Enumeration of Escherichia coli cells on chicken carcasses as a potential measure of microbial process control in a random selection of slaughter establishments in the United States.

To evaluate whether the number of Escherichia coli bacteria in carcass rinses from chicken slaughter establishments could be monitored for the purpose of microbial process control, we drew a random sample from 20 of 127 large USDA-inspected operations. In 2005, every 3 months, two sets of 10 carcass rinses, 100 ml each, were collected from establishments, netting 80 sample sets from the rehang and postchill stages. E. coli and Campylobacter numbers and Salmonella prevalence were measured. Mixed-effect models were used to estimate variance of mean log(10) E. coli cell numbers of 10-carcass rinse sample sets. Relationships between E. coli and Campylobacter and Salmonella were examined. For 10-carcass rinse sets, at both the rehang and postchill stages the mean log(10) E. coli CFU/ml fit the logistic distribution better than the normal distribution. The rehang overall mean log(10) E. coli was 3.3 CFU/ml, with a within-sample set standard deviation of 0.6 CFU/ml. The overall postchill mean log(10) E. coli was 0.8 CFU/ml, with 13 establishments having mean log(10) E. coli CFU/ml values of less than 1.0 and 7 having mean values of 1.2 or more. At the midpoint separating these establishments, a mean log(10) E. coli CFU/ml of 1.1, the within-sample set standard deviation was 0.5 CFU/ml, with smaller standard deviations as means increased. Postchill sample sets with mean log(10) E. coli counts less than or equal to 1.1 CFU/ml had lower overall prevalence of Salmonella and mean log(10) Campylobacter CFU/ml than sample sets with higher means. These findings regarding reductions in E. coli numbers provide insight relevant to microbial process control.

Rainfall and tillage effects on transport of fecal bacteria and sex hormones 17beta-estradiol and testosterone from broiler litter applications to a Georgia Piedmont Ultisol.

Poultry litter provides nutrients for crop and pasture production; however, it also contains fecal bacteria, sex hormones (17beta-estradiol and testosterone) and antibiotic residues that may contaminate surface waters. Our objective was to quantify transport of fecal bacteria, estradiol, testosterone and antibiotic residues from a Cecil sandy loam managed since 1991 under no-till (NT) and conventional tillage (CT) to which either poultry litter (PL) or conventional fertilizer (CF) was applied based on the nitrogen needs of corn (Zea mays L) in the Southern Piedmont of NE Georgia. Simulated rainfall was applied for 60 min to 2 by 3-m field plots at a constant rate in 2004 and variable rate in 2005. Runoff was continuously measured and subsamples taken for determining flow-weighted concentrations of fecal bacteria, hormones, and antibiotic residues. Neither Salmonella, nor Campylobacter, nor antimicrobial residues were detected in litter, soil, or runoff. Differences in soil concentrations of fecal bacteria before and after rainfall simulations were observed only for Escherichia coli in the constant rainfall intensity experiment. Differences in flow-weighted concentrations were observed only for testosterone in both constant and variable intensity rainfall experiments, and were greatest for treatments that received poultry litter. Total loads of E. coli and fecal enterococci, were largest for both tillage treatments receiving poultry litter for the variable rainfall intensity. Load of testosterone was greatest for no-till plots receiving poultry litter under variable rainfall intensity. Poultry litter application rates commensurate for corn appeared to enhance only soil concentrations of E. coli, and runoff concentrations of testosterone above background levels.

Effect of porcine-derived mucosal competitive exclusion culture on antimicrobial resistance in Escherichia coli from growing piglets.

While use of antimicrobial drugs in livestock production has made a significant impact on animal health, welfare, and productivity, interest in suitable alternatives such as pre/probiotics, organic acids, and cultures of normal flora or "competitive exclusion" cultures from young animals has increased significantly in the wake of the antimicrobial resistance issue. The present study was undertaken to determine the effect of porcine-derived mucosal competitive exclusion (PCE) culture on both the antimicrobial susceptibility of commensal E. coli and on growth performance in piglets. Two replicate trials were conducted using growing piglets fed standard antimicrobial-free production diets. Piglets in the treatment group were orally dosed with PCE (10(10) cfu/mL) twice within 24 h of birth, at weaning, and 18-24 h post-weaning; control group piglets were dosed with sterile broth as a placebo. Fecal samples from all piglets were cultured for commensal E. coli at dosing times and when feed type was changed. A significantly higher proportion of E. coli from PCE-treated piglets demonstrated resistance to tetracycline (p < 0.0001), and streptomycin (p < 0.0001) when compared to controls. Resistance to streptomycin resistance in E. coli from piglets treated with PCE culture was variable, returning to baseline levels by day 21 (weaning). Piglets treated with the PCE culture demonstrated improved feed efficiencies when compared to control piglets (p < 0.005) during feeding of the starter and first growth diets. The PCE culture used in the present study had previously been shown to effectively exclude Salmonella in pigs. To the best of the authors' knowledge, this is the first report characterizing the effect of a competitive exclusion culture on antimicrobial resistance of commensal E. coli.

Universal Preenrichment Broth for the Simultaneous Detection of Salmonella and Listeria in Foods.

A medium and method for preenriching food products which allow the simultaneous recovery and detection of Salmonella and Listeria are described. To prevent the pH of the medium from rapidly dropping in the presence of extraneous microorganisms found in foods, this medium, universal preenrichment (UP) broth, is highly buffered and low in carbohydrates. The medium allows sublethally injured bacteria to resuscitate and multiply to sufficiently high numbers so that highly selective, secondary enrichment media can be employed to help select the specific bacteria in question from a mixed bacterial background culture. As few as 10 heat-injured Salmonella multiplied to at least 106/ml following a 24 h enrichment in UP, even in mixtures of high levels of known competitive microflora or from naturally occurring microflora found in chicken, hot dogs, or Brie cheese. As few as 10 heat-injured Listeria monocytogenes multiplied to at least 105/ml in these same experiments. From the UP broth, secondary selective preenrichment broths which favor the growth of Salmonella or Listeria can be inoculated, and subsequent protocols for the recovery of either Salmonella or Listeria can then be followed.

A Comparison of an Enzyme Immunoassay, DNA Hybridization, Antibody Immobilization, and Conventional Methods for Recovery of Naturally Occurring Salmonellae from Processed Broiler Carcasses.

Three hundred and ninety raw processed broiler carcasses were obtained from four processing plants and evaluated for the presence of salmonellae by the whole bird rinse procedure. Enzyme immunoassay (Salmonella-Tek™), colorimetric DNA hybridization (GENE-TRAKR), and antibody immobilization (1-2 Test™) methods were compared to the Food Safety Inspection Service (FSIS) culture method for detection of salmonellae. All samples were preenriched in buffered peptone water incubated at 37°C then transferred to and enriched in TT broth (Difco, Detroit, MI) incubated at 42°C for 24 h. After enrichment, manufacturer's instructions were then followed for "rapid" procedures and the FSIS recovery and confirmation scheme was followed for the cultural method. For each sample, if discrepant results were observed between the four procedures, selective plates were streaked from both the TT selective broth and the GN postenrichment broth (Difco). All samples which were positive after initial sampling of TT broth plus additional positive samples from TT selective and GN postenrichment broths were called confirmed cultural positives. Salmonellae were detected on 71% of the carcasses using confirmed cultural procedures and 65% with FSIS culture. Presumptive salmonellae positive samples were found 66, 71, and 76% of the time with the 1-2 Test, GENE-TRAK, and Salmonella-Tek, respectively. As compared to confirmed culture, only 1.4% false positives were observed with the 1-2 Test and GENE-TRAK, whereas 6% false positives were obtained using Salmonella-Tek. When the false negatives for the four methods were compared to confirmed culture, Salmonella-Tek, GENE-TRAK, 1-2 Test, and FSIS culture had 0.4, 2.5, 7.2, and 8.3%, respectively. The close correlation of these rapid procedures to the conventional procedures warrants consideration of these procedures for detection of salmonellae from broiler chickens.

Bacteriological Profiles of Human Milk from Individual Donors and Pooled Samples from a Commercial Milk Bank.

The bacteriological profiles of human milk samples collected from individual donors under supervised conditions of collection were compared to pooled human milk samples obtained from a commercial human milk bank. Total aerobic counts and total coliform counts of individual donor samples were lower than those of pooled, banked human milk. All of the 200 isolates from ten individual samples were staphylococci with Staphylococcus epidermidis predominating (82%). Only 1% of the isolates was identified as Staphylococcus aureus . Forty-two percent of the 100 isolates from five pooled samples were staphylococci and all of these staphylococci were coagulase-negative. Three percent of the isolates from the pooled samples were Streptococcus faecalis . The remainder (55%) were gram-negative organisms. S. epidermidis was the microorganism that was isolated most frequently from either individual (9 of 10) or pooled (3 of 5) samples.

Effects of Meat Type, Storage Time and Temperature on Various Physical, Chemical and Microbiological Characteristics of Ground Pork.

Whole-hog sausage was prepared from hot- and cold-boned pork raw materials to determine the effects of meat type, storage temperature and length of storage on various processing and bacteriological characteristics. Samples were stored at -1 and 4°C for 0, 28 and 56 d. Various physical, chemical and microbiological properties of the sausage were evaluated. Thiobarbituric acid (TBA) values were not affected by meat type (pre or postrigor). Hunter-Color values varied significantly among the meat types and storage temperatures. Total bacterial counts varied significantly among the hot- and cold-boned pork sausage samples (day 0). Cold-boned sausage stored at -1°C had lower plate counts of the various treatments for days 28 and 56. Pseudomonas was the predominant organism found in hotand cold-boned sausage samples. Hot-boned sausage exhibited a more diverse bacterial population than did cold-boned sausage. More gram-positive organisms were found in hot-boned sausage samples. Cold-boned sausage had a lower total bacterial count at day 0 and maintained lower counts and therefore a longer shelf life throughout the study when held at -1°C.