MPN-PCR-quantification method for staphylococcal enterotoxin c1 gene from fresh cheese

• Published in: International journal of food microbiology Vol. 36; no. 2-3; pp. 135 - 143
• Main Authors: Maentynen, V. (Helsinki Univ. (Finland). Dept. of Applied Chemistry and Microbiology), Niemelae, S, Kaijalainen, S, Pirhonen, T, Lindstroem, K
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier 20.05.1997
• Subjects: Biological and medical sciences; CHEESE; Cheese - microbiology; DNA, Bacterial - isolation & purification; ENTEROTOXINAS; ENTEROTOXINE; ENTEROTOXINS; Enterotoxins - genetics; Food industries; FROMAGE; Fundamental and applied biological sciences. Psychology; GENE; GENES; Milk and cheese industries. Ice creams; PCR; Polymerase Chain Reaction - methods; QUESO; STAPHYLOCOCCUS AUREUS; Staphylococcus aureus - pathogenicity; Probabilistic approach; Microbiological testing; Amplification; Statistical method; Numeration; Polymerase chain reaction; Toxin; Gene; Fresh cheese; Pathogenic; Analytical method; Enterotoxin; Bacteria; Micrococcales; Micrococcaceae; Staphylococcus aureus
• ISSN: 0168-1605; 1879-3460
• DOI: 10.1016/S0168-1605(97)01243-9

PCR detection methods have been extensively used in diagnostic microbiology. However, a lack of a simple and reliable method for quantification of the PCR products has partly hindered the use of PCR in routine food laboratories. The quantification of PCR products can be done by combining the principles of MPN statistics and PCR technique. We have developed a simple and sensitive MPN-PCR assay for detection and enumeration of enterotoxin C producing Staphylococcus aureus NCTC 10655 from fresh cheese. By amplifying single copy chromosomal enterotoxin C gene fragment, we could detect as little as 20 cfu/g. By Moran's test, most of the DNA dilution series appeared to fulfill the basic mathematical assumptions of ordinary MPN methods. The analysis with MPN-PCR took one day to perform compared with three days analysis time with plate counting. This MPN-PCR method can be readily applied with different primer systems without extensive development work.