Abstract:
Trained African giant pouched rats (Cricetomys gambianus) have potential for diagnosis of tuberculosis
(TB). These rats target volatile compounds of Mycobacterium tuberculosis (Mtb) that cause TB. Mtb and
nontuberculous mycobacteria (NTM) species are related to Nocardia and Rhodococcus spp., which are also
acid-fast bacilli and can be misdiagnosed as Mtb in smear microscopy. Diagnostic performance of
C. gambianus on in vitro-cultured mycobacterial and related pulmonary microbes is unknown. This study
reports on the response of TB detection rats to cultures of reference Mtb, clinical Mtb, NTM, Nocardia;
Rhodococcus; Streptomyces; Bacillus; and yeasts. Trained rats significantly discriminated Mtb from other
microbes (p < 0.008, Fisher’s exact test). Detection of Mtb cultures was age-related, with exponential and
early stationary phase detected more frequently than early log phase and late stationary phase
(p < 0.001, Fisher’s test) (sensitivity ¼ 83.33%, specificity ¼ 94.4%, accuracy ¼ 94%). The detection of
naturally TB-infected sputum exceeded that of negative sputum mixed with Mtb, indicating that
C. gambianus are conditioned to detect odours of TB-positive sputum better than spiked sputum.
Although further studies on volatiles from detectable growth phases of Mtb are vital for identification of
Mtb-specific volatiles detected by rats, our study underline the potential of C. gambianus for TB diagnosis.
