The association between AIDS and pyomyositis was recently pointed out in temperate and tropical countries. In Western countries, the patients affected by pyomyositis associated with AIDS in most cases are neutropenic. We compare a group of 17 patients with pyomyositis and AIDS living in temperate climates from the literature, and 11 patients affected by the same association seen by us in northern Uganda. The patients from Western countries were significantly more neutropenic and their mean of the neutrophil count was significantly lower when compared with our group. We suggest that the defective neutrophil function associated with HIV infection play a major role in the pathogenesis of pyomyositis in our patients.
PIP: Pyomyositis is an infection of the skeletal muscle mostly caused by Staphylococcus aureus. Patients in Western countries affected by pyomyositis associated with AIDS tend to be neutropenic. The objective of this study was to find out whether neutropenia is a common feature of African AIDS patients with pyomyositis; therefore, an African sample was compared with a sample of Western patients obtained from the international literature. During January-December 1993, 30 patients with pyomyositis were admitted to the Surgical Ward of Dr. Ambrosoli Memorial Hospital in Kalongo, Uganda. 11 (36.6%) were found positive for HIV and were in stage IV of the disease. The mean age was 28 years, 3 were females and 8 were males. The neutrophil count was performed before the surgical evacuation of muscle abscess. In the international literature, eight reports of 17 patients with AIDS and pyomyositis were located during the period of 1988-92. All were males in stage IV with a mean age of 37.3 years; 8 were treated with zidovudine. When the neutrophil count was below 3000/cu. mm, the patient was considered neutropenic. 12 out of 17 Western patients were neutropenic, as opposed to only 1 out of 11 Ugandan patients (p 0.01). The mean neutrophil count of Western patients was 3547; that of Ugandan patients was 9077 (p 0.01). Neutrophils are primary effector cells in host defense against staphylococcal infections such as pyomyositis; hence, it has been suggested that neutropenia contributes to the development of pyomyositis in AIDS patients. Neutrophils from AIDS patients were demonstrated to be defective in their ability to kill Staphylococcus aureus in vitro, compared with neutrophils from seronegative controls. Therefore, the defective neutrophil function associated with HIV infection contributed to the development of pyomyositis in Ugandan patients, among whom neutropenia was not common.