NTM-PI) had higher death rates for all species combined, as well as for MAC and M. xenopi individually (Table 4).
A comprehensive population-based study from Denmark observed death rates of 39.7% for MAC-PD and 51.0% for M. xenopi disease, compared with 36.3% and 43.2% in our study.
The risk for death we observed with NTM-PD was generally greater than with NTM-PI, which was significant for all species combined, MAC, and M. xenopi. The lack of a significant difference in survival between NTM-PD and NTM-PI for the other species might have reflected the relatively small number of cases.
The significantly higher death rate for patients who had even 1 positive sputum specimen for MAC or M. xenopi is of particular interest.
To the Editor: Mycobacterium heckeshornense is a slow-growing scotochromogen phenotypically and phylogenetically related to M. xenopi. It was first identified as a cause of lung infection on the basis of unique 16s rRNA and 16S-23S spacer sequencing (1).
The 16S rRNA gene sequence analyzed for this isolate was 1,314 bp long and presented a divergence of 2.6% from its closest species, M. xenopi.
(8) found that most blood cultures for M. xenopi were detected with terminal AFB and visual growth inspection performed after the isolates had been determined as negative by conventional means at 42 days, which suggests a need for prolonged incubation.
Its phenotypic and genotypic resemblance to M. xenopi suggests that similar treatment may be reasonable.
To determine clinical relevance and determinants, we retrospectively reviewed medical files of all patients in the Netherlands in whom M. xenopi was isolated from January 1999 through March 2005 by using diagnostic criteria for nontuberculous mycobacterial infection published by the American Thoracic Society.
Pulmonary M. xenopi infections are most common, but extrapulmonary and disseminated infections have also been recorded (5, 6).
Its survival in flowing water systems and resistance to common disinfectants enables M. xenopi to contaminate laboratory samples and medical devices such as bronchoscopes, thus causing healthcare-acquired (pseudo) infections and laboratory cross-contaminations (3,6,8,9).
To assess frequency and clinical relevance of M. xenopi isolation and its determinants in the Netherlands, we performed a retrospective case study.