3M™ Molecular detection system versus MALDI-TOF mass spectrometry and molecular techniques for the identification of Escherichia coli 0157:H7, Salmonella spp. &Listeria spp.
The aim of this study was to compare standard selective plating, conventional PCR (16S rRNA and species specific primers), MALDI-TOF MS and the 3M™ Molecular Detection System for the routine detection of the pathogens Listeria, Salmonella and Escherichia coli 0157:H7 in wastewater and river water samples. MALDI-TOF MS was able to positively identify 20/21 (95%) of the E. coli isolates obtained at genus and species level, while 16S rRNA sequencing only correctly identified 6/21 (28%) as E. coli strains. None of the presumptive positive Listeria spp. and Salmonella spp. isolates obtained by culturing on selective media were positively identified by MALDI-TOF and 16S rRNA analysis. The species-specific E. coli 0157:H7 PCR described in this present study, was not able to detect any E. coli 0157:H7 strains in the wastewater and river water samples analysed. However, E. coli strains, Listeria spp., L. monocytogenes and Salmonella spp. were detected using species specific PCR. Escherichia coli 0157:H7, Listeria spp. and Salmonella spp. were also sporadically detected throughout the sampling period in the wastewater and river water samples analysed by the 3M™ Molecular Detection System. MALDI-TOF MS, which is a simple, accurate and cost-effective detection method, efficiently identified the culturable organisms, while in the current study both species specific PCR (Listeria spp. and Salmonella spp.) and 3M™ Molecular Detection System could be utilised for the direct routine analysis of pathogens in water sources.
Department of Microbiology, Faculty of Science, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, 7602 South Africa.
Marché
M
Loff
3M™ South Africa (Pty) Ltd., Private Bag X926, Rivonia, 2128 South Africa.
Louise
L
Mare
Department of Microbiology, Faculty of Science, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, 7602 South Africa.
Michele
M
de Kwaadsteniet
Department of Microbiology, Faculty of Science, Stellenbosch University, Private Bag X1, Matieland, Stellenbosch, 7602 South Africa. Electronic address: wesaal@sun.ac.za.
Wesaal
W
Khan
D004269:DNA, Bacterial / Q000032:analysis; D004926:Escherichia coli / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D008087:Listeria / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D058889:Molecular Typing / Q000379:methods*; D016133:Polymerase Chain Reaction / Q000379:methods; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D045483:Rivers / Q000382:microbiology; D012475:Salmonella / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D062065:Wastewater / Q000382:microbiology; D018508:Water Purification / Q000592:standards
D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D062065:Wastewater
3M™ Molecular Detection system; Escherichia coli 0157:H7; Listeria spp.; MALDI-TOF-MS; Salmonella spp.