AU2002230422A1

AU2002230422A1 - Compositions and methods for reducing the amount of salmonella in livestock

Info

Publication number: AU2002230422A1
Application number: AU2002230422A
Authority: AU
Inventors: Delbert L. Harris; Nkhyung Lee
Original assignee: University of Iowa Research Foundation UIRF; Iowa State University Research Foundation ISURF
Current assignee: Iowa State University Research Foundation ISURF
Priority date: 2000-11-13
Filing date: 2001-11-08
Publication date: 2002-05-21
Also published as: EP1341496A2; DE01990656T1; US6656463B2; CA2428370A1; US20020127207A1; MXPA03004182A; WO2002038104A3; WO2002038104A2; EP1341496A4

Description

COMPOSITIONS AND METHODS FOR REDUCING THE AMOUNT OF

SALMONELLA IN LIVESTOCK

[0001] This application claims priority to U.S. Provisional Patent

Application No. 60/246,972 filed on November 13, 2000 which is hereby incorporated by reference in its entirety.

[0002] The United States Government may have certain rights in this invention pursuant to Grant Number 453-40-30 from the United States Department of Agriculture.

BACKGROUND OF THE INVENTION

[0003] Enteric bacteria such as Salmonella, and Escherichia coli can cause food-borne illness in humans due to ingestion of contaminated food products. The economic and health consequences of contaminated livestock increase the importance of finding an inexpensive yet effective method of reducing or eliixiinating food-borne illness. Concern regarding the overuse of antibiotics has lead to a search for alternative mechanisms to combat livestock-related infection.

[0004] Bacteria resistant to antibiotics are a threat to human and animal health. New classes of antibiotics have not been discovered in the past 30 years. Furthermore, antimicrobial usage in animals is being restricted in order to protect the public health. Concurrently, changes in social awareness and concerns regarding food safety have increased the need for reduced levels of Salmonella in pigs and other livestock.

[0005] Previous studies reported that the culture positive rate of

Salmonella in market weight pigs gradually increases from farm to lariage, and ultimately to slaughterhouse. The sources of Salmonella contarnination in pigs includes environments (transportation vehicles, holding areas, etc.), active Salmonella shedding pigs, and recurrent Salmonella shedding among carriers because of stress during transport or delivery. Healthy pigs become Salmonella culture positive in tissue samples within as few as three hours after infection resulting from exposure to Salmonella infected pigs. No matter what the sources of Salmonella infection into market weight pigs, the rapid dissemination of Salmonella in pigs prior to slaughter is an important risk factor in pork product contamination.

[0006] Bacteriophage resemble human and animal viruses in a number of ways. For example, viruses infect specific cell types and can cause extensive damage to the infected cells. In animals, this can lead to the production of diseases. Likewise, phages have specific bacterial targets and can cause extensive damage to the bacteria. Lytic bacteriophage are a particularly efficient lάUing machine for bacterial cells. Lytic bacteriophage initially contact their hosts through specific receptors in their tail followed by injection of their DNA into the host bacterial cell. Like a "Trojan Horse," once inside the cell they direct the production ofquantiti.es of progeny phage that are released when the bacterium is lysed and killed by the phage. Lytic phages continue to proliferate in an animal as long as bacteria are present to be infected by the phage.

[0007] Experimentally, phage have been shown to reduce diarrhea and the numbers of Escherichia coli in the intestine of piglets. Smith, H.W. and Huggins, M.B., Effectiveness in Treating Experimental Escherichia coli Diarrhea in Calves, Piglets and Lambs, Journal of General Microbiology 129:2659-75 (1983). Phages lytic for Salmonella typhimurium were found to reduce the levels of Salmonella in both the digestive tract and liver of day-old chicks. Berchieri et al., The Activity In The Chicken Alimentary Tract Of Bacteriophages Lytic For Salmonella typhimurium, Res. Microbiol., 142:541-549 (1991). Research publications and review articles regarding phage have identified various problems, misconceptions, and pitfalls associated with their use as therapeutics. Of particular concern is the selection of resistant bacteria through long-term use of bacteriophage treatment. Resistant bacteria may be a more significant health threat than the initial disease if antibiotics or other bacteriophage are not available to treat the resistant organisms.

[0008] Because the reduction of Salmonella in livestock prior to slaughter can reduce the prevalence of food-borne human salmonellosis, there has been much interest in developing pre-harvest reduction strategies against Salmonella. Despite many studies, an effective strategy to control Salmonella in livestock has not previously been found.

SUMMARY

[0009] This invention provides compositions comprising Felix 0-1 Phage

(FOl phage) in an acceptable carrier and methods of using the compositions to reduce the amount of Salmonella in livestock and meat products. The present inventors have found that the FOl phage significantly reduces Salmonella in livestock. One embodiment of the invention provides a composition for reducing the amount of Salmonella in a livestock animal comprising a Salmonella reducing effect amount of the FOl phage in an acceptable carrier.

[0010] Also provided herein are methods of reducing the amount of

Salmonella in a swine prior to shipment by adniinistering a composition containing FOl phage, in an acceptable carrier to swine from about 24 hours to less than about 3 hours prior to harvest of the swine, in an amount effective to reduce the amount of Salmonella in the swine.

[0011] Additional embodiments of the present invention will be set forth in part in the description that follows, and in part will be obvious from the description, or may be learned through the practice of the invention. The objects and advantages of the invention will be attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. DESCRIPTION OF THE DRAWINGS

[0012] Fig. 1 shows the extent of Salmonella infection in the tonsil and cecum of pigs 3 hours post infection with Salmonella typhimurium.

[0013] Fig. 2 shows the reduction in Salmonella in infected pigs following a single injection of FOl phage 3 hours post-infection.

[0014] Fig. 3 shows the reduction in Salmonella in infected pigs following treatment with FOl phage at 1, 3, 5, 7, and 9 hours post-infection.

[0015] Fig. 4 shows the reduction in Salmonella in infected pigs following intermittent treatment with FOl phage at 1, 2, and 3 hours post-infection.

[0016] Fig. 5 shows the reduction in Salmonella in infected pigs following intermittent treatment with FOl phage at 1 and 2 hours post-infection.

[0017] Fig. 6 shows the reduction of Salmonella in LB broth at 15 minutes, 1, 2,4, 6, 8, 10, 15, and 20 hours after FOl phage inoculation.

DETAILED DESCRIPTION OF THE INVENTION

[0018] Salmonella can cUsseminate into the body organs of livestock within a few hours after mfection. Livestock susceptible to Salmonella infection are at greatest risk when confined with other animals as they are moved from farm to lariage, and ultimately to the slaughterhouse. Thus, Salmonella-negzάve livestock may be infected through transport and holding in the lariage just prior to slaughter. Rapid dissemination of the Salmonella results in a greatly increased risk of contaminated meat products. A pre-harvest intervention strategy that uses FOl phage to reduce the rapid dissemination of Salmonella and, concomitantly, the potential for selection of resistant Salmonella strains in livestock prior to slaughter, reduces the prevalence of food- borne salmonellosis in humans via the ingestion of Salmonella contaminated products.

[0019] One embodiment of the invention provides a composition comprising a Salmonella reducing effective amount of FOl phage (available from, for example, the Salmonella Genetic Stock Center, University of Calgary, Alberta, Canada) in an acceptable carrier (e.g., physiological saline, water, animal feed, Luria broth ("LB")). FOl phage is a well characterized Salmonella specific bacteriophage previously used to characterize and type Salmonella strains. See e.g. Macphee et al., Journal of General Microbiology 1975, 87:1-10; Lindberg, A.A., Journal of General Microbiology 1967, 8:225-233.

[0020] Compositions containing FOl phage can be provided in a variety of dosage forms (e.g., oral, injectable, aerosol, rectal). Oral dosage forms include FOl phage formulated in, for example, animal feed, water, bacterial media (e.g., LB), and saline. Injectable dosage forms include FOl phage formulated in, for example, saline and water. Aerosol dosage forms include FOl phage formulated in water or saline and combined under pressure with a suitable propellant. Rectal dosage forms include FOl phage combined in a suppository formulation. Other dosage forms include tablets and capsules for oral adrninistration and creams, lotions, gels, and transdermal patches for topical adrninistration.

[0021] The FOl phage has lytic activity against at least twelve strains of

Salmonella as shown in Table 2.

++: complete confluent lysis +: incomplete confluent lysis -: no effect

[0022] Salmonella serotypes most frequently isolated from swine with clinical signs of infection include S. derby, S. choleraesuis kunzendorf, S. typhimurium, S. heidelberg, S. choleraesuis, S. anatum, S. mbandaka, and S. schwarzengrund. However, Salmonella typhimurium is the major serotype causing foodborne illness and has a wide host range, including humans. The broad host range of the FOl phage makes it especially well suited for use against various serotypes of Salmonella, cluding Salmonella typhimurium, in a pre-harvest intervention strategy. Use of a phage having a broad host range to Salmonella, as a short term, pre-harvest intervention strategy minimizes the risk of developing Salmonella resistant bacteria. Development of Salmonella strains resistant to phage therapy is associated with previous attempts at long term phage therapy.

[0023] FOl phage can be propogated using a host strain of Salmonella

(e.g., Salmonella typhimurium). For example, S. typhimurium χ4232, a nalidixic acid resistant strain, can be used to infect swine and to propogate phages. Salmonella inoculum can be prepared by any suitable method, such as growing the bacteria in LB broth. Phage stock or lysate can also be prepared by any suitable method, such as using GCA (glycerol- Casamino acids) medium supplemented with calcium chloride, and filtered prior to use using, for example, a 0.45 micrometer filter. Phage particles can be further purified, if desired, by techniques such as precipitation with polyethylene glycol, centtifugation, and dialysis. [0024] An exemplary Salmonella reducing effective amount of FOl phage is about 10⁶ to about 10¹² plaque forming units (PFU) of FOl phage. In another embodiment of the invention, at least about 10⁹ to 10ⁿ total PFU of FOl phage are provided in a carrier. In yet another embodiment of the invention, about 10¹⁰PFU of FOl phage are provided in an acceptable carrier. Alternatively, phage can be lyophilized and dissolved in an acceptable carrier just prior to administration. Adπiinistration of FOl phage in a Salmonella reducing amount to a livestock animal prior to harvest will typically reduce the amount of Salmonella in the infected animal by at least about 10 to about 100,000 fold.

[0025] FOl phage can be administered to a livestock animal by a variety of routes, including, for example, oral, inhalation, nasal, intramuscular, intraperitoneal, intrathecal, vaginal, rectal, topical, and combinations thereof. FOl phage can be administered orally to an animal, for example, in a volume of about 1 to about 100 ml of a carrier. In one embodiment of the invention, phage lysate or stock can be used to replace water available for^' consumption by animals prior to leaving the farm, during transport, or during holding. FOl phage lysate can be provided in amounts up to about six gallons in a day depending on the size of the animal. The concentration of phage in the carrier can be adjusted to any desired level. Alternatively, FOl phage can be administered by injection in a volume of about 5 to about 50 ml of a carrier. In another embodiment of the invention, FOl phage is combined with animal feed and administered orally to an animal. The FOl phage animal feed formulation can be provided to animals at selected time intervals (as discussed below) and then replaced with regular animal feed as desired. FOl phage can also be combined with water and administered orally to an animal. Alternatively, FOl phage in an acceptable carrier, such as water or saline, may be instilled into the nose of the animal with, for example, a syringe with a nasal spray tip in a suitable volume (e.g., about 1 ml). FOl phage can also be administered in an acceptable carrier via a stomach tube in any suitable volume (e.g., about 50 ml). In yet another alternative, FOl phage can be formulated in an aerosol by combining the phage in a carrier, such as water or saline, or in a propellant (e.g., trichloromonofluoromet-hane, dicUorodifluoromet-hane, and oleic acid). Aerosol formulations of the FOl phage can administered in the nasal passage or oral cavity of the animal. FOl phage can also be administered rectally by providing the phage in a suppository.

[0026] In one embodiment of the invention, intramuscular injection of

FOl phage selectively reduces the level and dissen ination of Salmonella in body organs and tissue. In another embodiment of the invention, oral aclministration of FOl phage selectively reduces the level and dissemination of Salmonella in the gastrointestinal tract of an animal. Alternatively, FOl phage is administered by both oral and intramuscular injection routes of adrninistration to reduce the level and dissemination of Salmonella in organ systems and within the gasttomtestinal tract of an animal.

[0027] Healthy swine are exposed and susceptible to Salmonella infection when housed or transported with infected animals. Thus, intervention with FOl phage treatment following exposure to Salmonella and prior to harvest is effective in reducing the amount of Salmonella in an animal. Alternatively, treatment of animals prior to harvest will limit the risk of contamination of healthy swine by infected swine in the event the animals were exposed to Salmonella when housed with other animals or transported to the slaughterhouse.

[0028] Compositions according to the invention containing FOl phage in an acceptable carrier are preferably aciministered to livestock as a short-term treatment. "Short-term" refers to less than about 24 hours to about 12 hours prior to harvest, alternatively less than about 12 to about 6 hours prior to harvest or less than about 3 hours prior to harvest. In contrast to prior use of phage therapy, short term treatment minimizes the risk of developing resistant Salmonella strains.

[0029] FOl phage can be administered to animals in single or multiple doses. In one embodiment of the invention, FOl is administered to an animal in a single dose prior to harvest. Alternatively, FOl phage can be administered in 2 to 5 doses prior to harvest and after exposure of the animal to Salmonella. Each dose may contain, for example, about 10⁶ to about 10¹² PFU of FOl phage. In another embodiment, a dose contains about 10¹⁰ PFU of FOl phage. When administered in multiple doses, several routes of adniinistration may be used or combined. For example, phage can be administered in a first dose via injection followed by subsequent oral administration of the phage. Alternatively, FOl phage can be orally administered in a first dose followed by a second dose administered by injection. Any desired combination of routes of acuninistration may be used to optimize adniinistration of the phage and may be determined by one of ordinary skill given the teachings herein.

[0030] In another embodiment of the invention, the FOl phage is adniinistered to animals prior to harvest and after exposure to Salmonella. As discussed above, exposure and potential exposure to Salmonella can occur at several stages of an animal's life. For example, livestock animals are exposed to Salmonella when they are housed with infected animals, ingest contaminated food or water, during transport with infected animals, or by intentional or accidental infection with Salmonella. The terms "exposed to Salmonella" and "exposure to Salmonella" also refer to animals that may have been exposed to Salmonella whether or not they actually have been exposed to Salmonella. For example, co-mingling animals potentially exposes an animal to Salmonella since animals in the co-mingled group may be infected by or carry Salmonella.

[0031] In yet another embodiment of the invention, phage are administered to an animal prior to harvest in a single dose at about 3 hours following exposure to Salmonella. In another embodiment of the invention, FOl phage are adniinistered prior to harvest and at about hourly intervals for up to about nine hours following exposure to Salmonella. Alternatively, FOl phage are administered to an animal prior to harvest at about 3, 5, 7, and 9 hours following exposure to Salmonella. FOl phage can also be adniinistered to an animal about an hour after exposure to Salmonella and subsequently administered at about 2 and 3 hours after exposure to Salmonella. Administering a composition comprising the FOl phage and an acceptable carrier can reduce the measurable Salmonella CFU in phage-treated livestock ariimals by about 10 to about 100,000 fold compared to untreated animals.

[0032] The invention also provides methods of reducing dissemination of

Salmonella in livestock animals by administering a composition comprising a Salmonella reducing effective amount of FOl phage to a livestock animal after transferring livestock animals to a slaughterhouse but prior to harvest. Alternatively, FOl phage is adniinistered to livestock animals prior to or during transfer of the animal to the slaughterhouse. The term "dissemination" refers to, for example, transmission of Salmonella from one animal to another or within a single animal.

[0033] Methods of harvesting livestock animals are also provided. The term "harvest" refers to slaughtering a livestock animal by methods accepted in the food processing industry. FOl phage is administering to livestock animals prior to harvest in an amount effective to reduce the amount of Salmonella in livestock animals followed by harvest of the animal. Alternatively, FOl phage in an acceptable carrier is administered to livestock animals at least three hours prior to harvest.

[0034] In another embodiment of the invention, FOl phage in an acceptable carrier is applied to animal meat post-harvest in order to reduce the level of Salmonella in meat products. The term "meat products" refers to any food product made from an animal (e.g., beef, poultry, lamb, pork). Acceptable carriers for the FOl phage include water, saline, and LB broth. FOl phage can be applied to the surface of the meat product to, for example, prevent contamination or to reduce the number of bacteria on the surface. Phage can be applied by, for example, spraying the surface of or soaking the meat product in a solution containing at least about 10⁶ PFU of FOl phage. FOl phage can be applied to meat products at any time following harvest (e.g., processing, curing, cutting, shipping, packaging). FOl phage solution can also be provided in a consumer product to treat surfaces and food products to reduce or prevent contamination by Salmonella. FOl phage solution can be provided in a pump or aerosol spray bottle to facilitate use of the product.

[0035] It is to be understood that the application of the teachings of the present invention to a specific problem or environment will be within the capabilities of one having ordinary skill in the art in light of the teachings contained herein. Examples of the products of the present invention and processes for their use appear in the following examples.

EXAMPLE 1

[0036] A streak of Salmonella from frozen stock was inoculated into 10 ml of TSB and incubated overnight at 37 C. After incubation, 250 microliters of innoculum was transferred to 25 ml of TSB and incubated in the shaking incubator at 37° C until the number of Salmonella in the culture was estimated to contain 10⁸ colony forming units per ml. On the day of inoculation, pigs were withheld from feed until inoculation with either diluent or Salmonella inoculum. Pigs were manually restrained for the inoculation procedure. One ml of Salmonella inoculum or u-ninoculated TSB was instilled into the nose of the pig with a syringe and teflon nasal spray tip.

[0037] Tissue samples were taken from animals harvested at designated time points. The tissue samples were homogenized with a tissue grinder diluted by 10 -fold in phosphate buffered saline. 100 μl of each diluted tissue sample was spread on an XLD plate containing 50 μg/ml of nalidixic acid. After incubation overnight, the numbers of Salmonella in the tissue samples were determined by the direct culture method. EXAMPLE 2

[0038] Three week-old pigs were purchased from a Salmonella-free farm.

During the one week of acclimatization at the animal facility in Iowa State University, pigs were screened for indigenous Salmonella. Salmonella-free pigs were evaluated to deterrnine whether Salmonella rapidly disseminated after challenge with Salmonella. Pigs were intranasally challenged with S. typhimurium in a concentration of 10⁸ CFU (Group 1) and 10^s CFU (Group 2) in LB broth. Group 3 was a control group receiving only the carrier. Three hours post challenge, tonsil, liver, spleen, lung, ileocecal lymph node, and cecum contents samples were taken from sacrificed pigs and evaluated. As shown in Table 1, Salmonella rapidly disseminate to a variety of animal tissues mcluding tonsil, fiver, spleen, ICLN, and cecum, within three hours post infection with S. typhimurium at 10⁸ CFU but not as rapidly at 10⁵ CFU (Table 1). The data indicate that Salmonella infection in healthy market weight pigs may occur during the period from loading at the farm, transportation, holding in the lariage, and at the slaughterhouse prior to slaughter. In another experiment, five pigs were intranasally challenged with 1 X 10¹⁰ CFU of Salmonella. When the infected pigs were sacrificed three hours post-infection, the tonsil and cecum contents had approximately 1 X 10⁵ CFU and 1 X 10⁷ CFU of Salmonella respectively, as shown Figure 1.

Table 1. Culture positive of S. typhimurium in the tissues in pigs three hours post challenge with 10⁸, 10^s CFU of S. typhimurium intranasally (n=3)

Challenge dose blood tonsi liver spleen lung ICLN cecu feces 1 m lxl0⁸ CFU 0/3 2/3 2/3 2/3 0/3 2/3 3/3 1/3 lxl 0⁵ CFU 0/3 3/3 0/3 0/3 0/3 1/3 2/3 0/3 Control 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3 EXAMPLE 3

[0039] Salmonella-specific lytic Felix 0-1 phage (Salmonella Genetic Stock

Center, University of Calgary, Canada) were assessed for lytic activity against various Salmonella serotypes. Phage stock was prepared by GCA medium supplemented with CaCl₂, filtered (pore size 0.45um) and stored at 4°C until used. The lytic activity of the FOl phage was assessed using the spot test on the Salmonella serotypes listed in Table 2. Briefly, one drop of phage (lxl0⁸PFU/ml) lysate was dropped on the lawn grown Salmonella spp on TSA agar plates. After culture at 37° C overnight, the spot was observed for lytic activity (Table 2). As shown in Table 2, FOl phage has lytic activity against a wide variety of Salmonella serotypes.

[0040] A phage pool containing 26 isolated phages was used to determine if a phage pool would reduce Salmonella levels in Salmonella infected pigs. Phages were isolated from swine farms, and a human waste facility by enrichment method using S. typhimurium χ4232 as a target strain (Adams, M.H. 1959. Bacteriophages. Interscience Publishers, New York). Each phage stock was prepared by GCA medium supplemented with CaCl₂. Phage lysate was filtered (pore size 0.45 μm) and stored at 4°C until used. The isolated 26 phages were pooled together in the concentration of 10⁹ PFU.

[0041] Pigs were assigned into four groups (five animals per group): phage untreated positive control and three groups where each was treated with phage cocktail by a different route of administration: intramuscular treatment (IM), intraperitoneal treatment (IP), and oral treatment (Oral). Pigs in all groups were intranasally challenged with S. typhimurium at lxl 0⁸ CFU. Eighteen hours post challenge, pigs in all phage treatment groups received the phage cocktail consisting of 26 isolated phage in the concentration of 1.2x10⁹ PFU via IP, IM and oral routes, respectively. Twenty-four hours post phage treatment, two ariimals in each group were sacrificed.^' The remaining three ariimals were then sacrificed at 48 hours post phage treatment. Tonsil, mesenteric lymph node (MLN), ileum content, cecal content, blood, fiver, lung, and spleen samples were taken. The level of Salmonella in the samples was quantitated by direct culture on XLD (Salmonella selective) agar plates with 50 ug/ml of nalidixic acid. As shown in Tables 3 and 4, treatment with the pool of 26 isolated phages was not effective in reducing or preventing cfissemination of Salmonella.

Table 3. The population of S. typhimurium in tissues samples at 24 hours after phage pool (lxlO¹⁰ PFU) treatment into the pigs challenged with S. typhimurium (5xl0⁸ CFU) before phage treatment. Phage pool consisted of 26 isolated phages. The numbers indicate the number of S. t himurium er ram of sam les.

<10²: minimum limit to detect the number of bacteria in the samples.

*: Post inoculation with phage pool

*: Phage treatment showed the partial effect dependent on the adniinistration route of phage pool

Table 4. The population of S. typhimurium in tissues samples at 48 hours after phage pool (lxlO¹⁰ PFU) treatment in the pigs challenged with S. typhimurium (5xl0⁸ CFU). The Phage pool consisted of 26 isolated phages. The numbers indicate the number of S.

<10²: minimum limit to detect the number of bacteria in the samples. * Post inoculation with phage pool EXAMPLE 4

[0042] Five three week-old pigs each were assigned to a Salmonella positive control group and a phage treatment group. Pigs were intranasally challenged with 5x10⁸ CFU S. typhimurium. Pigs in the phage treatment group received 10 ml of 2x10¹⁰ PFU of Felix 0-1 phage via oral and IM routes of administration at three hours post infection. The pigs in the Salmonella positive control received an equivalent volume of carrier vial oral and IM routes of administration three hours post infection. At nine hours post infection with Salmonella, all pigs in both groups were sacrificed and tissue samples were removed for analysis. The level of Salmonella in tissue samples was quantitatively enumerated by direct culture method on XLD agar plate with 50ug/ml of nahdixic acid.

[0043] With phage treatment, the level of Salmonella in tonsil was significantly reduced by about 100,000 fold, the level of Salmonella in ICLN and feces was reduced by 10 fold, while the level of Salmonella in the cecum was reduce by about 100 fold (Table 5 and Figure 2). Thus, a composition comprising FOl phage is effective for use in a pre-harvest intervention strategy to reduce the amount of Salmonella in livestock animals such as swine. In addition, the use of other active agents including probiotics, cytokines, antibiotics and other phage may further reduce Salmonella in livestock

Table 5. The effect of Felix 0-1 phage administration (10¹⁰ PFU) three hours post phage treatment in pigs challenged with S. typhimurium at 5xl0⁸ CFU. The number of S. t himurium er ram of sam les was counted b direct s read method.

< 10²: It is the minimum limit to detect the number of bacteria by direct spread. *: Significant level by t-test is P<0.001 EXAMPLE 5

[0044] Five three-week old pigs each were assigned to a Salmonella positive control group and a phage treatment group. The pigs in each groups were intranasally challenged with 5 X 10⁹ CFU of Salmonella. One hour post-challenge, pigs in the phage treatment group were adniinistered 6 mis of FOl phage at a concentration of 1.5 X 10¹⁰ PFU/ml via intramuscular shot, and 20 mis of FOl phage at 1.5 X 10¹⁰ PFU/ml orally. The pigs were subsequently administered 15 ml of FOl phage at a concentration of 1.5 X 10¹⁰ PFU/ml orally at 3, 5, 7, and 9 hours post infection. The pigs in the control group received an equivalent volume of carrier in the volumes ^"and at the time intervals indicated above for the phage treatment group. The level of Salmonella in tonsil was reduced by about 100 fold, while the level of Salmonella in colon, cecum, and rectum was reduced by about 10 fold (Figure 3).

EXAMPLE 6

[0045] Figure 4 shows the Salmonella reduction in pigs following three post-infection treatments with FOl phage. Five pigs each were assigned to a control group and a phage treatment group and intranasally challenged with 5 X 10⁹ CFU of Salmonella. One hour post-challenge, pigs were adniinistered 1.5 X 10¹⁰ PFU/ml of FOl phage in 6 mis of carrier via intramuscular shot and orally acfnύnistered 1.5 X 10¹⁰ PFU/ml of FOl phage in 20 mis of carrier. The pigs were subsequently administered 15 mis of FOl phage orally at 2 and 3 hours post challenge. The level of Salmonella in tonsil and ileum was reduced by about 10 fold, while the level of Salmonella in colon, cecum, and colon apex was reduced by about 100 fold (Figure 4). EXAMPLE 7

[0046] Figure 5 shows the reduction in Salmonella levels in pigs following two post-infection treatments with phage FOl. Five pigs each were assigned to a control group and a phage treatment group and intranasally challenged with 5 X 10⁹ CFU of Salmonella. One hour post-challenge, pigs were adniinistered 6 mis of FOl phage at a concentration of 1.5 X 10¹⁰ PFU/ml via intramuscular shot and 20 mis of FOl phage orally at a concentration of 1.5 X 10¹⁰ PFU/ml. Two hours post- infection, the pigs were administered 15 mis of FOl phage at a concentration of 1.5 X 10¹⁰ PFU/ml orally. The level of Salmonella in cecum and colon was reduced by about 100 fold in the phage treatment group compared to the control group (Figure 5).

EXAMPLE 8

[0047] Figure 6 shows the reduction in Salmonella at various time points in broth culture foUowing inoculation adniinistration of the FOl phage. lxl 0⁴ PFU of FOl phage was inoculated into LB broth containing lxl 0⁴ CFU of Salmonella. While incubating at 37 C, the viable numbers of ^' Salmonella were monitored at 15 minutes, 1, 2, 4, 6, 8, 10, 15, and 20 hours post inoculation. The level of Salmonella was reduced from about 10 fold at 1 hour to about 10,000 at 20 hours (Figure 6).

0048] The above description and examples are only illustrative of embodiments which achieve the objects, features, and advantages of the present invention, and it is not intended that the present invention be limited thereto. Any modifications of the present invention which come within the spirit and scope of the following claims is considered part of the present invention.

Claims

CLAIMS[0049] What is claimed is:

1. A composition for reducing the amount of Salmonella comprising a

Salmonella reducing effective amount of FOl phage and an acceptable carrier.

2. The composition of claim 1, wherein said carrier comprises a material

selected from the group consisting of saline, water, feed, and Luria broth.

3. The composition of claim 1, wherein said carrier comprises water.

4. The composition of claim 1, wherein said carrier comprises feed.

5. The composition of claim 1, wherein said Salmonella reducing effective

amount of FOl phage is at least about 1 X 10⁶ PFU.

6. The composition of claim 5, wherein said Salmonella reducing effective

amount of FOl phage is less than about 1 X 10¹² PFU

7. The composition of claim 1, wherein said Salmonella reducing effective

amount of FOl phage is at least about 1 X 10¹⁰ PFU.

8. The composition of claim 1, wherein said Salmonella reducing effective

amount of FOl phage is in an oral dosage form.

9. The composition of claim 1, wherein said Salmonella reducing effective

amount of FOl phage is in an injectable dosage form.

10. The composition of claim 1, wherein said Salmonella reducing effective

amount of FOl phage is in aerosol dosage form.

11. The composition of claim 1, wherein said Salmonella reducing effective

amount of FOl phage is in a suppository dosage form.

12. A composition for reducing the amount of Salmonella in a livestock

animal comprising at least 10⁶ PFU of FOl phage wherein said Salmonella is reduced

by at least 10 fold following administration of said composition to said animal.

13. A method of reducing the amount of Salmonella in a swine prior to

harvest, comprising administering a composition containing FOl phage in an

acceptable carrier to said swine from about 24 hours to less than about 3 hours prior

to harvest of said animal in an amount effective to reduce the amount of Salmonella

in said animal.

14. The method of claim 13, wherein said carrier comprises a material

selected from the group consisting of saline, water, feed, and Luria broth.

15. The method of claim 13, wherein said composition is administered from

about 12 hours to about 6 hours prior to harvest of said animal.

16. The method of claim 13, wherein said composition is administered from

about 6 hours to about 3 hours prior to harvest of said animal.

17. The method of claim 13, wherein said the composition is adiriinistered

less than about 3 hours prior to harvest of said animal.

18. The method of claim 13, wherein said composition is administered in a

single dose.

19. The method of claim 13, wherein said composition is adniinistered in

multiple doses.

20. The method of claim 13, wherein said composition is administered from

2 to 5 doses.

21. The method of claim 13 , wherein said amount of Salmonella in said

swine is reduced by at least 10 to about 100,000 fold.

22. The method of claim 13, wherein said composition is administered at

least 1 hour following initial adniinistration of said composition.

23. The method of claim, 13 , wherein said composition is aα-ministered to

said swine at least two times prior to harvest.

24. The method of claim 13, wherein said composition is aα-ministered

orally.

25. The method of claim 13, wherein said composition is administered

intramuscularly.

26. The method of claim 13, wherein said composition is administered by

injection.

27. The method of claim 13, wherein said composition is administered by

instillation.

28. The method of claim 13, wherein said composition is administered as a

first dose and a second dose.

29. The method of claim 28, wherein said first dose is administered

intramuscularly and said second dose is adrninistered orally.

30. The method of claim 28, wherein said first dose is administered at least

one hour after said swine is exposed to Salmonella.

31. The method of claim 30, wherein said second dose is administered at

least one hour after said first dose.

32. A method of reducing the amount of Salmonella in a swine prior to

harvest, comprising adiriinistering a composition containing at least 10⁶ PFU of FOl

phage in an acceptable carrier to said swine less than about 3 hours prior to harvest

of said animal wherein said amount of Salmonella in said swine is reduced by at least

10 to about 100,000 fold.

33. A method of harvesting a fivestock animal comprising acuriinistering a

composition comprising FOl phage to a fivestock animal after exposure to

Salmonella and at least 24 hours prior to harvest of said animal in an amount

effective to reduce the amount Salmonella; and harvesting said animal.

34. The method of claim 33, wherein said livestock animal is harvested at

least 1 hours after administering said composition to said animal.

35. A method of reducing dissemination of Salmonella in livestock animals

comprising administering a composition comprising a Salmonella reducing effective

amount of FOl phage to a livestock animal prior to harvest wherein dissemination of

Salmonella infection is reduced by about 10 to about 10,000 fold.

36. The method of claim 35, wherein said Salmonella reducing effective

amount of FOl phage is about 10⁶ to about 10¹² PFU.

37. A method of reducing the amount of Salmonella in meat products

comprising applying a composition comprising a Salmonella reducing effective

amount of FOl phage to a meat product.

38. The method of claim 37, wherein said Salmonella reducing effective

amount of FOl phage is about 10° PFU.

39. The method of claim 37, wherein said meat products are selected from

the group consisting of beef, poultry, lamb, and pork.

40. The method of claim 37, wherein said composition is applied by

spraying.

41. The method of claim 37, wherein said composition is applied by

soaking.