WASHINGTON — The Food and Drug Administration has introduced several new regulations designed to reduce the incidence of Salmonella enteritidis in eggs. The pathogen may be found inside eggs that appear perfectly normal. If the eggs are eaten raw or undercooked, the bacterium may cause illness. Eggs in the shell become contaminated on the farm, primarily because of infection in the laying hens.

To reduce the incidence of Salmonella enteritidis, producers with at least 3,000 but fewer than 50,000 laying hens must comply within 36 months after the rule’s publication. Producers with 50,000 or more laying hens must be in compliance with the rule within 12 months after its publication in the Federal Register.

Under the rule, egg producers must buy chicks and young hens only from suppliers who monitor for Salmonella; establish rodent, pest control, and biosecurity measures to prevent spread of bacteria throughout the farm by people and equipment; and conduct testing in the poultry house for Salmonella enteritidis. If the tests find the bacterium, a representative sample of the eggs must be tested over an 8-week period. If any of the four egg tests is positive, the producer must further process the eggs to destroy the bacteria, or divert the eggs to a non-food use.

Egg producers also will have to clean and disinfect poultry houses that have tested positive for Salmonella enteritidis, and refrigerate eggs at 45° Fahrenheit temperature during storage and transportation no later than 36 hours after the eggs are laid.

Egg producers whose eggs receive treatments such as pasteurization still must comply with the refrigeration requirements. Similarly, certain persons such as distributors, packers, or truckers holding or transporting shell eggs also must comply with the refrigeration requirements.

To ensure compliance, egg producers will be required to maintain a written Salmonella enteritidis prevention plan and records documenting their compliance. Producers, except those who have less than 3,000 hens or who sell all their eggs directly to consumers, also must register with the F.D.A. The F.D.A. will develop guidance and enforcement plans to help egg producers comply with the rule.