Sourcing faecal pollution from onsite wastewater treatment systems in surface waters using antibiotic resistance analysis.
OBJECTIVE
To identify the sources of faecal contamination in investigated surface waters and to determine the significance of onsite wastewater treatment systems (OWTS) as a major contributor to faecal contamination.


RESULTS
Antibiotic resistance patterns (ARP) were established for a library of 717 known Escherichia coli source isolates obtained from human, domesticated animals, livestock and wild sources. Eight commonly used antibiotics, including amoxicillin, cephalothin, erythromycin, gentamicin, ofloxacin, chlortetracycline, tetracycline and moxalactam, at four different concentrations were used to obtain ARPs for E. coli isolates. Discriminant analysis (DA) was used to differentiate between the ARP of sources isolates. The developed ARP library was found to be adequate for discriminating human from nonhuman isolates, and was used to classify 256 enumerated E. coli isolates collected from monitored surface water locations.


CONCLUSIONS
The resulting ARP DA indicated that a majority of the faecal contamination in more rural areas was nonhuman; however, the percentage of human isolates increased significantly in urbanized areas using OWTS for wastewater treatment.


CONCLUSIONS
This study signifies the feasibility of using ARP for source tracking faecal contamination in surface waters, and linking faecal contamination to OWTS. The information will enable regulatory authorities to implement appropriate management practices to reduce the contamination of water resources caused by high densities and failing OWTS.
Carroll
S
S
School of Civil Engineering, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001, Australia. s.carroll@qut.edu.au
Hargreaves
M
M
Goonetilleke
A
A
D000658:Amoxicillin / Q000494:pharmacology; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002512:Cephalothin / Q000494:pharmacology; D002751:Chlortetracycline / Q000494:pharmacology; D015169:Colony Count, Microbial; D016002:Discriminant Analysis; D024881:Drug Resistance, Bacterial; D004917:Erythromycin / Q000494:pharmacology; D004926:Escherichia coli / Q000145:classification / Q000187:drug effects / Q000502:physiology*; D005243:Feces / Q000382:microbiology*; D005839:Gentamicins / Q000494:pharmacology; D006801:Humans; D009070:Moxalactam / Q000494:pharmacology; D015242:Ofloxacin / Q000494:pharmacology; D013752:Tetracycline / Q000494:pharmacology; D014871:Water Microbiology; D014876:Water Pollution
D000900:Anti-Bacterial Agents; D005839:Gentamicins; D004917:Erythromycin; D000658:Amoxicillin; D015242:Ofloxacin; D013752:Tetracycline; D002512:Cephalothin; D009070:Moxalactam; D002751:Chlortetracycline