Wastewater-Based Surveillance of Antibiotic Resistance Genes Associated with Tuberculosis Treatment Regimen in KwaZulu Natal, South Africa

Abstract

Essential components of public health include strengthening the surveillance of infectious diseases and developing early detection and prevention policies. This is particularly important for drug-resistant tuberculosis (DR-TB), which can be explored by using wastewater-based surveillance. This study aimed to use molecular techniques to determine the occurrence and concentration of antibiotic-resistance genes (ARGs) associated with tuberculosis (TB) resistance in untreated and treated wastewater. Raw/untreated and treated (post-chlorination) wastewater samples were taken from three wastewater treatment plants (WWTPs) in South Africa. The ARGs were selected to target drugs used for first- and second-line TB treatment. Both conventional polymerase chain reaction (PCR) and the more advanced droplet digital PCR (ddPCR) were evaluated as surveillance strategies to determine the distribution and concentration of the selected ARGs. The most abundant ARG in the untreated wastewater was the rrs gene, associated with resistance to the aminoglycosides, specifically streptomycin, with median concentration ranges of 4.69–5.19 log copies/mL. In contrast, pncA gene, associated with resistance to the TB drug pyrazinamide, was the least detected (1.59 to 2.27 log copies/mL). Resistance genes associated with bedaquiline was detected, which is a significant finding because this is a new drug introduced in South Africa for the treatment of multi-drug resistant TB. This study, therefore, establishes the potential of molecular surveillance of wastewater for monitoring antibiotic resistance to TB treatment in communities.

Wastewater surveillance of antibiotic-resistant bacterial pathogens: A systematic review

“…These studies mostly reported the seasonal variation and detection frequency of the ARB targets ( Supplementary Tables 1 , 5 ). Two other studies conducted at the single sewershed level used PCR-based methods ( Bich et al, 2019 ; Mtetwa et al, 2021 ), and one study used shotgun metagenomics ( Majeed et al, 2021 ). Most of these studies compared wastewater-based findings with clinical isolates collected at the single hospital level, while some studies also collected clinical isolates from human patients, and others compared the findings with government reports and secondary literature ( Supplementary Table 3 ).…”

“…Relatively few studies (only three) have reported PCR-based approaches with qPCR ( Bich et al, 2019 ), high-throughput qPCR ( Pärnänen et al, 2019 ), or dPCR ( Mtetwa et al, 2021 ). These approaches can overcome some limitations of culture-based methods and can detect microbes that are difficult to culture ( Tiwari et al, 2022b ).…”

Inactivation of antibiotic-resistant bacteria and antibiotic-resistance genes in wastewater streams: Current challenges and future perspectives

“…In response, S.A has redoubled efforts to track the incidence and prevalence of ARBs and ARGs in different environmental matrices and also identify their respective pathways and thresholds through the establishment of the South African Antimicrobial Resistance Strategy Framework. Although surveillance of WWTPs has not gained the momentum anticipated, snippets from recent investigations and reviews suggest there might be a lot more to uncover regarding occurrences of ARBs and ARGs in WWTPs ( Igwaran et al, 2018 ; Mbanga et al, 2021 ; Mpondo et al, 2021 ; Mtetwa et al, 2021 ; Conco et al, 2022 ; Ogunlaja et al, 2022 ; Ramasamy et al, 2022 ) other worthy mentions are captured in Table 2 . From the aforementioned studies, we observed a similar trend in occurrence and abundance of genes; moreover, genes coding for other virulence factors were also detected, which explains the persistence of their bearing organisms throughout the treatment processes of WWTPs.…”

Molecular surveillance of tuberculosis-causing mycobacteria in wastewater

“…This hospital also serves as a referral center for another hospital and clinic. WWTP C 70.0 Yes Conventional Yes No Yes Yes Receives from Hospital C complex which offers specialised services for Multi Drug Resistant (MDR) and complicated TB Information sourced from: Cross and Buckley (2016) ; Mtetwa et al. (2021).…”