[Effect of Photodynamic Inactivation (PDI) using Riboflavin-Conjugated Antibody against Staphylococcus aureus].
OBJECTIVE
Crosslinking/riboflavin-UVA photodynamic therapy is a potential treatment alternative in antibiotic resistant infectious keratitis. For photodynamic therapy a specific (against bacteria) conjugated antibody may be used in order to increase the effect of the treatment. In our present study we analysed the impact of photodynamic inactivation using riboflavin-conjugated antibody or riboflavin alone on Staphylococcus aureus, in vitro.


METHODS
Staphylococcus aureus (S. aureus) was incubated in 1 : 100 diluted riboflavin-conjugated antibody (R-AB) for 30 minutes in darkness. Following UVA-light illumination (375 nm) with an energy dose of 2, 3, 4 and 8 J/cm(2), bacteria were brought to blood agar Plates for 24 hours before colony-forming unit (CFU) counting. In an additional group, we incubated bacteria to 0, 0.05 or 0.1 % riboflavin 5-phosphate as described above followed by illumination using UVA light (375 nm) with an energy dose of 2 J/cm(2), before CFU counting.


RESULTS
The number of CFU decreased significantly (inactivation of 36 %, p = 0.022) using 1 : 100 diluted riboflavin-conjugated antibody and 2 J/cm(2) UVA-light illumination, compared to untreated controls. The use of 3, 4 und 8 J/cm(2) energy dose and R-AB in 1 : 100 dilution did not further change the decrease of CFU (inactivation of 39, 39 and 40 %; p = 0.016; p = 0.016; p = 0.015). The use of 0.05 % or 0.1 % riboflavin 5-phosphate alone and UVA-light illumination reduced the CFU count significantly (inactivation of 73 and 55 %; p = 0.002; p = 0.005), compared to untreated controls.


CONCLUSIONS
The use of riboflavin-conjugated antibody or 0.05 % or 0.1 % riboflavin 5-phosphate and UVA-light illumination reduces the number of CFU of S. aureus. However, none of these photodynamic therapies reached the necessary 99 % killing rate of these bacteria. Further work is needed to increase the efficacy of riboflavin-conjugated antibodies against antibiotic resistant bacteria.
Klinik für Augenheilkunde, Universitätsklinikum des Saarlandes UKS, Homburg/Saar.
X
X
Song
Klinik für Augenheilkunde, Universitätsklinikum des Saarlandes UKS, Homburg/Saar.
T
T
Stachon
Klinik für Augenheilkunde, Universitätsklinikum des Saarlandes UKS, Homburg/Saar.
B
B
Seitz
Klinik für Augenheilkunde, Universitätsklinikum des Saarlandes UKS, Homburg/Saar.
J
J
Wang
Institut für Mikrobiologie und Hygiene, Universitätsklinikum des Saarlandes UKS, Homburg/Saar.
M
M
Bischoff
Experimentelle Ophthalmologie, Universität des Saarlandes UKS, Homburg/Saar.
A
A
Langenbucher
Experimentelle Ophthalmologie, Universität des Saarlandes UKS, Homburg/Saar.
E
E
Janunts
Klinik für Augenheilkunde, Universitätsklinikum des Saarlandes UKS, Homburg/Saar.
N
N
Szentmáry
D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000627:therapeutic use; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D003432:Cross-Linking Reagents / Q000737:chemistry; D004203:Disinfection / Q000379:methods*; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000008:administration & dosage / Q000737:chemistry; D012256:Riboflavin / Q000008:administration & dosage* / Q000737:chemistry; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000502:physiology* / Q000528:radiation effects; D014464:Ultrasonic Therapy / Q000379:methods*
D000911:Antibodies, Monoclonal; D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents; D012256:Riboflavin