Molecular identification of Mycobacterium avium complex (MAC) members recovered from clinical samples in a hospital in a 3-year period
Poster communication in 34th Annual Congress of the European Society of Mycobacteriology
July 1st, 2013
Alvarez J., Romero B., Cuartero C., Bezos J., Casal C., Sanchez-Coppel N., Gimeno JA., Dominguez L. and Gomez-Mampaso E.
MAC infection may cause i) pulmonary disease in immunocompetent patients that suffer from other predisposing diseases ii) lymphadenopathies (mainly in children), iii) generalized infections usually in immunocompromised patients, and iv) pulmonary disease in immunocompetent patients without other predisposing diseases (“Lady Windermere syndrome”) primarily caused by M. intracellulare. However, the evaluation of the signifi cance of MAC isolation from clinical samples is seriously impaired by the wide environmental distribution of certain of its members (mainly Mycobacterium avium subsp. hominissuis, Mah), which leads to the finding of MAC in samples from asymptomatic (and nondiseased) individuals due to either a contamination of the sample or a transitory colonization of the host. The objective of this study was to identify to the species/ strain level using molecular tools a representative selection of the MAC members recovered from clinical samples in a hospital in 2010-2012 and to determine if an association between species/subspecies and a higher persistence/virulence in patients exists. 71 isolates were recovered from respiratory (n=53) and urine (n=18) samples from patients with different medical records (recurrent infection with MAC, VIH, predisposing respiratory diseases…) and identified as MAC using commercial probes. Detection of insertion sequences IS1245/IS901 and sequencing of the hsp65 and rpoβ genes and the internal transcribed spacer were carried out to perform species/subspecies/ strain identification. A subset of isolates was also subjected to MALDI-TOF analyses, and all laboratory results were then compared with the apparent clinical significance of the isolates. Overall 52 Mah, 14 M. intracellulare, 3 M. marseillense and 2 M. chimaera isolates were identified, with patients with chronic MAC infections usually harboring M. intracellulare. A notable degree of genetic heterogeneity was found with the exception of urine and a proportion of respiratory Mah isolates, suggesting the existence of contamination of the sample or exposure to common sources of prevalent environmental MAC strains. The different distribution of MAC species among patients suggest that distinct epidemiological patterns/colonization capacities may exist related with the environmental setting and/or MAC species implicated
 | Departamento de Sanidad Animal. Facultad de Veterinaria. Universidad Complutense (UCM). |
| Servicio de Micobacterias (MYC). Centro de Vigilancia Sanitaria Veterinaria (VISAVET). Universidad Complutense (UCM). |
Link to 34th Annual Congress of the European Society of Mycobacteriology
