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.
R. A. Martino,
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