Nontuberculous mycobacteria in children: a changing pattern

Nontuberculous mycobacteria (NTM) infections seem to be increasing in numbers and in severity in developed countries worldwide.

To document the severity and to assess whether an increase in cases has occurred over the years, we described the epidemiology, clinical presentation, investigations, and treatment of NTM adenitis seen at the Montreal Children's Hospital.

Cases were identified through revision of the microbiology laboratory database for positive NTM culture from any site and through retrieval by the medical records of charts of patients with a diagnosis of adenitis and a node biopsy or excision or a diagnostic code of NTM disease, between 1990 and 2004. These charts were reviewed retrospectively.

Over the 15-year period, we identified 36 patients with a median age of 2.8 years with NTM adenitis. Of these cases, 22 (61%) occurred in the past 5 years. Only 3 children were born outside Canada. The majority (92%) presented with a cervicofacial mass, and 25% had constitutional symptoms or fever. There were 3 cases of mediastinal adenitis and 2 cases of cervical disease extending to the deep neck vessels, all of which occurred in the past 5 years. The purified protein derivative (PPD) test for tuberculosis was positive (> or = 10 mm) in 11 of 15 patients tested (73%), none of whom had ever had contact with tuberculosis. Thirty-three patients had surgery. Of the 26 patients who had excisional biopsy or functional neck dissection, 15% required a second surgery for persistence or recurrence compared with 100% of those who had incision and drainage or curettage. Cultures were positive in 72% of the 32 specimens sent, mainly for Mycobacterium avium complex. Very few complications were noted.

The number of cases of NTM disease has almost doubled between 2000-2004 compared with between 1990-1999, with more invasive cases seen in the past 4 years. The significance of this important rise in numbers is still unclear. Resolution of NTM adenitis is higher with complete surgical excision of affected lymph nodes. Moreover, given the proportion of PPD > or = 10mm among those tested, a pan-Canadian study assessing the incidence of NTM disease compared with tuberculosis is required to determine if a change in the recommendations for PPD positivity is needed.