Kevin May

Pulmonary Nontuberculous Mycobacterial Disease, Ontario, Canada, 1998–2010

We measured the prevalence and temporal trends of pulmonary nontuberculous mycobacterial disease among residents of Ontario, Canada, during 1998–2010. Five-year prevalence increased from 29.3 cases/100,000 persons in 1998–2002 to 41.3/100,000 in 2006–2010 (p<0.0001). Improved laboratory methods did not explain this increase, suggesting a surge in disease prevalence.

Aging, COPD, and Other Risk Factors Do Not Explain the Increased Prevalence of Pulmonary Mycobacterium avium Complex in Ontario

BACKGROUND The cause of observed increases in pulmonary Mycobacterium avium complex (pMAC) isolation and disease is unexplained. To explore possible causes of the increase in pMAC isolation and disease prevalence in Ontario, Canada, we studied age and other population-level risk factors. METHODS We determined age and sex of patients with pMAC disease between 2003 and 2008. We then estimated whether the potential effect of population aging and changes in prevalence of HIV infection, solid organ transplant, COPD, and tumor necrosis factor-α (TNF-α) inhibition have contributed to the observed increase in pMAC disease. RESULTS During 2003 to 2008, pMAC isolation and disease prevalence (per 100,000) both increased (8.44 to 12.62 and 4.35 to 6.81, respectively). The total number of cases of disease increased by 348 (2.46 per 100,000). Based on actual contemporary population changes, aging could explain 70 additional cases (increase of 0.57 per 100,000). The increase in self-reported COPD prevalence could potentially explain 11 (95% CI, 0-42) additional cases (increase of 0.09 per 100,000 [95% CI, 0-0.34 per 100,000]). HIV infection, solid organ transplant, and TNF-α inhibition combined could potentially explain no more than 73 additional cases (increase of 0.60 per 100,000). CONCLUSIONS Although population aging appears to be a major risk factor, the increase in pMAC disease in Ontario could be only partly explained by aging, increases in COPD, HIV, solid organ transplantation, and TNF-α inhibition therapy. The increase in pMAC is likely multifactorial and may be affected by environmental or pathogen factors not addressed in this study.

Phenotypic and Molecular Characterization of Clinical Isolates of Mycobacterium elephantis from Human Specimens

ABSTRACT Eleven strains of a rapidly growing mycobacterium were isolated from patient specimens originating from various regions of the province of Ontario, Canada, over a 2-year period. Unique high-performance liquid chromatography (HPLC) and PCR-restriction enzyme pattern analysis (PRA) profiles initially suggested a new Mycobacterium species, while sequencing of the 16S rRNA gene revealed a sequence match with Mycobacterium sp. strain MCRO 17 (GenBank accession no. X93028 ), an isolate determined to be unique which is to date uncharacterized, and also a close similarity to M. elephantis (GenBank accession no. AJ010747 ), with six base pair variations. A complete biochemical profile of these isolates revealed a species of mycobacteria with phenotypic characteristics similar to those of M. flavescens. HPLC, PRA, and 16S rRNA sequencing of strain M. elephantis DSM 44368T and result comparisons with the clinical isolates revealed that these strains were in fact M. elephantis, a newly described species isolated from an elephant. All strains were isolated from human samples, 10 from sputum and 1 from an axillary lymph node.

Mycobacterium lacus sp. nov., a novel slowly growing, non-chromogenic clinical isolate

A strain of a novel non-chromogenic mycobacterium was isolated from synovial tissue from a 68-year-old female with bursitis of her right elbow. The slowly growing strain had a unique PCR-restriction enzyme analysis (PRA) profile of the hsp65 gene and 16S rRNA gene sequence in comparison with other mycobacterium species. The most closely related species, as determined by 16S rRNA gene sequence analysis, are Mycobacterium malmoense, Mycobacterium marinum, Mycobacterium ulcerans and members of the Mycobacterium tuberculosis complex. The HPLC and biochemical profiles resembled those of Mycobacterium gastri, although differences were noted in the peak-height ratio of the HPLC pattern and the nitrate and pyrazinamidase tests. On the basis of PRA, HPLC, biochemical and 16S rRNA gene sequence analyses, the name Mycobacterium lacus sp. nov. is proposed for this potential pathogen. The type strain is strain NRCM 00-255(T) (= ATCC BAA-323(T) = DSM 44577(T)).

Comparison of in-house and commercial 16S rRNA sequencing with high-performance liquid chromatography and genotype AS and CM for identification of nontuberculous mycobacteria

Sequencing of the 16S gene or other targets and line probe assay are in wide use for the identification of nontuberculous mycobacteria. We compared in-house and commercial sequencing with 3 sequence databases against high-performance liquid chromatography (HPLC) and line probe assay (HAIN Genotype AS and CM) for the identification of 84 reference, clinical, and unique strains representing 41 species. Consensus of methods was used as reference standard. Sequencing identification was more specific and flexible than HPLC, but it was limited by database content and quality as well as fragment length. No one database satisfied all requirements. In-house sequencing was lower in cost than commercial sequencing or line probe assay.

Sputum smear microscopy predicting mycobacterial culture in Ontario: A population-based laboratory report

Abstract RATIONALE: Tuberculosis (TB) and nontuberculous mycobacterial (NTM) pulmonary disease may present similarly but must be swiftly distinguished because of public health implications. The first diagnostic test usually available for suspected pulmonary mycobacterial disease is smear microscopy for acid-fast bacilli (AFB). OBJECTIVES: To measure the diagnostic utility of sputum AFB in Ontario. METHODS: All patients’ first AFB smears submitted to Public Health Ontario Laboratories during 2012–2014 were compared against final cultures. Diagnostic test characteristics were calculated for AFB smears in predicting TB and NTM separately. MEASUREMENTS AND MAIN RESULTS: Among 30 136 patients, AFB smears and cultures were positive in 4.2% (1279) and 17.4% (5233) respectively, comprising TB in 800 (2.7%, AFB-positive 489 [61.1%]) and NTM in 4433 (14.7%, AFB-positive 652 [14.7%]). Test characteristics for TB were: specificity 97.3%, negative predictive value 98.9%, sensitivity 61.1%, and positive predictive value 38.2%. Performance improved somewhat in males: specificity 97.4%, negative predictive value 98.8%, sensitivity 60.1%, positive predictive value 42.0%, and more so in people <60 years old: specificity 98.3%, negative predictive value 98.5%, sensitivity 60.9%, positive predictive value 56.8%. Test characteristics for NTM were: specificity 97.6%, negative predictive value 86.9%, sensitivity 14.7%, positive predictive value 51.0% in the entire population. CONCLUSIONS: Sputum AFB performed poorly in predicting TB because of the large proportion of AFB-positives caused by NTM (51.0%) and the relatively small proportion of AFB-positive TB cases (61.1%). The predictive ability for NTM was also poor. Regardless of age and sex, AFB remained an inadequate predictor of TB and NTM in Ontario.