Determination of pathogenic bacteria in wastewater using conventional and PCR techniques

Abstract

Theobjectivesofthisinvestigationweretodetectanddetermine somepathogenicbacteriainrawandtreatedwastewaterandto compareandevaluatedifferenttechniques.Toachievethisaim, pathogenic bacteria (salmonellae group, total vibrios and Listeria group) were determined in 30 samples collected from inlet and outlet of the treatment plants using PCR, MPN and surface plate techniques. The results of salmonellae group showed that all 30 samples (100%) were positive using PCR technique, 28 samples (about 93%) were positive using direct surface plate technique, and 27 samples (90%) were positive usingMPNtechnique. Incaseoftotalvibrios27samples(90%) were positive using direct surface plate technique while 28 samples(93%)werepositiveusingMPNtechnique.Whenusing multiplex PCR technique, detection of three species of Vibrio (V. vulnificus, V. parahaemolyticus, V. cholerae andClassicalor El-Tor)werenegative.Listeriagroupwasdetectedin29samples (97%)usingPCRtechnique,in28samples(93%)usingsurface platetechnique,andin27samples(90%)usingMPNtechnique. The removal percentages showed that oxidation pond of ElSadat City is more efficient in removal of these pathogenic bacteria than the activated sludge system. Statistical analysis (Student t-test) showed that there were significant differences between MPN and surface plate techniques in revealing the