Dan Carpenter | University of Memphis (original) (raw)
Address: Memphis, United States
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Background Orthopaedic biomaterials are susceptible to biofilm formation. A novel lipid-based mat... more Background Orthopaedic biomaterials are susceptible to
biofilm formation. A novel lipid-based material has been
developed that may be loaded with antibiotics and applied
as an implant coating at point of care. However, this
material has not been evaluated for antibiotic elution,
biofilm inhibition, or in vivo efficacy.
Questions/purposes (1) Do antibiotic-loaded coatings
inhibit biofilm formation? (2) Is the coating effective in
preventing biofilm in vivo?
Methods Purified phosphatidylcholine was mixed with
25% amikacin or vancomycin or a combination of 12.5%
of both. A 7-day elution study for coated titanium and
stainless steel coupons was followed by turbidity and zone
of inhibition assays against Staphylococcus aureus and
Pseudomonas aeruginosa. Coupons were inoculated with
bacteria and incubated 24 hours (N = 4 for each test
group). Microscopic images of biofilm were obtained.
After washing and vortexing, attached bacteria were
counted. A mouse biofilm model was modified to include
coated and uncoated stainless steel wires inserted into the
lumens of catheters inoculated with a mixture of S aureus
or P aeruginosa. Colony-forming unit counts (N = 10) and
scanning electron microscopy imaging of implants were
used to determine antimicrobial activity.
Results Active antibiotics with colony inhibition effects
were eluted for up to 6 days. Antibiotic-loaded coatings
inhibited biofilm formation on in vitro coupons (log-fold
reductions of 4.3 ± 0.4 in S aureus and 3.1 ± 0 for P
aeruginosa in phosphatidylcholine-only coatings, 5.6 ± 0
for S aureus and 3.1 ± 0 for P aeruginosa for combinationloaded
coatings, 5.5 ± 0.3 for S aureus in vancomycinloaded
coatings, and 3.1 ± 0 for P aeruginosa for amikacinloaded
coatings (p\0.001 for all comparisons of antibiotic-
loaded coatings against uncoated controls for both
bacterial strains, p\0.001 for comparison of antibioticloaded
coatings against phosphatidylcholine only for S
aureus, p = 0.54 for comparison of vancomycin versus
combination coating in S aureus, P = 0.99 for comparison
of antibiotic- and unloaded phosphatidylcholine coatings in
P aeruginosa). Similarly, antibiotic-loaded coatings
reduced attachment of bacteria to wires in vivo (log-foldreduction of 2.54 ± 0; p\0.001 for S aureus and
0.83 ± 0.3; p = 0.112 for P aeruginosa).
Conclusions Coatings deliver active antibiotics locally to
inhibit biofilm formation and bacterial growth in vivo.
Future evaluations will include orthopaedic preclinical
models to confirm therapeutic efficacy.
Clinical Relevance Clinical applications of local drug
delivery coating could reduce the rate of implant-associated
infections.
Background Orthopaedic biomaterials are susceptible to biofilm formation. A novel lipid-based mat... more Background Orthopaedic biomaterials are susceptible to
biofilm formation. A novel lipid-based material has been
developed that may be loaded with antibiotics and applied
as an implant coating at point of care. However, this
material has not been evaluated for antibiotic elution,
biofilm inhibition, or in vivo efficacy.
Questions/purposes (1) Do antibiotic-loaded coatings
inhibit biofilm formation? (2) Is the coating effective in
preventing biofilm in vivo?
Methods Purified phosphatidylcholine was mixed with
25% amikacin or vancomycin or a combination of 12.5%
of both. A 7-day elution study for coated titanium and
stainless steel coupons was followed by turbidity and zone
of inhibition assays against Staphylococcus aureus and
Pseudomonas aeruginosa. Coupons were inoculated with
bacteria and incubated 24 hours (N = 4 for each test
group). Microscopic images of biofilm were obtained.
After washing and vortexing, attached bacteria were
counted. A mouse biofilm model was modified to include
coated and uncoated stainless steel wires inserted into the
lumens of catheters inoculated with a mixture of S aureus
or P aeruginosa. Colony-forming unit counts (N = 10) and
scanning electron microscopy imaging of implants were
used to determine antimicrobial activity.
Results Active antibiotics with colony inhibition effects
were eluted for up to 6 days. Antibiotic-loaded coatings
inhibited biofilm formation on in vitro coupons (log-fold
reductions of 4.3 ± 0.4 in S aureus and 3.1 ± 0 for P
aeruginosa in phosphatidylcholine-only coatings, 5.6 ± 0
for S aureus and 3.1 ± 0 for P aeruginosa for combinationloaded
coatings, 5.5 ± 0.3 for S aureus in vancomycinloaded
coatings, and 3.1 ± 0 for P aeruginosa for amikacinloaded
coatings (p\0.001 for all comparisons of antibiotic-
loaded coatings against uncoated controls for both
bacterial strains, p\0.001 for comparison of antibioticloaded
coatings against phosphatidylcholine only for S
aureus, p = 0.54 for comparison of vancomycin versus
combination coating in S aureus, P = 0.99 for comparison
of antibiotic- and unloaded phosphatidylcholine coatings in
P aeruginosa). Similarly, antibiotic-loaded coatings
reduced attachment of bacteria to wires in vivo (log-foldreduction of 2.54 ± 0; p\0.001 for S aureus and
0.83 ± 0.3; p = 0.112 for P aeruginosa).
Conclusions Coatings deliver active antibiotics locally to
inhibit biofilm formation and bacterial growth in vivo.
Future evaluations will include orthopaedic preclinical
models to confirm therapeutic efficacy.
Clinical Relevance Clinical applications of local drug
delivery coating could reduce the rate of implant-associated
infections.