We prospectively studied 298 patients with cystic fibrosis (mean age 11.3 years; range 2 months to 32 years; sex ratio, 0.47) for nontuberculous mycobacteria in respiratory samples from January 1, 1996, to December 31, 1999. Mycobacterium abscessus was by far the most prevalent nontuberculous mycobacterium: 15 patients (6 male, 9 female; mean age 11.9 years; range 2.5–22 years) had at least one positive sample for this microorganism (versus 6 patients positive for M. avium complex), including 10 with >3 positive samples (versus 3 patients for M. avium complex). The M. abscessus isolates from 14 patients were typed by pulsed-field gel electrophoresis: each of the 14 patients harbored a unique strain, ruling out a common environmental reservoir or person-to-person transmission. Water samples collected in the cystic fibrosis center were negative for M. abscessus. This major mycobacterial pathogen in children and teenagers with cystic fibrosis does not appear to be acquired nosocomially.

We studied the prevalence and species distribution of nontuberculous mycobacteria (NTM) in relation to age in 385 patients with cystic fibrosis (CF) (mean age ؎ standard deviation [range], 12.0 ؎ 6.1 [1 to 24] years; sex ratio, 0.53) attending three Parisian centers. The overall prevalence of NTM in sputum was 8.1% (31 out of 385). The following NTM were isolated (n ‫؍‬ 33): Mycobacterium abscessus (n ‫؍‬ 13, 39.4%), Mycobacterium avium complex (MAC) (n ‫؍‬ 7, 21.2%), Mycobacterium gordonae (n ‫؍‬ 6, 18.2%), and other (n ‫؍‬ 7, 21.2%). Sixteen patients met the American Thoracic Society microbiological criteria for NTM infection, including 11 patients positive for M. abscessus, 4 for MAC, and 1 for MAC and Mycobacterium kansasii. The overall prevalence of NTM was significantly lower in patients under 15 years old than for patients equal to or more than 15 years old (4.8 versus 14.9%, respectively; P ‫؍‬ 0.001). M. abscessus was isolated at all ages, while MAC was not recovered before 15 years (prevalence of 0.0 and 5.2% in patients aged 1 to 14 and 15 to 24, respectively; P ‫؍‬ 0.001).Since 1990, an increasing number of studies have reported the recovery of nontuberculous mycobacteria (NTM) from the respiratory tract of patients with cystic fibrosis (CF) (1,12,13,16). In a recent multicenter study carried out in the United States using standardized bacteriological methods, the overall prevalence of NTM in sputum (percent of patients with at least one positive NTM culture) was 13%, ranging from 7 to 24% depending on the center (16). Mycobacterium avium complex (MAC) (72%) and Mycobacterium abscessus (16%) were the most common species. Other NTM (Mycobacterium gordonae, Mycobacterium kansasii, Mycobacterium lentiflavum, Mycobacterium peregrinum) were much rarer. About 20% of the culture-positive subjects met the American Thoracic Society (ATS) microbiological criteria for NTM pulmonary disease (2); most of these patients were positive for MAC or M. abscessus.Paradoxically, although we know that CF children are vulnerable to bacterial infections from birth, most previous studies on NTM in CF have been conducted in populations mostly or exclusively composed of adults (1, 13, 16). For example, only patients who were 10 years or older were recruited in the multicenter United States study cited above, and the mean age Ϯ standard deviation (SD) was 21 Ϯ 9 years (16). Very few case series involving children with CF have been carried out, and those that have been done mainly used inadequate culture and species identification techniques. However, although imperfect, these studies suggest some differences in the epidemiology of NTM between pediatric and adult CF populations. One of the most intriguing differences is the apparent propensity of CF children to be infected with rapidly growing mycobacteria (RGM). In 1980, Boxerbaum reported that 8 out of 430 CF children were infected with RGM: 6 with organisms referred to as Mycobacterium chelonei (now the M. chelonaeabscessus group) and two with M. fortuitum (4). M. chelonei in...

Mycobacterial identification is based on several methods: conventional biochemical tests that require several weeks for accurate identification, and molecular tools that are now routinely used. However, these techniques are expensive and time-consuming. In this study, an alternative method was developed using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). This approach allows a characteristic mass spectral fingerprint to be obtained from whole inactivated mycobacterial cells. We engineered a strategy based on specific profiles in order to identify the most clinically relevant species of mycobacteria. To validate the mycobacterial database, a total of 311 strains belonging to 31 distinct species and 4 species complexes grown in Löwenstein-Jensen (LJ) and liquid (mycobacterium growth indicator tube [MGIT]) media were analyzed. No extraction step was required. Correct identifications were obtained for 97% of strains from LJ and 77% from MGIT media. No misidentification was noted. Our results, based on a very simple protocol, suggest that this system may represent a serious alternative for clinical laboratories to identify mycobacterial species.