Epidemiological characteristics of non-tuberculosis Mycobacteria isolated from adult patients in a teaching hospital in Madrid from January 2000 to August 2004

Abstract number: 1134_04_266

Díaz-Regañón J., Domingo D., Monclús Arroyo D., Abanades S., López-Brea M.

Objectives:  

1) To determine the Mycobacteria isolated from adult patients in a Teaching Hospital in Madrid from January 2000 to August 2004. 2) To study the epidemiological characteristics of the atypical Mycobacteria isolated in that population.

Methods:  

We evaluated retrospectively 20228 samples sent to the Microbiology laboratory for mycobacterial research from January 2000 until to 2004 in adult patients. Samples were processed following standard procedures and cultured in solid medium (Coletsos) and liquid medium (modified Middlebrook 7H9). The growth in solid medium compatible with Mycobacteria and those detected as positive in the liquid medium system were stained with the Ziehl–Neelsen technique. Identification was performed by hybridation probes (Accuprobe-Gen Probe) for M. tuberculosis and MAC, and in a national referral centre for the rest of them. Epidemiology information was obtained for further studies.

Results:  

From the total of the 20228 samples sent to the laboratory, 1015 were rejected as inadmissible (5.02%), 623 were contaminated (3.08%) and 17954 were negative after 2 months (88.76%). 636 samples were positive for Mycobacteria (3.14%) being 71.70%M. tuberculosis (456 samples), 21.38% slow grow Mycobacteria (136 samples of which 86 were MAC, 13 M. simiae, 13 M. xenopi and others), 6.29% rapid grow Mycobacteria (40 samples with 14 M. fortuitum, 12 M. chelonae and others) and 0.63% not viable atypical Mycobacteria (4 samples). Sputum was the most common sample sent to the laboratory (60.55%) and the Neumology Department was the origin in 39.44% of the cases. In 100 cases the patients were male (55.55%) and in 80 cases female (44.45%). We considered significant the isolation of the same Mycobacteria in two or more samples and 34 patients had this condition being the microorganisms isolated: MAC in 18 patients, M. simiae in 4, M. xenopi in 3, M. chelonae and M. kansasi in 2 and M. gordonae, M. abscessus, M. lentiflavum, M. mucogenicum and M. senegalense in 1 patient. In 18 of them the isolation was in more than three samples.

Conclusions:  

Non tuberculosis Mycobacteria are an important burden of work in our laboratory and the clinical significance of these microorganisms remains controversial in an important number of cases.