USEPA Method 1623 is the standard method in the United States for the detection of Cryptosporidium in water samples, but quantitative real-time polymerase chain reaction (qPCR) is an alternative technique that has been successfully used to detect Cryptosporidium in aqueous matrices. This study examined various modifications to a commercial nucleic acid extraction procedure in order to enhance PCR detection sensitivity for Cryptosporidium. An alternative DNA extraction buffer allowed for qPCR detection at lower seed levels than a commercial extraction kit buffer. In addition, the use of a second spin column cycle produced significantly better detection (P = 0.031), and the volume of Tris–EDTA buffer significantly affected crossing threshold values (P = 0.001). The improved extraction procedure was evaluated using 10 L of tap water samples processed by ultrafiltration, centrifugation and immunomagnetic separation. Mean recovery for the sample processing method was determined to be 41% using microscopy and 49% by real-time PCR (P = 0.013). The results of this study demonstrate that real-time PCR can be an effective alternative for detecting and quantifying Cryptosporidium parvum in drinking water samples.
- real-time PCR
- tap water
- First received 8 January 2015.
- Accepted in revised form 18 June 2015.
- © IWA Publishing 2015