Investigation of Salmonella contamination and disinfection in farm egg-packing plants.
OBJECTIVE
As part of a field-based study of the distribution and persistence of Salmonella infection on commercial egg-laying farms, sampling was carried out on one or more occasions in egg-packing areas of 12 farms infected with Salm. Enteritidis.


RESULTS
Salmonellas were isolated by cultural methods. Contamination was common, with Salmonella being found in 23.1% of floor swab samples, 30.8% of grading tables, 23.1% of conveyor belts or rollers and 23.8% of candlers. Four farms were sampled after cleaning and disinfection of packing plants had been carried out on the previous day, and residual contamination was found on 6.9% of samples from grading tables, 16.0% holding/sorting tables, 12.6% of conveyors or rollers, 16.7% of vacuum egg lifters, 21.4% of floor surfaces and 5.0% of egg store floor surfaces. Sterilized eggs passed through five farm packing plants showed a contamination rate of at least 16/5,948 (0.3%) egg passages.


CONCLUSIONS
It is apparent that contamination in egg-packing plants may be a significant contributory factor to external contamination of shell eggs, and improved methods of cleaning and disinfecting egg-handling equipment are required.


CONCLUSIONS
The presence of Salmonella contamination in egg-packing plants presents a contamination hazard for eggs from Salmonella-free flocks. Samples from equipment in the packing plant could also be used for screening for detection of Salmonella in the throughout of the plant.
Davies
R H
RH
Department of Bacterial Diseases, Veterinary Laboratories Agency-Weybridge, Addlestone, UK. r.h.davies@vla.defra.gsi.gov.uk
Breslin
M
M
D000383:Agriculture / Q000295:instrumentation; D004203:Disinfection / Q000379:methods*; D004531:Eggs / Q000382:microbiology*; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology; D012477:Salmonella enteritidis / Q000302:isolation & purification*