Novel methods for rapid diagnosis of tuberculosis (TB) are urgently needed to
complement the widely used smear microscopy in low income settings. Trained TB
detection rats offer a promising tool for rapid diagnosis of TB in resource limited
settings. The Mycobacterium tuberculosis (Mtb) specific volatile compounds detected by
trained Cricetomys gambianus rats in sputum of TB patients are unknown. It is also not
known whether rats detect odour signals from other mycobacteria and microorganisms
related to Mtb, which cause pulmonary infections resembling TB. In this thesis I
investigated Mtb-specific volatile compounds detected by trained rats and whether the
target compounds are found in other mycobacterial species and related pulmonary
pathogens. The ability of rats to discriminate cultures of different microorganisms,
clinical sputa with different Mycobacterium spp., Mtb genotypes and other respiratory
tract microorganisms was investigated. Finally, the ability of the rats to discriminate Mtbspecific odour compounds from shared compounds found in Mtb and other
microorganisms was determined. Results show that Mtb produce specific volatile
compounds which are not produced by other mycobacterial species, mycobacteria-related
Nocardia spp. and Rhodococcus spp. and other microorganisms. Trained rats use these
Mtb-specific compounds to distinguish TB-positive sputa from TB-negative sputa.
Volatile compounds shared by Mtb and other mycobacteria and non-mycobacterial
species are not detected by trained rats. A blend of Mtb-specific compounds is detected
by rats better than individual compounds. Rats can discriminate cultures of Mtb from
those of other microorganisms. Detection of Mtb cultures is influenced by growth stage.
Rats detect more frequently TB-positive sputa than negative sputa spiked with Mtb or
specific volatiles. Clinical sputa containing Mtb are well discriminated by rats from sputa
containing other microorganisms. Sputa containing different Mtb genotypes are also
detected. It is concluded that trained rats can reliably diagnose TB. Further studies are
needed to determine the optimal combinations/ratios of Mtb-specific volatile compounds
to yield similarly higher responses of rats as those of detection of typical TB-positive
sputa. Future studies should assess detection of sputa with frequent nontuberculous
mycobacterial species. Further investigations including recovery of dormant Mtb in
sputum may give insights on actual cause of detection of false positive sputa currently
judged by microscopy and conventional Mtb culture in which dormant Mtb cannot grow.
Mgode, G (2021). Determination Of Mycobacterium Tuberculosis Odour Compounds Detected By Cricetomys Gambianus Rats For Diagnosis Of Pulmonary Tuberculosis In Low-Income Settings. Afribary. Retrieved from https://afribary.com/works/determination-of-mycobacterium-tuberculosis-odour-compounds-detected-by-cricetomys-gambianus-rats-for-diagnosis-of-pulmonary-tuberculosis-in-low-income-settings
Mgode, Georgies "Determination Of Mycobacterium Tuberculosis Odour Compounds Detected By Cricetomys Gambianus Rats For Diagnosis Of Pulmonary Tuberculosis In Low-Income Settings" Afribary. Afribary, 14 May. 2021, https://afribary.com/works/determination-of-mycobacterium-tuberculosis-odour-compounds-detected-by-cricetomys-gambianus-rats-for-diagnosis-of-pulmonary-tuberculosis-in-low-income-settings. Accessed 10 Aug. 2022.
Mgode, Georgies . "Determination Of Mycobacterium Tuberculosis Odour Compounds Detected By Cricetomys Gambianus Rats For Diagnosis Of Pulmonary Tuberculosis In Low-Income Settings". Afribary, Afribary, 14 May. 2021. Web. 10 Aug. 2022. < https://afribary.com/works/determination-of-mycobacterium-tuberculosis-odour-compounds-detected-by-cricetomys-gambianus-rats-for-diagnosis-of-pulmonary-tuberculosis-in-low-income-settings >.
Mgode, Georgies . "Determination Of Mycobacterium Tuberculosis Odour Compounds Detected By Cricetomys Gambianus Rats For Diagnosis Of Pulmonary Tuberculosis In Low-Income Settings" Afribary (2021). Accessed August 10, 2022. https://afribary.com/works/determination-of-mycobacterium-tuberculosis-odour-compounds-detected-by-cricetomys-gambianus-rats-for-diagnosis-of-pulmonary-tuberculosis-in-low-income-settings