HIV infection and drug resistant TB
Investigators confirmed HIV-positive serostatus as a risk factor for resistance to at least isoniazid, for both isoniazid and rifampin resistance (multidrug-resistant {MDR} TB) and for rifampin monoresistance (TB resistant to rifampin only).Of critical importance for HIV-infected persons is implementation of TB prevention and control strategies such as a) appropriate use of therapy for latent M. tuberculosis infection, b) early diagnosis and effective treatment of active TB (i.e., administering four-drug antituberculosis regimens by DOT to all coinfected patients), and c) prompt compliance with requirements for reporting TB cases and drug-susceptibility test results. Implementing these strategies for persons coinfected with HIV will not only help reduce new cases of TB in general; it also could decrease further transmission of drug-resistant strains and new cases of drug-resistant TB. Treatment of Drug-Resistant TB
- TB disease resistant to isoniazid only. The treatment regimen
should generally consist of a rifamycin (rifampin or rifabutin), pyrazinamide, and ethambutol for the duration of treatment. Intermittent therapy administered twice weekly can be used following at least 2 weeks (14 doses) of daily induction therapy (see Duration of TB Treatment). The recommended duration of treatment is 6-9 months or 4 months after culture conversion. Isoniazid is generally stopped when resistance (greater than 1% of bacilli resistant to 1.0 ug/mL of isoniazid) to this drug is discovered; however, when low-level resistance is discovered (greater than 1% of bacilli resistant to 0.2 ug/mL of isoniazid, but no resistance to 1.0 ug/mL of isoniazid), some experts suggest continuing to use isoniazid as part of the treatment regimen. Because the development of acquired rifamycin resistance would result in MDR TB, clinicians should carefully supervise and manage TB treatment for these patients.
- TB disease resistant to rifampin only. The 9-month treatment
regimen should generally consist of an initial 2-month phase of isoniazid, streptomycin, pyrazinamide, and ethambutol. The second phase of treatment should consist of isoniazid, streptomycin, and pyrazinamide administered for 7 months. Because the development of acquired isoniazid resistance would result in MDR TB, clinicians should carefully supervise and manage TB treatment for these patients.
- Multidrug-resistant TB (resistant to both isoniazid and
rifampin). These patients should be managed by or in consultation with physicians experienced in the management of MDR TB. Findings from a retrospective study of patients with MDR TB strongly indicate that early aggressive treatment with appropriate regimens (based on the known or suspected drug-resistance pattern of the M. tuberculosis isolate) markedly decreases deaths associated with MDR TB . Most drug regimens currently used to treat MDR TB include an aminoglycoside (e.g., streptomycin, kanamycin, amikacin) or capreomycin, and a fluoroquinolone. The recommended duration of treatment for MDR TB in HIV-seropositive patients is 24 months after culture conversion, and posttreatment follow-up visits to monitor for TB relapse should be conducted every 4 months for 24 months.
Because of the serious personal and public health concerns associated with MDR TB, health departments should always use DOT for these patients and take whatever steps are needed to ensure their adherence to therapy.
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Early diagnosis and effective treatment of TB among HIV-infected patients
are critical for curing TB, minimizing the negative effects of TB on the
course of HIV, and interrupting the transmission of Mycobacterium tuberculosis
to other persons in the community.
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All HIV-infected persons at risk for infection with M. tuberculosis must be
carefully evaluated and, if indicated, administered therapy to prevent the
progression of latent infection to active TB disease and avoid the
complications associated with HIV-related TB.
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All HIV-infected patients undergoing treatment for TB should be evaluated
for antiretroviral therapy, because most patients with HIV-related TB are
candidates for concurrent administration of antituberculosis and
antiretroviral drug therapies. However, the use of rifampin with protease
inhibitors or non-nucleoside reverse transcriptase inhibitors is
contraindicated.
Prerequisites for antiretroviral therapy
Due to the high cost of antiretroviral drugs, the complexity of the
regimens and the need for careful monitoring, specific services and
facilities must be in place before considering the introduction of ART
into any setting.
The following conditions are essential to the introduction of ART:
- Assured access to voluntary HIV counselling and testing (VCT) and
institution of follow up counselling services for ART to ensure
continued psychosocial support and to enhance adherence to treatment.
- Capacity to recognise and appropriately manage common HIV related
illnesses and opportunistic infections.
- Reliable laboratory monitoring services including routine
haematological and biochemical tests for the detection of drug toxicity
as well as access to facilities for monitoring the immunologic and
virologic parameters of HIV infection.
- Assurance of an adequate supply of quality drugs, including drugs
for the treatment of opportunistic infections and other HIV related
illnesses.
- Identification of sufficient resources to pay for treatments on a
long-term basis.
- Information and training on safe and effective use of antiretroviral
drugs for health professionals in a position to prescribe ART.
- Establishment of reliable regulatory mechanisms against misuse and
misappropriation of antiretroviral drugs.
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