Laser-induced shock waves enhance sterilization of infected vascular prosthetic grafts.
OBJECTIVE
Bacteria that cause infection of vascular prosthetic grafts produce an exopolysaccharide matrix known as biofilm. Growth in biofilms protects the bacteria from leukocytes, antibodies and antimicrobial drugs. Laser-generated shock waves (SW) can disrupt biofilms and increase drug penetration. This study investigates the possibility of increasing antibiotic delivery and sterilization of vascular prosthetic graft.


METHODS
Strains of Staphylococcus epidermidis and S. aureus were isolated from infected prosthetic grafts obtained directly from patients. Dacron grafts were inoculated with the isolated bacteria, which were allowed to form adherent bacterial colonies. The colonized grafts underwent the following treatments: (a) antibiotic (vancomycin) alone; (b) antibiotic and SW (c) saline only; and (d) saline and SW. Six hours after treatment, the grafts were sonicated, the effluent was cultured and the colony forming units (CFU) were counted.


RESULTS
CFU recovered from control grafts colonized by S. epidermidis were comparable: saline, 3.05 x 10(8) and saline+SW 3.31 x 10(8). The number of S. epidermidis CFU diminished to 7.61 x 10(6) after antibiotic treatment but the combined antibiotic+SW treatment synergistically decreased CFU number to 1.27 x 10(4) (P<0.001). S. aureus showed a higher susceptibility to the antibiotic: 2.26 x 10(6) CFU; antibiotic +SW treatment also had an incremental effect: 8.27 x 10(4) CFU (P<0.001).


CONCLUSIONS
This study demonstrates that laser-generated shock waves have no effects alone, but can enhance the effectiveness of antibiotics against bacteria associated with prosthetic vascular graft biofilms, suggesting that this treatment may be of value as adjunctive therapy for prosthetic graft infections.
Nigri
G R
GR
Division of Vascular Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA.
Tsai
S
S
Kossodo
S
S
Waterman
P
P
Fungaloi
P
P
Hooper
D C
DC
Doukas
A G
AG
LaMuraglia
G M
GM
D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D001807:Blood Vessel Prosthesis / Q000009:adverse effects*; D003131:Combined Modality Therapy; D006801:Humans; D007834:Lasers; D016459:Prosthesis-Related Infections / Q000188:drug therapy / Q000517:prevention & control* / Q000532:radiotherapy*; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000517:prevention & control* / Q000532:radiotherapy*; D013211:Staphylococcus aureus / Q000302:isolation & purification; D013212:Staphylococcus epidermidis / Q000302:isolation & purification; D013242:Sterilization / Q000295:instrumentation / Q000379:methods*; D013530:Surgical Wound Infection / Q000517:prevention & control / Q000532:radiotherapy; D016896:Treatment Outcome
D000900:Anti-Bacterial Agents