RESUMEN
This study defines performance characteristics of the temperature-modified ISO 9308-1 method for E. coli enumeration in bathing water. After a 4-hour resuscitation period at 36⯱â¯2⯰C, the incubation temperature was changed to 44⯱â¯0.5⯰C. Elevated incubation temperature significantly suppressed the growth of thermo-intolerant bacteria, and enhanced the selectivity of Chromogenic Coliform Agar (CCA) up to 49.5% for inland and up to 66.0% for coastal water. Consequently, most of the selectivity-related performance characteristics are improved. Relative recovery was determined by comparing an alternative method against the reference, ISO 9308-1:2014 method, following the criteria set out in ISO 17994:2014. Temperature modification did not significantly alter the results and the methods were evaluated as "not different" for both, coastal and inland waters. Chromogenic Coliform Agar was assessed as a suitable medium for reliable E. coli enumeration in bathing water when incubated for 17-19â¯h at 44⯱â¯0.5⯰C after the 4-5â¯h resuscitation period at 36⯱â¯2⯰C.