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Fig. 6.25 A-E. Infections with Actinomadura madurae. A, B Early infection in the lower end of the radius (A) and the lower end of the tibia (B) (different patients). C A large abscess in the os calcis causing a lytic lesion and breaking through the cortex inferiorally. There is already loss of trabecular pattern and some increased sclerosis due to multiple microfractures. These can be better demonstrated by standard tomography or CT. D An extensive infection of the foot involving all the metatarsals and the adjoining tarsals and spreading through the joints into the second toe. E Marked soft tissue swelling and extensive bone involvement. The metatarsal heads are splayed outwards. There are multiple lytic foci (5-6 mm) and the cortex is notched. There are spicules of periosteal new bone and the joints are affected. Most of the tarsal bones, including the os calcis, were also affected in this patient. (B courtesy of Professor Harold Jacobson)

 

 

 

 

 

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Streptomycosis Somaliensis

Infection by Streptomyces somaliensis closely resembles the pathological, clinical, and radiological findings due to A. madurae. It occurs in the people who live in deserts in the tropics, particularly in East Africa. Colonies grow more rapidly on culture, and are variable in shape and color. The yellow grain is usually very hard, regular, and round or oval.

Skeletal infection causes marked periosteal new bone formation. The holes are slightly smaller than those of infection by Nocardia spp. or A. madurae. The granules are smaller than those of A. madurae, yellow to brown, and hard.

Actinomadura Pelletieri

Synonyms

Nocardia africanus. Micrococcus pelletieri. Madura foot (there are other causes of this condition, refer to prior section on Madura Foot; Mycetoma; Maduromycosis). Ger: Nocardia madurae, pelletieri. Fr: Actinomycete de madurae pelletieri. Sp. Streptomices pelletieri.

Definition

A chronic granulomatous, suppurative mycotic disease usually localized to one foot, caused by Actinomadura pelletieri. The deep structures are affected.

Geographic Distribution

This infection is common in India, Africa, Mexico, and countries around the Mediterranean. It is particularly frequent in West Africa and India.

Epidemiology and Pathology

The mode of entry is through the skin. The organism grows slowly in culture. The grains are garnet red and vary from soft to quite firm. Multiple bones and the sesamoids are affected, as are the joints, which may ankylose. A pelletieri is more aggressive than A. madurae, but less aggressive than Nocardia spp. It causes a marked inflammatory reaction.

Clinical Characteristics

The clinical findings are much the same as those of A. madurae, but the infection is more likely to extend from the foot up to the leg and is much more locally aggressive. The soft tissue sinus holes are smaller than those in Nocardia spp. and A. madurae infections.

Imaging Diagnosis

The soft tissue nodules are smaller than those caused by A. madurae or Nocardia spp. The lucent bone defects are very small, averaging about 2 mm (Fig. 6.26). The periosteal spicules are also smaller but there is intense periosteal new bone, with sclerosis. This results in apparent thickening of the shafts of the metatarsals, which may become double their normal diameter. There is no sequestration, because the multiple lucent areas (the microabscesses) and the sinus tracts effectively decompress the cortex and the periosteum and prevent devitalization of the remaining bone (see Fig. 6.18 D).

Actinomadura pelletieri is the most aggressive of the three streptomyces and frequently extends up the tibia and fibula, whereas A. madurae and S. somaliensis tend to remain below the level of the ankle. The increased aggressiveness also causes joint involvement, destruction of the articular cartilage, and eventually fusing of the joints by bony ankylosis. Even large joints, such as the ankle, may be fused by A. pelletieri.

Table 6.2 assists with the differential diagnosis of bone infection with Nocardia, A. pelletieri, and A. madurae.

 

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