First human isolate ofMycobacterium madagascariensein the sputum of a patient with tracheobronchitis

Abstract

Reports on the isolation and identification of unusual Mycobacteria species in humans, animals and plants have increased considerably recently due, largely, to the implementation of Molecular Biology methods which have higher discriminative powers than the classical phenotype-based techniques [1] . Since the year 2000, several authors have identified a variety of Mycobacteria in clinical specimens, including M. elephantis [2,3] , M. branderi [4] , M. monacense [5,6] , and M. poriferae [7] .M. madagascariense was first described by Kazda et al. [8] . It grows rapidly at temperatures ranging between 22 ° C and 31 ° C and is scotochromogenic [1] . Phylogeny studies based on DNA sequence classify M. madagascariense within the group of thermo-tolerant rapid growers, phylo-genetically close to M. confluentis [9] . Experimental studies in animals indicate that this microorganism is not a pathogen [1] . To date, M. madagascariense has not been identified in any human sample. The present letter reports, to the best of our knowledge for the first time in the literature, the identification of M. madagascariense in the sputum of a patient with tracheobronchitis.In August 2009, a 22-year-old Russian male was admitted to the Pneumology Department of the Hospital Universitari Sant Joan de Reus (Catalonia, Spain). He complained of a cough with purulent sputum dating from a year previously, with bloody sputum on occasions. He had no evidence of fever or toxic syndrome. Standard biochemical and hematological tests were normal. Serology for hepatitis B and C and human immunonodeficiency virus (HIV) infection were negative. Thorax X-ray showed calcified adenopathies in the right mediastinum and hilium, indicating previous tuberculosis. Three serial sputum samples were collected and Zhiel-Neelsen staining was negative. A standard culture in agar plates was negative for bacterial respiratory pathogens. Cultures in Lowenstein-Jensen (LJ) medium with pyruvate (but not LJ medium alone) showed, 7 days later, abundant mucous, 2 mm sized, acid-fast, orange colonies, that were composed of Grampositive rods. Acid fast bacilli staining was performed in the sputum samples before and after decontamination, and prior to inoculation into the LJ medium. These colonies were identified as M. madagascariense using molecular and phenotypic methods in a reference laboratory at the Hospital Universitari de Bellvitge (Barcelona, Spain). Currently, this mycobacterial species cannot be identified by routine commercial tests since the organism is not recognized with the available diagnostic systems. Although growth and chromogenic characteristics as well as biochemical tests (Table 1 ) were important for microbiology diagnosis, definitive identification relied on partial 16S rRNA gene sequencing (first 500 bp) [10] . The patient was