1125. The Use of Colorimetric Sensor Arrays to Identify Volatile Metabolic Signature for M. tuberculosis in the Culture Headspace
Session: Oral Abstract Session: Lab Diagnostics
Friday, October 4, 2013: 2:00 PM
Room: The Moscone Center: 300
Background: Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), is one of the leading causes of morbidity and mortality.  The accurate diagnosis of MTB relies on either complex or lengthy microbiologic techniques or costly nucleic acid testing, neither of which are available in much of the developing world. An easy to use inexpensive means to identify MTB in culture would improve laboratory diagnosis of TB in resource poor settings. The purpose of this study was to evaluate if the colorimetric sensor array had the required sensitivity and selectivity to identify VOC signatures for MTB in culture.

Methods: A colorimetric sensor array (CSA) was used to continuously monitor the volatile metabolites released by bacteria in solid media culture.  Our measurements of pathogenic bacteria include M. tuberculosis, M. bovis BCG, S. pneumoniae, K. pneumoniae, M. catarrhalis, and P. aeruginosa.  These species were prepared at concentration ranging 1-50 million CFU/mL, and inoculated on the Middlebrook 7H9 media.  A kinetic profile of each bacterium was obtained and analyzed by principal component analysis and support vector machine.

Results: The outgas profile of M. tuberculosis is discriminable with the CSA.  Preliminary in vitro data reveals that M. tuberculosis evokes a highly distinctive sensor response that readily stands out against other possible sources of respiratory pathogens.  MTB was recognized with 100% accuracy within this set of related species. 

Conclusion: These preliminary results suggest that disposable colorimetric sensor arrays can be an effective diagnostic tool to identify M. tuberculosis.  Identification with a colorimetric sensor array requires instrumentation no more complex than what is found in most mobile phones, a camera and simple image analysis.  The CSA could create an easy to use inexpensive means to identify MTB in culture to improve TB screening in resource poor settings. Our experience with other species indicates that MTB detection will likewise be feasible at a range of lower inoculum concentrations with time periods far shorter than that required for existing liquid culture.

Raymond A. Martino1, Paul Rhodes, PhD1, Samantha Mix2, Brian Taba, PhD1, Indre Budvytiene2, Sung Lim, PhD1 and Niaz Banaei, MD3, (1)Specific Technologies, Mountain View, CA, (2)Stanford University, Palo Alto, CA, (3)Departments of Pathology and Medicine, Division of Infectious Diseases and Geographic Medicine, Stanford University, Palo Alto, CA


R. A. Martino, Specific Technologies: Employee and Shareholder, Salary

P. Rhodes, Specific Technologies: Employee and Shareholder, Salary

S. Mix, Specific Technologies: Collaborator, Research support

B. Taba, Specific Technologies: Employee and Shareholder, Salary

I. Budvytiene, Specific Technologies: Collaborator, Research support

S. Lim, Specific Technologies: Employee, Salary

N. Banaei, Specific Technologies: Collaborator, Research support

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