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. 2011 Jan-Feb;18(1):19-24.
doi: 10.1155/2011/865831.

Isolation prevalence of pulmonary nontuberculous mycobacteria in Ontario in 2007

Mohammed Al Houqani  1 , Frances Jamieson, Pamela Chedore, Mauli Mehta, Kevin May, Theodore K Marras
Affiliations

Isolation prevalence of pulmonary nontuberculous mycobacteria in Ontario in 2007

Mohammed Al Houqani et al. Can Respir J. 2011 Jan-Feb.

Abstract
in English, French

Background: The reported prevalence of pulmonary nontuberculous mycobacteria (NTM) infections is increasing.

Objective: To determine the 'isolation prevalence' of NTM in 2007 and compare it with previously published research that examined the increasing rates of isolation of NTM from clinical pulmonary specimens between 1997 and 2003.

Methods: Isolation prevalence was investigated retrospectively by reviewing a cohort of all positive pulmonary NTM culture results from the Tuberculosis and Mycobacteriology Laboratory, Public Health Laboratory (Toronto, Ontario) in 2007, which identifies at least 95% of NTM isolates in Ontario. Isolation prevalence was calculated as the number of persons with a pulmonary isolate in a calendar year divided by the contemporary population and expressed per 100,000 population. Changes in isolation prevalence from previous years were assessed for statistical significance using generalized linear models with a negative binomial distribution.

Results: In 2007, 4160 pulmonary isolates of NTM were collected from 2463 patients. The isolation prevalence of all species (excluding Mycobacterium gordonae) was 19 per 100,000 population in 2007 - an increase from previous observations reported for Ontario - corresponding to an average annual increase of 8.5% from 1997 to 2007 (P<0.0001). Average annual increases in isolation prevalence of Mycobacterium avium complex (8.8%, P<0.0001) and Mycobacterium xenopi (7.3%, P=0.0005) were largely responsible for the overall increase, while prevalence rates of rapidly growing mycobacteria remained relatively stable.

Conclusion: The isolation prevalence of pulmonary NTM continues to increase significantly in Ontario, supporting the belief that pulmonary NTM disease is increasingly common.

HISTORIQUE :: La prévalence déclarée d’infections pulmonaires mycobactériennes non tuberculeuses (MBN) est à la hausse.

OBJECTIF :: Déterminer la « prévalence d’isolement » des infections MBN en 2007 et la comparer avec des recherches déjà publiées qui portaient sur les taux croissants d’isolement des infections MBN dans des échantillons pulmonaires cliniques entre 1997 et 2003.

MÉTHODOLOGIE :: Les chercheurs ont examiné rétrospectivement la prévalence d’isolement en examinant une cohorte de résultats de cultures pulmonaires MBN positives provenant du Tuberculosis and Mycobacteriology Laboratory, Public Health Laboratory de Toronto, en Ontario, en 2007, qui dépiste au moins 95 % des isolats pulmonaires MBN en Ontario. Les chercheurs ont calculé la prévalence d’isolement comme le nombre de personnes ayant un isolat pulmonaire au cours d’une année civile, divisé par la population contemporaine et exprimé sur 100 000 habitants. Ils ont évalué les modifications à la prévalence d’isolement par rapport aux années précédentes pour en établir la signification statistique au moyen des modèles linéaires généralisés selon une distribution binomiale négative.

RÉSULTATS :: En 2007, les chercheurs ont colligé 4 160 isolats pulmonaires d’infections MBN chez 2 463 patients. La prévalence d’isolement toutes espèces confondues (à l’exception du Mycobacterium gordonae) était de 19 cas pour 100 000 habitants en 2007, une augmentation par rapport aux observations antérieures déclarées en Ontario, correspondant à une augmentation annuelle moyenne de 8,5 % entre 1997 et 2007 (P<0,0001). Les augmentations annuelles moyennes de prévalence d’isolement du complexe Mycobacterium avium (8,8 %, P<0,0001) et Mycobacterium xenopi (7,3 %, P=0,0005) étaient largement responsables de l’augmentation globale, tandis que les taux de prévalence de mycobactéries à croissance rapide demeuraient relativement stables.

CONCLUSION :: La prévalence d’isolement d’infections pulmonaires MBN continue d’augmenter considérablement en Ontario, ce qui étaye la conviction que la maladie pulmonaire MBN est de plus en plus courante.

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Figures

Figure 1)
Figure 1). Prevalence of pulmonary nontuberculous mycobacteria (NTM) infections and tuberculosis (TB) case rates in Ontario from 1997 to 2003, and 2007
Dashed lines represent interpolated values. The isolation prevalence rates of all NTM infections significantly increased, while TB rates significantly decreased (P≤0.0001 for all). TB rates were calculated from the total number of TB cases (references to 12) and population data from the Statistics Canada website for 1999 to 2007 (http://www.statcan.ca/) and estimated by back extrapolation (for 1997 and 1998). The comparison of NTM and TB rates is limited: NTM data represent isolation prevalence, while TB data represent the incidence of all new cases (including culture-negative cases). Kansasii Mycobacterium kansasii; MAC Mycobacterium avium complex; RGM Rapidly growing mycobacteria; Xenopi Mycobacterium xenopi
Figure 2)
Figure 2)
Total number of specimens submitted to the Toronto Public Health Laboratory (Toronto, Ontario) for mycobacterial culture according to calendar quarter (Q). The outbreak of severe acute respiratory syndrome occurred in Toronto in the second Q of 2003 (2003-Q2)
See this image and copyright information in PMC

Comment in

  • Nontuberculous mycobacteria.
    Anthonisen NR. Anthonisen NR. Can Respir J. 2011 Jan-Feb;18(1):9-10. doi: 10.1155/2011/235614. Can Respir J. 2011. PMID: 21369543 Free PMC article. No abstract available.

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