Tuberculosis Research and Treatment Volume 2012
Setting. Tanzania. Objective. To compare microscopy as conducted in direct observation of treatment, short course centers to
pouched rats as detectors of Mycobacterium tuberculosis. Design. Ten pouched rats were trained to detect tuberculosis in sputum
using operant conditioning techniques. The rats evaluated 910 samples previously evaluated by smear microscopy. All samples
were also evaluated through culturing and multiplex polymerase chain reaction was performed on culture growths to classify the
bacteria. Results. The patientwise sensitivity of microscopy was 58.0%, and the patient-wise specificity was 97.3%. Used as a group
of 10 with a cutoff (defined as the number of rat indications to classify a sample as positive for Mycobacterium tuberculosis) of 1,
the rats increased new case detection by 46.8% relative to microscopy alone. The average samplewise sensitivity of the individual
rats was 68.4% (range 61.1–73.8%), and the mean specificity was 87.3% (range 84.7–90.3%). Conclusion. These results suggest that
pouched rats are a valuable adjunct to, and may be a viable substitute for, sputum smear microscopy as a tuberculosis diagnostic
in resource-poor countries.