Prevalence and antimicrobial resistance of Salmonella isolated from conventional and antimicrobial-free (ABF) swine herds in North Carolina

The main objective of this stdy was to compare prevalence and antimicrobial resistance of Salmonella isolated from swine reared in antimicrobial-free (ABF) and conventional production systems in North Carolina

Comparison of multidrug resistant Salmonella between intensively - and extensively-reared antimicrobial - free (ABF) swine herds

This cross-sectional study was conducted to determine the prevalence and antimicrobial resistance of Salmonella species in swine reared in the intensive (indoor) and extensive (outdoor) ABF production systems at farm and slaughter in North Carolina, U.S.A. We sampled a total of 279 pigs at farm (Extensive 107; Intensive 172) and collected 274 carcass swabs (Extensive 124; Intensive 150) at slaughter. Salmonella species were tested for their susceptibility against 12 antimicrobial agents using the Kirby-Bauer disk diffusion method. Serogrouping was done using polyvalent and group specific antisera. A total of 400 salmonellae were isolated in this study with a significantly higher Salmonella prevalence from the Intensive (30%) than the extensive farms (0.9%) (P \u3c 0.001 ). At slaughter, significantly higher Salmonella was isolated at the pre and post-evisceration stages from extensively (29 % pre-evisceration and 33.3 % post-evisceration) than the intensively (2 % pre-ev1sceration and 6 % post-evisceration) reared swine (P \u3c 0.001 ). The isolates were clustered in six serogroups including B, C, E1, E4, G and R. Highest frequency of antimicrobial resistance was observed against tetracycline (78.5%) and streptomycin (31 .5%). A total of 13 antimicrobial resistance patterns were observed including the pentaresistant strains with ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, tetracycline resistance pattern observed only among isolates from the intensive farms (n=28) and all belonged to serogroup B. This study shows that multidrug resistant Salmonella are prevalent in ABF production systems despite the absence of antimicrobial selection pressure

Salmonella prevalence in pigs reared on farms with and without antimicrobials

A convenience sample of farms using antimicrobials (antimicrobial-using, AMU) post-weaning for therapy and/or growth promotion (n=21) were contrasted to a convenience sample of farms not using antimicrobials post-weaning (antimicrobial-free, AMF, n=21) distributed across three US geographic areas

Campylobacter Prevalence and Diversity in Antimicrobial Free and Conventionally Reared Market Swine

The objectives of this study were to determine the prevalence and antimicrobial resistance of Campylobacter spp. among pigs raised antimicrobial free (ABF) and those raised conventionally. Bacterial isolation was done on-farm and at slaughter using conventional methods and antimicrobial susceptibility tests were done for 12 antimicrobials using Kirby-Bauer and epsilometric test (E-test) methods. All 14 herds were positive for Campylobacter. On-farm prevalence among ABF herds was 71% and 81% among conventional herd. In contrast, the prevalence among carcass swabs was higher among ABF herds than conventional herds with 60% and 29% respectively. There was significant reduction after chilling in all groups (p\u3c0.05). On-farm frequency of antimicrobial resistance was significantly higher among isolates from conventional herds than ABF (p\u3c0.05). In contrast frequency of resistance to five of the seven antimicrobials was higher among carcass swabs of ABF herds than conventional herds

Campylobacter prevalence and antimicrobial resistance in swine reared in antimicrobial-free and conventional production systems

The objective of this study was to determine and compare the prevalence and antimicrobial resistance of Campylobacter species in swine reared in the conventional and antimicrobial free production (ABF) production systems as part of a multi-state study. To date, 19 conventional and 16 ABF groups have been followed

Prevalence and antimicrobial resistance profile of Campylobacter isolated from conventional and antibiotic free swine farms in three geographic locations

The prevalence and antimicrobial resistance of Campylobacter were examined from swine reared in conventional and antimicrobial-free (ABF) production systems in three geographical locations: North Carolina (NC), Ohio (OH) and Wisconsin (WI). Methods: A total of 1500 pigs and 1930 carcass swab samples were evaluated for the prevalence of Campylobacter. Fecal samples from 662 pigs from NC (370 conventional farms and 292 ABF farms), 379 from OH (268 conventional and 111 ABF) and 459 from WI (160 conventional and 299 ABF) were included. Antimicrobial susceptibility testing was performed using agar dilution method against a panel of six antimicrobials

Effect of withdrawing feed from hogs prior to slaughter on the prevalence of gastrointestinal lacerations at slaughter

To help producers decide whether they should withdraw feed prior to slaughter, we designed a study that examined the effect of feed withdrawal on the proportion of gastrointestinal tract lacerations, prevalence of Salmonella spp. in cecal contents at slaughter, prevalence and severity of gastric ulcers, and meat quality as measured by ultimate pH, color, and water holding capacity. Finally, we analyzed the economic impact of the treatments. This report focuses on the prevalence of lacerations of the gastrointestinal tract found at slaughter. We followed to slaughter, in 3 marketing groups, 900 National Pig Development barrows that we had assigned to treatment. Each marketing group (feed withdrawn once, first group; twice, second group; or three times, third group) had an equal number of pigs that had feed withdrawn for 0 (control) 12, or 24 hours. Overall, 15.7% of gastrointestinal tracts were lacerated in one or more sections including the stomach (8.4%), colon (5.7%), small intestine (2.1 %), and ceca (0.9%). The withdrawal of feed before slaughter decreased the weight of the gastrointestinal tract. The proportion of lacerations in this study (15.5%) is higher than previously reported (4.5%). The difference may be due to the higher rate of evisceration (18 pigs per minute), or our more detailed examination of the gastrointestinal tracts

Evaluation of the association between pen fecal accumulation and prevalence of Salmonella enterica shedding in swine

One of the recommended control measures for Salmonella enterica is improved or adequate fann hygiene. Although loosely defined, a component of good hygiene practice is to minimize animal contact with feces. Increased exposure to feces would he expected to increase the likelihood of transmission and fecal shedding of Salmonella enterica. There are indications in the literature that decreased animal contact with feces may result in a decreased risk for Salmonella enterica infection. Davies et al. demonstrated increased mean prevalence in open-flush gutter and dirt lot systems when compared to pigs housed on total slatted flooring systems. Paradoxically, three-site, all-in!all-out pig flow systems did not have a significantly different mean Salmonella enterica prevalence when compared to one-site continuous flow fanns. A similar incongruity is the evidence that in poultry barns, birds placed on used litter had lower risk of salmonella shedding than birds placed on clean litter.(5) Proposed mechanisms of this result are colonization with competitive flora from the used litter as well as an inhibitory environment for Salmonella enterica. The subjective nature of determining adequate hygiene as well as the presence of apparently contradictory results regarding hygiene and prevalence of Salmonella shedding in animals warrants inquiry into the question of what is good hygiene in respect to Salmonella shedding in animals

Salmonella serotypes in a multiple-site production system

Long-term trends in production agriculture in the USA are towards fewer and larger producers. The number of hog operations declined from 430,000 in 1984 to 209,000 in 1994. In 1991, although 84% of operations had less than 1000 head, these accounted for only 22% of hogs produced. Increased farm size means that emergence of a foodbome pathogen on a farm can affect a greater volume of product and potentially affect more consumers (Hueston and Fedorka-Cray 1995). Alternatively, some intensive production practices allow greater control of the environment and may lead to an overall safer food supply. Improving production systems is popularly promoted to reduce exposure of animals to Salmonella. However, apart from historically important measures such as banning swill feeding and general improvement of hygiene, recommendations on how to achieve this are often superficial. This is a consequence of lack of information about the epidemiology of sub-clinical Salmonella infection on swine farms

Epidemiology of Salmonella in Swine Production Systems in North Caroline

Background: Program initiated in 1994 when Dr. Davies joined the College of Veterinary Medicine, NCSU. Long term goal: to make a major contribution to knowledge of the epidemiology, in swine production systems, of food borne pathogens of humans