Pulmonary Disease Caused by Rapidly Growing Mycobacteria: A Retrospective Study of 44 Cases in Japan
Department of Respiratory Medicine, National Hospital Organization National Toneyama Hospital, Toyonaka, Japan.Respiration (Impact Factor: 2.59). 08/2012; 85(4). DOI: 10.1159/000339631
Background: The features of pulmonary disease caused by rapidly growing mycobacteria (RGM) have not been sufficiently documented. Objectives: To establish these features, we retrospectively evaluated 44 patients. Methods: We screened respiratory isolates at the National Toneyama Hospital (Osaka, Japan) between 2003 and 2007. Diagnosis was based on the latest guidelines of the American Thoracic Society. The patients were classified into 3 types according to their radiographic findings: fibrocavitary, nodular bronchiectatic and unclassified variant. Results: We obtained 1,348 nontuberculous mycobacteria respiratory isolates from 1,187 patients, including 119 RGM isolates from 100 patients. Forty-four of these 100 patients were definitively diagnosed with respiratory disease due to RGM. The most common pathogen was Mycobacteriumabscessus, which accounted for 65.9% of cases, followed by Mycobacterium fortuitum at 20.5%. There was a statistically significant difference in smoking history between patients infected with these 4 RGM species (excluding those with an unknown smoking history; p = 0.039). The overall evaluation of radiographic findings revealed 18.2% as fibrocavitary, 43.2% as nodular bronchiectatic and 38.6% as unclassified variants in these 44 patients. There was a significant difference in radiographic findings between the 4 RGM species (p = 0.002). There was also a significant difference in radiographic findings between M. abscessus and M. fortuitum infected patients (p = 0.022). Conclusions: Patients with M. abscessus seem to have less of a smoking history and more frequent nodular bronchiectatic radiographic patterns than patients with M. fortuitum. In contrast, fibrocavitary patterns might be more frequent with M. fortuitum infection.
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ABSTRACT: A 70-year-old woman with methotrexate (MTX)-refractory rheumatoid arthritis (RA) was referred to our hospital for introduction of biological therapy. On high-resolution computed tomography scans, the patient exhibited abnormal findings such as bronchiectasis and centrilobular small nodules, which were highly suggestive of pulmonary nontuberculous mycobacterial (NTM) disease. Although mycobacterial cultures of sputum specimens yielded negative results, cultures of bronchoalveolar lavage fluids grew Mycobacterium abscessus. Frequent follow-up chest radiographs indicated that the patient's pulmonary disease became rapidly worse in 1 month following dose escalation of MTX and administration of low-dose prednisolone. Oral clarithromycin and levofloxacin, chosen on the basis of in vitro susceptibility testing, led to a dramatic recovery from this potentially life-threatening complication. Through our experience with this case, we have learned that (1) pulmonary M. abscessus disease can progress rapidly, even during nonbiological anti-RA therapy; (2) regular follow-up chest radiographs are useful to ensure timely implementation of anti-NTM treatment; (3) bronchoscopic testing should be considered when patients are suspected of pulmonary NTM disease but do not meet the diagnostic criteria; and (4) early isolation, identification, and susceptibility testing of causative NTM species are critical for favorable outcomes.
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ABSTRACT: Species identification of nontuberculous mycobacteria (NTM) is challenging due to the increasing number of identified NTM species and the lack of standardized testing strategies. The objectives of this study were to investigate the distribution of NTM species recovered from respiratory specimens by multigene sequence-based typing and to evaluate the clinical significance of identified species. Two hundred thirty-two consecutive clinical NTM isolates were subjected to sequencing of multiple genes, including hsp65, rpoB, and 16S-23S rRNA internal transcribed spacer (ITS) sequence. In addition, clinical data from all patients whose specimens had NTM isolates were analyzed to examine clinical virulence and treatment history. Eighteen strains from 227 isolates from 169 patients were successfully identified at the species level by multigene sequence-based typing. Mycobacterium avium complex and M. abscessus complex made up the majority of isolated NTM (88%; 199/227), followed by M. fortuitum complex (4%; 10/227). The pathogenic potential of NTM differs enormously by species, and M. avium complex and M. abscessus complex revealed especially high levels of virulence compared with findings for other NTM species. The results from our work support M. avium complex and M. abscessus complex being the most common NTM species with highly pathogenic potential isolated from clinical respiratory specimens and could be a good resource for molecular epidemiology of NTM species in South Korea.
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ABSTRACT: Nontuberculous mycobacteria infection is a growing global concern, but data from Asia are limited. This study aimed to describe the distribution and antibiotic susceptibility profiles of rapidly growing mycobacterium (RGM) isolates in Singapore. Clinical RGM isolates with antibiotic susceptibility tests performed between 2006 and 2011 were identified using microbiology laboratory databases and minimum inhibitory concentrations of amikacin, cefoxitin, clarithromycin, ciprofloxacin, doxycycline, imipenem, linezolid, moxifloxacin, sulfamethoxazole or trimethoprim-sulfamethoxazole, tigecycline and tobramycin were recorded. Regression analysis was performed to detect changes in antibiotic susceptibility patterns over time. A total of 427 isolates were included. Of these, 277 (65%) were from respiratory specimens, 42 (10%) were related to skin and soft tissue infections and 36 (8%) were recovered from blood specimens. The two most common species identified were Mycobacterium abscessus (73%) and Mycobacterium fortuitum group (22%), with amikacin and clarithromycin being most active against the former, and quinolones and trimethoprim-sulfamethoxazole against the latter. Decreases in susceptibility of M. abscessus to linezolid by 8.8% per year (p 0.001), M. fortuitum group to imipenem by 9.5% per year (p 0.023) and clarithromycin by 4.7% per year (p 0.033) were observed. M. abscessus in respiratory specimens is the most common RGM identified in Singapore. Antibiotic options for treatment of RGM infections are increasingly limited. Copyright © 2014 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.
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