Abstract:
Purpose: Veterinary antibiotics are
physiologically highly active substances
which are being used on a large scale as
therapeutic drugs and as feed additives in
modem agricultural practice. Major purposes
of use of antibiotics are prevention and
treatments of bacterial infections and for the
improvements of growth rates of farm
animals. Therefore, the present study was
focused on quantification of some selected
groups of antibiotics; tetracycline
[Tetracycline (TET), Oxytetracycline
(OTC)] and penicillin [Amoxicillin (AMX),
Ampicillin (AMP)] in wastewater discharge
drains in large-scale livestock and poultry
farms and to isolate antibiotic resistant
bacteria.
Methods: Twenty wastewater discharge
drains in livestock and poultry farms were
selected to collect samples for the study.
Solid-Phase Extraction (SPE) was employed
and antibiotic quantification was done by
High Performance Liquid Chromatography
(HPLC). Isolation of resistance (r) bacteria
was done by standard pour plate method
where Minimum Inhibitory Concentration
(MIC) of bacteria was determined using the
range of 60 to 720ppm concentrations of the
antibiotics by agar dilution method.
Results: Oxytetracycline (55%), and
tetracycline (38%) were recorded as most
frequent antibiotics in samples and having
concentrations of 0.005 ppm and 0.004 ppm
respectively. The highest concentration of
AMX was recorded as 0.003±0.004 ppm.
However, AMP was not detected during the
study period. Oxytetracycline and
tetracycline resistance bacteria were
identified as Enterococcus sp., E. faecium,
E.coli and Clostridium sp. while, A.
baumanii, E. clocae, A. Iwoffii and H.pylori
were identified as AMPr and AMXr bacteria
by 16S rRNA sequencing. The MIC values
of tetracycline (TET, OTC) resistant bacteria
ranged from 360 ppm to 720 ppm whereas
for penicillin (AMX, AMP) from 360 to 760
ppm.
Conclusion: The contamination of
antibiotics leads to develop antibiotic
resistance in environmental bacteria. Thus,
the results of the study indicate that presence
of antibiotic resistant bacteria may limit the
effectiveness of antibiotics in treating animal
illness, thereby causing a potential risk to the
productivity of livestock and poultry farms.
Description:
Centre for Water Quality and Algae Research, Department of Zoology, University of Sri
J ayewardenepura.
