If systematic evidence were needed to show that nontuberculous mycobacterial (NTM) disease isn’t always confined to the lungs, here it is: a report on more than 100 cases of extrapulmonary NTM over a 3-year period in one not-very-large state.
To be precise, the Oregon Health Authority recorded 134 cases during 2014-2016, according to CDC and state officials writing Thursday in Morbidity and Mortality Weekly Report.
This exact count was possible, the authors noted, because Oregon had made extrapulmonary NTM a reportable condition as of Jan. 1, 2014.
Although NTM usually affects the lungs, the organism can infect many tissues in the body and the consequences can be extremely severe. The report from Oregon found that 33% of cases involved hospital admission and, in 15%, patients developed sepsis. One death was attributed to NTM.
Previous reports (primarily individual cases or small series) had linked extrapulmonary NTM to tattoo parlors and nail salons. While these were also associated with some of the Oregon cases, they accounted only for a handful (two and seven, respectively). The most common “predisposing factor” identified in the investigation was exposure to potting soil (41 cases).
After that, however, most such factors were iatrogenic or nosocomial: surgery, immune deficiency and/or immunosuppressive therapy, acupuncture, and outpatient infusion/injection procedures. Two-thirds of cases involved more than one predisposing factor.
The investigators, led by the CDC’s David C. Shih, MD, also emphasized that extrapulmonary NTM cases can come in clusters. They pointed to one beginning in 2013 (but extending into the study period) related to joint replacement procedures; also, the two tattoo-parlor cases involved the same establishment.
Because NTM can have an incubation period of months, even years, systematic surveillance is vital for identifying outbreaks, the authors said.
“Detection of extrapulmonary NTM outbreaks can be delayed if the condition is not reportable. For example, NTM is not reportable in Georgia,” Shih and colleagues wrote.
Individual clinicians are also important sentinels in uncovering outbreaks, the report noted: “In 2013, a clinician reporting two extrapulmonary NTM cases among medical tourists led to detection of an NTM outbreak traced to cosmetic surgery centers in the Dominican Republic; subsequent case finding identified outbreak cases from four other states.”
An important surveillance tool developed by the CDC is now available for state and local public health authorities — a standardized case definition. Shih and colleagues encouraged its adoption to ensure consistency from one location to another.