DETECTING INCIPIENT WOUND INFECTION BY

EMPLOYING INFECTION MARKERS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit under 35 U.S.C. § 119(e) to U.S. provisional application serial No. 61/774,529, filed March 7, 2013, the contents of which are

incorporated here by reference in their entirety.

FIELD OF THE INVENTION

[0002] This invention generally relates to methods, preferably non-invasive methods, and devices, suitable for real time detection of incipient wound infection. Preferably, the methods comprise detection of markers that appear or disappear in the presence of infected wound exudate.

STATE OF THE ART

[0003] Wounds carry an inherent risk of bacterial and microorganism based infections. Such infection of wounds can lead to serious iilness, and even death, if the infection is unnoticed and untreated for even a relatively short period of time. Often, such infection is first detected by the presence of inflamed red skin around a wound site. Visualization of the wound by skin redness is often at a point where the infection has significantly progressed within the diseased patient

[0004 j Examples of such wounds are those resulting from abrasions, burns, surgical incisions, injection sites, and the like and those generated by use of central venous catheters, cannulas, and related medical devices (hereafter "catheters") which are inserted and maintained through the skin, or wounds.

[0005] For example, catheter insertion into the body can cause serious complications. Specifically, catheter related bloodstream infection (CR-BSI) is a serious and potentially life- threatening complication when catheter insertion sites into blood vessel lumen become infected with bacterial microorganisms. Conventional state of the art care now requires that these insertion sites be covered with a wound dressing as a preventive measure against such infections. |θθθ&| The use of a wound covering (sometimes referred to as a "dressing" or "wound dressing") in conjunction with a wound is conventional but does not entirely obviate the underlying infection risk. Such wound dressings are typically placed proximate to wound site and contact exudate exuding from that site.

(0007] in hospital settings, infections caused by antibiotic resistant bacteria such as Staphylococcus is a major concern and a cause of morbidity, Therefore, a need exists for methods and medical devices and wound coverings for the detection of bacterial growth contamination in or about a wound that can readily detect and indicate the presence of microorganisms well before the infection has progressed to the point that it manifests itself by skin redness.

SUMMARY OF THE INVENTION fOO08J Provided herein are methods, preferably non-invasive methods, for detecting incipient wound infection by detecting the presence, absence, and/or the levels of a signal generated through reaction with an infected area, tissue, or exudate. In one embodiment, the method entails contacting the wound with a dressing comprising an agent that reacts with an infected tissue or exudate to generate a detectable signal, wherein the presence of the signal indicates incipient infection. The signal, in some aspects, is the increase or decrease of a visual sign or indicator such as a color, and the reaction with the infected tissue or exudate can cause such increase or decrease in the visual sign or indicator.

[Θ009] A dressing can be a wound cover such as, for example, a bandage. In one embodiment, the level of the signal can correlate positively or negatively with the level of infection, for example, by showing an increase or decrease of a visual sign or indicator. For example, in one embodiment, the signal can appear as the wound dressing contacts an infected area or the exudate from a region of body; in such circumstances, the level of the signal can increase as the level of infection in the area or exudate increases. In another embodiment, the signal can disappear or decrease as the wound dressing contacts an infected area or exudate from a region of the body; in such circumstances, the level of the signal can decrease as the level of infection in the area or exudate increases. In certain embodiments, two or more visual signs or indicators can be detected, for example, simultaneously wherein one sign appears and the other starts to disappear with increasing le vel of infection in the wound tissue or exudate.

SUBSTITUTE SHEET RULE 26 [001 Θ] in a preferred embodiment, the sign or indicator is generated by the reaction of art agent in the wound dressing that reacts with a product or a byproduct of an infectious microorganism. For example, a compound may appear or provide a visual signal when an agent in the wound dressing reacts with a product or a byproduct of an infectious microorganism In another preferred embodiment, the sign or indicator may decrease due to the reaction of an agent in the wound dressing with a product or a byproduct of an infectious microorganism, For example, in another preferred embodiment, the decrease of the sign can be caused by a compound that disappears when the agent in the wound dressing reacts with a product or a byproduct of an infectious microorganism.

[ΘΘ11 J In preferred embodiments, the sign or indicator may have unique bond stretching, absorption, and/or emission properties that are detected and/or measured by

infrared/ultraviolet absorption and/or emission spectroscopy. In some embodiments, the unique stretching, absorption, and/or emission properties, refer to stretching, absorption, and/or emission that are not present, are comparatively less present, or preferably not substantially present, in the wound tissue or exudate.

[0012] in one embodiment, the wound dressing, until in contacted with infected wound tissue or exudate, does not provide a visual signal, or does not contain or does not substantially contain a molecule or ail necessary reactants, that generates the sign or indicator. For example, in some embodiments, the wound dressing, when in contact with infected wound exudate, starts showing the signal. The appearance of such a sign or indicator indicates that the wound is infected arid/or has a developing infection,

[0013J in another embodiment, the wound dressing provides a visual signal or contains an agent that generates a sign sufficient for detection, for example when not in contact with an infected tissue, exudate or substance in those that will react with the agent, but when the wound dressing is contacted with infected wound tissue or exudate, mat sign starts to disappear. The disappearance of such a sign or indicator indicates that the wound is infected or is getting infected.

|0Θ14] Without being bound by theory, the pH of the wound exudate can lower, or the acidity of the exudate increases due to microbial infection. A number of chemical moieties present in the wound dressing, which contacts the infected exudate, can react with the acidic exudate to provide a new chemical moiety or reaction capable of generating a sign or indicator for detection. These reactions occurring on the wound dressing, for example, can provide for appearance and disappearance of markers, and of signals or indicators.

[ΘΘ15] in another aspect, provided herein is a method of detecting presence or absence of an incipient infection at a wound, the method comprising ascertaining the presence, absence, or the level of an endogenous marker included in an exudate of the wound, wherein the presence, absence, or the level of the marker is correlated with the incipient infection at the wound. A non limiting example of the endogenous marker in lactic acid,

DETAILED DESCRIPTION OF THE INVENTION

Definitions

[ΘΘ16] "Alky!" refers to monovalent saturated aliphatic hydrocarbyi groups having from 1 to 10 carbon atoms and, in some embodiments, from 1 to 6 carbon atoms. This term includes, by way of example, linear and branched hydrocarbyi groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-buryl, n-pentyl and neoperavL

[0017| "C _x »C _y " with respect to a group refers to that group having from x to y carbon atoms.

f 0018J "Heteroaikylene" refers to alkylene wherein 1 -8 carbon atoms, are replaced with a heteroatom, preferably, with one or more of-N(CGR')-, -S-, -8(0)-, -§(02)~, and -0-, where R' is CrQ, aikyi.

[0019] '"Alkoxy" refers to the group -O-alkyl, and includes, by way of example, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, t-butoxy, sec-butoxy, and n-pentoxy.

[0020] "Aryl" refers to an aromatic group of from 6 to 14 carbon atoms and no ring heteroaioms and having a single ring (e.g., phenyl) or multiple condensed (fused) rings (e.g., naphthyl or anthryl). For multiple ring systems, the term "Aryl" applies when the point of attachment is at an aromatic carbon atom (e.g., 5,6,7,8 tetrahydronaphthalene-2-yl is an aryl group as its point of attachment is at the 2-position of the aromatic phenyl ring). "Electron rich aryl" refers to an aryl that is substituted with 1-3 alkoxy and/or amino, aikylammo or dialkylamino group,

£0021] "Heteroaryl" refers to an aromatic group of from 5 to 14 ring atoms and 1-3 ring heteroatoms and having a single ring (e.g., fury!) or multiple condensed (fused) rings (e.g., benzofuryl). For multiple ring systems, the terra "heteroaryl" applies when the point of attachment is at an aromatic ring atom containing at least one heteroatom. "Electron rich heteroaryl" refers to an aryl that is substituted with 1-3 aikoxy and/or amino, alkyianiino or dialkylamino group.

The woimd dressing

[0022] The wound dressings employed in the present invention may include one or more polymeric materials. The polymeric material in a wound dressing that contacts the wound tissue or exudate can be chosen so as to contain functionaSizable groups such as -NH? or a mono or a dialkylatcd version thereof, -CO ₂ H, -OH, -SH, and such other functional groups well known to the skilled artisan. These groups can be f nctionaSized with reagents to provide the markers useful in this invention.

[0O23| In one embodiment, the polymeric material can comprise an agent, in some non- limiting aspects, the agent can be eovalently bound to the polymeric material. In some embodiments the agent can include a formula -X-L~R ^! wherein,

X is a bond, -0-, -C0 ₂ ~, -S-, or -NR' ¹ - wherein R ² is hydrogen or C Co aikyl,;

L is a bond or a linker containing 1-10 atoms selected f om carbon, oxygen, nitrogen, and sulfur atoms, which are appropriately substituted with hydrogen and/or aikyl groups; ' is a moiety that reacts with the acidic infected exudate to cause an unique signal to appear or disappear.

[0024] In another embodiment, R ^! is a moiety that reacts under mild acidic conditions, preferable at pH >3, more preferably at pH >4, and yet more preferably at pH>5. In any of these embodiments, R ^! has the formula:

wherein R ³ is hydrogen or Cj-Ce aikyl;

each R ³ independently is C ₆ -Cio aryl, preferably an electron rich C ₆ -C ₁₀ aryl, C2-C10 heteroaryl, preferably an electron rich Cj-Cio heteroaryl, or Cj-Ce aikyl;

R ⁴ is hydrogen, Cj-Ce aikyl, Cs-Cio aryl, preferably an electron rich Ce-Cio aryl, C2-C10 heteroaryl, preferably an electron rich C2- 0 heteroaryl,; R ⁵ Is C -Cso aryl, preferably an electron rich Os-Cio aryl, C2-C10 heteroaryl, preferably an electron rich C2-C10 heteroaryl;

R ⁶ is hydrogen, C _r C ₆ alkyl, Cg-Cio aryl, preferably an electron rich Q-Cto aryl, C ₂ -Cio heteroaryl, preferably an electron rich C2-C10 heteroaryl;

R ⁷ is -OR ⁸ , wherein ^s is hydrogen or - alkyl; each R ⁹ independently is election rich Ce-Cio aryl, an electron rich C ₂ -Cio heteroaryl, or C ₆ alkyl;

R ⁱ⁰ is hydrogen, Ci-Ce alkyl, or is --OR ⁹ ,

[0025] Certain non-limiting examples of visual signs appearing and/or disappearing from a wound dressing when the wound cover contacts a wound tissue or exudate (e.g., an acidic wound exudate) can be generated by chemicals, including the non-limiting examples schematically shown below:

; new UV/visib!e carbamate C=0 absorption/erni ssi on signal IR stretch disappears

inline related signals new UV /visible/ IR.

disappear; ketone related absorption emission signals signals appear

imine related signals

disappear; ketone related

Signals appear

new C-0 stretching/absorption

si gnais appear

[0Θ26] The compounds of this invention are synthesized following art recognized methods with the appropriate substitution of commercially available reagents as needed. Other compounds are synthesized following modifications of the methods illustrated herein, and those known, based on this disclosure, protecting groups useful for synthesizing the

compounds of this inven tion, and metliods for protection and deprotection employed herein, are found in standard reference works such as Greene and Wilts, Protective Groups in Organic Synthesis., 2d Ed., 1991 , John Wiley & Sons, and McOmie Protective Groups in Organic Chemistry, 1 75, Plenum Press.

10027 j in another embodiment, this disclosure provides a wound dressing comprising the polymeric material disclosed herein. In another embodiment, this disclosure provides a method of detecting incipient infection in a wound comprising covering the wound at least partly with a wound dressing provided herein, such that the wound dressing contacts the wound tissue and-'or exudate, and observing the appearance and/or disappearance of a visual sign or indicator to detect the presence of an infection, for example, an incipient infection. In the absence of change or substantial change of the visual sign, upon contacting the wound tissue or exudate, the method indicates that the wound is not infected or not substantially infected to require any anti-infective treatment.

[0028| in certain aspects of this disclosure provided are methods of detecting presence or absence of an incipient infection at a wound, the method comprising:

(i) contacting the wound with a wound dressing, the wound dressing permitting the accumulation therein of microbial byproducts or derivatives thereof;

(ii) measuring a change of an electromagnetic radiation absorption and/or emission band of wound dressing; and

(iii) correlating the change of the electromagnetic radiation absorption band with the presence or absence of the incipient infection.

[00291 As used herein, "derivative" of microbial byproducts include, without limitation, carbon dioxide and hydrolytic products thereof, lactic acid, and reaction products of carbon dioxide and such hydrolytic products with other compounds.

Determining absorption of electromagnetic radiation

[0030J Various methods for determining the absorption of the electromagnetic radiation by the byproduct or the derivative thereof or is well known to the skilled artisan, including, but not limited to, transmission and reflection based methods, which are applicable for determining IR and UV -visible absorption. Reflection based methods are suitable in some embodiments to determine the absorption from a wound cover, bandage, a wound dressing, and such other coatings covering a wound, The signal to noise ratio in such detection can be improved, as is well known to the skilled artisan, following Fourier Transform (FT)

g techniques, Nort-!iraitmg examples of reflection based FT-iR methods for determining absorption include attenuated total reflection, specular reflection, and diffuse reflection methods.

Uses

[ Θ3 If Compositions and devices of this invention can be used for wound caring, particularly at a wound site (scrap, cut, catheter insertion site, etc.) that has bodily fluids which are potentially subject to infection, in use, the composition or device of this invention, such as a wound cover, is affixed to the wound site, either with an external dressing, or via the adhesive surface on the device, or any other means. The composition or device keeps dirt and microorganisms out of the wound site. When infection occurs, the composition or device releases it antibiotic content which is used to treat infection.