FECAL STREPTOCOCCI AS FECAL POLLUTION INDICATORS - A REVIEW .2. SANITARY SIGNIFICANCE, SURVIVAL, AND USE

Some New Zealand regional councils are examining the use of faecal str eptococci (or the subset, enterococci) to assist in identifying pollut ion sources, or as better indicators of disease risk in bathing waters than faecal coliforms. However, in spite of worldwide investigation, faecal streptococci have largely failed to fulfil their potential as p ollution source (human versus animal) indicators in receiving waters. Many qualifications accompany the use of faecal coliform: faecal strep tococci (FC:FS) ratios, and the species identification approach (using biochemical and DNA-based methods) has produced inconclusive results. Nevertheless, the FC:FS shift method (in which the ratio changes unde r sample storage) may warrant further investigation. Although reported results vary widely, most studies indicate that faecal streptococci o utlive faecal coliforms in receiving waters and are more resistant to sunlight-induced inactivation. USEPA epidemiological studies showed th at enterococcus concentrations were better correlated than faecal coli form concentrations with disease risk associated with bathing in sewag e-polluted waters. These results, which implied that the enterococci b etter represented viral hazard, led the USEPA to recommend the use of enterococci (or Escherichia coli in freshwaters) as bathing water qual ity indicators. These recommendations have largely been followed in pr ovisional New Zealand Department of Health guidelines. However, adopti on of the USEPA criteria should be approached cautiously, because of d oubts about their epidemiological applicability in New Zealand, and a lack of information about streptococcal concentrations and species pro files in local effluents and receiving waters.