Assessment of microbial contaminants present on vacuum loaders in shell egg processing facilities

This study was conducted to determine the pathogen prevalence on vacuum loader cup surfaces. An off-line (birds housed off-site) and a mixed (birds housed on-site and eggs brought from outside production) operation shell egg processing facility were sampled three times each. Twenty vacuum loader cups were randomly rinsed with sterile saline per visit. Total aerobic microorganisms and Enterobacteriaceae were enumerated, and the prevalence of Salmonella, Campylobacter and Listeria was determined. Aerobic microorganisms were ~5 log cfu/mL, with higher levels noted in the mixed operation. Enterobacteriaceae levels averaged 2.5 log cfu/mL but were higher in the off-line facility. Campylobacter was detected in 1.6% of the samples. Salmonella was detected in 3.3% of the samples with isolates serotyped as Salmonella anatum and Salmonella heidelberg. There was a high prevalence of Listeria (72%). Confirmed isolates were identified as Listeria innocua (98.8%) and Listeria monocytogenes (1.2%). Identification of the populations present on the cup surfaces will allow for the development of more effective cleaning and disinfection programs. Vacuum loaders have previously been determined to be reservoirs for microorganisms in shell egg processing plants. Assessing the prevalence of prominent foodborne pathogens (Salmonella, Campylobacter and Listeria) on the vacuum loader cup surface would allow for more targeted approaches to cleaning and sanitation. High levels of aerobic organisms and Enterobacteriaceae were detected (~5 and 2.5 log cfu/mL, respectively). Furthermore, Campylobacter and Salmonella were also found, but at low prevalence. Listeria was detected in 72% of the samples. Cleaning and sanitation programs currently utilized in shell egg processing facilities need to be reassessed, and new technologies need to be developed to address the presence of Salmonella, Campylobacter and Listeria.