Antibiotic-resistant bacteria have proliferated in some of the natural water bodies of Kuttanad and have found way to the tiger prawns which grow there, according to a scientific analysis.
The presence of the drug-resistant bacteria was found to be comparatively higher in natural waters than in prawns grown in a farmed environment, indicating that antibiotic residues are reaching the natural systems of the region. A team of scientists from Kerala reached this conclusion after isolating nearly 1,000 strains of bacteria from both the natural and farmed environments of the prawns.
The group of researchers comprising K.M. Mujeeb Rahiman, A. A. Mohamed Hatha of the Department of Marine Biology, Microbiology and Biochemistry, School of Marine Sciences of the Cochin University of Science and Technology, and A Deborah Gnana Selvam and A. P Thomas of the School of Environmental Sciences, Mahatma Gandhi University, Kottayam, have come out with their conclusions in a scientific paper titled, ‘Relative prevalence of antibiotic resistance among heterotrophic bacteria from natural and culture environments of freshwater prawn, Macrobrachium Rosenbergii. ’
Selection pressureIt was found during the analysis that the “occurrence of multiple drug resistance were higher among the bacteria associated with the samples from the natural environment of M. rosenbergii, pointing to more favourable selection pressure for the drug-resistant mutants in the natural environment,” the paper noted.
M. rosenbergii is a “widely cultivated fresh water prawn in Kerala because of its inherent resistance to many bacterial diseases, good price realisation and preference among the consumers. The extensive backwater systems in Kerala also offer good natural habitat for M. rosenbergii. However these natural water bodies are highly contaminated and harbour a wide range of microbial pathogens,” the scientists observed.
The samples were collected from the natural water systems of Kumarakam and Arookutty region of Vembanad estuary and the farmed samples a prawn farm in Ramankary village of Alappuzha district.
Antibiotic residues and multidrug-resistant bacteria are of increasing concern in seafood industry. There is also intense international focus to monitor the residues and drug resistant bacteria in seafood.
There has been a consensus to source seafood from organically raised farms in order to demote antibiotics usage in culture operations. Hence, a study was taken up to compare the antibiotic resistance among bacteria associated with various samples from the natural and culture environment of Macrobrachium rosenbergii, reasoned the researchers.
Samples from natural environment included water, sediment, eggs, larvae, post larvae, feed items and gut samples of the prawns and those from culture environment were water, sediment, eggs, feed pellets and gut samples of the species grown in culture pond.
The bacterial isolates from the water samples of natural and culture environment were found resistant to ampicillin, erythromycin and penicillin, while more than 50 per cent of strains from sediment samples were resistant to erythromycin, nalidixic acid and penicillin. Bacterial isolates from commercial feed had relatively high degree of antibiotic resistance, the paper noted.
