Surgical suture abstract
An antibacterial vascular prosthesis obtained by winding a tube,
fiber or sheet formed from a polymeric material and combined with
an antibacterial substance on the outer surface of a vascular prosthesis
composed of a tubular porous body formed of a synthetic resin is
provided. The antibacterial vascular prosthesis can exhibit an antibacterial
activity over a long period of time without impairing the porous
structure, antithrombogenicity and histocompatibility inherent in
the vascular prosthesis composed of the tubular porous body formed
of the synthetic resin. An antibacterial surgical suture comprising
a tube or fiber formed from a polymeric material and combined with
an antibacterial substance is also provided.
Surgical suture claims
We claim:
1. An antibacterial vascular prosthesis obtained by winding a tube,
fiber or sheet formed from a polymeric material and combined with
an antibacterial substance on the outer surface of a vascular prosthesis
composed of a tubular porous body formed of a synthetic resin, wherein
the tube, fiber or sheet combined with an antibacterial substance
is wound on the outer surface of the vascular prosthesis such that
portions of the outer surface of the antibacterial vascular prosthesis
are uncovered and the porosity of the antibacterial vascular prosthesis
is substantially unimpaired.
2. The antibacterial vascular prosthesis according to claim 1
wherein the tube, fiber or sheet combined with the antibacterial
substance is obtained by impregnating with and/or depositing the
antibacterial substance into and/or on at least part of the pores,
inner surface and outer surface of a porous tube, fiber or sheet
formed from the polymeric material.
3. The antibacterial vascular prosthesis according to claim 2
wherein the polymeric material from which the porous tube, fiber
or sheet is formed is polytetrafluoroethylene or a tetrafluoroethylene-hexafluoropropylene
copolymer.
4. The antibacterial vascular prosthesis according to claim 1
wherein the tube, fiber or sheet combined with the antibacterial
substance is obtained by impregnating with and/or depositing a mixture
of a biodegradable polymer and the antibacterial substance into
and/or on at least part of the pores, inner surface and outer surface
of a porous tube, fiber or sheet formed from the polymeric material.
5. The antibacterial vascular prosthesis according to claim 4
wherein the polymeric material from which the porous tube, fiber
or sheet is formed is polytetrafluoroethylene or a tetrafluoroethylene-hexafluoropropylene
copolymer.
6. The antibacterial vascular prosthesis according to claim 4
wherein the biodegradable polymer is selected from agarose, dextran,
polylactic acid, gelatin, fibrinogen, chitin and chitosan.
7. The antibacterial vascular prosthesis according to claim 1
wherein the tube, fiber or sheet combined with an antibacterial
substance is formed from a mixture of a biodegradable polymer and
the antibacterial substance.
8. The antibacterial vascular prosthesis according to claim 7
wherein the biodegradable polymer is selected from agarose, dextran,
polylactic acid, gelatin, fibrinogen, chitin and chitosan.
9. The antibacterial vascular prosthesis according to claim 1
wherein the antibacterial substance is an antibiotic or a heavy
metal.
10. The antibacterial vascular prosthesis according to claim 9
wherein the antibiotic is selected from .beta.-lactam, aminoglycoside,
chloramphenicol, tetracycline, macrolide and lincomycin.
11. The antibacterial vascular prosthesis according to claim 9
wherein the heavy metal is a silver compound.
12. The antibacterial vascular prosthesis according to claim 1
wherein the outer diameter of the tube combined with the antibacterial
substance, the size of the fiber combined with the antibacterial
substance, or the thickness and width of the sheet combined with
the antibacterial substance are smaller than the outer diameter
of the vascular prosthesis.
13. The antibacterial vascular prosthesis according to claim 1
wherein the outer diameter of the tube combined with the antibacterial
substance, the size of the fiber combined with the antibacterial
substance, or the thickness and width of the sheet combined with
the antibacterial substance are about a half or smaller of the outer
diameter of the vascular prosthesis.
14. The antibacterial vascular prosthesis according to claim 1
wherein the tubular porous body composing the vascular prosthesis
and made of a synthetic resin is a tubular porous body formed from
polytetrafluoroethylene.
Surgical suture description
FIELD OF THE INVENTION
The present invention relates to a vascular prosthesis suitable
for use as a substitute for an artery, vein or the like and a surgical
suture, and more particularly to a vascular prosthesis and a surgical
suture, both, given with an antibacterial activity.
BACKGROUND OF THE INVENTION
Vascular prostheses composed of a tubular porous body formed of
a synthetic resin such as polytetrafluoroethylene (hereinafter abbreviated
as "PTFE") or polyester are widely used in repair of circulation
or for internal shunts upon dialysis. However, such vascular prostheses
involve a serious problem that they tend to be infected with bacteria.
More specifically, the bacteria entered upon implantation of a vascular
prosthesis, or the like are easy to proliferate on an artificial
material such as the vascular prosthesis because an immune system,
which is an innate protective system in the living body, is hard
to normally and sufficiently operate in such circumstances. In addition,
tissue cells and intracellular substances damaged or destroyed by
grafting, or blood coagulation occurred in the damaged site provide
suitable proliferative sites for the entered bacteria.
As methods for preventing the bacterial infection, for example,
it has been conducted to sterilize a vascular prosthesis before
its use, and to make a surgical field thoroughly sterile. However,
the infection rate is considerably high as reported to be 1-5%.
In order to treat an infectious disease, it is conducted to administer
one or more antibiotics. By this method, however, it is difficult
to topically exert their antibacterial effect on the site in which
bacteria are grown. It has hence been only necessary to excise or
remove the vascular prosthesis once it has become infected.
As methods for protecting a vascular prosthesis from bacterial
infection, there have heretofore been proposed various methods in
which an antibacterial activity is imparted to the vascular prosthesis
itself. For example, there have been proposed (1) a vascular prosthesis
obtained by applying or depositing a silver-antibiotic complex on
a porous structure formed of PTFE or polyester [A. I. Benvenisty
et al., J. Surgical Research, 44 1-7 (1988)], and (2) a vascular
prosthesis obtained by coating a PTFE or polyester material with
a surfactant and then bonding an antibiotic to the surfactant by
ionic bonding [W. B. Shue et al., J. Vascular Surgery, 8 600-605
(1988)]. However, these methods have involved problems that it is
impossible to last the antibacterial effect of the antibiotic over
a long period of time until peripheral tissues including the interior
of the wall of the vascular prosthesis become healed because the
amount of the antibiotic combined is small, and that the antibiotic
and surfactant present in the wall and on the inner wall surface
of the vascular prosthesis impair the innate antithrombogenicity
and histocompatibility in the vascular prosthesis.
In addition to the above methods, there have been proposed (3)
methods in which a mixture of a biopolymer such as glucosaminoglycan-keratin
or collagen and an antibiotic is applied onto the inner wall or
outer surface of a vascular prosthesis [K. R. Sobinsky et al., Surgery,
100 629-634 (1986), and M. D. Colburn et al., J. Vascular Surgery,
16 651-660 (1992)]. According to these methods, the amount of the
antibiotic to be combined can be increased, and the release rate
of the antibiotic can be controlled. However, the methods have involved,
in addition to a problem that the antibiotic and biopolymer present
in the wall and on the inner wall surface of the vascular prosthesis
impair the innate antithrombogenicity and histocompatibility in
the vascular prosthesis, a problem that since the porous structure
within the wall of the vascular prosthesis is filled with the biopolymer,
the penetration of living tissues through the outer and inner walls
is not caused to progress, and so the healing of the vascular prosthesis
is not performed.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide an antibacterial
vascular prosthesis capable of exhibiting an antibacterial activity
over a long period of time without impairing the porous structure,
antithrombogenicity and histocompatibility inherent in a vascular
prosthesis composed of a tubular porous body formed of a synthetic
resin.
Another object of the present invention is to provide an antibacterial
surgical suture.
The present inventors have carried out an extensive investigation
with a view toward overcoming the above-described problems involved
in the prior art. As a result, it has been found that the above
object can be achieved by winding a tube, fiber or sheet composed
of a polymeric material and combined with an antibacterial substance
on the outer surface of a vascular prosthesis.
The tube, fiber or sheet combined with the antibacterial substance
may be produced by impregnating with and/or depositing the antibacterial
substance or a mixture of the antibacterial substance and a biodegradable
polymer into and/or on the whole or parts of the pores, inner surface
and outer surface of a porous tube, fiber or sheet formed from a
polymeric material. The tube, fiber or sheet combined with the antibacterial
substance may also be formed from a mixture of a biodegradable polymer
and an antibacterial substance.
Since the tube, fiber or sheet combined with the antibacterial
substance is wound on the outer surface of the vascular prosthesis
with a desired space, the porous structure of the vascular prosthesis
is not impaired, and besides the functions of the vascular prosthesis,
such as antithrombogenicity and histocompatibility are not impeded.
The antibacterial substance can be gradually released over a long
period of time from the tube, fiber or sheet combined with the antibacterial
substance. The antibacterial substance gradually released in the
vicinity of the outer surface of the vascular prosthesis inhibits
the growth of bacteria attached to the vascular prosthesis over
a long period of time. Of these tube, fiber and sheet combined with
the antibacterial substance, the tube or fiber may be used as an
antibacterial surgical suture by itself.
The present invention has been led to completion on the basis of
these findings.
According to the present invention, there is thus provided an antibacterial
vascular prosthesis obtained by winding a tube, fiber or sheet formed
from a polymeric material and combined with an antibacterial substance
on the outer surface of a vascular prosthesis composed of a tubular
porous body formed of a synthetic resin.
According to the present invention, there is also provided an antibacterial
surgical suture comprising a tube or fiber formed from a polymeric
material and combined with an antibacterial substance.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 diagrammatically illustrates the amount of an antibacterial
substance released with time from an antibacterial vascular prosthesis
obtained in an example of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will hereinafter be described in detail.
Tubular porous body
In the present invention, a tubular porous body formed of a synthetic
resin is used as a vascular prosthesis. Examples of the synthetic
resin from which the vascular prosthesis is formed may include polytetrafluoroethylene,
polyester, polyurethane, polyethylene, polypropylene, polysiloxane
and the like.
No particular limitation is imposed on the process for producing
the tubular porous bodies from these synthetic resin materials.
They may be produced in accordance with a process known per se in
the art according to the material used. For example, a tubular porous
body made of PTFE can be produced in accordance with the process
described in Japanese Patent Publication No. 13560/1967. More specifically,
a liquid lubricant is first mixed into unsintered PTFE powder, and
the mixture is extruded through a ram extruder into a tubular form.
The tube is stretched at least in its axial direction after removing
liquid lubricant from the tube or without removing the liquid lubricant.
Both ends of the tube are then fixed so as to prevent it from shrinking,
and the tube is heated from both inner and outer sides thereof at
327.degree. C. which is a sintering temperature of PTFE, or higher,
thereby obtaining a tubular PTFE porous body having a fine fibrous
structure composed of fibers and knots joined to each other by the
fibers.
When a continuous temperature gradient is given between the inner
and outer surfaces of the PTFE tube upon the sintering in such a
manner that the temperature of the outer surface is higher than
that of the inner surface by 50.degree.-300.degree. C., the fiber-knot
structure is rearranged from the inner surface of the tube to the
outer surface, so that portions whose fibers are more stretched
than those before the treatment and hence made longer, and portions
whose fiber are made shorter than those before the treatment are
obtained.
Besides, when portions of the PTFE tube after the stretching are
heated further at a temperature of 327.degree. C. or higher in accordance
with the process described in Japanese patent Publication No. 1656/1983
or Japanese Patent Application Laid-Open No. 76648/1980 a tubular
PTFE porous body excellent in strength in the direction perpendicular
to the stretching direction can be produced.
Tube, fiber and sheet combined with antibacterial substance
The tube, fiber or sheet combined with the antibacterial substance
can be produced by (1) a process in which an antibacterial substance
is mixed and dispersed in a polymeric material, and the resulting
mixture is formed into a tube, fiber or sheet, (2) a process in
which an antibacterial substance is impregnated into and/or deposited
on a porous tube, fiber or sheet formed from a polymeric material,
(3) a process in which a mixture of a biodegradable polymer and
an antibacterial substance is impregnated into and/or deposited
on a porous tube, fiber or sheet formed from a polymeric material,
or the like.
In the process in which the mixture of the polymeric material and
the antibacterial substance is formed into the tube, fiber or sheet,
the tube, fiber or sheet may preferably be made porous.
In the process in which the antibacterial substance or the mixture
of the biodegradable polymer and the antibacterial substance is
impregnated into and/or deposited on the porous tube, fiber or sheet
formed from the polymeric material, the antibacterial substance
or the mixture of the biodegradable polymer and the antibacterial
substance is impregnated into and/or deposited on the inner and
outer surfaces of the porous tube, the outer surface of the porous
fiber, the outer surface of the porous sheet and the inner surfaces
defining pores in these porous bodies. The impregnation and/or deposition
may be performed to the whole or parts of the pores, inner surface
and outer surface of the porous tube, fiber or sheet. The antibacterial
substance or the mixture of the biodegradable polymer and the antibacterial
substance may be only impregnated into the pores in the porous body
and deposited on the inner surfaces defining the pores in the porous
body. In this invention, the term "impregnation" means
that the antibacterial substance or the mixture of the biodegradable
polymer and the antibacterial substance is impregnated into void
spaces (i.e., pores) in the porous body to hold it therein. On the
other hand, the term "deposition" means that the antibacterial
substance or the mixture of the biodegradable polymer and the antibacterial
substance is deposited on the inner surface (in the case of the
porous tube) and outer surface of the porous body and the inner
surfaces defining the pores in the porous body. In fact, both impregnation
and deposition often take place.
Examples of the polymeric material from which the porous tube,
fiber or sheet is formed may include synthetic polymeric materials
such as polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene
copolymers, polyester, polyurethane, polyethylene and polypropylene.
Besides, as the polymeric material, may be used biodegradable polymers
(biotransformable polymers) such as agarose, dextran, polylactic
acid, gelatin, fibrinogen, chitin and chitosan.
No particular limitation is imposed on the process for producing
the porous tubes, fibers or sheets from these synthetic resin materials.
For example, in the case where PTFE is used as a polymeric material,
a porous tube may be produced in the same manner as in the tubular
PTFE porous body in the vascular prosthesis described above. Following
the process described in Japanese Patent Publication No. 18977/1990
PTFE containing a liquid lubricant may be formed into a fine rod.
After removing the liquid lubricant, the rod may be stretched in
its longitudinal direction into a porous fiber. Alternatively, a
porous sheet may be produced in accordance with the process described
in Japanese Patent Publication No. 3842/1985. Similarly, a porous
tube may be formed by producing a porous thin-film material composed
of PTFE in advance, winding the thin-film material on a metallic
wire to fix it and then integrally sintering the thin-film material
under heat.
No particular limitation is also imposed on the process for producing
the porous tubes, fibers or sheets from the biodegradable polymers.
Examples thereof may include (1) a process for producing a tube
composed of a biodegradable polymer, in which a solution of the
biodegradable polymer is coated on the outer wall surface of a tube
made of a suitable material to dry the polymer, and the tube situated
inside the biodegradable polymer is then drawn out in this state,
(2) a process for forming a fiber, in which a solution of a biodegradable
polymer is filled into the bore of a tube made of a suitable material
to dry the polymer, and the dried polymer is then drawn out of the
tube, and (3) a process in which a solution of a biodegradable polymer
is spread on a flat plate made of a suitable material, and the polymer
is then dried.
In the process for producing the tube, fiber or sheet from the
mixture of the polymeric material and the antibacterial substance,
it is preferable that the biodegradable polymer be used as the polymeric
material. In this case, when a mixed solution obtained by mixing
a solution of the biodegradable polymer and the antibacterial substance
in advance is used in the above-described production process of
the tube, fiber or sheet composed of the biodegradable polymer,
the antibacterial substance can be evenly dispersed in the biodegradable
polymer, whereby the antibacterial substance can be dispersed and
fixed in the biodegradable polymer in the form of a tube, fiber
or sheet after drying the polymer. The antibacterial substance may
bond to the biodegradable polymer by ionic bonding. As a solvent,
there is generally used an organic solvent which does not decompose
the biodegradable polymer and antibacterial substance. The tube,
fiber or sheet composed of the biodegradable polymer is preferably
made porous. The tube, fiber or sheet composed of the biodegradable
polymer and combined with the antibacterial substance in accordance
with this process can gradually release the antibacterial substance
over a long period of time.
In the method of impregnating with and/or depositing the antibacterial
substance into and/or on the porous tube, fiber or sheet formed
from the polymeric material, it is only necessary to immerse the
porous tube, fiber or sheet in a solution with the antibacterial
substance dissolved therein and then dry the porous body. By this
method, the antibacterial substance can be impregnated into and/or
deposited on the whole or part of the pores, inner surface and outer
surface of the porous body.
In order to control the release of the antibacterial substance
over a long period of time, it is preferable that a mixture of the
biodegradable polymer and the antibacterial substance be impregnated
into and/or deposited on the porous tube, fiber or sheet formed
from the polymeric material. In this method, it is only necessary
to immerse the porous tube, fiber or sheet in a mixed solution of
the biodegradable polymer and the antibacterial substance and then
dry the porous body. By this method, the antibacterial substance
evenly dispersed in the biodegradable polymer can be impregnated
into and/or deposited on the whole or part of the pores, inner surface
and outer surface of the porous body. In this case, the above-mentioned
various biodegradable polymers may be used as the biodegradable
polymer. As a solvent, there is generally used a volatile organic
solvent which can enter void spaces in the porous body and does
not decompose the biodegradable polymer and antibacterial substance.
As the antibacterial substance, may be used antibiotics such as
.beta.-lactam, aminoglycoside, chloramphenicol, tetracycline, macrolide
and lincomycin and heavy metals such as silver compounds. These
substances may be used either singly or in any combination thereof.
The tube, fiber or sheet combined with the antibacterial substance
is wound on the outer surface of the vascular prosthesis. However,
it is wound with a desired space, not on the whole outer surface,
so that the porous structure of the vascular prosthesis is not impaired.
It is desirable that the outer diameter (size) of the tube or fiber
combined with the antibacterial substance, or the thickness and
width of the sheet combined with the antibacterial substance be
smaller than the outer diameter of the vascular prosthesis, for
example, about a half or smaller, preferably about a third or smaller,
more preferably about a fourth or smaller of the outer diameter
of the vascular prosthesis.
The release rate of the antibacterial substance is basically determined
by the diffusion rate in the humor in which the antibacterial substance
exudes after the implantation of the antibacterial vascular prosthesis
according to the present invention. However, it may be controlled
by selecting the pore size, porosity, wall thickness, size or width
of the porous tube, fiber or sheet combined with the antibacterial
substance, the kind of the biodegradable polymer, the compositional
ratio of the biodegradable polymer to the antibacterial substance,
the bonding between the biodegradable polymer and the antibacterial
substance, the winding pitch on the vascular prosthesis of the tube,
fiber or sheet, or the like. The combined amount of the antibacterial
substance can be suitably determined. According to the present invention,
however, it is possible to combine the antibacterial substance in
a comparatively great amount compared with the conventional methods
in which the antibacterial substance is bonded to the vascular prosthesis
itself because the antibacterial substance is combined with the
tube, fiber or sheet composed of the polymeric material. It is therefore
possible to combine the antibacterial substance in an amount sufficient
to gradually release it until an immune system normally operates
in vivo after the implantation of the vascular prosthesis. The amount
can be experimentally determined from the kind and release rate
of the antibacterial substance, and the like by those skilled in
the art.
Since the antibacterial substance and the tube, fiber or sheet
combined with the antibacterial substance exist only on the outer
surface of the vascular prosthesis, they do not directly contact
with the blood stream. Therefore, the innate antithrombogenicity
in the vascular prosthesis is not impaired. According to the antibacterial
vascular prosthesis of the present invention, the antibacterial
substance released exists only on the outer surface of the vascular
prosthesis or in its wall in the vicinity of the outer surface.
Therefore, the histocompatibility of the vascular prosthesis is
not impaired. Besides, since the porous structure of the vascular
prosthesis is maintained, the penetrability of living tissues through
the vascular prosthesis is kept good, and so the healing process
is also not inhibited.
After the implantation of the antibacterial vascular prosthesis
according to the present invention, the antibacterial substance
is released near the outer surface of the vascular prosthesis. In
this case, the antibacterial substance is gradually released over
a long period of time owing to such that a sufficient amount of
the antibacterial substance can be combined with the tube, fiber
or sheet, and that such a combination of the antibacterial substance
permits the control of release rate. The gradual release of the
antibacterial substance allows the antibacterial substance to inhibit
the growth of bacteria attached to the outer surface of the main
vascular prosthesis over a long period of time. Meanwhile, the innate
immune system in the living body comes to fully operate, and the
tissues penetrates into the main vascular prosthesis, so that the
healing is caused to progress.
The tube or fiber according to the present invention, which has
been formed from the polymeric material and combined with the antibacterial
substance, is also useful in applying to a surgical suture by itself.
An incision site upon surgery has the highest possibility of being
the source of infection. However, the use of the surgical suture
composed of the tube or fiber combined with the antibacterial substance
in such a site permits inhibiting the growth of the bacteria attached
to the incision site as the source of infection over a long period
of time because the antibacterial substance is gradually released
over a long period of time.
ADVANTAGES OF THE INVENTION
According to the present invention, there is provided an antibacterial
vascular prosthesis capable of exhibiting an antibacterial activity
over a long period of time without impairing the porous structure,
antithrombogenicity and histocompatibility inherent in a vascular
prosthesis composed of a tubular porous body formed of a synthetic
resin.
The present invention also provides an antibacterial surgical suture
capable of exhibiting an antibacterial activity over a long period
of time.
EMBODIMENTS OF THE INVENTION
The present invention will hereinafter be described more specifically
by the following examples. However, it should be borne in mind that
this invention is not limited to and by these examples only.
EXAMPLE 1
One gram of ofloxacin (antibiotic, product of Daiich Seiyaku Co.,
Ltd.) was suspended in 10 ml of a 1% solution of polylactic acid
(molecular weight: 50000 product of Polyscience Co.) in dioxane
(product of Wako Pure Chemical Industries, Ltd.) which had been
prepared in advance.
After a tape obtained by cutting a porous PTFE sheet (LUP-300
product of Sumitomo Electric Industries, Ltd.) into a width of 5
mm was spirally wound at the pitch of 2.5 mm on a stainless steel
rod 1 mm in outer diameter, both ends of the tape were fixed to
the rod, followed by heating of the tape at a temperature not lower
than the melting point of PTFE to integrally sinter the tape, thereby
forming the tape in the form of a tube. The stainless steel rod
was then drawn out of the tube.
The porous PTFE tube thus obtained was immersed in the above-prepared
mixed solution of ofloxacin and polylactic acid in dioxane to sufficiently
penetrate the solution into the wall of the porous body. The thus-treated
tube was then air-dried. This procedure was repeated 3 times, whereby
the mixture of polylactic acid and ofloxacin was impregnated into
the wall and deposited on the inner surface of the tube to obtain
a composite tube.
The thus-obtained tube combined with ofloxacin and polylactic acid
was lightly immersed in a 1% solution of polylactic acid in dioxane
to wash out polylactic acid and ofloxacin present on the outer surface
of the tube and at the same time, soften the tube as a whole. Thereafter,
the tube was wound at a pitch of 5 mm on a stretched PTFE vascular
prosthesis (Technograft, product of Sumitomo Electric Industries,
Ltd.) 4 mm across and 5 cm long and then air-dried.
Both ends of the thus-obtained antibacterial vascular prosthesis
were separately connected to a silicone tube, and a PBS solution
(phosphate buffered-saline solution) was caused to flow at a rate
of 10 ml/min through the bore of the tube by a peristaltic pump.
At the same time, only the part of the vascular prosthesis was immersed
in the same PBS solution as described above in a beaker to determine
whether ofloxacin was dissolved out of the inner surface and outer
surface of the vascular prosthesis by the measurement of absorbance
at 280 nm of the PBS solution. As a result, no dissolving-out of
ofloxacin from the inner surface of the vascular prosthesis was
detected. As illustrated in FIG. 1 however, ofloxacin was gradually
being released from the outer surface of the vascular prosthesis
even after 48 hours.
The antibacterial activity against Escherichia coli (JM109) of
the antibacterial vascular prosthesis obtained above was evaluated.
On an agar LB medium (1% bactotryptone, 0.5% yeast extract, 0.5%
common salt, 1.5% agar) on a plate 10 cm across, were spread 10.sup.4
cells of Escherichia coli. The antibacterial vascular prosthesis
1 cm long was left at rest in the center of the medium, and the
cells were then cultured at 37.degree. C. for 18 hours. As a result,
no proliferation of Escherichia coli was observed within a radius
of 22 mm from the antibacterial vascular prosthesis. It was hence
confirmed that the antibacterial vascular prosthesis according to
the present invention has excellent antibacterial activity.
EXAMPLE 2
A tube combined with ofloxacin and polylactic acid, which had been
produced in the same manner as in Example 1 was wound 75 mm in
length on a stretched PTFE vascular prosthesis (Technograft) 4 mm
across and 5 cm long. The thus-obtained composite vascular prosthesis
was implanted under the back skin of a rabbit (New Zealand White,
male). After a week, the back was incised to take the prosthesis
sample out of the back. The sample was evaluated in the antibacterial
activity against Escherichia coli (JM109) in the same manner as
in Example 1. As a result, no proliferation of Escherichia coli
was observed within a radius of 17 mm from the sample. It was hence
confirmed that the antibacterial vascular prosthesis according to
the present invention has excellent antibacterial activity even
in the living body. |