Table 1.
Range of Effectiveness of Photosensitization
| No. of strains (%) | ||||
|---|---|---|---|---|
| Log10-unit reduction | Classificationa | MRSA | MSSA | Total |
| 0.01–0.99 | Resistant | 166 (62.4)* | 76 (47.8)* | 242 (57.1) |
| 1–1.99 | Intermediate sensitive | 62 (23.4)* | 51 (32.1)* | 113 (26.6) |
| 2–4.82 | Sensitive | 37 (14.0)** | 32 (20.1)** | 69 (16.3) |
| Total | 265 (62.5) | 159 (37.5) | 424 (100) | |
a
The cutoffs for the categorization of PDI response was made according to lethal or sublethal damage caused for Staphylococcus aureus strains. Strains reaching lethal or sublethal damage were deemed sensitive or resistant to PDI, respectively. Strains revealing reduction in viable counts that ranged between lethal and sublethal damage were deemed intermediate sensitive.
*
p<0.001; **p<0.05 (comparison of MRSA vs. MSSA); higher incidence of PDI resistant strains was observed for MRSA group; higher incidence of PDI intermediate sensitive and sensitive strains was reported for MSSA group.
MRSA, methicillin-resistant S. aureus; MSSA, methicillin-sensitive S. aureus; PDI, photodynamic inactivation.