Introduction The incidence of nontuberculous mycobacteria (NTM) isolation from humans is increasing worldwide. In England, Wales and Northern Ireland (EW and NI) the reported rate of NTM more than doubled between 1996 and 2006. It is unclear if this trend has continued. We present an updated analysis with national NTM data from 2007 to 2012.
Methods All individuals with culture positive NTM isolates between 2007–2012 reported to Public Health England by the five mycobacterial reference laboratories serving EW and NI, were included. The annual incidence of NTM was calculated based on the year of the first positive NTM isolate from each individual.
Results 21,024 individuals had NTM culture positive samples. Over the study period the incidence rose from 5.57 (n = 3126) to 7.63 (n = 4454) per 100,000 population. The majority were male (57%) and older (71% >50 years of age). 77% of individuals had a pulmonary isolate – and here the incidence increased from 3.97 to 6.05 per 100,000 population between 2007 and 2012. In those with extra-pulmonary samples it remained stable at 1.61 per 100,000 population. In patients
Table 1 indicates the seven most frequently reported organisms; M. avium-intracellulare (MAI) accounted for 35% of isolates (75% in people >50 years). 78% of these were from pulmonary samples. 42% of M. abscessus isolates were in patients 60 years.
Conclusion The incidence of NTM has continued to rise since the last national survey. This represents an almost ten-fold increase since 1995. The majority of these are pulmonary isolates (in particular MAI). Possible explanations include greater awareness amongst clinicians leading to increased sampling, improvements in laboratory techniques for speciation or laboratory reporting practices. However, such a large increase most likely reflects a genuine rise in NTM infection in the population. Given this change in culture confirmation, it is imperative that a comprehensive clinical database is set up to provide national monitoring of clinically significant infections, and establish the true burden of disease present in EW and NI.
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