Pulmonary Mycobacterium avium-intracellulare is the main driver of the rise in non-tuberculous mycobacteria incidence in England, Wales and Northern Ireland, 2007–2012

Abstract

BackgroundThe incidence of non-tuberculous mycobacteria (NTM) isolation from humans is increasing worldwide. In England, Wales and Northern Ireland (EW&NI) the reported rate of NTM more than doubled between 1996 and 2006. Although NTM infection has traditionally been associated with immunosuppressed individuals or those with severe underlying lung damage, pulmonary NTM infection and disease may occur in people with no overt immune deficiency.Here we report the incidence of NTM isolation in EW&NI between 2007 and 2012 from both pulmonary and extra-pulmonary samples obtained at a population level.MethodsAll individuals with culture positive NTM isolates between 2007 and 2012 reported to Public Health England by the five mycobacterial reference laboratories serving EW&NI were included.ResultsBetween 2007 and 2012, 21,118 individuals had NTM culture positive isolates. Over the study period the incidence rose from 5.6/100,000 in 2007 to 7.6/100,000 in 2012 (p < 0.001). Of those with a known specimen type, 90 % were pulmonary, in whom incidence increased from 4.0/100,000 to 6.1/100,000 (p < 0.001). In extra-pulmonary specimens this fell from 0.6/100,000 to 0.4/100,000 (p < 0.001).The most frequently cultured organisms from individuals with pulmonary isolates were within the M. avium-intracellulare complex family (MAC). The incidence of pulmonary MAC increased from 1.3/100,000 to 2.2/100,000 (p < 0.001). The majority of these individuals were over 60 years old.ConclusionUsing a population-based approach, we find that the incidence of NTM has continued to rise since the last national analysis. Overall, this represents an almost ten-fold increase since 1995. Pulmonary MAC in older individuals is responsible for the majority of this change.We are limited to reporting NTM isolates and not clinical disease caused by these organisms. To determine whether the burden of NTM disease is genuinely increasing, a standardised approach to the collection of linked national microbiological and clinical data is required.

British Thoracic Society guidelines for the management of non-tuberculous mycobacterial pulmonary disease (NTM-PD)

“…Most studies also report a rise in prevalence over the last four decades 6 10 18–21 23 25–29. Estimates from the USA suggest that the prevalence of NTM-positive cultures is currently between 1.4 and 6.6/100 000,6 while recent data from the UK suggest that the incidence of pulmonary NTM-positive cultures increased from 4.0/100 000 in 2007 to 6.1/100 000 in 2012 30…”

Microbiological problems and biofilms associated with Mycobacterium chimaera in heater–cooler units used for cardiopulmonary bypass

“…have comorbidities and/or are immunosuppressed but infections are increasingly being seen in otherwise healthy individuals 26 . In the majority of countries, the most common manifestation of NTM infection is sporadic pulmonary disease caused by members of the Mycobacterium avium complex (MAC) -a group of organisms that includes M. avium, M. intracellulare and M. chimaera [26][27][28][29][30][31] .…”

Evaluation of GenoType NTM-DR Assay for Identification of Mycobacterium chimaera

“…Similarly to Mycobacterium avium and Mycobacterium intracellulare, M. chimaera is associated with infections primarily in immunosuppressed patients and in those with an underlying lung disease (2)(3)(4). However, identifying M. chimaera as the cause of these infections is difficult, as it is often misidentified as M. intracellulare using current phenotypic and molecular tests (5).…”