Pulmonary Disease From Nontuberculous Mycobacteria in Patients With Human Immunodeficiency Virus: Discussion
Tuberculosis (MTb) affects patients with all stages of HIV infection, although the likelihood of dissemination and atypical presentations may increase with progressive immunodeficiency. On the other hand, NTM species appear to cause serious infection only in patients with advanced HIV infection. Unique epidemiologic situations, such as exposure to contaminated water supplies, may be additional risks. Mycobacterium kansasii, in particular, may be more common in certain geographic regions.
Possible explanations for the paucity of reported cases of NTM pulmonary disease may include the diversity of clinical presentations, the difficulty in ascribing clinical significance to positive cultures, and the potential for concurrent infection with more than one opportunistic pathogen. Canadian family pharmacy read more Established criteria for diagnosis of NTM disease (in the pre-AIDS era), which include the presence of a plausible clinical setting, repeated isolation of a single organism in significant numbers, and the exclusion of other pathogens, may be difficult to apply in the setting of AIDS.
The isolation of multiple potential pathogens (as in our case 3), the likelihood of concurrent opportunistic infections, and the atypical nature of clinical and radiographic features (compared to patients without HIV) illustrate this problem. It is therefore necessary, whenever safe, to obtain actual tissue specimens for histologic and microbiologic examination when NTM lung disease is suspected. The presence of systemic mycobacterial infection may increase the likelihood that concurrent pulmonary disease is related to the identified mycobacterium. However, disseminated MAC is so common that it often occurs concomitantly with opportunistic infections such as PCP; in this setting, pulmonary disease cannot be assumed to be due to MAC.
The radiographic manifestations of NTM pulmonary infections in patients with AIDS are protean. It is difficult to collect a large series of cases since most of these infections, with the exception of MAC, are rare. Even with MAC, sputum cultures may be positive without any clinical or radiographic evidence of pulmonary disease or systemic disease may develop without any pulmonary manifestations.
Category: Respiratory Symptoms
Tags: AIDS, atypical Mycobacterium infections, HIV infection, Mycobacterium avium-intracellulare infection