The inability of a bacteriophage to infect Staphylococcus aureus does not prevent it from specifically delivering a photosensitizer to the bacterium enabling its lethal photosensitization.
OBJECTIVE
It has been demonstrated that the efficiency of lethal photosensitization can be improved by covalently binding photosensitizing agents to bacteriophage. In this study we have investigated whether a bacteriophage requires the capacity to infect the bacterium to enhance lethal photosensitization when linked to a photosensitizer.


METHODS
Tin (IV) chlorin e6 (SnCe6) was conjugated to bacteriophage Phi11, a transducing phage that can infect Staphylococcus aureus NCTC 8325-4, but not epidemic methicillin-resistant S. aureus (EMRSA)-16. The conjugate and appropriate controls were incubated with these bacteria and either exposed to laser light at 632.8 nm or kept in the dark.


RESULTS
The SnCe6/Phi11 conjugate achieved a statistically significant reduction in the number of viable bacteria of both 8325-4 and EMRSA-16 strains by 2.31 log(10) and 2.63 log(10), respectively. The conjugate could not however instigate lethal photosensitization of Escherichia coli. None of the other combinations of controls, such as an equivalent concentration of SnCe6 only, an equivalent titre of bacteriophage only or experiments conducted without laser light, yielded significant reductions in the number of viable bacteria recovered.


CONCLUSIONS
The inability of a bacteriophage to infect S. aureus does not prevent it from specifically delivering a photosensitizer to a bacterium enabling its lethal photosensitization.
Division of Microbial Diseases, UCL Eastman Dental Institute, London, UK.
C K
CK
Hope
S
S
Packer
M
M
Wilson
S P
SP
Nair
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001435:Bacteriophages / Q000737:chemistry* / Q000254:growth & development*; D003624:Darkness; D006801:Humans; D007834:Lasers; D050296:Microbial Viability; D017319:Photosensitizing Agents / Q000737:chemistry / Q000494:pharmacology*; D013211:Staphylococcus aureus / Q000187:drug effects / Q000528:radiation effects* / Q000821:virology*
D000900:Anti-Bacterial Agents; D017319:Photosensitizing Agents