The results of this experiment show that digital FSSM counts are higher than standard FSSM counts, whether these counts are compared for each data set (paired, 1-tailed t test; P < .
The goal of this experiment was to estimate the sensitivity and specificity of a diagnostic examination performed by using the miniature objective and digital FSSM and to compare the diagnostic performance to standard FSSM.
As with standard FSSM counting in the previous experiment, the standard FSSM diagnosis was done by the pathologists using the Primo Star with the x 40 objective.
The total area imaged by digital FSSM was approximately 7.
The sensitivities and specificities of the diagnoses obtained in this experiment were calculated and are tabulated in Table 5 for each pathologist using either standard FSSM or digital FSSM.
The Fleiss k statistic for digital FSSM by the 2 pathologists, standard FSSM by 2 pathologists, and the reference diagnostic (standard FSSM confirmed by a modified Kinyoun stain, SSM) was calculated as 0.
Counting bacteria in matched fields of view shows that more bacteria are counted with digital FSSM than standard FSSM.
This set of experiments tested the sensitivity and specificity of standard and digital FSSM with respect to detection of AFBs as opposed to M tuberculosis detection.
The preliminary estimates of sensitivity and specificity for digital FSSM, using the prototype microscope for detection of AFBs, are 100% and 95%, respectively.
Further experiments will need to address the low throughput of digital FSSM seen in these experiments, seek better estimates of the sensitivity and specificity of digital FSSM, and reduce the size, weight, and cost of the evaluation setup as a step toward achieving the goal of a low-cost portable device for point-of-care M tuberculosis detection.
The increase in the number of bacteria counted with digital FSSM compared to standard FSSM is an interesting result, particularly because the root cause is unknown and it does not seem to lead to a significant difference in diagnostic results.