IMS-free DNA extraction for the PCR-based quantification of Cryptosporidium parvum and Giardia lamblia in surface and waste water

Int J Environ Health Res. 2007 Aug;17(4):297-310. doi: 10.1080/09603120701372573.

Abstract

Extremely limited knowledge exists on the occurrence of protozoan pathogens in surface and waste water in the developing world. The article addresses one of the major reasons for this: prohibitively costly immunomagnetic separation (IMS) and commercial DNA extraction kits are required for the pathogen detection. As the presence of inhibitory substances critically impedes the polymerase chain reaction (PCR)-based detection of Cryptosporidium and Giardia in environmental samples, several direct DNA extraction methods based on the combination of physico-chemical means were evaluated in terms of reducing the impact of PCR inhibitors present in (oo)cyst-spiked water concentrates. Modifications that included the use of guanidine thiocyanate as a lysis agent and a sonication step were found to be more efficient in extracting DNA from (oo)cysts, while treatment with Chelex 100 chelating resin at post-lysis proved to be effective in the removal of the PCR inhibitors rather than the inclusion of the PCR facilitators during thermocycling. Direct DNA extraction protocol at a substantially reduced cost is proposed for the use in the PCR-based detection/quantification of the pathogens.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cryptosporidium parvum / genetics
  • Cryptosporidium parvum / isolation & purification*
  • DNA / classification
  • DNA / isolation & purification*
  • Environmental Monitoring / methods*
  • Genotype
  • Giardia lamblia / genetics
  • Giardia lamblia / isolation & purification*
  • Immunomagnetic Separation
  • Polymerase Chain Reaction / methods
  • Water / parasitology*

Substances

  • Water
  • DNA