The concentration of triclosan in antiseptics, disinfectants and preservatives in
products exceeds the minimal lethal levels. Extensive use of triclosan and antibiotics
results in bacterial resistance to their active ingredients. The precise relationship
between use and resistance, however, has been challenging to define. The aim of
the study was to identify and determine antibiotic resistance profiles of triclosan
tolerant heterotrophic plate count bacteria isolates from sewage influent and effluent.
R2 agar supplemented with triclosan was utilised to isolate the triclosan resistant
bacteria. To determine the minimum inhibitory concentration (MIC), organisms were
incubated for 24 hours at selected concentrations of triclosan. Polymerase chain
reaction (PCR) amplification of the 16S rRNA region was done to identify isolates.
An assay for cross resistance to various antibiotics was performed. Determination of
enhanced resistance to antibiotics by adding antimicrobials to the medium will be
performed by using three antibiotics. High performance liquid chromatography was
conducted to quantified levels of triclosan persistent in sewage water. Forty-four
isolates were resistant to levels of triclosan ranging from 0.25 mg/l to 0.5 mg/l.
Minimum inhibitory concentration values of these isolates ranged from 0.125 mg/l to
>1 mg/l of triclosan. 16S rDNA methods were used and five main genera namely,
Bacillus, Pseudomonas, Enterococcus, Brevibacillus and Paenibacillus were
identified. Cell wall targeting antibiotics showed more pronounced relation with the
triclosan concentration. Relation to triclosan concentration is not as apparent with
the antibiotic targeting protein synthesis. Combination of antimicrobials indicated
that at certain triclosan concentrations synergism or antagonism is observed. The
importance of applying the correct concentration and combination of antimicrobials is
observed. Levels of triclosan were found throughout the sewage water. HPLC
values indicated the presence of triclosan at post-grid removal and effluent of the
WWTP. The triclosan concentrations decrease through the WWTP but small
concentrations enter our water bodies. The presence of bacterial species that are
resistant to high concentrations of triclosan and multiple antibiotics enter our natural
water bodies and is cause for concern. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015
| Identifer | oai:union.ndltd.org:NWUBOLOKA1/oai:dspace.nwu.ac.za:10394/14910 |
| Date | January 2015 |
| Creators | Coetzee, Ilsé |
| Source Sets | North-West University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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