Bacteriological study of Balu and Turag River

Abstract

Bangladesh, being a riverine country, depends highly on the river water for various purposes including agriculture, domestic use and industrial usage. Thus, water pollution is also a massive conundrum for this country. Furthermore, antibiotic resistance is a globally rising topic nowadays. In this study we have tried to address these two major problems and conducted this research based on Dhaka city to demonstrate which kind of bacteria is responsible for the water pollution in the two most prominent rivers of Dhaka and to what extent these bacteria are resistant to antibiotics. The target sites for this study were the starting and ending points of the Balu and Turag river. Selective agar media were used to isolate different species of bacteria and then a set of biochemical tests were performed on these isolates for identification purposes. Using the Kirby-Bauer Disk Diffusion method, we checked for antibiotic susceptibility of these bacteria to different antibiotics. And finally, we wanted to confirm which bacteria were prominent in the ending points of these rivers especially, as the confirmed isolates from the end points represent what kind of bacteria are entering into Dhaka with the river flow and residing in them. We found that among 43 isolates, all of them were susceptible towards Amikacin and Meropenem. The resistance rate for Ceftriaxone (6.98%), Tetracycline (6.98%), Amoxicillin-clavulanic acid (4.65%) and Ciprofloxacin (2.33%) were not very alarming but still to be concerned about. However, the resistance rate of these organisms isolated from rivers showed an alarming rate of resistance against Erythromycin and Cefixime at 39.53% and 90.70%. We ran PCR on the isolates found in site A and site D. These two sites mark the end point of the rivers which shows the state of the water in Dhaka. We found that 66% suspected cases of Staphylococcus aureus had positive results and 20% were identified as Vibrio spp. Finally, the PCR test yielded negative results for all three of the suspected cases of Salmonella typhi. From this study we conclude that Staphylococcus aureus was the most prevalent in the Balu and Turag river water. And the second most prominent species was Vibrio spp. Thus, these river water can cause diseases like Cholerae and Bloodstream Infections (BSI) if people use it for a long time for domestic and drinking purposes. We have also found a significant number of fecal coliforms in these samples. It was also demonstrated that almost all the bacteria have become resistant to Cefixime which is also a strong antibiotic. Thus, necessary steps should be taken immediately to treat these river water and set up a treatment plant to purify the water and also to stop industrial and chemical wastes from being dumped in these rivers.