Patent Description:
Humans are always in contact with a great many microorganisms in daily life. Particularly, the skin, which is always in contact with external environment, is more frequently exposed to a risk of infection with pathogenic microorganisms, compared to other tissues. A wide variety of microorganisms specific to the skin also reside on the skin and these microorganisms are collectively called as resident bacterial flora. Recently, the balance of resident bacterial flora and homeostasis of the skin has been aggressively studied and skin condition is found to deteriorate if a specific bacterium abnormally grows. If infection with a pathogenic microorganism occurs or if a specific bacterium abnormally grows, symptoms such as eczema, rough skin, swelling, blister and bleeding are observed, and itching and pain occur. Particularly when infectious skin roughness occurs at a site such as a face that can be seen well by others, QOL (quality of life) of the infected person markedly decreases. Recently, in specific skin diseases (e.g., atopic dermatitis), it is also suggested that abnormal growth of Staphylococcus aureus may be connected with exacerbation of clinical symptoms (see, Non Patent Literature <NUM>). Likewise, even in skin diseases that had not been known for its connection with infections, it has also been suggested that a risk such as bacterial transmission and abnormal growth is strongly connected with skin diseases.

Since a treatment for a skin infection differs between a bacterial infection and a viral infection, diagnosis for the causative microorganism is important. In the case of a bacterial infection, an antibiotics substance is principally administered for treatment. However, heavy use of the antibiotic substance has a risk for emerging a resistant bacterium. In the case of a viral infection, since existing antiviral drugs act only on limited viral species, the treatment is nothing more than a symptomatic therapy.

Because of this, an idea that attracts attention is preventing a bacterial infection by enhancing the barrier function of keratinocytes of the skin. It has been confirmed that Lactobacillus rhamnosus, Lactobacillus reuteri and Bifidobacterium longum have such an effect (see, Patent Literature <NUM>). Another idea that attracts attention is controlling skin bacterial flora by a specific organism co-present on the skin, thereby successfully promoting healthy conditions or inhibiting a disease. A lactic acid bacterium belonging to the genus lactobacillus is known to aggregate with Streptococcus pyogenes to effectively inhibit growth of Streptococcus pyogenes (see, Patent Literature <NUM>). For example, it is known that lactic acid bacteria, such as Lactobacillus delbrueckii (see Patent Literature <NUM>) and Lactobacillus buchneri (see Patent Literature <NUM>), bind to transient pathogenic skin bacteria and inhibit their growth, thereby suppressing bacterial infection. It is also known that Lactobacillus saniviri, Lactobacillus salivarius and Lactobacillus pentosus adhere to Staphylococcus aureus, Pseudomonas aeruginosa, pyogenic streptococcus to inhibit their growth (see Patent Literature <NUM>). However, all lactic acid bacteria exhibit their functions only by direct application onto the skin and it is actually impossible to always keep on applying these lactic acid bacteria on the whole body. For the reason, it has been desired to develop a method for more simply preventing/treating infections of the skin of the whole body. <CIT> refers to cosmetic use of microorganisms for the treatment of oily skin. <CIT> refers to pharmaceutical composition for preventing or treating inflammatory diseases, containing Lactococcus chungangensis. <CIT> refers to composition of lactic bacteria for use in the treatment of infections due to Propionibacterium acnes and in particular for acne. <CIT> refers to novel lactic acid bacteria and compositions containing them. <CIT> refers to novel acid tolerant Lactobacillus sakei Probio-<NUM> with the ability of growth suppression of pathogenic microorganisms and the anti-allergic effect. <CIT> refers to methods for preventing and/or treating infections, colonisations, or illnesses related to Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus pyogenes, Enterococcus faecium, Enterobacter cloacae, Proteus mirabilis, Bacteroides fragilis, Staphylococcus epidermidis, Propionibacterium acnes, Candida albicans and/or Malassezia furfur.

An object of the present invention is to provide a food composition and a pharmaceutical composition for preventing or ameliorating deterioration of skin condition caused by abnormal growth of a specific bacterium, by oral intake of the composition comprising a lactic acid bacterium.

The present inventors intensively studied on whether or not deterioration of skin condition caused by abnormal growth of a specific bacterium can be reduced by oral intake of a lactic acid bacterium.

As a result, the inventors have found that growth of Staphylococcus aureus, which was applied to the skin to infect the skin therewith, and deterioration of skin condition can be prevented by oral intake of a lactic acid bacterium. Based on the findings, the present invention has been achieved.

Also described as part of the disclosure are:.

Owing to the present invention, it is possible to provide a food composition and a pharmaceutical composition exerting a suppression effect on specific-bacterium abnormal growth in the skin, thereby preventing or ameliorating deterioration of skin condition, by oral intake of the lactic acid bacteriumLactococcus lactis JCM5805 stain.

Now, the present invention will be more specifically described below.

The present invention is a composition comprising the lactic acid bacterium Lactococcus lactis JCM5805 stain as an active ingredient, for use in a method of preventing or ameliorating deterioration of skin condition caused by abnormal growth of a specific bacterium.

Examples of the deterioration of skin condition caused by bacterial abnormal growth include rough skin, swelling and eczema, and further include a pathological condition of the skin exacerbated by infection with a pathogenic bacterium. The composition of the present invention can reduce or suppress exacerbation of a pathological change of the skin caused by infection of the skin with a pathogenic bacterium.

Examples of the pathological change of the skin include papule and erosion on the skin; scab, epidermal thickening, pustule, erosion/ulceration, intercellular edema and intracellular edema on the epidermis; and inflammatory cell infiltration on the dermis and subcutaneous tissue. The composition of the present invention reduces the severity of these pathological changes.

The skin condition caused by bacterial abnormal growth includes a skin disease developed by infection with a pathogenic bacterium. The skin disease developed by infection with a pathogenic bacterium is also referred to as a skin infection caused by a pathogenic bacterium. The skin disease is preferably a rough skin with inflammation or dermatitis.

More specifically, the present invention is a composition comprising the lactic acid bacterium Lactococcus lactis JCM5805 stain as an active ingredient, for use in a method of suppressing or preventing deterioration of skin condition caused by abnormal growth of a specific bacterium, i.e., a composition for use in a method of treating or preventing a skin infection with a pathogenic bacterium.

Examples of a bacterium causing abnormal growth or deterioration of skin condition include bacteria belonging to the genus staphylococcus such as Staphylococcus aureus and Staphylococcus epidermidis; bacteria belonging to the genus streptococcus such as group-A β-hemolytic streptococcus (Streptococcus pyogenes); bacteria belonging to the genus pseudomonas such as Pseudomonas aeruginosa; bacteria belonging to the genus corynebacterium such as fluorescent diphtheroid; and bacteria belonging to the genus propionibacterium such as Propionibacterium acnes. The composition of the present invention can be used for suppression, treatment or prevention of deterioration of skin condition caused by abnormal growth of these bacteria or transmission of them, and particularly preferably can be used for suppression, treatment or prevention of deterioration of skin condition caused by Staphylococcus aureus. However, the effect against deterioration of skin condition caused by abnormal growth of Staphylococcus aureus, is an example, and the effect is not limited to that against Staphylococcus aureus alone.

As the skin disease that can be treated or prevented by the composition of the present invention, the following diseases are mentioned. In the following, names of skin diseases and causative bacteria are shown; however, the following skin diseases are just examples, the skin diseases are not limited to these.

The symptom of atopic dermatitis is reported to worse by infection with Staphylococcus aureus, and the composition of the present invention can be used for reduction and amelioration of the symptom of atopic dermatitis.

Lactococcus lactis JCM5805 mentioned above can be obtained from the RIKEN BioResource Research Center (<NUM>-<NUM>-<NUM>, Koyadai, Tsukuba-shi, Ibaraki, Japan). An equivalent strain to Lactococcus lactis JCM5805 can be used. The equivalent strain herein refers to a strain derived from Lactococcus lactis JCM5805, an original strain from which Lactococcus lactis JCM5805 is derived or a descendant strain of the original strain. The equivalent strain is sometimes stored in another culture collection. Examples of the culture collection include, but are not limited to, the American Type Culture Collection (USA) and Culture Collection Room of Tokyo University of Agriculture, (<NUM>-<NUM>-<NUM> Sakuragaoka, Setagaya-ku, Tokyo, Japan).

The composition of the present invention contains a culture of the lactic acid bacterium Lactococcus lactis JCM5805 stain as mentioned above. The culture refers to living cells, dead cells, a disrupted material of living cells or dead cells, a lyophilizate of living cells or dead cells, a disrupted material of the lyophilizate, a culture solution and a culture-solution extract, and includes part of the lactic acid bacterial cell and the treated lactic acid bacterial cell. Further, DNA or RNA of the lactic acid bacterium is included in the culture of the lactic acid bacterium.

A lactic acid bacterium can be cultured by a method known in the art using a medium known well. As a medium, a commercially available medium for culturing a lactic acid bacterium such as MRS medium, GAM medium and LM17 medium, can be used. The medium, appropriately supplemented with additives such as an inorganic salt, a vitamin, an amino acid, an antibiotic substance and a serum, may be put in use. Culture may be carried out at <NUM> to <NUM> for several hours to several days.

After culture, lactic acid bacterial cells are collected by centrifugation or filtration. If dead lactic acid bacterial cells are used, the cells may be killed by, e.g., an autoclave.

Oral intake of the composition containing a lactic acid bacterium as mentioned above promotes and augments expression of an antibacterial gene (antimicrobial gene) in the skin to prevent or ameliorate deterioration of the skin condition caused by abnormal growth of a specific bacterium or infection with a pathogenic microorganism. A protein, which is an expression product of the antibacterial gene, binds to a bacterium and destroys the cell membrane to kill the bacterial cell. Examples of the antibacterial gene include β-defensin <NUM> (BD-<NUM>), β-defensin <NUM> (BD-<NUM>), β-defensin <NUM> (BD-<NUM>) and S100A8.

The lactic acid bacterium used as the active ingredient of the composition of the present invention, is exerting therapeutic or prophylactic effect on a skin infection of a living body even if it is orally taken. Such a lactic acid bacterium is highly resistant to gastric juice and intestinal fluid, in other words, has strong resistance to an acid and can be delivered live to the intestinal tract. Lactococcus lactis JCM5805 mentioned above can exert a therapeutic or prophylactic effect on a skin infection even if it is orally taken.

The composition of the present invention includes a food composition, more specifically, food and drink. The food composition can be used for preventing or ameliorating deterioration of the skin condition, such as rough skin, swelling and eczema, that is caused by abnormal growth of a specific bacterium or infection with a pathogenic microorganism mentioned above. Preventing or ameliorating deterioration of skin condition caused by abnormal growth of a specific bacterium or infection with a pathogenic microorganism refers to suppressing abnormal growth of a specific bacterium in the skin or infection with a pathogenic microorganism, thereby suppressing exacerbation of skin inflammation.

A lactic acid bacterium can be used as a food composition as it is or may be used as a component of a food and drink. The type of food and drink to be used is not particularly limited as long as an active ingredient, which is used for reducing or ameliorating the symptom of a skin disease caused by abnormal growth of a specific microorganism or infection with a pathogenic bacterium, is not inhibited. Examples of the food and drink that can be used include dairy products; beverages; seasonings; alcoholic beverages; agricultural and forestry processed products; confectioneries and breads; cereal flours and noodles; fishery processed products; livestock processed products; oils and fats, and processed products of these; prepared frozen foods; retort foods; instant foods; and food materials. Of them, fermented dairy products such as yogurt and cheese, lactic acid bacteria beverages or beverages such as soft drinks, non-alcoholic beverages and sports drinks, can be used. If a lactic acid bacterium is used in a fermented food and drink, lactic acid bacterial cells can be inactivated and added to a fermented food and drink in a requisite amount or can be used as a lactic acid bacterium starter to produce a fermented food and drink.

Examples of the food composition include dietary supplements and food additives.

Examples of the food and drink of the present invention include functional foods, health foods and drinks, specified health foods and drinks, nutritional function foods and drinks and health food and drink supplements. The specified health foods and drinks herein refer to foods and drinks that are allowed to display that they are taken as diets for special purpose for health reason and expected to attain the purpose for health reason. The functional foods are foods having functions that are supported by a scientific ground and displayed on its package under responsibility of a business operator (the display can be allowed by registering to the Consumer Affairs Agency).

A food composition containing a lactic acid bacterium may be orally taken for reducing or ameliorating the skin condition that was changed by abnormal growth of a specific microorganism or infection with a pathogenic bacterium. If the composition is orally taken in advance, it can suppress abnormal growth of a specific microorganism and infection of the skin with a pathogenic bacterium. Even if the skin is infected with a pathogenic microorganism, the food composition can suppress growth of the pathogenic bacterium. More specifically, the food composition can reduce and ameliorate the symptoms of a skin disease caused by abnormal growth of a specific microorganism or infection with a pathogenic bacterium and suppress exacerbation of a pathological change of the skin.

The composition of the present invention comprising the lactic acid bacterium Lactococcus lactis JCM5805 stain as an active ingredient for use in a method of treating or preventing a skin disease caused by infection with a pathogenic bacterium includes a pharmaceutical composition. The pharmaceutical composition can be used for treating or preventing the skin disease caused by infection with a pathogenic bacterium. The pharmaceutical composition can be used for reducing and ameliorating the symptoms of the skin disease caused by infection with a pathogenic bacterium and suppressing exacerbation of a pathological change of the skin caused by infection with a pathogenic bacterium.

The pharmaceutical composition may be referred to as a therapeutic or prophylactic agent for a skin disease caused by infection with a pathogenic bacterium, as an agent for reducing and ameliorating the symptoms of a skin disease caused by infection with a pathogenic bacterium or as an inhibitor of exacerbation of a pathological change of the skin caused by infection with a pathogenic bacterium.

Examples of the form of the pharmaceutical composition include, but are not particularly limited to, powder, granule, tablet and syrup. The pharmaceutical composition of the present invention is administered orally. The pharmaceutical composition may contain an excipient, a disintegrant, a binder, a lubricant and a colorant. Examples of the excipient include glucose, lactose, cornstarch and sorbitol. Examples of the disintegrant include starch, sodium alginate, gelatin powder, calcium carbonate, calcium citrate and dextrin. Examples of the binder include dimethylcellulose, polyvinyl alcohol, polyvinyl ether, methylcellulose, ethylcellulose, gum Arabic, gelatin, hydroxypropylcellulose and polyvinylpyrrolidone. Examples of the lubricant include talc, magnesium stearate, polyethylene glycol and hydrogenated vegetable oil.

The dosage amount can be appropriately determined depending on the age, body weight and gender of the patient to be administered, the disease and severity of the symptom. The dosage amount is administered once a day or separated into several portions and administered several times a day. A culture may be administered in an amount equivalent to <NUM> × <NUM><NUM> to <NUM> × <NUM><NUM> bacterial cells per time. Alternatively, <NUM> to <NUM>/time in terms of dry weight of lactic acid bacterial cells and preferably <NUM> to <NUM>/time may be administered.

The present invention encompasses the lactic acid bacterium Lactococcus lactis JCM5805 stain for use in a method of suppressing bacterial abnormal growth or preventing or ameliorating deterioration of skin condition caused by bacterial abnormal growth, by oral intake.

The present invention will be more specifically described by way of Examples; however, the present invention is not limited by these Examples.

Staphylococcus aureus cells used in the present invention were prepared by the method as shown below.

Staphylococcus aureus MX2 strain was obtained from the American Type Culture Collection (ATCC), which is a biological resources bank in USA. In each test, a nutrient broth medium (<NUM>) (manufactured by Eiken Chemical Co. ) was added in a test tube, and then, a frozen bacterial suspension (<NUM>µL) was thawed and inoculated to the medium. The medium was cultured in an isothermal shaking culture machine (manufactured by TAITEC CORPORATION) at <NUM> while shaking. After culture, the bacterial suspension was centrifugally separated (<NUM> rpm, <NUM> minutes) by a centrifuge and the supernatant was removed. To obtain an inoculum suspension stock, physiological saline (<NUM>) was added to the bacterial precipitate and stirred.

The inoculum suspension stock was diluted with physiological saline and the turbidity of the diluted suspension was visually controlled in accordance with the McFarland turbidimetric method so as to obtain a turbidity of <NUM>. An aliquot was taken from the bacterial suspension controlled to have McFarland <NUM> and diluted <NUM> fold with physiological saline to prepare an inoculum suspension.

The number of bacterial cells in the inoculum suspension was determined by taking an aliquot of the inoculum suspension, diluting it <NUM><NUM> or <NUM><NUM> fold with physiological saline, smearing the diluted suspension to an nutrient broth agar plate and culturing the medium in an incubator (MTR-<NUM>, SANYO Electric Co. ) set at <NUM> for <NUM> days, thereafter, counting the number of colonies by a pen-type colony counter, and calculating the number of living bacterial cells contained in the inoculum suspension (<NUM>) to obtain a bacterial concentration (cfu/mL).

The concentration of Staphylococcus aureus used in Example <NUM> was <NUM> × <NUM><NUM> cfu/mL and that in Example <NUM> was <NUM> × <NUM><NUM> cfu/mL.

Staphylococcus aureus was inoculated in the skin of mice allowed to orally take Lactococcus lactis JCM5805 and evaluation on the severity of pathological score, counting of the number of living Staphylococcus aureus cells, histopathological examination and determination of antibacterial genes expression were carried out. In this manner, the protective effect against bacterial infection was evaluated.

In the Example, the pathological score is sometimes called as a skin pathological severity or skin pathological score.

BALB/C mice (<NUM> weeks-old females, purchased from Japan SLC, Inc. ) were divided into two groups each constituted of <NUM> mice. One was a standard diet intake group (AIN-<NUM> diet manufactured by Oriental Yeast Co. The other was a Lactococcus lactis JCM5805 intake group, which was fed AIN93G, mixed with Lactococcus lactis JCM5805. The dosage amount of the lactic acid bacterium per day per mouse was set to be <NUM>. The day on which administration of the lactic acid bacterium was initiated was specified as Day <NUM>. On Day <NUM>, the back of each mouse was shaved by an electric razor, and applied hair removal cream (Epilat (R), Kracie Home Products Ltd. ) to set an infection area having about <NUM> squares, and then striped three times with a cloth adhesive tape under anesthesia with ketamine hydrochloride (intramuscular administration, <NUM>/kg, ketamine hydrochloride injection; animal KETALAR (R) <NUM> injection solution; Bayer Yakuhin, Ltd. On Day <NUM> after administration, the infection area was stripped again three times with a cloth adhesive tape under anesthesia with ketamine hydrochloride, and then, the inoculum suspension of Staphylococcus aureus was added dropwise by means of a micropipette in an amount of <NUM> (<NUM> × <NUM><NUM> cfu/head) per mouse.

On Day <NUM> corresponding to two days after Staphylococcus aureus inoculation suspension was inoculated, severity of pathological score of the infection area was evaluated. Individual mice were checked for papule and erosion of the infection area in accordance with the following <NUM> criteria: <NUM>: asymptomatic, <NUM>: mild, <NUM>: moderate, <NUM>: severe. The sum of evaluation scores on papule and erosion was used as a skin pathological score.

On Day <NUM>, mice each were dissected and the whole infection area and an ear were collected. The samples of the infection area in <NUM> mice per group were subjected to determination of the number of living cells in the skin and those in the rest <NUM> mice were used as histopathological examination. The ear samples of all mice were used for antibacterial-gene expression analysis by quantitative PCR.

The number of living cells were determined as follows. The skin of the infection area sample was cut into pieces and homogenized in <NUM> of physiological saline by means of a stirrer to obtain a skin-tissue suspension. An aliquot was taken from the skin-tissue suspension and diluted with physiological saline up to an optimal concentration to obtain a skin-tissue diluent. The skin-tissue diluent (<NUM>µL) was smeared onto a staphylococcus agar plate (manufactured by Eiken Chemical Co. ) by a bacteria spreader and cultured at <NUM> for <NUM> days. The number of colonies (cfu/head) contained in the whole infection area was calculated.

Histopathological examination was carried out by embedding the skin of the infection area sample in paraffin in accordance with a routine method and preparing HE (Hematoxylin-Eosin)-stained tissue preparations. The items examined were severities of scab, epidermal thickening, pustule, erosion/ulceration, intercellular edema and intracellular edema in the epidermis. In addition, the severities of inflammatory cell infiltration in the dermis and subcutaneous tissue were examined. Individual examination items were separately evaluated based on the <NUM> criteria: <NUM>: asymptomatic, <NUM>: mild, <NUM>: moderate, <NUM>: severe.

The ear samples each were cut into pieces by a Multi Beads Shocker, and then, suspended with TRIzol (manufactured by Life Technologies Corporation) and centrifuged. The aqueous layer was taken and isopropanol precipitation was carried out, and then, the precipitate was suspended in RNase-free water. In this manner, total RNA was extracted. RNA was purified by means of RNeasy Mini Kit (manufactured by QIAGEN). Using iScript cDNA Synthesis Kit (manufactured by BIO-RAD Laboratories, Inc. ), cDNA was synthesized from the total RNA (<NUM> ng). Using the cDNA as a template, Real-time PCR was carried out for analyzing the expression levels of S100A8 gene, β-defensin <NUM> gene, β-defensin <NUM> gene and β-defensin <NUM> gene (GAPDH gene as a reference). In the Real-time PCR analysis, SYBR Premix Ex Taq (manufactured by Takara Bio Inc. ) was used and primers having the sequences shown in Table <NUM> were used. As a thermal cycler, Roche Light Cycler (R) 480II was used. A cycle consisting of a holding step at <NUM> for <NUM> seconds, a reaction step at <NUM> for <NUM> seconds, a reaction step at <NUM> for <NUM> seconds and a reaction step at <NUM> for <NUM> seconds was repeated <NUM> times.

Skin pathological score and the number of living Staphylococcus aureus cells were analyzed by Mann-Whitney U-test; and antimicrobial gene expression in the ear was analyzed by Student's t-test. In this manner, significant difference between the Lactococcus lactis JCM5805 intake group and the standard diet intake group was analyzed.

As shown in <FIG>, it was found that the score on severity of the skin pathological score caused by skin infection with Staphylococcus aureus is significantly low in the Lactococcus lactis JCM5805 intake group compared to the standard diet intake group. In other words, it was demonstrated that Lactococcus lactis JCM5805 has a reduction effect against exacerbation of a pathological change of the skin caused by Staphylococcus aureus infection.

As shown in <FIG>, it was found that the number of Staphylococcus aureus cells contained in the infection area is significantly low in the Lactococcus lactis JCM5805 intake group compared to the standard diet intake group. In other words, it was demonstrated that Lactococcus lactis JCM5805 has a suppression effect against growth of Staphylococcus aureus in the skin.

As shown in Table <NUM>, average scores on all symptoms such as scab, epidermal thickening, pustule, intercellular edema and intracellular edema in the epidermis, and inflammatory cell infiltration in the dermis and subcutaneous tissue were low in the Lactococcus lactis JCM5805 intake group compared to the standard diet intake group. In other words, it was demonstrated that Lactococcus lactis JCM5805 has a suppression effect against exacerbation of a pathological change of the skin caused by Staphylococcus aureus infection.

As shown in <FIG>, the expression levels of antibacterial genes such as β-defensin <NUM> gene and β-defensin <NUM> gene in the ear, i.e., a site not infected with Staphylococcus aureus, were significantly high in the Lactococcus lactis JCM5805 intake group compared to the standard diet intake group. Also, a tendency of the expression levels of S100A8 gene and β-defensin <NUM> gene to increase was observed. In other words, it was demonstrated that Lactococcus lactis JCM5805 has an augmentation effect on expression of antibacterial genes in the skin.

From the results, it was estimated that intake of Lactococcus lactis JCM5805 augments the expression of antimicrobial genes in the skin to suppress growth of bacterial cells in the skin infected with Staphylococcus aureus, with the result that exacerbation of various pathological changes of the skin caused by the infection can be suppressed.

Staphylococcus aureus was inoculated in the skin of mice allowed to orally take Lactococcus lactis JCM5805 as shown in Example <NUM> and the severity of pathological score of the skin caused by infection was determined chronologically. In this manner, the protective effect against bacterial infection until the pathological change remitted was evaluated.

BALB/C mice (<NUM> weeks-old females, purchased from Japan SLC, Inc. ) were divided into two groups each constituted of <NUM> mice. One was a standard diet intake group (AIN-<NUM> diet). The other was a Lactococcus lactis JCM5805 intake group, which was fed AIN-<NUM>, mixed with Lactococcus lactis JCM5805. The dosage amount of the lactic acid bacterium, administration method thereof and method for inoculating Staphylococcus aureus were the same as in Example <NUM>, and the skin pathological score was evaluated from Day <NUM> to Day <NUM> after inoculation of Staphylococcus aureus.

In this Example, the skin pathological score may be sometimes referred to as a pathological-change score value or a pathological-change evaluation score.

After inoculation with Staphylococcus aureus suspension, individual mice were checked for papule and erosion of the infection area in accordance with the following <NUM> criteria: <NUM>: asymptomatic, <NUM>: mild, <NUM>: moderate, <NUM>: severe. The sum of evaluation scores on papule and erosion was used as a skin pathological score.

<FIG> shows the skin pathological scores of the skin infected with Staphylococcus aureus. It was found that the Lactococcus lactis JCM5805 intake group shows low pathological-change evaluation score values at all time points, compared to the standard diet intake group.

From the above, it was demonstrated that Lactococcus lactis JCM5805 has a suppression effect on exacerbation of a pathological change of the skin induced by skin infection with Staphylococcus aureus.

The antibacterial activity against Staphylococcus aureus of an extract from the skin of a mouse allowed to orally take Lactococcus lactis JCM5805 was compared to that of a mouse allowed to take a standard diet.

BALB/C mice (<NUM> weeks-old females, purchased from Charles River Laboratories Japan, Inc. ) were divided into two groups each constituted of <NUM> mice. One was a standard diet intake group (AIN-<NUM> diet). The other was a Lactococcus lactis JCM5805 intake group, which was fed AIN-<NUM> mixed with Lactococcus lactis JCM5805. The dosage amount of the lactic acid bacterium was <NUM> per mouse per day. The day on which administration of lactic acid bacterium was initiated was determined as Day <NUM>. On Day <NUM>, mice were dissected to obtain dorsal skin.

The dorsal skin was disrupted with a cell disruptor for multiple specimens, Multi-Beads Shocker (R) (manufactured by Yasui Kikai Corporation). To a disrupted sample, RIPA buffer (manufactured by Thermo Fisher Scientific) was added. The mixture was stirred at room temperature for <NUM> minutes and centrifuged as <NUM>,<NUM> × g for <NUM> minutes. The supernatant was recovered to obtain a skin extract. The concentration of a protein in the skin extract was measured by BCA Protein Quantitation kit (manufactured by Thermo Fisher Scientific).

The number of bacterial cells determined was analyzed by Student's t-test to obtain significant difference between the Lactococcus lactis JCM5805 intake group and the standard dietary intake group.

As shown in <FIG>, it was apparent that the number of bacterial cells of Staphylococcus aureus MW2 strain is significantly low in the Lactococcus lactis JCM5805 intake group compared to the standard diet intake group and demonstrated that the antibacterial effect is enhanced.

As shown in <FIG>, it was apparent that the number of bacterial cells of Staphylococcus epidermidis JCM12993 strain is significantly low in the Lactococcus lactis JCM5805 intake group compared to the standard diet intake group and demonstrated that the antibacterial effect is enhanced.

As shown in <FIG>, it was apparent that the number of cells of Propionibacterium acnes JCM6425 strain is significantly low in the Lactococcus lactis JCM5805 intake group compared to the standard diet intake group and demonstrated that the antibacterial effect is enhanced.

From the results, it was apparent that the expression of antimicrobial gene s of the skin was augmented by intake of Lactococcus lactis JCM5805, and antibacterial activities against not only Staphylococcus aureus but also representative skin resident bacteria that deteriorate the condition of skin if they are abnormally grown, are augmented.

Claim 1:
A composition comprising a lactic acid bacterium as an active ingredient for use in a method of preventing or ameliorating deterioration of skin condition caused by bacterial abnormal growth, or suppressing bacterial abnormal growth, by oral intake thereof, wherein the lactic acid bacterium is Lactococcus lactis JCM5805 strain.