Figure 7
Identification of bacteria on a human cadaveric epidermis. (a–e) Data obtained from the photodiode array designed by scanning human cadaveric epidermis samples inoculated with sterile LB, E. coli, or S. aureus. Incident light angle was changed for each of the five data sets; 135° (a), 120° (b), 110° (c), 100° (d), and 90° (e). At each individual incident light angle, significant differences result between bacterial inoculation and control samples as well as between each species of inoculation; E. coli or S. aureus. As expected, the trend changes as the incident light angle changes, but distinct differences are maintained despite changing trends with changing incident angles. One data point is considered to be the average of 12 readings from each photodiode (3 s scan). (f) Principle component analysis (PCA) of the data shown in (a–e) shows distinct differences between infections of the human cadaveric epidermis with E. coli vs. S. aureus vs. only the commensal bacteria present on control samples. The two principle components shown, PC1 and PC2, account for 70% of the data shown in (a–e), 49% and 21% for PC1 and PC2, respectively. Adding an additional PC, PC3 would account for an additional 14% of the data shown in (a–e). Each of 2 human cadaveric epidermis samples was scanned at three unique locations for 3 s at each location. Error bars represent standard error of the mean, the control group of (f) has standard error of zero. * is shown to the left side of each data point indicating significant difference (p < 0.05) between E. coli vs. control samples or between S. aureus vs. control samples. † is shown to the right side of each data point indicating significant difference (p < 0.05) between E. coli vs. S. aureus samples.
