Phenotypic and molecular characterization of three clinical isolates of Mycobacterium interjectum

Abstract

Introduction of molecular biology-based technology into an Australian mycobacterial reference laboratory has resulted in the identification of three isolates of Mycobacterium interjectum in the past 12 months. Conventional phenotypic methods failed to identify the species of these isolates, and high-performance liquid chromatography found that only one of the three isolates had a mycolic acid pattern similar to that of the type strain. In contrast, all three isolates were rapidly identified as M. interjectum by 16S rRNA gene sequence analysis. Two isolates were recovered from the lymph nodes of children with cervical lymphadenitis, confirming the pathogenicity of this organism. However, the third isolate was obtained from the sputum of an elderly male with chronic lung disease without evidence of clinical or radiological progression, suggesting that isolation of M. interjectum should not imply disease. With the increasing use of molecular biology-based technology in mycobacterial laboratories, M. interjectum may be recognized more frequently as a pathogen or commensal organism.

Cervical lymphadenitis due to mycobacterium interjectum

“…The isolated species are frequently identified as M. avium, M. scrofulaceum, and M. malmoense; they often cause indolent cervical adenitis and the treatment of choice is radical excision. [1][2][3][4] In recent times, new mycobacteria species have been described: M. lentiflavum, M. interjectum, which cause lymphadenitis in children as in the case presented here. [1][2][3][4][5][6] A 2-year-old boy presented with a 3-month history of a 2 Â 2 cm submandibular adenopathy in the right cervical area, which did not remit with antibiotic treatment (amoxicillin-clavulanate).…”

“…[1][2][3][4] In recent times, new mycobacteria species have been described: M. lentiflavum, M. interjectum, which cause lymphadenitis in children as in the case presented here. [1][2][3][4][5][6] A 2-year-old boy presented with a 3-month history of a 2 Â 2 cm submandibular adenopathy in the right cervical area, which did not remit with antibiotic treatment (amoxicillin-clavulanate). On examination, a tumor was found in the right submandibular region, which was indolent, fluctuant, inflamed and with a high temperature.The patient had not received a BCG vaccination and tested positive (14 mm) on the PPD RT-23 2 TU Mantoux tuberculin test.…”

“…1 The phenotypical and biochemical characteristics are similar to those described in M. scrofulaceum, but after carrying out genetic testing it can be seen that our strain is a new species of mycobacteria. 1,3,4 Macroscopic growth in Löwenstein-Jensen agar is dysgonic, scotochromogenic and small at 358C. The mycobacteria expresses multidrug resistance in vitro,…”

Lymphadenitis cervicalis due to Mycobacterium interjectum in immunocompetent children

“…In healthy young children, cervical lymphadenitis is among the most common manifestations. Clinically significant disease caused by the NTM Mycobacterium interjectum has increasingly been recognized in recent years, especially due to improvements in laboratory isolation methods and the introduction of molecular biologybased methods for species identification (1). This report presents two cases of this uncommon infection and discusses diagnostic approaches.…”

The Many Lives of Nontuberculous Mycobacteria

“…NTM include species that colonize human epithelia, as well as species that are found in soil and aquatic environments. The NTM species that colonize human epithelia are largely nonpathogenic and can be found on skin (2)(3)(4) and along the genitourinary (5)(6)(7), gastrointestinal (7), and respiratory (8)(9)(10)(11)(12)(13)(14) tracts. The NTM species that are found in soil and aquatic environments include Mycobacterium vaccae, the Mycobacterium avium complex (MAC), and the Mycobacterium abscessus complex (MABSC) (15,16).…”