Mycobacterium celatum Pulmonary Infection in the Immunocompetent
Mycobacterium celatum Pulmonary Infection in the Immunocompetent
Mycobacterium celatum has been shown to cause disease in immunocompromised patients. We report a case of serious pulmonary infection caused by M. celatum in an apparently immunocompetent patient and review the characteristics of two other reported cases. Clinical and radiologic symptoms and signs included cough, malaise, and weight loss associated with cavitary lesions and pulmonary infiltrates. Although M. celatum is easy to detect in clinical specimens by liquid and solid media, it may be misidentified as a member of the M. tuberculosis complex or as M. xenopi. M. celatum pulmonary infection appears to respond to antimycobacterial chemotherapy, particularly with clarithromycin.
Mycobacterium celatum was first described in 1993 as a new species whose mycolic acid pattern closely resembled that of M. xenopi (xenopi-like) but was biochemically indistinguishable from M. avium complex MAC). By sequencing studies of the 16S rRNA gene, now known to exist in two different copies within M. celatum genome, three different types could be differentiated. Cross-reactivity with the Accuprobe assay (Gen-Probe Inc., San Diego, CA) for the M. tuberculosis complex (MTB) was observed by probing types 1 and 3 but not type 2. DNA sequencing showed that M. celatum type 1 differs by one nucleotide from the probe used in the Accuprobe assay, type 2 differs by four nucleotides, and the type 3 DNA sequence for the probe region is unknown.
Although M. celatum has been reported to cause infection mainly in AIDS patients, recently a growing amount of clinical evidence indicates that the infection can lead to serious disease in immunocompetent subjects as well. In this case, the principles for diagnosis of diseases caused by nontuberculous mycobacteria, recently updated by the American Thoracic Society, need to be properly followed. We report a well-documented case of a pulmonary disease with this mycobacterium in an apparently immunocompetent woman and review the characteristics of two similar published cases.
Mycobacterium celatum has been shown to cause disease in immunocompromised patients. We report a case of serious pulmonary infection caused by M. celatum in an apparently immunocompetent patient and review the characteristics of two other reported cases. Clinical and radiologic symptoms and signs included cough, malaise, and weight loss associated with cavitary lesions and pulmonary infiltrates. Although M. celatum is easy to detect in clinical specimens by liquid and solid media, it may be misidentified as a member of the M. tuberculosis complex or as M. xenopi. M. celatum pulmonary infection appears to respond to antimycobacterial chemotherapy, particularly with clarithromycin.
Mycobacterium celatum was first described in 1993 as a new species whose mycolic acid pattern closely resembled that of M. xenopi (xenopi-like) but was biochemically indistinguishable from M. avium complex MAC). By sequencing studies of the 16S rRNA gene, now known to exist in two different copies within M. celatum genome, three different types could be differentiated. Cross-reactivity with the Accuprobe assay (Gen-Probe Inc., San Diego, CA) for the M. tuberculosis complex (MTB) was observed by probing types 1 and 3 but not type 2. DNA sequencing showed that M. celatum type 1 differs by one nucleotide from the probe used in the Accuprobe assay, type 2 differs by four nucleotides, and the type 3 DNA sequence for the probe region is unknown.
Although M. celatum has been reported to cause infection mainly in AIDS patients, recently a growing amount of clinical evidence indicates that the infection can lead to serious disease in immunocompetent subjects as well. In this case, the principles for diagnosis of diseases caused by nontuberculous mycobacteria, recently updated by the American Thoracic Society, need to be properly followed. We report a well-documented case of a pulmonary disease with this mycobacterium in an apparently immunocompetent woman and review the characteristics of two similar published cases.
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