Salmonella collected from nest run cart shelves in commercial shell egg processing facilities.

Salmonella, a member of the bacterial family Enterobacteriaceae, may be recovered from foods and processing facilities. High levels of Enterobacteriaceae in the processing plant environment can be an indication of inadequate sanitation. This experiment was designed to determine if nest run egg carts serve as reservoirs for Salmonella. Eggs that are produced by hens not housed in buildings connected to the processing plant are referred to as nest run. Many of these eggs are transported to a central processing facility before they are washed, graded, and packed. Two plants in the Southeastern United States were sampled; one was a mixed operation and the other was an off-line operation. On each of 3 visits, 5 shelves on each of 5 carts were sampled (n = 25/visit). A 12 × 12 cm area on each shelf was swabbed with a sterile gauze pad moistened with PBS and transported on ice back to the laboratory. Each swab was preenriched in buffered peptone at 37°C for 24 h, selectively enriched using TT and Rappaport-Vassiliadis broth at 42°C overnight, then plated onto brilliant green sulfa and XLT-4 incubated at 37°C for 24 h. Presumptive colonies were transferred to lysine iron agar and triple sugar iron slants for 24 h at 37°C. Isolates with presumptive reactions were confirmed using commercial polyclonal antisera. After initial confirmation, serogrouping was performed using commercial antisera. Mixed-operation swab samples were 12% positive for Salmonella, whereas off-line samples were 36% positive for Salmonella; isolates were confirmed as serogroups B, C1, and C2. Kauffman-White serotyping was performed by a contract laboratory. Serotypes (n = 30) recovered were Anatum, Heidelberg, Infantis, Kentucky, Mbandanka, and Typhimurium. This work demonstrated that nest run egg carts may serve as reservoirs for Salmonella in the shell egg processing environment.

Comparison of environmental and egg microbiology associated with conventional and free-range laying hen management.

Eggs from alternative production practices are a growing niche in the market. Meeting consumer requests for greater diversity in retail egg options has resulted in some unique challenges such as understanding the food safety implications of eggs from alternative production practices. A study was conducted to determine what, if any, differences exist between nest run conventional cage-produced eggs and free range-produced eggs. A sister flock of brown egg layers was maintained in conventional cage and free-range production with egg and environmental sampling every 6 wk from 20 to 79 wk of age. Aerobic, coliform, and yeast and mold populations were monitored. Environmental microbial levels were not always indicative of egg contamination levels. When significant differences (P < 0.05 and P < 0.0001, dependent on season) were observed among treatments for coliforms, shell contamination levels of free-range nest box eggs and free-range floor eggs were always greater than those of conventional cage eggs, which remained low throughout the study (0.42-0.02 log cfu/mL). Shell yeast and mold levels were significantly greater in free-range floor eggs than in free-range nest box eggs and conventional cage eggs throughout the entire study. Egg contents contamination levels were extremely low for all monitored populations and treatments. Season of the year played a role in both environmental and egg microbial levels. Winter had the lowest levels of all populations monitored for all treatments, except for aerobic free-range floor egg shell emulsions, which were increased (3.6 log cfu/mL). Understanding the differences in microbial populations present on conventional cage-produced and free range-produced eggs can lead to the development of effective cleaning procedures, enhancing food safety.

Comparison of shell bacteria from unwashed and washed table eggs harvested from caged laying hens and cage-free floor-housed laying hens.

These studies evaluated the bacterial level of unwashed and washed shell eggs from caged and cage-free laying hens. Hy-Line W-36 White and Hy-Line Brown laying hens were housed on all wire slats or all shavings floor systems. On the sampling days for experiments 1, 2, and 3, 20 eggs were collected from each pen for bacterial analyses. Ten of the eggs collected from each pen were washed for 1 min with a commercial egg-washing solution, whereas the remaining 10 eggs were unwashed before sampling the eggshell and shell membranes for aerobic bacteria and coliforms (experiment 1 only). In experiment 1, the aerobic plate counts (APC) of unwashed eggs produced in the shavings, slats, and caged-housing systems were 4.0, 3.6, and 3.1 log(10) cfu/mL of rinsate, respectively. Washing eggs significantly (P < 0.05) reduced APC by 1.6 log(10) cfu/mL and reduced the prevalence of coliforms by 12%. In experiment 2, unwashed eggs produced by hens in triple-deck cages from 57 to 62 wk (previously housed on shavings, slats, and cages) did not differ, with APC ranging from 0.6 to 0.8 log(10) cfu/mL. Washing eggs continued to significantly reduce APC to below 0.2 log(10) cfu/mL. In experiment 3, the APC for unwashed eggs were within 0.4 log below the APC attained for unwashed eggs in experiment 1, although hen density was 28% of that used in experiment 1. Washing eggs further lowered the APC to 0.4 to 0.7 log(10) cfu/mL, a 2.7-log reduction. These results indicate that shell bacterial levels are similar after washing for eggs from hens housed in these caged and cage-free environments. However, housing hens in cages with manure removal belts resulted in lower APC for both unwashed and washed eggs (compared with eggs from hens housed in a room with shavings, slats, and cages).

Physical quality and composition of retail shell eggs.

There are a number of specialty shell eggs available to consumers in the US retail market. A survey consisting of white and brown large shell eggs with various production and nutritional differences (traditional, cage-free, free-roaming, pasteurized, nutritionally enhanced, and fertile) was conducted to determine if physical quality and compositional differences exist. Identical brands of eggs were purchased from the same retail outlets on 3 occasions (replicates) in a single city. The average range of time from processing to purchase for all eggs was 7.67 to 25.33 d, with traditional white eggs in retail having the shortest time. Haugh unit values ranged from 66.67 (cage-free, docosahexaenoic acid, and n-3 enhanced) to 84.42 (traditional white). Albumen height followed a similar pattern. Egg weight was greater for brown eggs (61.12 vs. 58.85 g). Brown eggs also had greater static compression shell strength than white eggs (4,130.61 vs. 3,690.31 g force). Vitelline membrane strength was greatest for traditional brown eggs (2.24 g force). Percentage of total solids and crude fat was greatest in the cage-free, n-3-enhanced white eggs (25.07 and 11.71%, respectively). Although significant differences were found between white and brown shell eggs and production methods, average values for quality attributes varied without one egg type consistently maintaining the highest or lowest values.

The effects of commercial cool water washing of shell eggs on Haugh unit, vitelline membrane strength, aerobic microorganisms, and fungi.

Current egg washing practices use wash water temperatures averaging 49 degrees C and have been found to increase internal egg temperature by 6.7 to 7.8 degrees C. These high temperatures create a more optimal environment for bacterial growth, including Salmonella Enteritidis if it is present. Salmonella Enteritidis is the most common human pathogen associated with shell eggs and egg products. Its growth is inhibited at temperatures of 7.2 degrees C and below. The objective of this study was to determine if commercially washing eggs in cool water would aid in quickly reducing internal egg temperature, preserving interior egg quality, and slowing microbial growth. During 3 consecutive days, eggs were washed using 4 dual-tank wash water temperature schemes (HH = 49 degrees C, 49 degrees C; HC = 49 degrees C, 24 degrees C; CC = 24 degrees C, 24 degrees C; CH = 24 degrees C, 49 degrees C) at 2 commercial processing facilities. A 10-wk storage study followed, in which vitelline membrane strength, Haugh unit, and aerobic microorganisms and fungi (yeasts and molds) were monitored weekly. As storage time progressed, average Haugh unit values declined 14.8%, the average force required to rupture the vitelline membrane decreased 20.6%, average numbers of bacteria present on shell surfaces decreased 11.3%, and bacteria present in egg contents increased 39.5% during storage. Wash water temperature did not significantly affect Haugh unit values, vitelline membrane strength, or the numbers of aerobic microorganisms and fungi within the shell matrices of processed eggs. Results of this study indicate that incorporating cool water into commercial shell egg processing, while maintaining a pH of 10 to 12, lowers postprocessing egg temperatures and allows for more rapid cooling, without causing a decline in egg quality or increasing the presence of aerobic microorganisms and fungi for approximately 5 wk postprocessing.

Enterobacteriaceae and related organisms isolated from nest run cart shelves in commercial shell egg processing facilities.

Enterobacteriaceae, including Salmonella, may be recovered from foods and processing facilities. High levels of Enterobacteriaceae in the processing plant environment can be an indication of inadequate sanitation. This experiment was designed to determine if nest run egg carts serve as reservoirs for Enterobacteriaceae. Eggs that are produced by hens not housed in buildings connected to the processing plant are referred to as nest run. Many of these eggs are transported to the plant on carts to be processed. Two plants in the southeastern United States were sampled. On each of 3 visits, 5 shelves on each of 5 carts were sampled (n=25/visit). A 12x12 cm area on each shelf was swabbed with a sterile gauze pad moistened with PBS and transported on ice back to the laboratory. Enterobacteriaceae were enumerated using violet red bile glucose agar incubated at 37 degrees C for 24 h. There was 100% prevalence for Enterobacteriaceae at plant A with an average 3.8 log10 cfu/mL swab diluent. Plant B had 90% prevalence for Enterobacteriaceae with an average 3.2 log10 cfu/mL swab diluent. Two randomly selected isolates from each positive sample were recultured 3 times to increase the likelihood of clonality and were then identified biochemically. Of the 124 isolates analyzed, genera identified were Citrobacter spp., Escherichia spp., Enterobacter spp., Klebsiella spp., Hafnia spp., Kluyvera spp., Leclercia spp., and Salmonella spp. Pseudomonas spp. was the only non-Enterobacteriaceae identified by our methods. This work demonstrates that nest run egg carts serve as reservoirs for Enterobacteriaceae in the shell egg processing environment.

Identification of yeasts isolated from commercial shell eggs stored at refrigerated temperatures.

Yeasts and molds can grow on or in eggs, causing spoilage. Washed and unwashed eggs (treatments) were collected aseptically on three separate days (replications) from a commercial processing facility and stored for 10 weeks at 4 degrees C. Ten eggs from each treatment were sampled weekly (110 eggs per treatment per replication). Yeasts and molds were enumerated from external shell rinses by plating onto acidified potato dextrose agar. Yeast colonies were picked randomly and stored for subsequent identification by gas chromatographic analysis of fatty acid methyl esters using the MIDI Microbial Identification System. Of 688 isolates analyzed, 380 were identified to genus or species. Genera identified by this method included Candida, Cryptococcus, Hansenula, Hyphopichia, Metschnikowia, Rhodotorula, Sporobolomyces, and Torulaspora. Candida spp. accounted for 84.5% (321 of 380) of the isolate identifications. Candida famata was the most prevalent species (n = 120), followed by Candida lusitaniae (n = 38). A group of 20 isolates was subjected to molecular or biochemical analyses for comparison with the MIDI results. Biochemical tests were performed using automatic and mini systems. Results of biochemical tests and ribosomal DNA sequencing were in agreement for 11 of the isolates, but only 7 of the 20 MIDI-identified isolates were in agreement with the sequencing results. C. famata, an anamorph of Debaryomyces hansenii var. hansenii, was the most commonly identified isolate by all methods. These data indicate that there was limited correlation between results obtained with the MIDI system and the information obtained from molecular databases. However, both systems were able to correctly identify C. famata, the species most often isolated throughout egg storage.

Effect of blood spots in table egg albumen on Salmonella growth.

Presence of blood spots in eggs has been correlated with a greater rate of Salmonella Enteritidis contamination. Therefore, this study was conducted to determine whether Salmonella inoculated into egg albumen with naturally occurring blood spots would survive or grow. In each of 3 trials, white shell table eggs with blood spots were collected from a commercial egg-processing plant after candling. In each trial, eggs were broken out, and approximately 4 mL of clear albumen (CLEAR) and 4 mL of bloody albumen (BLOOD) from each of 10 eggs were placed in sterile test tubes and inoculated with a nalidixic acid-resistant Salmonella Typhimurium. For inoculation, 0.1 mL of the Salmonella Typhimurium suspension (containing 7.1, 7.7, or 7.0 log cfu/mL in trials 1 to 3, respectively) was added to each tube. Tube contents were mixed and incubated at 25 degrees C for 24 h. Immediately after inoculation (0 h) and again after 24 h, 0.1 mL from each tube was plated onto Brilliant Green-Sulfa agar with 200 ppm nalidixic acid and incubated at 37 degrees C for 24 h. Results are reported as log colony-forming units per milliliter of albumen. No significant differences (P < 0.05) in mean Salmonella Typhimurium counts were found between CLEAR or BLOOD samples at 0 h (5.6 vs. 5.8, respectively), indicating that initial inoculation levels were consistent between treatments. After 24 h, CLEAR samples were slightly but significantly lower than BLOOD samples for Salmonella Typhimurium (6.5 vs. 6.8, respectively). Salmonella Typhimurium numbers increase somewhat in albumen with or without blood, but slightly greater numbers are produced in albumen with blood spots. In this experiment, blood in the albumen of table eggs contributed to the survival and growth of Salmonella Typhimurium inoculated into egg albumen.

Identification of enterobacteriaceae on vacuum loaders in shell egg processing.

Cleaning and sanitation are paramount in food processing. Gaining an understanding of the microbial populations present in a processing facility can help in the development of effective and efficient cleaning. The current study was undertaken to gain a better understanding of the Enterobacteriaceae present on vacuum loader cups used in shell egg processing to transfer nest run eggs to the processing line. Twenty cups were rinsed on each of 3 visits to both an off-line operation and a mixed operation. A total of 442 Enterobacteriaceae isolates were biochemically identified from vacuum loader cup rinses. The predominant genera isolated from the 2 facilities were Enterobacter, Klebsiella, Escherichia, Citrobacter, and Serratia. The primary organisms from the off-line facility were Klebsiella oxytoca, Enterobacter amnigenus 2, and Klebsiella pneumoniae. The isolates found in the greatest proportion from the mixed operation were Enterobacter cloacae and Klebsiella oxytoca. A total of 18 genera were recovered from the 2 facilities, with 9 being present in both processing facilities. The findings of this study can be used in assessing the sources of bacterial contamination in egg processing and in developing more effective, targeted cleaning programs for processing equipment and facilities.

Enterobacteriaceae and related organisms isolated from shell eggs collected during commercial processing.

In the United States, commercial shell eggs are washed and graded before retail. Since passage of the Egg Products Inspection Act in 1971, processing guidelines have been set to ensure that external and internal characteristics are maintained. However, less is known about how commercial processing affects the safety of shell eggs. To identify enteric bacteria entering plants and persisting throughout processing, eggs were collected from 3 US commercial shell egg-processing plants on 3 separate visits. On each plant visit, 12 eggs were collected from each of 12 sites along the processing line: accumulator, prewash rinse, first washer, second washer, sanitizer rinse, dryer, oiler, check detection/scales, 2 egg grader/packer head lanes, rewash belt entrance, and rewash belt exit. Each egg was sampled by a rinse technique, and the rinsate was plated onto violet red bile glucose agar with overlay for the detection and enumeration of Enterobacteriaceae. From each plate, up to 5 colonies were randomly selected and isolated for identification to genus or species by using biochemical tests. Several genera and species were detected at each of the 3 plants. Sites from which the greatest numbers of isolates were identified were those collected from eggs during preprocessing (accumulator, prewash rinse) or from eggs judged as dirty (rewash belt entrance or exit). Sites yielding the smallest number of isolates were those during or at the end of processing. Escherichia coli and Enterobacter spp. were isolated from each of the 9 plant visits. Other genera isolated from at least 1 of the 3 plants included Cedecea, Citrobacter, Erwinia, Hafnia, Klebsiella, Kluyvera, Leclercia, Morganella, Proteus, Providencia, Rahnella, Salmonella, and Serratia. Non-Enterobacteriaceae isolated and identified included Aeromonas, Chryseomonas, Listonella, Pseudomonas, Sphingobacterium, Vibrio, and Xanthomonas. All of the genera and species were recovered less frequently from fully processed eggs than from unwashed eggs, indicating that shell eggs are less contaminated with bacteria as a result of commercial washing procedures.

Pathogen prevalence and microbial levels associated with restricted shell eggs.

Restricted shell eggs that do not meet quality standards for retail but maintain acceptable quality for inclusion in further processed eggs are often diverted to further processing. A study was conducted to characterize the microbiological populations present on and in these eggs. On a single day, restricted eggs were collected from three shell egg processing plants a total of three times (replicates). Six shells or egg contents were combined to create a pool. Ten pools of shells and contents were formed for each plant per replicate. Shells and membranes were macerated in 60 ml of diluent. Contents were stomacher blended to form a homogeneous mixture. Total aerobic microorganisms and Enterobacteriaceae were enumerated. The prevalence of Salmonella, Campylobacter, and Listeria was determined by cultural methods. Average aerobic counts were 4.3 log CFU/ml for the shells and 2.0 log CFU/ml for the contents. There were plant x replicate differences for both (P < 0.05 and P < 0.01, respectively). The average Enterobacteriaceae level associated with the shell was 2.4 log CFU/ml and less than 0.1 log CFU/ml for the egg contents, with 36.7% of the samples being positive. One shell sample (0.5% of total samples) was Campylobacter positive. Two shell samples (1.1% of total samples) were Salmonella positive. Twenty-one percent of samples were positive for Listeria (33 shells and 5 contents). Although current pasteurization guidelines are based on Salmonella lethality, the results of this study reiterate the need to revisit the guidelines to determine the effectiveness for other pathogenic species.

Spoilage microflora of broiler carcasses washed with electrolyzed oxidizing or chlorinated water using an inside-outside bird washer.

The effect of acidic, electrolyzed oxidizing (EO) water and chlorinated water on the spoilage microflora of processed broiler carcasses was examined. Carcasses were sprayed for 5 s at 80 psi with tap, chlorinated, or EO water in an inside-outside bird washer. Treated carcasses were then stored at 4 degrees C for 0, 3, 7, or 14 d, and the microbial flora of the carcasses was sampled using the whole-carcass rinse procedure. Populations of psychrotrophic bacteria and yeasts in the carcass rinsates were enumerated. Results indicated that immediately after spraying the carcasses, significantly fewer psychrotrophic bacteria were recovered from carcasses sprayed with chlorinated or EO water than from carcasses sprayed with tap water. Furthermore, significantly fewer yeasts were recovered from carcasses sprayed with EO water than from carcasses sprayed with tap or chlorinated water. The population of psychrotrophic bacteria and yeasts increased on all carcasses during refrigerated storage. However, after 14 d of storage, significantly fewer psychrotrophic bacteria and yeasts were recovered from carcasses sprayed with EO water than from carcasses sprayed with tap or chlorinated water, and significantly fewer microorganisms were recovered from carcasses sprayed with chlorinated water than from carcasses sprayed with tap water. Pseudomonas spp. and Candida spp. were the primary microbial isolates recovered from the broiler carcasses. Findings from the present study indicate that EO water can effectively be used in inside-outside bird washers to decrease the population of spoilage bacteria and yeasts on processed broiler carcasses.

Antimicrobial resistance in Salmonella and Escherichia coli isolated from commercial shell eggs.

The development of antimicrobial resistance in bacteria has become a global problem. Isolates of Salmonella and Escherichia coli recovered from shell egg samples, collected at 3 commercial plants, were analyzed for resistance to 16 antimicrobial agents (n=990). Eggs were sampled by rinsing in a saline solution. Pooled samples were preenriched in buffered peptone water and then selectively isolated using standard broths and agars. Salmonella-positive isolates were serogrouped immunologically before being serotyped. Enterobacteriaceae were enumerated from individual samples using violet red bile glucose agar plates. Escherichia coli were identified biochemically from presumptive Enterobacteriaceae isolates. Salmonella and generic E. coli antimicrobial-susceptibility testing was conducted using a semiautomated broth microdilution system. More resistance was observed in the Salmonella isolates (n=41) than in the E. coli isolates (n=194). Salmonella Typhimurium was the most prevalent (69.0%) serotype and demonstrated the greatest multiple resistance. Salmonella Kentucky, the least prevalent (5.0%) serotype recovered, was the most susceptible. Although 34.1% of the Salmonella serotypes were susceptible to all antimicrobial agents, 60.1% were resistant to 11 or more compounds. Many Salmonella isolates exhibited resistance to tetracycline (63.4%), nalidixic acid (63.4%), and streptomycin (61.0%). Most E. coli isolates (73.2%) were susceptible to all antimicrobial drugs. Many E. coli isolates exhibited resistance to tetracycline (29.9%), streptomycin (6.2%), and gentamicin (3.1%). Only 1% of the E. coli isolates were resistant to 4 antimicrobial agents. These data indicate that shell eggs can harbor resistant foodborne and commensal bacteria; among Salmonella isolates, resistance was serotype-dependent.

Microbiological impact of spray washing broiler carcasses using different chlorine concentrations and water temperatures.

A study was conducted to investigate the microbiological impact of spray washing broiler carcasses with chlorinated water (0 or 50 ppm) at different temperatures (21.1, 43.3, or 54.4 degrees C). A whole carcass rinse (WCR) was performed on each carcass before (control) and after spray washing (final). After the control WCR, carcasses were inoculated with 0.1 g of cecal material containing 2 x 10(5) cells per gram of Campylobacter and 2 x 10(5) cells per gram of nalidixic acid-resistant Salmonella. Carcasses were held at room temperature for 12 min before washing in an inside-outside bird washer (80 psi for 5 s). Chlorine level and water temperature had no effect on total aerobic bacteria, Escherichia coli, or Campylobacter numbers recovered from the final WCR. Levels of bacteria found on carcasses before and after washing were 4.6, 3.6, and 3.5 log10 cfu/mL rinse for total aerobic bacteria, E. coli, and Campylobacter, respectively. Average counts for nalidixic acid-resistant Salmonella after washing were 3.1 log10 cfu/ mL rinse irrespective of water temperature or chlorine level (P < 0.05). In addition, chlorine level and water temperature had no effect on the breast skin color, with average values of L* = 66.6; a* = -0.09; b* = -0.05 (P < 0.05). Under the conditions outlined in the present study, adding chlorine and/or elevating the water temperature during spray washing in an inside-outside bird washer did not enhance the removal of bacteria from broiler carcasses and had no effect on carcass skin color.

Correlation of eggshell strength and Salmonella enteritidis contamination of commercial shell eggs.

Shell quality has been identified as a heritable trait that can be manipulated by genetic selection. Previous research has concluded that many methods of determining shell quality produce variable results. With the development of newer, more precise measuring technologies, shell strength can now be assessed in a consistent, objective fashion. A research project was conducted to determine what role shell strength might play in affecting external Salmonella Enteritidis contamination of egg contents. Visibly clean eggs were collected from an in-line shell egg-processing facility at the accumulator. Eggs were inoculated by dipping in a concentrated suspension of nalidixic acid-resistant Salmonella Enteritidis. After storage, eggs were assessed for shell strength and both external and internal Salmonella Enteritidis contamination. In the first study, there was a significant difference (P < 0.05) in shell strength among the three replicates. No differences between treatments were found for shell strength or Salmonella Enteritidis contamination of contents. In the second study, there were no replicate differences for any of the monitored factors. When rinsate and content samples were enriched, 100% of the rinsates were positive for Salmonella Enteritidis. No content samples were shown to be contaminated with Salmonella Enteritidis during direct plating, but 3 to 5% of the samples from each replicate were positive after enrichment. Correlation analysis of the results from each study found only weak correlations between shell strength and Salmonella Enteritidis contamination on eggshell surface or contents. Within the range of shell strengths recorded in this study, the correlation analysis suggests that shell strength does not play a major role in Salmonella Enteritidis contamination. Further work with eggs that represent a greater range of shell strengths could provide a clearer indication of the interaction of shell strength and Salmonella Enteritidis contamination.

Shell rinse and shell crush methods for the recovery of aerobic microorganisms and enterobacteriaceae from shell eggs.

Recovery of bacteria from shell eggs is important for evaluating the efficacy of processing and the quality and safety of the final product. Shell rinse (SR) techniques are easy to perform and widely used. An alternative sampling method involves crushing and rubbing the shell (CR). To determine the most appropriate method for recovering microorganisms from shell eggs, 358 shell eggs were collected from a commercial egg processor and sampled by SR and CR techniques. Total aerobic mesophiles and Enterobacteriaceae were enumerated on plate count and violet red bile glucose agar plates, respectively. Unwashed, in process, and postprocess eggs were evaluated in the study. Aerobic microorganism prevalence for eggshells sampled was similar for both methods (approximately 100%), but the log CFU per milliliter values were higher in the SR than the CR samples (3.2 and 2.2, respectively). Average Enterobacteriaceae recovery was similar for both methods (45 versus 40% for the SR and CR methods, respectively) when all eggs were considered together. This population was detected more often by SR when unwashed eggs were sampled (90 versus 56% for the SR and CR methods, respectively), equally by SR and CR for in-process eggs (30 versus 29.3% for the SR and CR methods, respectively), but more often by CR for postprocess eggs (10 versus 36% for the SR and CR methods, respectively). The SR technique was easier to perform and recovered larger numbers of aerobic organisms, particularly for unwashed eggs. However, the CR technique was more efficient for recovery of Enterobacteriaceae from postprocess eggs. Stage of shell egg processing may be an important consideration when choosing egg sampling methods.

Presence of Campylobacter jejuni in various organs one hour, one day, and one week following oral or intracloacal inoculations of broiler chicks.

Day-old broiler chicks (n=30) were obtained from a commercial hatchery and inoculated, either orally or intracloacally, with a characterized strain of Campylobacter jejuni. At 1 hr, 1 day, and 1 wk after inoculation, broilers (n = 5) from the orally and intracloacally inoculated groups along with control birds (n=4) were humanely killed by cervical dislocation. The broilers from the control and treatment groups were aseptically opened, and the thymus, spleen, liver/gallbladder, bursa of Fabricius, and ceca were aseptically removed and individually analyzed for C. jejuni. Overall, C. jejuni was isolated after oral inoculation from 13% (10/ 75), 17% (13/75), and 28% (14/50) of the 1-hr, 1-day, and 1-wk samples, respectively. Campylobacter jejuni was isolated from 10% (4/ 40), 8% (3/40), 10% (4/40), 25% (10/40), and 40% (16/40) of the thymus, spleen, liver/gallbladder, bursa of Fabricius, and ceca samples, respectively. Following the intracloacal route of inoculation, C. jejuni was recovered from 32% (24/75), 8% (6/75), and 16% (8/50) of the 1-hr, 1-day, and 1-wk samples, respectively. Campylobacter jejuni was isolated from 5% (2/40), 5% (2/40), 5% (2/40), 45% (18/40), and 40% (16/40) of the thymus, spleen, liver/gallbladder, bursa of Fabricius, and ceca samples, respectively, for all sampling periods. Campylobacter spp. were not recovered from sample sites examined from the control broilers from trial one, trial two, or trial three samples examined after 1 hr and 1 day. However, one control sample was positive from the 1-wk sampling from repetition three; therefore, those data were omitted. The rapid movement of Campylobacter to internal organs following both oral and intracloacal inoculation may be significant, particularly if it persists in these organs as reservoirs throughout the 65-wk life cycle of breeding birds.

Recovery of Salmonella from commercial shell eggs by shell rinse and shell crush methodologies.

Salmonella is the most important human pathogen associated with shell eggs. Salmonella Enteritidis is the serotype most often implicated in outbreaks, although other serotypes have been recovered from eggs and from the commercial shell egg washing environment. Many sample methods are used to recover microorganisms from eggshells and membranes. A shell rinse and modified shell-and-membrane crush method for recovery of Salmonella were compared. Eggs were collected from 3 commercial shell-washing facilities (X, Y, and Z) during 3 visits. Twelve eggs were collected from each of 10 to 12 locations along the egg processing chain. After being transported back to the laboratory, each egg was sampled first by a shell rinse method and then by a shell crush method. For each technique (rinse or crush), 2 pools of 5 eggs per location sampled were selectively enriched for the recovery of Salmonella. Presumptive samples positive for Salmonella were confirmed serologically. Overall, there were 10.1% (40/396) Salmonella-positive pooled samples. Salmonella were recovered by the shell rinse and shell crush techniques (4.8 vs. 5.3%, respectively). Plant X yielded 21.5% Salmonella positives, whereas less than 5% of samples from plants Y and Z were found to be contaminated with the organism (4.2 and 4.5%, respectively). Salmonella was recovered more often from unwashed eggs (15.8%) than from washed eggs (8.3%). For some eggs, Salmonella was only recovered by one of the methods. Use of both approaches in the same experiment increased sampling sensitivity, although in most cases, crushing provided more sensitive Salmonella recovery.

Recovery of Campylobacter jejuni in feces and semen of caged broiler breeder roosters following three routes of inoculation.

We previously reported the recovery of Campylobacter (naturally colonized) from the ductus deferens of 5 of 101 broiler breeder roosters, and four of those five positive roosters had previously produced Campylobacter-positive semen samples. Those results prompted further evaluation to determine if inoculation route influenced the prevalence or level of Campylobacter contamination of semen, the digestive tract, or reproductive organs. Individually caged roosters, confirmed to be feces and semen negative for Campylobacter, were challenged with a marker strain of Campylobacter jejuni either orally using 1.0 ml of a diluted cell suspension (log(10)4.3 to 6.0 cells), by dropping 0.1 ml of suspension (log(10)5.3 to 7.0 cells) on the everted phallus immediately after semen collection or by dip coating an ultrasound probe in the diluted cell suspension (log(10)4.3 to 6.0 cells) and then inserting the probe through the vent into the colon. Six days postinoculation, individual feces and semen samples were again collected and cultured for Campylobacter. Seven days postinoculation, roosters were killed, the abdomen aseptically opened to expose the viscera, and one cecum, one testis, and both ductus deferens were collected. The samples were then suspended 1:3 (weight/volume) in Bolton enrichment broth for the culture of Campylobacter. Samples were also directly plated onto Cefex agar to enumerate Campylobacter. Campylobacter was recovered 6 days after challenge from feces in 82% of samples (log(10)4.1 colony-forming units [CFU]/g sample), 85% of semen samples (log(10)2.9 CFU/ml), and on the seventh day postchallenge from 88% of cecal samples (log(10)5.8 CFU/g sample). Campylobacter was not directly isolated from any testis sample but was detected following enrichment from 9% (3/33) of ductus deferens samples. Roosters challenged with Campylobacter orally, on the phallus, or by insertion of a Campylobacter dip-coated ultrasound probe were all readily colonized in the ceca and produced Campylobacter-positive semen and feces on day 6 after challenge. The low prevalence of recovery of Campylobacter from the ductus deferens samples and failure to recover from any testis sample suggests that semen may become Campylobacter positive while traversing the cloaca upon the everted phallus. The production of Campylobacter-positive semen could provide a route in addition to fecal-oral for the horizontal transmission of Campylobacter from the rooster to the reproductive tract of the hen.

Effects of extended storage on egg quality factors.

Eggs were collected from a single inline processing facility weekly for 3 wk (replicates). The eggs were stored at 4 degrees C and 80% RH. Sampling began the day after collection and continued each week for 10 wk. During analysis, 24 eggs were examined for egg weight, albumen height, Haugh units (HU), shell strength, and vitelline membrane strength for each replicate. Egg weight decreased (P < 0.0001) from approximately 61 to 57 g after 10 wk of storage. Eggs from the second replicate were significantly (P < 0.0001) heavier than the other replicates by an average of 3 g. On average, albumen height decreased with extended storage (P < 0.0001) from 7.05 to 4.85 mm. Albumen height was approximately 0.2 mm higher for the eggs in replicate 2 compared with the other replicates (P < 0.01). Haugh unit values decreased during cold storage from 82.59 to 67.43 (P < 0.0001). There were no differences between replicates for HU values. No differences were detected for shell strength between replicates or during extended storage. A significant difference (P < 0.05) was found in detectable vitelline membrane strength between replicates, but this difference was less than 0.05 g. The elasticity of the vitelline membrane decreased during storage (P < 0.01) remaining low after 6 wk. Extended cold storage led to decreases in egg weight, albumen height, and HU. However, average HU values were still within the range for grade A. Shell strength was not affected by extended storage. Vitelline membrane elasticity also decreased, which could lead to yolks more easily rupturing as consumers crack the eggs. The results indicated that although the physical quality factors monitored in this study decreased during storage, egg quality was still acceptable beyond current recommended shelf life guidelines.