia. The condition tends to occur in the muscles of the trunk and upper thigh and can lead to a misdiagnosis of septic arthritis (described with pyomyositis in the adductor, iliacus and psoas muscles) 1. Diagnosis is often delayed but ultrasound, gallium-67 scans, computed tomography and MRI have all been proved effective tools for con®rming the cause 2,3. Blood cultures are positive in less than 5% of patients 4. Treatment in most cases includes surgical incision and drainage but resolution without surgical intervention is well recognized 5. Rare complications include toxic shock syndrome and staphylococcal scalded skin syndrome 5. The diagnosis should be suspected in any child with the triad of pyrexia,¯ank pain and hip symptoms 2 .