Abstract:
The treatment of bacterial infections is increasingly complicated due to development of resistance to antimicrobial
agents. The present study records, occurrence of tetracycline (TET) and oxytetracycline (OTC) resistance bacteria in the
effluent waste water of Zoological garden, Sri Lanka. Moreover, corresponding antibiotics resistance genes of the isolated
bacteria were screened.Four bacterial strains which were resistant to both TET and OTC were isolated by enrichment culture
method following standard pour plate. Different concentrations of OTC and TET (0 - 900 ppm) were used to detect
Minimum Inhibition Concentration (MIC) of isolated bacteria using standard pour plate and 96 well plate methods.
Chromosomal DNA of the bacterial isolates was extracted and the presence of resistance genes (tetA, tet M, tet S) were
identified by Polymerase Chain Reaction (PCR). Isolated bacterial strains were identified as Acinetobacter junii,
Acinetobacter calcoaceticus, Staphylococcus aureus and Staphylococcus arlettae by 16S rRNA sequencing. The MICs of the
A. junii (OTC=480ppm, TET= 540ppm), A. calcoaceticus (OTC= 540ppm, TET= 660ppm), S. aureus (OTC =780ppm,
TET= 840ppm), and S. arlettae (OTC= 600ppm, TET= 540ppm) were detected respectively. It was identified that S. aureus
bear tetA, tet S and tet M genes where tet A gene was detected fromA. junii, A. calcoaceticus. The resistant genes of tet M
and tet S were detected in S. arlettae. Acinetobacter strains were commonly known for transmitting antibiotic resistance
genes which are associated with urinary tract infections, pneumonia and wound infections. Thus, the finding of the present
study shows the contamination status of antibiotics in the environment and it would lead to develop antibiotic resistance in
most of the pathogenic bacteria.
