[Spectrum of gram-negative rods in waste water from Jeddah/Saudi Arabia]

23 samples of effluent of the wastewater treatment plant of Jeddah/Saudi Arabia were investigated between September 1983 and November 1984. A total of 395 strains of gram-negative fermentative bacteria were isolated and differentiated at species level. Neither vibrios, salmonellae, or shigellae were detected notwithstanding of enrichment procedures used. Furthermore, the occurrence of E. coli producing heat labile enterotoxin (LT) was studied using both Biken test and GM1-ELISA. The Biken test produced many false positive results which could not been confirmed by the more specific GM1-ELISA. All strains of E. coli investigated were negative. Therefore, the Biken test seems not to be a recommended method for detection of E. coli LT.