Figure 2. Effect of temperature (A), storage time (B), and temperature and storage times (C–E) on yield of rickettsial DNA, Marseille, France. Guinea pigs (n = 3) were infected with Rickettsia conorii and inspected daily for skin lesions. After lesions appeared, 12 swab specimens/animal were obtained daily for 5 days and stored in groups of 3 at 22°C, 4°C, −20°C, or −80°C. DNA was extracted after storage for 24 h, 48 h, or 72 h at each temperature in a final volume of 100 μL, and numbers of bacterial DNA copies were quantified in 5 μL of swab DNA extracts by using quantitative PCR. Box plots indicate 25th and 75th percentiles, horizontal lines indicate medians, and error bars indicate minimum and maximum values.