The use of antibiotic resistance profiling as a means of tracing sources of fecal contamination in source waters

摘要

Fecal contamination of source waters and its associated intestinal pathogens continues tonpose risks to public health although the extent and effect of microbial contamination of sourcenwaters gets very little attention in designing treatment plants in most developing countries.nColiform counts give an indication of the overall bacterial contamination of water and thus itsnsafety for human consumption. However, their presence fails to provide information about thensource of fecal contamination which is vital to managing fecal contamination problems in surfacenwaters. This study explored the use of multiple antibiotic resistance (MAR) indexing as means ofndifferentiating E. coli isolates from different sources. A total of 322 E. coli isolates werenobtained from municipal wastewater and from fecal samples from domestic and wild animals.nConventional culture methods and standard chemical and biochemical tests were used fornisolation and identification of E. coli. Isolates were assayed against 10 antibiotics using thenmicro-dilution technique. The results obtained generated antibiotic resistance profiles whichnwere used to statistically group the isolates into different subsets. Correct source classificationnwas obtained for 60% of human-derived and 95% non-human-derived E. coli respectively.nThese results indicate the validity of the usefulness of MAR indexing as a method of bacterialnsource tracking.