FIG. 4.

Quantitation of P. carinii organisms passaged serially (⧫). For each subculture, a 1:10 dilution was performed. For reference, the calculated inoculated amount of DNA for each subculture is graphed to show the expected value if there were no replication and no loss of DNA during culture (▪). The dashed line indicates the level of sensitivity and lower limit of quantitation (5 copies/tube equal to 150 organisms/ml). The first subculture was derived from a primary culture inoculated to a density of 5.4 × 10⁶ copies/ml by passage after 10 days of incubation. ∗, subcultures 4, 5, and 6 were negative by QTD PCR.