TABLE 2.

Contemporary evidence for environmental contamination of Mycobacterium tuberculosis (post-1960)

First author, year [ref.]	Methodology and medium	Description of results
Kozlov, 1977 [45]	Three strains of M. tuberculosis cultured for several months in a natural turf-podzol sandy soil	Samples culturable for up to 3 months after seeding
Ghodbane, 2014 [44]	Inoculated soil with M. tuberculosis, M. bovis and M. canetti; survival of the distinct mycobacteria in the soil for 12 months	Soil samples culturable; all types of mycobacteria found in soil after 12 months; mice inoculated with contaminated soil all developed granulomas; control mice did not grow M. tuberculosis
Tshilombo, 2015 [46]	Prospective in vitro study; mixed 20 mL of 106 CFU·mL−1 M. smegmatis with 125 mg of sterile dust; air sampling was conducted pre- and post-re-aerosolisation, and the number of CFUs was measured based on plate count	M. smegmatis survived in dust for 19 days and could be successfully re-aerosolised, remaining viable
Velayati, 2015 [47]	1500 random samples of soil and water	M. tuberculosis isolated from 1% of soil samples and 10% of water samples; persisted for 9 months

M. bovis: Mycobacterium bovis; M. canetti: Mycobacterium canetti; M. smegmatis: Mycobacterium smegmatis.