Isolation and antibiotic resistance profiles of bacteria from influent, effluent and downstream: A study in Botswana

Antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) have been globally considered environmental contaminants that pose a serious problem to the health of humans, animals and the ecosystem. The primary objective of the study was to characterize the antibiotic resistance phenotypes and genotypes of bacterial isolates from Gaborone wastewater treatment plant (GWWTP) and the downstream environment receiving effluent wastewater. Culture dependent and independent approaches were used to determine occurrence and diversity of ARGs in viable and potentially pathogenic bacteria from samples of wastewater influent, effluent and downstream environment. Higher frequencies of potentially pathogenic ARB; Staphylococcus species, Escherichia coli, Enterobacter aerogenes, Pseudomonas species, Brucella species, Salmonella species, Listeria species and Campylobacter species, and ARGs to clinically relevant antibiotics; tetA (tetracycline), mphA (macrolides), strB (streptomycin), sul1 (sulphonamide), dfr (trimethoprim) and int1 (mobile ARG cassette) were detected from the samples. Taken together, the results suggest accumulation of these antibiotic resistance determinants in wastewater treatment facilities and subsequent release into the water ecosystems downstream of the WWTP. This research is critical in Botswana because of lack of data and awareness on the threat posed by antibiotic resistance, poor wastewater treatment infrastructure, and lack of policies/guidelines on the safe use/handling of effluent wastewater for agricultural purposes. Data from this research will help sensitize relevant government health officials to carefully consider the environment contamination and spread of antibiotic resistance. This study further advocates for development of new water quality monitoring schemes and implementation of locally relevant policies on the safe and sustainable use of effluent contaminated water particularly for irrigation purposes in many developing countries.