Investigation of a Cluster of Mycobacterium interjectum Cases at a Tertiary Care Cancer Center
Mycobacterium interjectum is a rare NTM infection that was first described in 1993 in a patient with submandibular lymphadenitis, since then 15 additional cases have been reported. The diagnosis of infection is often delayed as identification of the organism is based on 16S rRNA sequencing. No outbreaks due to M. interjectumhave been reported in the literature.
Retrospective review of medical records.
Results: The five cases occurred between July 23 and November 5, 2013. The mean age was 60.6 years (range 54-71 years); 4 were females. The underlying cancers were ovary, prostate, colon, CLL and Hodgkin’s lymphoma. 3 patients had pre-existing lung conditions, 2 had history of smoking. 4/5 patients had respiratory symptoms at clinical presentation. M. interjectum was isolated from sputum (4) and bronchoalveolar lavage (1); time to culture positivity was 6-8 weeks. CT findings were present in all cases- bronchiectasis (3), nodules (4) and ground glass infiltrates were most common (2); cavitary changes were noted in one case. Co-pathogens included M. avium-intracellulare (MAI) (2) and Pseudomonas aeruginosa(1). Two patients received treatment for MAI with symptomatic improvement and recurrence of symptoms after discontinuation. Two patients that were untreated had symptomatic and radiographic progression of lung infection. None of the patients overlapped in time or space during their hospitalization, ambulatory visits or procedures; 4/5 isolates were genetically characterized by rep-PCR and were found to be distinct from each other. Laboratory review did not identify any contamination during processing of samples.
M. interjectum is an emerging pathogen among persons undergoing treatment for cancer. The clinical and radiographic presentation is indistinguishable from other nontuberculous mycobacteria (NTM) infections, especially MAI. Our cluster of five cases of M. interjectumwas attributed to increasing use of sequence-based technologies for difficult to identify NTM. No evidence of common source, patient –to- patient transmission or laboratory contamination was found.
R. Webb, None
P. Revell, None
J. Eagan, None
N. E. Babady, None
Y. W. Tang, None
M. Kamboj, None