Disseminated Mycobacterium celatum disease with prolonged pulmonary involvement

A rare case of pulmonary mycobacteriosis caused by rifabutin resistant Mycobacterium celatum and review of the literature

The present case demonstrates an atypical pulmonary mycobacteriosis that mimicked classical symptoms and radiology findings for tuberculosis. While T-SPOT Test and PCR analyses proved negative for tuberculosis, microscopic sputum evaluation showed acid-fast bacilli and Mycobacterium celatum was found in culture. Uniquely, in our case M. celatum was resistant to rifabutin. Therefore, after not responding to combination treatment including rifabutin, our patient was treated with ethambutol, clarithromycin and protionamide. Classical risk factors for atypical mycobacteriosis such as immunodeficiency (including medication-induced), preexisting pulmonary disease or multimorbidity were not present. We conclude that the high age of the patient (92 y) may have been the main contributing factor for the infection.

TB or not TB? Mycobacterium celatum mimicking Mycobacterium tuberculosis: A case of mistaken identity

Mycobacterium celatum is a slow-growing, non-tuberculous mycobacterium (NTM) and a rare cause of infection in humans. Infection occurs primarily by inhalation or direct inoculation from environmental sources, and this pathogen has been reported to cause localized infections in the lungs and lymph nodes of both immunocompetent and immunocompromised patients, and disseminated disease in immunocompromised patients. Here, we present a case of pulmonary infection with M. celatum in an immunocompetent 68-year-old male with clinical features similar to tuberculosis. The patient initially developed palpitations, worsening fatigue, night sweats, dyspnea, productive cough, and weight loss. Computed tomography angiogram of the chest revealed a right upper lobe pulmonary artery embolus and extensive biapical fibronodular cavitary densities. Two separate sputum samples were positive for acid-fast bacilli (AFB) and sputum cultures were positive for M. celatum. The patient responded well to treatment with clarithromycin, ciprofloxacin, and ethambutol. We advise physicians to consider M. celatum infection in the differential diagnosis of patients with symptoms and radiographic and microbiologic evidence suggestive of NTM pulmonary infection.

Other Slow-Growing Nontuberculous Mycobacteria

The list of clinically important slow-growing nontuberculous mycobacteria (NTM) continues to expand as new species are identified and older ones are found to be pathogenic. Based on pigment production, the strains may be classified as photochromogenic, scotochromogenic, or unpigmented. Some of these organisms are not newly discovered but have heretofore been considered virtually nonpathogenic. Previously, many were regarded as contaminants when isolated from clinical specimens. Ubiquitous in nature, many NTM have been isolated from groundwater or tap water, soil, house dust, domestic and wild animals, and birds. Most infections result from inhalation or direct inoculation from environmental sources. They are not spread from person to person. The infections may be localized or disseminated. In most cases, the optimal regimen or duration of therapy has not been firmly established. The results of in vitro susceptibility testing may be used to select a therapeutic regimen. Many experts recommend clarithromycin with companion drugs such as rifampin and ethambutol for most, but not all, slowly growing species. Aminoglycosides, clofazimine, fluoroquinolones, linezolid, pyrazinamide, or trimethoprim-sulfamethoxazole also may be effective against some strains. Immunocompetent patients with clinically significant infections with NTM usually should receive 18 to 24 months of therapy. Infected immunocompromised patients, particularly those with disseminated infection, probably should receive therapy as long as their immune systems remain impaired. Some of the species discussed include Mycobacterium alsiense, M. celatum, M. gordonae, M. haemophilum, M. kyorinense, M. malmoense, M. simiae complex, M. szulgai, M. terrae complex, M. ulcerans, and M. xenopi.