Presumed Pott’s disease

Sir—Workers from the UK^{1, 2} have discussed management of cases of biopsy-proven spinal tuberculosis or Pott’s disease of the spine. However, in developing countries, the diagnostic of Pott’s disease is usually made without biopsy on the basis of clinical and radiological features, which have been shown to be highly specific in a series of Medical Research Council Studies.³ However, these diagnostic criteria were established before AIDS became common.

In the tertiary referral centre for orthopaedic diseases in Zambia, we have noted a striking increase in the frequency of presumed Pott’s disease, with 112 inpatients since l991. 57% of adult patients were HIV-positive, which is double the rate in the general population. Much of the presumed pott’s disease we have treated in HIV-positive people has atypical features, including involvement of a single vertebra and more frequent involvement of the lumbar spine (40% vs 20%), suggesting that organisms other than Mycobacterium tuberculosis might be the cause of the localised spinal infection. Microbiological diagnosis is difficult to achieve because of the lack of facilities for fluoroscopically guided spinal biopsy and the considerable risks of open surgical bone biopsy in African patients with AIDS. Even after clean orthopaedic operations in Zambia, 70% of patients with AIDS developed wound infections, compared with an infection rate of 4% for clean surgery in HIV-seronegative patients.⁴

Many patients die despite antituberculous chemotherapy, and it is possible other opportunistic pathogens are being treated empirically and inappropriately as tuberculosis. Since tissue diagnosis of spinal infection is not practicable in much of the developing world, there is an urgent need for re-evaluation of clinically based diagnostic and therapeutic strategies in the presence of AIDS so that appropriate empiric therapy can be given.