Submandibular lymphadenitis caused by Mycobacterium interjectum: contribution of new diagnostic tools

Abstract

Mycobacterium interjectum is a rare causative agent of cervical lymphadenitis. We describe a 2-year-old girl with suspected tuberculous cervical lymphadenitis.Sequencing of the 16S rRNA gene allowed the correct identification of Mycobacterium interjectum. As yet, only nine case reports of infections due to M. interjectum in children have been reported in the literature, and in all of them a correct identification could only be obtained using gene sequencing.

DisseminatedMycobacterium interjectumInfection with Bacteremia, Hepatic and Pulmonary Involvement Associated with a Long-Term Catheter Infection

“…It was originally first described in 1993 in an 18-month-old boy with lymphadenitis [ 3 ]. At least ten cases of M. interjectum lymphadenitis have been reported since then in very young immunocompetent children [ 4 ], possibly from sources such as oral exposure to contaminated objects [ 12 ]. M. interjectum has also been isolated in sputum cultures of asymptomatic patients [ 7 , 13 ] and from the gastrointestinal tract in a patient with acquired immunodeficiency syndrome [ 14 ].…”

“…Advances in mycobacteriology techniques have allowed the identification of new NTM species [ 1 ], previously undiagnosed or misclassified [ 2 , 3 ]. Mycobacterium interjectum is an uncommon pathogen that has been associated with lymphadenitis in children and pulmonary involvement in adults [ 4 , 5 ]. There are currently no specific guidelines for management of this uncommon infection.…”

Mycobacterium interjectumLung Infection

“…It was first described in 1993, causing cervical lymphadenitis in an 18-month-old German boy [1]. It was subsequently reported in 9 pediatric cases of necrotizing lymphadenitis [2–6]. It has also been isolated in the sputum of patients with chronic obstructive lung disease or HIV infection, in the urine of an asymptomatic elderly female, and in the stool of an AIDS patient with diarrhea [7, 8].…”

“…It produces inconsistent reactions for pyrazinamidase, urease, and heat stable catalase [12]. Misclassifications have involved both of these organisms, and accurate diagnosis requires sequencing of the 16S rDNA that codes the ribosomal RNA or high-performance liquid chromatography (HPLC) of the mycolic acids of the cell wall, a more time-consuming and cumbersome technique [2]. Although commonly there is agreement between these tests, discrepant results have been reported [12, 14], and it appears that variants within the M. interjectum species may express different HPLC patterns [12].…”

“…It is possible that many cases of M. interjectum producing destructive lung disease have been misdiagnosed in the past and that the prevalence of disease is higher than previously suspected. Outgrowth by other NTM could have also contributed to underdiagnosis, a problem that is overcome by DNA sequencing [2]. Due to phenotypic similarities with other NTM but different drug susceptibility patterns, accurate identification of this organism is necessary.…”