Food Safety: Romaine Lettuce- Factors Leading to food borne outbreaks, recent outbreaks, control met

Romaine Lettuce has been a target for food recalls because of its nature to harbor deadly food-borne illnesses. The main illness that can be found on contaminated romaine lettuce is Escherichia coli (abbreviated as E. coli). Leafy vegetables, like romaine lettuce, make up 21 percent of all foodborne E. coli outbreaks (Heiman, 2015). E. coli is a bacterium that is found in the digestive system of animals and humans. In large quantities and certain strains, E. coli has the ability to make people sick, and in some cases, cause death. Those who are most susceptible to this disease are infants, those who are pregnant, immunosuppressed, or elderly. The best way to avoid these bacteria on lettuce is to ensure that the lettuce you consume has been washed thoroughly under running water. Most infected people do not show symptoms of E. coli until 3 to 4 days after ingesting the germ. Symptoms of E. Coli infection are severe stomach cramps, diarrhea (often bloody), and vomiting. Some people experience fever and healthy persons are usually better within 5 to 7 days after infection. ‘

The USDA has certain standards set in place for romaine lettuce. These regulations were last updated in September of 2016. Romaine lettuce is defined as “consists of romaine plants of similar varietal characteristics which are fresh, well developed, well-trimmed, and which are free from decay, and free from damage caused by seed stems, broken, bruised or discolored leaves, tip burn, wilting, foreign material, freezing, dirt, disease, insects, mechanical or other means” (United States Standards for Grades of Romaine). These standards also have different grades for romaine lettuce. The first grade is “Fresh”. “Fresh” is defined by the moisture content in the plant. To be labeled as “fresh” the plant can also have some wilting in the outermost leaves. The next grade for romaine lettuce is “Well-Developed”. This means the plant has normal growth and shape and similar to this grade is “Well-Trimmed”. “Well-Trimmed” graded romaine lettuce has been cut close to the where the outermost leaves are. Opposite of these first grades, “Damaged” graded lettuce means that there are visible defects to the appearance of the lettuce. These include when the seedstem is longer than 1/4th of the plant or the edibility of the plant has been harmed. Like damaged graded lettuce, “Serious Damage” graded lettuce can be multiple defects to the plant that affect its consumption and appearance.

From September 2019 to December 2019, a recall was placed on romaine lettuce. The incident was isolated to a farm in Sallnas Valley, California leading to a massive recall of the product. During the time of the outbreak, there were 167 cases of food-borne illness traced to the lettuce at Sallnas Valley and 85 Hospitalizations. The outbreak reached 27 states across the county (CDC, 2020). In 2018, a similar case from Adam Bros. Farming, INC in Santa Barbara County was reported. All lettuce produced at the facility was recalled. This outbreak led to 62 reported cases and 25 hospitalizations in over 16 states in the country (CDC, 2019). In 222 foodborne outbreaks, the most common setting that attributed to E. Coli outbreaks was restaurants (Heiman, 2015). Another recent E. coli outbreak resulted in the death of 5 individuals. This outbreak resulted from contaminated canal water that was used for irrigation. By the end of this outbreak in June of 2018, 210 cases were reported across 36 states.96 people had been hospitalized (CDC, 2018). Food-borne illnesses caused by Escherichia coli are prevalent but preventable. These foodborne outbreaks cost company’s millions and consumers' lives. Once a company has been hit with an outbreak, consumers lose trust in the company’s standards for health. It would take years to build consumer trust after an outbreak or cause the company bankruptcy in some cases. These issues are preventable; all precautions should be taken to prevent an outbreak from occurring to your company. Below are some guidelines to follow.

For commercial industries that produce Romaine Lettuce, there are certain FDA guidelines that must be followed. Once the lettuce has been contaminated, removing or killing the bacteria load is extremely difficult. There have been studies done on food-grade sanitizing detergents that can be sprayed directly on the leaves of romaine lettuce. The study showed that Short-Chain Fatty Acid formulations were shown to be the most effective in sanitizing romaine lettuce (Keskinen & Annous, 2011). Commercial producers must understand that the best line of defense against E coli is prevention methods. Raw agricultural commodities like romaine lettuce are harvested from Field Production that is sustainable to the elements and nature. The first potential contaminants that can affect the infection of lettuce is water used in field production. Water sources can wash potential infections onto the lettuce (Solomon et al., 2003). To reduce contamination from water, the water used on the lettuce must be monitored for the microbial load. It is also important to ensure that human pathogens cannot contaminate the lettuce from runoff of sewer systems or animal pastures nearby. Another large contaminate for lettuce is composting material added to the soil in field composting. Any manure used in human food production should be thermally treated to reduce the risk of contamination. Raw animal manure should never be used with romaine lettuce production.

Another potential hazard for commercial industries that produce romaine lettuce is the equipment and machinery used to harvest the lettuce. Equipment should be thoroughly sanitized before and after each use to limit the amount of potential exposure to harmful bacteria that could be hiding on the equipment. Establishing SSOP’s (Standard Operating Procedures) and sanitation schedules for machine operations is important to this production. Although there is issues with potential hazards to mechanical harvest, there are also hazards associated with hand-harvest also. Human hands are susceptible to E coli strains that are contracted from poor hygiene associated with not washing your hands after defecating. Knives, gloves, and bins used for harvest should be sanitized.

Hazards that are associated with natural occurrences and romaine lettuce are floodwaters. The FDA states that any crop that has come into contact with floodwaters is considered “adulterated” and cannot be sold for human consumption. In 2018, an outbreak of E. coli that killed 5 people was linked to canal water flooding in the crops field. While this issue cannot be avoided in most cases, animals can also harbor E. coli and can contaminate romaine lettuce. Actions should be taken to avoid contact with wild and domestic animals. In a study done in 2014, researchers showed that unleashed dogs and wild coyotes played a role as E. coli reservoirs in production near the Mexico border. Dog and Coyote feces harbored large amounts of E. coli (Jay-Russell et al, 2014). Even though dogs’ feces can carry E. coli, there have been studies down with scent detection dogs to detect E. coli contamination in romaine lettuce in distribution centers before the lettuce reaches consumers (Partyka et al., 2014). In the study, they concluded that scent detection dogs could be used to reduce food-borne illness.

During post-harvest operations, romaine lettuce is cooled after harvest. Water used in this post-harvest cooling has the potential to contaminate the lettuce with E. coli bacteria. The water source used in cooling should come from a clean source. The equipment used in cooling should also be disinfected frequently to ensure bacteria loads stay at safe levels. Developing SSOP’s for the cooling equipment is highly recommended. Any containers that are used to carry the lettuce from field to facility should also have SSOP’s developed. Proper sanitation is key in these areas. In distribution facilities of the lettuce, all vehicle transportation should have SSOP’s in place to ensure that proper sanitation standards are being conducted. Implementing inspection and evaluation of vehicles and regulating the number of bacteria they transfer to the romaine lettuce. Establishing GAP’s or cGMP procedures with written sanitation, pest control, and worker hygiene requirements should also be established at the distribution center.

In conclusion to the information stated above, E. coli in romaine lettuce is a deadly foodborne bacterium, that if managed correctly, can be reduced and minimized for the safety of consumers. The best line of defense against E. coli in romaine lettuce is prevention methods. Prevention methods include sanitization of all equipment used in production, harvest, and post-harvest operations regularly and thoroughly. They also include good worker hygiene practices to prevent the spread of E. coli from human contact. GMP should be in place to prevent these issues. Companies have also had success with hygiene workshops to properly show and explain good hygiene practices to their employees. Wildlife and animals should not be prohibited from the production of romaine lettuce. Fences and wild animal deterrence mechanisms should be in place to prevent animals such as wild pigs, wild or domestic dogs, birds, rabbits, and other animals from getting into contact with lettuce production. Any fields that experience flooding are considered adulterers and cannot be used for human consumption. Flooding can cause water runoff from nearby contaminated sources; the most common being runoff from livestock pastures. Any water source used in irrigation should be tested for high levels of the bacterium. Irrigation systems should also be cleaned and sanitized thoroughly to prevent bacteria buildup. Establishing SSOP’s (Standard Operating Procedures) and sanitation schedules are key for the prevention of deadly outbreaks. Escherichia coli in romaine lettuce is a common, preventable bacteria outbreak in the food industry. To prevent harming consumers' health and damaging the company’s reputation and consumer trust, E coli preventative practices should be taken seriously and managed properly. It only takes one mistake or gap in a company’s prevention and HACCP plan to cause a disease outbreak. Outbreaks are dangerous to the public’s health and are especially dangerous to persons who are immunosuppressed, elderly, young children, or infants. Washing romaine lettuce thoroughly with running water and food-grade sanitizers can prevent and inhibit the growth of E. coli.

In conclusion, plans should be in place to prevent these outbreaks. Escherichia coli in romaine lettuce is easily preventable and should be taken seriously. It only takes one mistake and one outbreak to cause an E. coli outbreak.

References:

Center for Food Safety and Applied Nutrition. (n.d.). Investigation report on THREE outbreaks of E. COLI o157:h7 in 2019. Retrieved March 29, 2021, from https://www.fda.gov/food/outbreaks-foodborne-illness/factors-potentially-contributing-contamination-romaine-lettuce-implicated-three-outbreaks-e-coli#:~:text=In%20November%20and%20December%202019,Salinas%20Valley%20area%20of%20California.

E. coli (escherichia coli). (2021, March 11). Retrieved March 29, 2021, from https://www.cdc.gov/ecoli/index.html

Heiman, K. E., Mody, R. K., Johnson, S. D., Griffin, P. M., & Gould, L. H. (2015). Escherichia coliO157 outbreaks in the United States, 2003–2012. Emerging Infectious Diseases,21(8). doi:10.3201/eid2108.141364

Jay-Russell, M. T., Hake, A. F., Bengson, Y., Thiptara, A., & Nguyen, T. (2014). Prevalence and characterization of Escherichia coli and salmonella strains isolated from stray dog and Coyote feces in a MAJOR leafy Greens production region at the UNITED States-Mexico Border. PLoS ONE, 9(11). doi:10.1371/journal.pone.0113433

Keskinen, L. A., & Annous, B. A. (2011). Efficacy of adding detergents TO SANITIZER solutions for inactivation of Escherichia COLI O157:H7 on romaine lettuce. International Journal of Food Microbiology, 147(3), 157-161. doi:10.1016/j.ijfoodmicro.2011.04.002

Outbreak of E. coli Infections linked to romaine lettuce. (2019, January 09). Retrieved March 29, 2021, from https://www.cdc.gov/ecoli/2018/o157h7-11-18/index.html

Outbreak of E. coli Infections linked to romaine lettuce. (2020, January 15). Retrieved March 29, 2021, from https://www.cdc.gov/ecoli/2019/o157h7-11-19/index.html

PARTYKA, M. L., BOND, R. F., FARRAR, J., FALCO, A., CASSENS, B., CRUSE, A., & ATWILL, E. R. (2014). Quantifying the sensitivity of scent detection dogs to identify fecal contamination on raw produce. Journal of Food Protection, 77(1), 6-14. doi:10.4315/0362-028x.jfp-13-249