Infections of the spine in patients with human immunodeficiency virus

Abstract

Marc Weinstein, MD, Nathan H. Lebwohl, MD, Mark D. Brown, MD, Frank J. Gismont, Miami, FL, USAIntroduction: Infectious diseases in patients with human immunodeficiency virus (HIV) are common and the management of the various bacterial and fungal infections can be a challenge in the immunocompromised host. Skeletal manifestations of patients with HIV have been described in various case reports. Many authors have suggested that spinal infections will occur with greater frequency in the HIV population. However, the incidence and characteristics of spinal infections in these patients have not been reported. The purpose of this study was to evaluate our experience with spinal infections in the HIV population.Methods: The computerized records of all patients discharged with the diagnosis of HIV from our institution from October 1994 through September 2000 were reviewed. Patients with the diagnosis of spinal osteomyelitis, discitis, epidural abscess and tuberculosis were identified, and the charts were examined in detail. In addition to demographic data, the following parameters were recorded: HIV risk factor, admission white blood cell count (WBC), absolute lymphocyte count, erythrocyte sedimentation rate, CD4 count, imaging studies, blood culture results, biopsy results, surgical procedure, antibiotic treatments and duration, length of stay, hospital charges and outcome.Results: For the 6-year period studied, there were 17,717 patient discharges with the diagnosis of HIV. Of these, 17 patients (0.095%) were also treated for a spinal infection. This included eight patients with discitis/osteomyelitis, six patients with tuberculosis (TB) and three patients with an epidural abscess. Of the total number of patients discharged from our institution with these diagnoses, these patients represent 7% of all patients with discitis/osteomyelitis, 35% of patients with spinal TB and 5.5% of patients with epidural abscess. In the eight patients with disc discitis/osteomyelitis, the mean WBC was 8.4, mean absolute lymphocyte count 1,910 and mean CD4 count 339.6. Blood cultures were positive in one of six patients, and a biopsy/surgical specimen was positive in three of six patients. The organism identified in these patients was Staphylococcus aureus (sensitive to oxacillin). The remainder of these patients had positive findings on magnetic resonance imaging or nuclear medicine studies. All eight patients had clinical resolution of infection after 6 to 12 weeks of appropriate antibiotics. In contrast, in the six patients with spinal TB the mean WBC was 10.34, mean absolute lymphocyte count 823 (p=.007) and mean CD4 count 57.2 (p=.003). One of the six patients died during the admission. All were treated with antituberculosis medication protocols. The three patients with epidural abscesses had a mean WBC of 16.17, mean absolute lymphocyte count of 913.3 (p=.007) and mean CD4 count of 20.67 (p=.004). Two of three patients had a computed tomography–guided biopsy. The other was diagnosed by imaging and a positive blood culture. The two biopsies grew Nocardia species, and both of these patients died during the admission. The other patient had Group A streptococcus and was treated with a third-generation intravenous cephalosporin for 6 weeks with clinical improvement. There was no significant difference between the groups with regard to age, gender, race, HIV risk factor or length of hospital stay.Conclusion: Spinal infections in patients with HIV at our institution occur at a rate of 0.095%. This is more than the incidence in the general population but much less then originally suspected. Discitis/osteomyelitis occurs in the HIV patient with a mild to moderate decrease in the CD4 count. These patients would fall into the Center for Disease Control (CDC) class 2 (of 3) classification. The organism identified is consistent with that seen in the general population (S aureus), and the disease responds to appropriate antibiotics. Patients with markedly decreased CD4 counts (CDC class 3) were found to have spinal TB, and patients with the lowest CD4 counts developed epidural abscesses with more malignant species. The three in-hospital deaths occurred in the latter two groups. Although the CD4 count can be used as a predictor of the clinical course of the HIV patient with spinal infection, the identification of the organism still remains paramount in the treatment of this complex patient population.