Increasing nontuberculous mycobacteria reporting rates and species diversity identified in clinical laboratory reports

Abstract

Background: Nontuberculous Mycobacteria (NTM) are environmental microorganisms that can affect human health. A 2009-2010 occurrence survey of NTM in potable tap water samples indicated an increased recovery rate for many clinically significant species such as M. avium (30%) and M. abscessus (12%). To determine if these trends by species were mirrored in human infections, isolation rates of NTM species identified in clinical laboratory reports from four states were evaluated.

Method: Clinical laboratory reports from the Mississippi, Missouri, Ohio, and Wisconsin Health Departments were used to investigate the species of NTM isolated from human specimens in 2014. The NTM positive specimen reports were tabulated for each species and complex/group. The number of reports by month were used to investigate seasonal trends. The 2014 isolation rates were compared to historic values to examine longitudinal trends.

Results: The positive rate of NTM specimens increased from 8.2 per 100,000 persons in 1994 to 16 per 100,000 persons in 2014 (or 13.3 per 100,000 after excluding Mycobacterium gordonae). Changes in NTM diversity were observed in complex/groups known to be clinically significant. Between 1994 and 2014 the rate implicating M. abscesses-chelonae group and M. avium complex increased by 322 and 149%, respectively.

Conclusions: Based on public health data supplied by the four State's Health Departments and the 2014 U.S. population, 50,976 positive NTM specimen reports per year were projected for the nation; serving as an indicator for the national potential disease burden that year.

Keywords: Clinical laboratory reports; Epidemiology; Isolation rates; Nontuberculous mycobacteria (NTM); Report rates; Seasonal; Species; United States.

Fig. 1

Numbers, rates, and percent change of NTM reports by species, 1994 and 2014 comparison. See Table 2 for clarity on which NTM species were considered in each complex or group. *2014: M. chelonae-abscessus Group plus. M. mucogenicum-phocaicum report numbers were combined, ‡ NS = Not significant, § per 100,000 persons: 1994 population 23,795,000 (as reported by Butler and Crawford, 1999); 2014 population 26,414,700

Fig. 2

Longitudinal analysis (1980–2014) of M. avium complex report rate per 100,000 persons for Mississippi, Missouri, Ohio, Wisconsin, and combined. * Butler and Crawford, 1999: 1994 rates

Fig. 3

NTM reports by state by month