Effect of boiling water carcass immersion on aerobic bacteria counts of poultry skin and processed ground poultry meat.

This study was conducted to determine the relationship between bacteria destruction on poultry carcass skin and bacteria in raw ground poultry meat from the same carcasses. Immersion time in boiling water of broiler chicken whole carcasses required for maximum reduction of naturally occurring aerobic bacterial count on skin was measured. Treatments for chicken carcasses consisted of immersion in boiling water (approximately 95 degrees C) for 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, and 4 min. Four skin samples taken following treatment and three taken from subsequently ground carcass meat were analyzed for total aerobic plate counts (APC). Analysis of the data indicated a linear increase in bacterial destruction on skin with increased boiling water immersion time from 0 to 4 min. Reduction of skin bacteria to less than 1 log10 occurred at 3 min carcass immersion or longer. The analysis also indicated that treatment with boiling water and removal of skin was effective in reducing bacterial counts in ground meat to similar levels at all treatment times from 0.5 to 4.0 min. Findings from this study indicated that a boiling water immersion intervention and removal of skin could reduce subsequent bacteria contamination of ground meat. This intervention could minimize the risk of pathogen-contaminated primary processed poultry carcasses used in further processing.

Subtherapeutic tetracycline effects on recovery patterns of calves after Salmonella typhimurium challenge.

Holstein calves were maintained on a subtherapeutic dose of chlortetracycline to determine if an oxytetracycline therapy, given after a Salmonella typhimurium challenge, would be compromised by the previous subtherapy. Two of the four groups of seven calves were maintained on a subtherapeutic amount of chlortetracycline. All calves then were challenged with Salmonella typhimurium, and with the onset of clinical symptoms one group with and one group without subtherapy were given a therapeutic dose of oxytetracycline. The two groups receiving a therapeutic dosage of oxytetracycline had the most quickly declining body temperatures and the highest average body weights post-challenge. Two calves died in the group receiving no antibiotic treatments, and one calf died in the group receiving only the subtherapeutic treatment. There were no differences in postchallenge body temperatures or body weight changes between subtherapeutic and nonsubtherapeutic groups of calves. The conclusion was that the subtherapeutic dosing of chlortetracycline did not affect the therapeutic treatment effects of oxytetracycline after a Salmonella typhimurium challenge.

Microbial Quality of Ground and Comminuted, Raw and Cooked Turkey Meat 1.

The microbial quality of ground and comminuted turkey meat was examined using raw meat and meat after two cooking times. Eight triplicate samples were obtained from a commercial processing plant over an 8-month period and analyzed for aerobic plate count (APC), coliforms, Escherichia coli , Staphylococcus aureus , Clostridium perfringens and Salmonella . The APC for 29%of the raw ground and 0% of the raw comminuted turkey meat samples was greater than 5.0 × 106/g. Raw ground and comminuted meat yielded a mean coliform most probable number (MPN) of 2.2 × 102 and 6.2 × 102/g respectively. Mean E. coli MPNs per gram were 12 for raw ground and 49 for raw comminuted meat. Twenty-five percent of the 24 raw ground samples, and 46% of the comminuted samples exceeded 50 E. coli MPN/g. S aureus was isolated from 25% of the raw ground and 54% of raw comminuted samples. Salmonellae were isolated from 8% of the raw ground samples and 12% of raw comminuted samples. C. perfringens was isolated from 50 and 55% of 40 ground and 40 comminuted meat samples, respectively. Cooking reduced the microbial numbers and isolation frequency from all samples.

Recovery of 61 Salmonella serotypes from artificially contaminated turkey skin.

Selenite brilliant-green sulfa enrichment broth containing Tween 80 was streaked to brilliant-green sulfa plates for use in comparing recoverability of 61 different salmonella serotypes from turkey tails artifically contaminated with very low levels of each serotype. Recoverability was 100% with 43 of the serotypes, 80% with eight, 60% with four, and 40% or less with six.

Reduction of airborne microorganisms by filtering recycled air in a chick hatcher.

An experimental chick hatcher designed to filter recycled ventilation air was tested for its effectiveness in reducing the number of viable airborne microorganisms. Chicks in a filtered hatcher and a control hatcher (no filter) were artificially contaminated with Serratia marcescens as ventilation air was recycled in the hatchers for twelve hours. The number of viable S. marcescens particles in the filtered air of the conditioning chamber was less than detectable. The number of viable airborne S. marcescens particles in the hatching chamber of the filtered hatcher indicated a reduction of greater than 90 percent over the number in the unfiltered hatcher. The filter was effective in reducing the number of airborne particles carrying viable S. marcescens organisms in the hatcher.

Effect of filtering recycled air in a chick hatcher on airborne pathogenic microorganisms.

Two experimental chick hatchers in which ventilation air within the hatcher was partially recirculated in a positive pressure system, one with an air filter in the system and the other without a filter, were simultaneously tested to determine effect of the filter on quantitative reduction of viable airborne microorganisms. Chicks were artificially contaminated with either Escherichia coli or Staphylococcus aureus (coagulase-positive). Air was sampled for total test bacteria per cubic foot of hatcher air. The filter effectively reduced the number of viable airborne particles contaminated with E. coli and S. aureus contributed by chicks in the hatcher.

Subcutaneous bacteria in turkey carcasses.

Two methods were employed to quantitate the subcutaneous bacteria in fresh, refrigerated, and frozen turkey carcasses. Relatively few bacteria were detected in the skin-flesh interface and in the flesh as compared with the number of bacteria on the skin surface and in the skin layer. No subcutaneous bacteria were detected in 49% of the skin-flesh interface and flesh samples. The number of bacteria detected in skin samples from carcasses chemically disinfected to kill skin surface bacteria was smaller than that in nondisinfected skin samples. These results indicate that the skin blending method used to quantify microorganisms on poultry carcass skin measures the skin layer flora and that the number of subcutaneous membrane or flesh bacteria measured is not normally large enough to have a significant influence on the results.

Optimum skin blending method for quantifying poultry carcass bacteria.

Optimum blending fluids and blending times for use in quantifying bacteria on poultry carcass skin by the skin "blending" method were determined. Butterfield's buffered-phosphate diluent, physiological saline solution (0.85% NaCl), peptone water (0.1% peptone), and deionized water, each at four different skin blending times of 1, 2, 3, and 4 min, were compared. The comparison was based on relative numbers of bacteria per cm(2) of skin, enumerated by each combination on turkey carcasses. Peptone water and physiological saline solution each yielded significantly (P < 0.01) higher bacteria counts from turkey carcass skin samples than did Butterfield's buffered-phosphate diluent or deionized water. There were no significant differences among the four skin blending times and no significant interaction effect between the two factors tested.

Effect of electrostatic charge on the contamination of plastic food containers by airborne bacterial spores.

Electrostatic charge of approximately -10 kv was produced by friction on polystyrene food container samples. This charge quickly decayed to a lower, more stable, level. Exposure of samples to positively charged red and negatively charged green fluorescent particles resulted in a particle-distribution pattern on the plastic surface. The dynamic attraction of fluorescent particles was illustrated by time-lapse photography. Similar distribution patterns of airborne bacterial spores were shown to develop. In controlled bacterial aerosol exposure tests, an increase in surface contamination of the plastic samples was found to be quantitatively related to an increase in negative electrostatic charge on the plastic. Static charge was found to accumulate on plastic food containers during their manufacture, and to remain indefinitely on many of the finished products. This charge was of the intensity and polarity to attract positively charged bacterial cells if such particles were present in the air.