Reactivation of Osteomyelitis Caused by Staphylococcus Aureus After 50 Years

To the Editor: Two different patterns of disease relating to the diagnosis of chronic osteomyelitis are described in the literature. The first is of symptomatic infection of 5- to 7-weeks duration, occasionally characterized by fistulisation persisting for years, with local inflammatory signs. The second is an osteomyelitis relapsing after a long asymptomatic period.1,2 We describe the case of an old man who presents with reactivation of osteomyelitis after 50 years. Mr. G., a 73-year-old retired garage owner, diabetic but in good everyday health, is referred by his daughter because of descreased short-term memory. During the clinical interview, he complains of painful swelling of the right thigh, worsening over the past 2 months, without fever or chills; the pain is accentuated while walking and disappears on resting. He recalls having been treated with a sulfonamide (Cibazol®) in 1946 for osteomyelitis of the right femur, followed by rapid improvement and apparently complete healing. The clinical examination shows an afebrilc patient with a large inflammatory swelling infiltrating the musculature of the middle third of the right thigh. The laboratory tests reveal an ESR of 70 mm/h, WCC of 10.4, Hg of 13.3 g/dL, an increase in α2-Globulin, normal Ca and P, but an alkaline phosphatase at 119 U/I. The X-ray of the right femur shows a deformity with increased cortical thickness in the middle third, no sequestration, and no signs for a primary bone tumor (Figure 1). Radiography of the right femur. The bone scintigraphy shows hyperactivity in the middle third of the right femur. CT scan and MRI show a swelling of the anterior rectus muscle, whose thickness is three times that of the contralateral muscle. Anteriorly, between the bone surface and the quadriceps muscle there is a structure of low density compatible with inflammatory tissue (Figure 2). A sonography-guided needle biopsy reveals a chronic inflammation that is partly purulent and granulomatous but without epitheloid granulomas, no vasculitic signs, and no malignant tissue. The bacteriologic examination of the biopsy material shows numerous poly-sensitive staphylococci. NMR right thigh. The clinical picture is that of reactivation of a hematogenous osteomyelitis by staphylococcus aureus after 50 years. Combined ciprofloxacin-rifampicin antibiotherapy of 3-months duration resulted in rapid improvement, with normalization of clinical and laboratory parameters. There was the tendency by the infection specialist to treat the situation aggressively with radical excision of the infected necrotic tissues combined with antibiotics. The surgeon, however, in the absence of sequester formation or bony abscesses, had a more conservative attitude. The pathogenic hypothesis was the diminished immune defense attributable to diabetes mellitus and old age, when, in the presence of inert surfaces, there is an adherence of germs.3 The intracellular survival of Staph. aureus (sometimes in a metabolically altered state) may explain the persistence of bone infection.2 We did not proceed to a scintigraphy with indium-labeled leucocytes, but CT-scan and MRI were sufficiently conclusive. From the microbiological point of view, it is important to note the good correlation between the germs grown from secretion and those found in infected bone, a feature that is found in 78% of Staph. aureus infections.4 Therapy is based on a combined surgical (replacement of dead bone and scar tissues with durable vascularized tissue) and antibiotherapeutic approach. In the absence of sequester formation, the conservative approach is safe.5 The selection of the antibiotic is based on the identified germ: the methicillin-sensitive Staph. aureus infections are usually treatable with flucloxacillin, whereas for the Gram-negative germs, the quinolones are a good choice because of the good bioavailability of some when taken orally as well potentially shorter hospitalization and lower cost.6,7 The combination of ciprofloxacin and rifampicin (the regimen we chose) has proven to be efficacious in the treatement of serious staphylococcal infections.8,9