Methicillin-resistant Staphylococcus aureus in pork production shower facilities.

As methicillin-resistant Staphylococcus aureus (MRSA) has been found in pigs, we sought to determine if MRSA is present in pork production shower facilities. In two production systems tested, 3% and 26% of shower samples were positive for MRSA. spa types identified included t034, t189, t753, and t1746.

Evaluation of phage treatment as a strategy to reduce Salmonella populations in growing swine.

Salmonella is a foodborne pathogenic bacterium that causes human illnesses and morbidity and mortality in swine. Bacteriophages are viruses that prey on bacteria and are naturally found in many microbial environments, including the gut of food animals, and have been suggested as a potential intervention strategy to reduce Salmonella levels in the live animal. The present study was designed to determine if anti-Salmonella phages isolated from the feces of commercial finishing swine could reduce gastrointestinal populations of the foodborne pathogen Salmonella Typhimurium in artificially inoculated swine. Weaned pigs (n = 48) were randomly assigned to two treatment groups (control or phage-treated). Each pig was inoculated with Salmonella Typhimurium (2 × 10(10) colony forming units/pig) via oral gavage at 0 h and fecal samples were collected every 24 h. Swine were inoculated with a phage cocktail via oral gavage (3 × 10(9) plaque forming units) at 24 and 48 h. Pigs were humanely killed at 96 h, and cecal and rectal intestinal contents were collected for quantitative and qualitative analysis. Fecal Salmonella populations in phage-treated pigs were lower (p < 0.09) than controls after 48 h. Phage treatment reduced intestinal populations of inoculated Salmonella Typhimurium in pigs compared to controls at necropsy. Cecal populations were reduced (p = 0.07) by phage treatment >1.4 log(10) colony forming units/g digesta, and rectal populations were numerically reduced. The number of pigs that contained inoculated Salmonella Typhimurium was reduced by phage treatment, but a significant (p < 0.05) reduction was only observed in the rectum. We conclude that phages can be a viable tool to reduce Salmonella in swine. Further research needs to be performed to determine the most efficacious dosing regimens and the most effective combinations of phages targeting the diverse Salmonella population found in swine before they can enter the food supply.

Occurrence of Salmonella-specific bacteriophages in swine feces collected from commercial farms.

Salmonella is one of the leading causes of human foodborne illness and is associated with swine production. Bacteriophages are naturally occurring viruses that prey on bacteria and have been suggested as a potential intervention strategy to reduce Salmonella levels in food animals on the farm and in the lairage period. If phages are to be used to improve food safety, then we must understand the incidence and natural ecology of both phages and their hosts in the intestinal environment. This study investigates the incidence of phages that are active against Salmonella spp. in the feces of commercial finishing swine. Fecal samples (n = 60) were collected from each of 10 commercial swine finishing operations. Samples were collected from 10 randomly selected pens throughout each operation; a total of 600 fecal samples were collected. Salmonella spp. were found in 7.3% (44/600) of the fecal samples. Bacteriophages were isolated from fecal samples through two parallel methods: (1) initial enrichment in Salmonella Typhimurium; (2) initial enrichment in Escherichia coli B (an indicator strain), followed by direct spot testing against Salmonella Typhimurium. Bacteriophages active against Salmonella Typhimurium were isolated from 1% (6/600) of the individual fecal samples when initially enriched in Salmonella Typhimurium, but E. coli B-killing phages were isolated from 48.3% (290/600) of the fecal samples and only two of these phages infected Salmonella Typhimurium on secondary plating. Collectively, our results indicate that bacteriophages are widespread in commercial swine, but those capable of killing Salmonella Typhimurium may be present at relatively low population levels. These results indicate that phages (predator) populations may vary along with Salmonella (prey) populations; and that phages could potentially be used as a food safety pathogen reduction strategy in swine.

The Take Care program and responsible use of antibiotics.

While the contribution of antimicrobial use in pork production to resistant bacteria in human health is uncertain, pork producers have the responsibility to deliver safe and wholesome pork to consumers. The development of a comprehensive producer education and awareness program focused on the responsible use of antimicrobials in pork production is described. The Take Care - Use Antibiotics Responsibly program is based on principles and guidelines that provide the producer and veterinarian the basis for antibiotic use decision-making. The goal of the program is to protect public health while preserving animal health and welfare.

Trichinae certification in the United States pork industry.

Control of Trichinella infection in U.S. pork has traditionally been accomplished by inspection of individual carcasses at slaughter or by post-slaughter processing to inactivate parasites. We propose that an alternative to individual carcass testing or processing can be used when pigs are raised in production systems where risk of exposure to Trichinella spiralis has been mitigated. Declines in prevalence of this parasite in U.S. domestic swine during the last 30 years, coupled with improvements in pork production systems, now allow Trichinella control to be shifted to the farm through implementation of specific pork production practices. Knowledge of risk factors for exposure of swine to T. spiralis was used to develop an objective audit of risk that can be applied to pork production sites. In a pilot study, 461 production site audits were performed by trained veterinary practitioners. The on-farm audit included aspects of farm management, bio-security, feed and feed storage, rodent control programs and general hygiene. Of the 461 production site audits, 450 audits (97.6%) indicated compliance with the required good production practices. These sites are eligible for certification under the U.S. Trichinae Certification Program and will be audited regularly to maintain that status. The described trichinae certification mechanism will establish a process for ensuring the Trichinella safety of swine, and ultimately food products derived from swine, at the production level.

An outbreak of Pontiac fever with respiratory distress among workers performing high-pressure cleaning at a sugar-beet processing plant.

BACKGROUND: In August 2000, the Minnesota Department of Health was notified of and investigated an outbreak of febrile respiratory illness among workers at a sugar-beet processing plant. METHODS: A case was defined as fever and respiratory symptoms occurring in a worker at the sugar-beet plant on or after 31 July 2000. Case patients were interviewed, medical and work records were reviewed, and clinical samples were obtained. The plant was inspected, and environmental samples were collected. RESULTS: Fourteen of 15 case patients performed high-pressure water cleaning in the confined space of an evaporator vessel. Symptoms included fever and chills (100%), chest tightness (93%), cough (80%), and shortness of breath (73%). In case patients, median temperature was 39.4 degrees C, median oxygen saturation was 93%, and median white blood cell count was 12x10(3) cells/ mu L. Four (29%) of 14 case patients showed evidence of Legionella pneumophila exposure, according to serologic testing. Water sources contained up to 10(5) cfu/mL of L. pneumophila and 22,200 endotoxin units/mL. CONCLUSIONS: Outbreak features were consistent with Pontiac fever. Respiratory symptoms, which are atypical for Pontiac fever, could be attributed to a high exposure dose of L. pneumophila from confined-space aerosolization or to endotoxin exposure. This outbreak demonstrates the potential occupational hazards for those performing high-pressure cleaning in confined spaces.

Outbreaks of enteric infections caused by multiple pathogens associated with calves at a farm day camp.

BACKGROUND: Transmission of enteric pathogens at venues where the public contacts farm animals is a growing problem, particularly among children. In 2000 and again in 2001, enteric illness outbreaks caused by multiple pathogens occurred at a farm day camp for children in Minnesota. METHODS: Camp attendees were interviewed about illness history and potential exposures each year. Stool samples from children and calves at the camp were tested for enteric pathogens. RESULTS: Eighty-four illnesses were documented among camp attendees in the 2 outbreaks; laboratory-confirmed infections included Cryptosporidium parvum (17 cases), Escherichia coli O157:H7 (4), non-O157 Shiga toxin-producing E. coli (STEC) (7) and Salmonella enterica serotype Typhimurium and Campylobacter jejuni (1 each). Kindergarten-fourth grade children provided 1-on-1 care for a bottle-fed calf. Sixty of 83 calves tested carried at least 1 pathogen, including Giardia spp. (26 calves), C. parvum (25), non-O157 STEC (17), Campylobacter spp. (11), 3 serotypes of Salmonella enterica (10) and E. coli O157:H7 (2). Risk factors among children included caring for an ill calf and getting visible manure on their hands. Always washing hands with soap after touching a calf and washing hands before going home were protective. Prevention measures implemented in 2000 failed to prevent the second outbreak. CONCLUSIONS: Calves were the reservoir of multiple enteric pathogens for children at a farm day camp. Health care providers should consider numerous zoonotic pathogens in patients presenting with gastroenteritis after contact with cattle. Public health officials should help venue operators prospectively implement published guidelines to prevent zoonotic disease transmission.