Acute respiratory failure due to Mycobacterium kansasii infection: immune reconstitution disease in a patient with AIDS

Isoniazid-resistant Mycobacterium kansasii in an HIV-positive patient, and possible development of immune reconstitution inflammatory syndrome after initiation of highly active antiretroviral therapy: case report

Non-tuberculous mycobacteria are rare but important causes of infection in HIV-positive individuals. A 28-year-old HIV-positive male presented with a high fever, non-productive cough, right subcostal pain, splenomegaly, a very low CD4 count, elevated C-reactive protein and erythrocyte sedimentation rate, and a normal white blood cell count. The suspicion of tuberculosis (TB) was very high, and sputum samples were positive for acid-fast bacilli. Standard quadruple anti-TB therapy was initiated, but once culture of the sample revealed Mycobacterium kansasii, pyrazinamide was withdrawn. Highly active antiretroviral therapy (HAART) was initiated soon after, consisting of abacavir/lamivudine and efavirenz. The patient's general condition deteriorated 2 weeks after HAART initiation, which could have been due to the development of immune reconstitution inflammatory syndrome (IRIS). The patient recovered and was discharged in good condition. However, the results of resistance testing of the isolated organism arrived after discharge, and showed isoniazid and streptomycin resistance. This is the first case report of M. kansasii infection from Serbia and shows the difficulties encountered during the course of treatment.

Pulmonary manifestations of the immune reconstitution inflammatory syndrome

PURPOSE OF REVIEW

Immune reconstitution inflammatory syndrome (IRIS) is a common occurrence in HIV patients starting antiretroviral therapy (ART), and pulmonary involvement is an important feature of tuberculosis-IRIS and pneumocystis-IRIS. Pulmonologists need an awareness of the timing, presentation and treatment of pulmonary IRIS.

RECENT FINDINGS

Case definitions for tuberculosis-IRIS and cryptococcal-IRIS have been published by the International Network for the Study of HIV-associated IRIS (INSHI). A number of studies have addressed validation of clinical case definitions and the optimal time to commence ART after diagnosis of an opportunistic infection in HIV patients. The pathogenesis of IRIS is being assessed at a molecular level, increasing our understanding of mechanisms and possible targets for future preventive and therapeutic strategies.

SUMMARY

Tuberculosis-IRIS, nontuberculosis mycobacterial-IRIS and pneumocystis-IRIS occur within days to weeks of starting ART, causing substantial morbidity, but low mortality. Cryptococcal-IRIS usually occurs later in the course of ART, and may be associated with appreciable mortality. Early recognition of unmasking and paradoxical IRIS affecting the lung allows timely initiation of antimicrobial and/or immunomodulatory therapies.

Immune reconstitution inflammatory syndrome in HIV-infected patients receiving antiretroviral therapy : pathogenesis, clinical manifestations and management

The use of antiretroviral therapy (ART) to treat HIV infection, by restoring CD4+ cell count and immune function, is associated with significant reductions in morbidity and mortality. Soon after ART initiation, there is a rapid phase of restoration of pathogen-specific immunity. In certain patients, this results in inflammatory responses that may result in clinical deterioration known as 'the immune reconstitution inflammatory syndrome' (IRIS). IRIS may be targeted at viable infective antigens, dead or dying infective antigens, host antigens, tumour antigens and other antigens, giving rise to a heterogeneous range of clinical manifestations. The commonest forms of IRIS are associated with mycobacterial infections, fungi and herpes viruses. In most patients, ART should be continued and treatment for the associated condition optimized, and there is anecdotal evidence for the use of corticosteroids in patients who are severely affected. In this review, we discuss research relating to pathogenesis, the range of clinical manifestations, treatment options and prevention issues.

Immune reconstitution inflammatory syndrome (IRIS): review of common infectious manifestations and treatment options

The immune reconstitution inflammatory syndrome (IRIS) in HIV-infected patients initiating antiretroviral therapy (ART) results from restored immunity to specific infectious or non-infectious antigens. A paradoxical clinical worsening of a known condition or the appearance of a new condition after initiating therapy characterizes the syndrome. Potential mechanisms for the syndrome include a partial recovery of the immune system or exuberant host immunological responses to antigenic stimuli. The overall incidence of IRIS is unknown, but is dependent on the population studied and its underlying opportunistic infectious burden. The infectious pathogens most frequently implicated in the syndrome are mycobacteria, varicella zoster, herpesviruses, and cytomegalovirus (CMV). No single treatment option exists and depends on the underlying infectious agent and its clinical presentation. Prospective cohort studies addressing the optimal screening and treatment of opportunistic infections in patients eligible for ART are currently being conducted. These studies will provide evidence for the development of treatment guidelines in order to reduce the burden of IRIS. We review the available literature on the pathogenesis and epidemiology of IRIS, and present treatment options for the more common infectious manifestations of this diverse syndrome and for manifestations associated with a high morbidity.

Immune reconstitution disease associated with mycobacterial infections in HIV-infected individuals receiving antiretrovirals

Immune reconstitution disease (IRD) in HIV-infected patients is an adverse consequence of the restoration of pathogen-specific immune responses during the initial months of highly active antiretroviral treatment (HAART). Previously subclinical infections are "unmasked" or pre-existing opportunistic infections clinically deteriorate as host immunopathological inflammatory responses are "switched on". IRD is most frequently associated with mycobacterial infections. Our literature search identified 166 published cases of IRD associated with mycobacterial infections. We review the underlying immunological mechanisms, difficulties surrounding case definition and diagnosis, the wide diversity of clinical manifestations, and treatment. The importance of screening patients for mycobacterial disease before starting HAART and the critical impact of the timing of commencement of HAART in patients receiving treatment for tuberculosis are highlighted. We also discuss the problem of IRD associated with mycobacterial diseases in developing countries where tuberculosis prevalence is high and access to HAART is currently expanding.