HIV: Opportunistic infections, treatment of tuberculosis

There is a close connection between HIV infection and tuberculosis. Many tuberculosis patients in Africa are HIV patients and approximately 50% of the HIV patients develop tuberculosis. This makes the struggle against tuberculosis much more difficult. The diminished resistance of the patient often results in a reactivation of tuberculosis bacteria. New infections of course also occur. Clinical symptoms of tuberculosis can appear quite early, even before the CD4-lymphocyte count has substantially decreased. Infections with atypical mycobacteria (for example MAI = Mycobacterium avium intracellulare) are more frequent in the West and seldom occur in developing countries. The discovery of acid-fast bacilli in a patient in Africa is therefore usually synonymous with tuberculosis. Most atypical mycobacterioses in fact occur only when the immunosuppression has advanced much further. However, many patients will have died before this stage is reached.

The Mantoux-test is unreliable in AIDS (frequently negative due to anergy). Tuberculosis proceeds more aggressively and quickly in HIV patients. Extrapulmonary tuberculosis occurs more in seropositive persons. Fortunately, treatment gives good results. Any new case of tuberculosis that has never been treated before should be given: isoniazid + rifampin + pyrazinamide + ethambutol for 2 months, followed by isoniazid + rifampin for 4 months. It is better not to give streptomycin injections due to the risk of HIV transmission in cases of poor sterilization of needles. AIDS patients often have severe cutaneous side-effects (including Stevens-Johnson syndrome) upon use of thiosemicarbazone, and hence this product is best avoided. The increase in resistant tuberculosis and the lack of cheap alternative therapies may in the near future give rise to extra problems, not only for the patients themselves but also for the non-seropositive population. Compliance with therapy is of utmost importance for the patients themselves and for preventing development of resistance and for counteracting further transmission (also to non-HIV infected persons). Respiratory precautions, till negativity of the sputum (Ziehl-Neelsen), should be implemented.

Active tuberculosis should be excluded before TB prophylaxis is started in a patient. INH (1 year) combined with pyridoxine (vitamin B6), the latter for prevention of neuritis, is used as prophylaxis. Rifampicin can be given with pyrazinamide for two months as an equally effective alternative.

Mycobacterium avium is not very sensitive to the conventional tuberculostatic drugs. Treatment of Mycobacterium avium relies on administration of rifabutin [Mycobutin®] + ethambutol [Myambutol®]+ clarithromycin [Maclar®, Biclar®, Heliclar®].

Category: Medical Subject Notes , Medicine Notes , Pharmacology Notes