TABLE 4.

Enumeration of C. albicans cells added to different water samples by QPCR by using different sample preparation methods and extract dilutions

Sample type	Turbidity (NTU)a	Sample volume (1)	Cells added to sampleb	Extract prep. method	Extract dilution	Measured cells/ samplec
Tap	2	1	90	CFEd	1:1	163
			20			35
			6			4
			0			<1e
Tap	2	1	90	CFE+Qf	1:1	123
			20			30
			6			4
			0			<1
Pond	20	0.1	1,000	CFE	1:10	1,237
			0			2g
Pond	20	0.1	1,000	CFE+Q	1:1	692
			0			1g
River	200	0.02	90	CFE	1:100	93
			20			30
			6			<22
			0			<37
River	200	0.02	90	CFE+Q	1:10	335
			20			32
			6			10
			0			<19

^aNTU, nephelometric turbidity units.

^bArithmetic mean for three to five replicate analyses, estimated from solid-phase cytometry.

^cGeometric mean for three to six replicate samples, estimated from QPCR analysis.

^dCFE, collection filter extraction.

^e<, no target detection: C_T = 40. Accompanying values are minimum cell detection limits determined by using this C_T result, the reference C_T results of the test samples, and target and reference C_T results of the corresponding calibrator samples in the ΔΔC̄_T calculation.

^fCFE+Q, collection filter extraction with the added step of a Qiagen kit purification.

^gPresumptive indigenous target organisms in the water sample.