Molecular surveillance of tuberculosis-causing mycobacteria in wastewater

Hlengiwe N Mtetwa; Isaac D Amoah; Sheena Kumari; Faizal Bux; Poovendhree Reddy

doi:10.1016/j.heliyon.2022.e08910

Molecular surveillance of tuberculosis-causing mycobacteria in wastewater

Heliyon. 2022 Feb 4;8(2):e08910. doi: 10.1016/j.heliyon.2022.e08910. eCollection 2022 Feb.

Authors

Hlengiwe N Mtetwa^{1

2}, Isaac D Amoah², Sheena Kumari², Faizal Bux², Poovendhree Reddy¹

Affiliations

¹ Department of Community Health Studies, Faculty of Health Sciences, Durban University of Technology, PO Box 1334, Durban, 4000, South Africa.
² Institute for Water and Wastewater Technology (IWWT), Durban University of Technology, PO Box 1334, Durban, 4000, South Africa.

Abstract

The surveillance of tuberculosis infections has largely depended on clinical diagnostics and hospitalization data. The advancement in molecular methods creates an opportunity for the adoption of alternative surveillance systems, such as wastewater-based epidemiology. This study presents the use of conventional and advanced polymerase chain reaction techniques (droplet digital PCR) to determine the occurrence and concentration of total mycobacteria and members of the Mycobacterium tuberculosis complex (MTBC) in treated and untreated wastewater. Wastewater samples were taken from three wastewater treatment plants (WWTPs) in the city of Durban, South Africa, known for a high burden of TB/MDR-TB due to HIV infections. All untreated wastewater samples contained total mycobacteria and MTBC at varying percentages per WWTP studied. Other members of the MTBC related to tuberculosis infection in animals, M. bovis and M. caprae were also detected. The highest median concentration detected in untreated wastewater was up to 4.9 (±0.2) Log10 copies/ml for total mycobacteria, 4.0 (±0.85) Log10 copies/ml for MTBC, 3.9 (±0.54) Log10 copies/ml for M. tuberculosis, 2.7 (±0.42) Log10 copies/ml for M. africanum, 4.0 (±0.29) Log10 copies/ml for M. bovis and 4.5 (±0.52) Log10 copies/ml for M. caprae. Lower concentrations were detected in the treated wastewater, with a statistically significant difference (P-value ≤ 0.05) in concentrations observed. The log reduction achieved for these bacteria in the respective WWTPs was not statistically different, indicating that the treatment configuration did not have an impact on their removal. The detection of M. africanum in wastewater from South Africa shows that it is possible that some of the TB infections in the community could be caused by this mycobacterium. This study, therefore, highlights the potential of wastewater-based epidemiology for monitoring tuberculosis infections.

Keywords: Droplet digital PCR; Mycobacteria; Mycobacterium tuberculosis complex; Tuberculosis; Wastewater.