This paper investigates the antibiotic resistance of pollution indicators within three coastal areas in India. This is a major concern as antibiotic resistance is expected in any environment were antibiotics are implemented. The improper and unnecessary use of antibiotics by humans could provide the selection of resistant pathogenic bacterial strains not indigenous to the local environment. However, due to domestic and commercial sewage, this change in the marine environment poses not only a threat to the marine community but also creates a hazard to public health.
Samples of water and sediment were taken from three different sites: The coastal areas of Chennai port and Kasimeda fishing harbour and the Coovum estuary. Four indicator genera were isolated - Escherichia coli, Vibrio spp., Salmonella spp. and Enterococcus spp. from both the water and the sediment samples taken from each site between march and may 2010.
These sample were then tested for antimicrobial sensitivity and challenged with ten different antibiotics. The antimicrobial resistance patterns were not due to specific bacteria species or taxonomic groups but among isolates among different samples and sample sites.
In the sea water samples, Salmonella and E. coli stains were predominantly resistant to vancomycin followed by penicillin, whereas Vibrio and Salmonella isolates were resistant to all of the antibiotics challenged. Kasimeda Harbour samples had the highest percentage resistance to antibiotics challenged.
In sediment samples higher resistant frequencies were observed in the Coovum estuary. Vibrio spp. and Salmonella spp. were found to be resistant to all of the antibiotics challenged whereas E. coli and Enterococcus indicators were resistant to all of the antibiotics tested.
The antibiotic resistance index (ARI) for all indicator organisms present in the sea water samples was highest in the Kasimeda harbour whereas the ARI was highest in the Coovum estuary among indicator organisms found in sediment samples.
The authors thought this was likely due to the Coovum estuary and the Kasimeda harbour having slums nearby meaning the greater population will be causing a greater volume of sewage to be present in the samples.
The authors found Vibrio spp. to be the most resistant to antibiotics and faecal indicators resistant to antibiotics were greater in the sediment samples due to the higher nutrient concentrations. This paper flags up the issue that the improper use of antibiotics may be more widespread and on a much larger scale than we currently believe.
A Review of: Vignesh, S., et al.; 2012; Antibiotic resistant pathogens versus human impacts: A study from three eco-regions of the Chennai coast, southern India; Marine Pollution Bulletin; doi:10.1016/j.marpolbul.2012.01.015.
5 comments:
An intersting and slightly scary study.
Although it states that they have assumed that the results of this study are due to the nearby slums it would be interesting if another study was done to investigate whether this occurs in other coastal areas around the world.
The fact that some of the isolates were resistant to all of the antibiotics challenged is really worrying! This paper highlights the need for better waste management, as well as an end to improper use of antibiotics.
While reading this review i wondered if does already exist some kind of treatment process capable of selectively removing antibiotics from sewage, or at least reducing their concentration or activity.
Since antibiotics are very small molecules with a very low molecular weight, in my opinion, it seems almost impossible to find a selective way of removing them from waste-water. Did any of you guys know something more about?
I think its a really tricky one, because it seems antibiotics can never be completely eliminated from waste water.
This paper talks generally about pharmaceuticals in waste water, and also describes some of the methods used to remove drugs, if you are interested:
http://www.scielo.br/pdf/qn/v33n2/32.pdf
This is quite a lengthy paper but does discuss waste water and antibiotic resistance in some detail:
http://www.formatex.info/microbiology2/509-519.pdf
It also mentions that hospital sewage contributes massively to the problem.
Hi Theodora did the authors say if they used a range of concentrations of antibiotics, for example were the concentrations of antibiotics over the MIH for the bacteria?
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