Presence of Escherichia Coli O157:H7 on Lettuce

3531 words (14 pages) Essay

8th Feb 2020 Biology Reference this

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Escherichia coli bacteria make up many different serotypes.  The serotype that was determined to affect humans is E. coli 0157:H7.  Serotyping is completed to determine the different complements of the bacteria (Bell et al. 1349). 

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Escherichia coli (E. coli) O157:H7 is a bacterial pathogen and is considered a hazard to human health (Perna et al. 529).  The results of contracting this bacterium is food poisoning (Riley et al. 681).  E. coli is known to cause severe abdominal pain, diarrhea, and on occasion vomiting.  It is estimated that approximately 75,000 cases of E. coli infection occur yearly in the Unites States.  One common way that E. coli O157:H7 is often contracted is through consummation of contaminated food (Perna et al. 529).  The first case of E. coli infecting humans was following an epidemic of spoiled ground beef in 1982.  This meat infected individuals across multiple states and was concluded to have started from Michigan (Perna et al. 529).  After this outbreak individuals started recognizing infection from E. coli as an issue. 

  The main reason why infection from E. coli is threatening to humans is because of the Shiga toxin it produces (Griffin and Tauxe, 60).  Shiga toxin is known to be a leading cause for cases developing into hemolytic uremic syndrome (HUS) (Tarr et al.1073).  The symptoms of this syndrome are the following: abdominal pain, dysentery, fever, pale skin, vomiting, and diarrhea (Parmar).  This would be an extreme case of infection and does not often occur for those who get food poisoning from E. coli.  Hemolytic uremic syndrome is mainly seen in the elderly and children under five years of age.  Most others who experience signs of infection have bloody diarrhea and abdominal pain but not severe.  Symptoms usually appear 2-5 days following exposure to the pathogen, and can last 5-10 days.  In most cases, there is no treatment given because symptoms disappear in a few days.  Studies have been completed to determine if the idea that individuals who receive antibiotic treatment then develop HUS (Wong et al. 1930).  According to, “The Risk of the Hemolytic–Uremic Syndrome after Antibiotic Treatment of Escherichia coli O157:H7 Infections” article no evidence has been provided supporting this hypothesis.  However, the researchers still do not recommend treatment by antibiotics for this momentary infection (Wong et al. 1930). 

 E. coli 0157:H7 has been linked to meat from multiple animals including cattle, pigs, chicken, sheep, and deer (Keen et al. 780).  The other major transmission of this pathogen is through crops. Lettuce is one of the leading reservoirs for this bacterium and has been responsible for multiple outbreaks.  E. coli bacteria can persist in small numbers in soils and on crops.  On occasion, conditions in the field lead to contamination of the produce.  This is a problem for lettuce and other crops because it is often eaten uncooked.  Poisoning of the produce can occur when the being harvested and processed or before while still growing.  Application of raw manure or contaminated water source are ways that lettuce could be polluted prior to harvest.  The raw manure can come from livestock or wild-animals which is hard to regulate.  Manure is also often applied as a fertilizer but the manure could have not been composted properly leading to contamination of the crop.  Escherichia coli 0157:H7 can subsist in the field a duration of approximately four to eight weeks.  The National Organic Program gives a standard of at least one hundred twenty days between when the manure is applied to the crop and when it is gathered.  The bacterium can have greater longevity of survival when in cool temperatures and clay soils (Cooley et al. 2329).

 Microorganisms are responsible for some reduction of bacterium that are found in the field.  Microorganisms compete with the pathogens thus reducing their prevalence on the produce (Cooley et al. 2329).  Studies have been completed with how the effects of other bacteria effect the growth of E. coli.  Endurance of the 0157:H7 E. coli was increased by Wausteria paucula when the lettuce was grown from vaccinated lettuce seed.  However, Enterobacter asburiae diminished the survival of E. coli 0157:H7 on the leaves of the lettuce (Cooley et al. 2329). 

 With these techniques in mind, the options of how to control E. coli 0157:H7 production on leaf lettuce will be discussed.  The options of water irrigation and its effect on lettuce will be analyzed, and if the idea of E. coli being contracted at industrial plants where the lettuce is packaged and distributed is a concern. 

 Today many foods are prepared in large industrial facilities.  The companies have numerous amounts of product circulating daily.  This is especially true of produce and namely lettuce.  Many gardeners may plant lettuce in their yearly garden but due to small production (one plant only produces one head of iceberg lettuce) most leafy greens are bought in grocery stores.  This mass production of lettuce can lead to contamination of the product by bacterium (Stuart).  E. coli 0157:H7 is a concern for lettuce and must be regulated and observed carefully to ensure products sold to the public are clean and healthy for consumption.  One noteworthy outbreak of E. coli 0157:H7 from a manufacturing setting was an episode with contaminated spinach in 2006 (Stuart).  In general, the packaging companies tend to devote their time to sterilizing the growing environment and not to making the necessary changes in the processing system (Stuart). 

 Many efforts are being made by production facilities to confirm that the produce shipped out to consumers is safe.  Through major outbreaks the concern for food safety has heightened, and new ideas of isolation have sprung forth.  For example, industrial facilities have quality assurance staff who inspect the trailers delivering the produce for mold or bugs.  This is one avenue to prevent bacterium from entering the work environment.  If the inspector identifies any bacterium on the lettuce the produce will not be accepted.  Also, numerous swabs for bacteria are taken daily in most facilities to check for bacteria in the work environment and on the equipment the lettuce and other produce travel on. 

 Another method of protection from bacterium like E. coli from infecting lettuce and other produce is antimicrobial food packaging.  This process is known as active packaging and it works by adding active components into the packaging system.  This process is capable to eliminate pathogenic microorganisms and prevent spoilage of the lettuce.  Antimicrobial packaging works by reducing the growth rate of bacterium and lessening the number of live counts of microbes.  This type of packaging is explicitly designed to increase shelf-life and ensure safety and quality of the product (Ahvenainen, 50).  Treatment for various foods can include antimicrobials like bacteriocins, fungicides, or polymers (Ahvenainen, 54).  However, to treat E. coli on lettuce natural extracts are used; for example, grapefruit seed extract, herb-extract, and silver-zirconium (Ahvenainen, 55).  This is a harmless way to prevent bacterium on lettuce and supply the produce lasting effects. 

 Another way that E. coli 0157:H7 is spread to lettuce is from polluted water irrigation systems and contaminated soil.  These are simple forms of transportation that take place while the crops are still growing.  As has been discussed, Escherichia coli 0157:H7 prospers well in cool wet climates which makes unclean water and soil an excellent reservoir for the bacterium.  This phenomenon was tested by using laser scanning microscopy, fluorescence microscopy, and retrieval of viable cells from the inside tissues of the lettuce plants.  The bacterium moves inside of the plant tissues and are then protected from the sanitizing agents because they can not reach the E. coli.  Through research it has been proven that E. coli comes enter into the lettuce by means of the root system and moves throughout the edible section of the plant.  The soil is contaminated when untreated or improperly treated manure is used (Solomon et al. 397).  According to the article, “Transmission of Escherichia coli O157:H7 from Contaminated Manure and Irrigation Water to Lettuce Plant Tissue and Its Subsequent Internalization” 8.3% of cattle have E. coli 0157:H7 present in their waste.  If this feces is not handled properly it can easily infect the crops.  Even though a time of composting is required for all feces, E. coli 0157:H7 has longevity that may have not been originally expected.  In the event of flooding, the feces have the opportunity to enter the fields of lettuce and contaminate the crop (Solomon et al. 397).  Likewise, if contaminated water enters the irrigation system the same process is able to take place.  Escherichia coli 0157:H7 is able to survive in water for an extended amount of time (Solomon et al. 397).

 When lettuce is taken to a production facility washing of the crop takes place.  However, since the bacterium is not on the surface area the washing step is not fully effective to alleviate the plant of all of the E. coli 0157:H7.  If the bacterium was on the surface the washing would be enough to clean the product.  Chlorine is added to the water as an extra measure of sanitation, but it is only slightly effective for the cells that are below the surface of the leaf (Solomon et al. 397). 

Furthermore, direct contact with the contaminated water or manure is not required for the crop to become infected with bacterium.  The roots of the plant are the only mechanism necessary to infect the lettuce with E. coli.  E. coli is able to go beyond the surface of the lettuce and contaminate the edible portion of the plant making washing alone not enough to ensure safety for consumption (Solomon et al. 400).

There are specific steps the consumers can take to help prevent consumption of the E. coli 0157:H7 on the lettuce they eat.  The main issues that seem to occur when preparing food at home for individuals is the incomplete washing of the lettuce, not properly washing hands when working with food, cross-contamination, and not storing produce at the correct temperature (Cohen and Bruhn, 1287).

When consumers buy produce at the grocery store it is recommended to bag the produce separately from other products, such as meat and poultry.  However, when shoppers were inquired about bagging produce separately to limit microbe contamination few reported they followed these recommendations (Cohen and Bruhn, 1289).

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Next, the consumers were asked how they wash their lettuce after getting it home.  The following ways to wash were questioned: “rubbing with hands, washing under running water, scrubbing with a brush, chlorine solution, and soaking the product” (Cohen and Bruhn, 1289).  The results were overwhelming for simply washing the lettuce by rinsing it under running water.   The second most common technique was to the lettuce in a container or the sink.  A small percentage of individuals chose to not wash the lettuce at all (Cohen and Bruhn, 1289).  By not washing the lettuce the chance for contraction contamination by E. coli is increased.

 The means of storage of the product is another form that leads to questioning when concerned with keeping microbe counts limited.  Most consumers keep lettuce on the refrigerator shelf or located in the refrigerator fruit/vegetable drawer (Cohen and Bruhn, 1290).  Proper storage of lettuce in the refrigerator is vital to keeping it fresh and good to eat. 

Hand washing before handling food is a necessary step to keep bacteria off of food.  According to the study, only approximately half of the people wash their hands before handling produce (Cohen and Bruhn, 1289).  Without this important step the likelihood of microbes contaminating the food is increased. 

Cleaning of the refrigerator regularly is another means of keeping microbe levels to a minimum.  If the refrigerator is cleaned and disinfected the number of contaminations on produce and other food would be minimized.  For the majority of people when asked how often they clean their refrigerator responded with once a month or two to three times a year.  It was less often for individuals to report cleaning once a week.  There were a few exceptions of people cleaning yearly or less than one time per year (Cohen and Bruhn, 1291).  

It is also important to clean the preparation area before and after handling fresh produce.  It is also vital to not cross-contaminate preparation areas.  For example, do not cut meat and then chop lettuce with the same knife and same area where the raw meat was prepared.  If there was E. coli on the meat it would then infect the lettuce which is consumed raw.  Most people wash the work station following cutting of lettuce than they do before cutting.  In contrast, most people reported cleaning the sink before preparing fresh produce as opposed to after (Cohen and Bruhn, 1292). 

Overall, consumers need to improve handling of lettuce and other produce while at the store by bagging separately to prevent contact with raw meat.  Lettuce should be stored away from meat in the refrigerator to prevent cross-contamination.  Hand-washing before preparation of food should be conducted routinely.  Food preparation surfaces should be cleaned before and after cutting of lettuce.  Disinfection and cleaning the refrigerator regularly at least once a month is suggested.  If these recommendations are followed the occurrence of E. coli 0157:H7 on lettuce could be limited by these techniques of precaution.

In conclusion, Escherichia coli 0157:H7 is a bacterial pathogen that can be found on lettuce.  Lettuce can become contaminated by raw manure, contaminated water, and manure that has not been composted properly and is being used as a fertilizer.  Another form of contamination is from packaging facilities and industrial plants where lettuce is shipped from.  Bacterium is able to go beyond the surface and will not be washed off with merely chlorinated water.  The bacterium can travel through the roots of the lettuce plant and infect the edible portion of the vegetable without direct contact with the E. coli

When lettuce is prepared at a packaging facility there is chance of contamination by the equipment used in transportation of the food.  Quality assurance technicians swab the areas and test for microbes to ensure that bacterium is not viable.  The technicians also evaluate the product before the facility accepts the lettuce in case of previous contamination or bugs on the lettuce.  Antimicrobial food packaging is an inventive way that companies have discovered to treat lettuce and other produce in order to eliminate microbe growth and give increase longevity of the product. 

Lettuce can become infected by E. coli 0157:H7 by polluted water irrigation and/or contaminated soil.  E. coli is often found in cattle’s feces.  This can be applied to the lettuce as a fertilizer or by flooding of water which spreads it to the fields with the crop.  Also, wild animals travel through the fields of the crop and can drop contaminated waste onto the lettuce.  E. coli is able to move through the root system of lettuce and infect the leaves below the surface level.  Laser scanning, fluorescence microscopy, and viable cell harvesting are laboratory techniques that can be used to test if E. coli has infected tissues inside the plants.  Chlorine is added to the water as a way to ensure cleaning of the lettuce when taken to a processing facility.  However, for the plants infected with E. coli below the surface chorine will only be slightly effective.  The chlorine water will not be able to remove all of the E. coli because it is below the exterior level. 

There are techniques that can be used to minimize the concern of being infected with E. coli by taking precautions with handlings, preparation, and storage of the lettuce.  Proper bagging of the lettuce, washing of the surfaces and knives used to prepare the product, washing hands before handling food, storing the lettuce in the refrigerator away from raw meat, and maintaining clean facilities are all ways to reduce the chance of infection by E. coli 0157:H7 from lettuce.  Eliminating cross-contamination of vegetables and meat will also alleviate a major opportunity for E. coli to be spread. 

Through these techniques and a growing understanding of E. coli 0157:H7 on lettuce the prevalence of infections can be limited. 

Works Cited

Escherichia coli bacteria make up many different serotypes.  The serotype that was determined to affect humans is E. coli 0157:H7.  Serotyping is completed to determine the different complements of the bacteria (Bell et al. 1349). 

Escherichia coli (E. coli) O157:H7 is a bacterial pathogen and is considered a hazard to human health (Perna et al. 529).  The results of contracting this bacterium is food poisoning (Riley et al. 681).  E. coli is known to cause severe abdominal pain, diarrhea, and on occasion vomiting.  It is estimated that approximately 75,000 cases of E. coli infection occur yearly in the Unites States.  One common way that E. coli O157:H7 is often contracted is through consummation of contaminated food (Perna et al. 529).  The first case of E. coli infecting humans was following an epidemic of spoiled ground beef in 1982.  This meat infected individuals across multiple states and was concluded to have started from Michigan (Perna et al. 529).  After this outbreak individuals started recognizing infection from E. coli as an issue. 

  The main reason why infection from E. coli is threatening to humans is because of the Shiga toxin it produces (Griffin and Tauxe, 60).  Shiga toxin is known to be a leading cause for cases developing into hemolytic uremic syndrome (HUS) (Tarr et al.1073).  The symptoms of this syndrome are the following: abdominal pain, dysentery, fever, pale skin, vomiting, and diarrhea (Parmar).  This would be an extreme case of infection and does not often occur for those who get food poisoning from E. coli.  Hemolytic uremic syndrome is mainly seen in the elderly and children under five years of age.  Most others who experience signs of infection have bloody diarrhea and abdominal pain but not severe.  Symptoms usually appear 2-5 days following exposure to the pathogen, and can last 5-10 days.  In most cases, there is no treatment given because symptoms disappear in a few days.  Studies have been completed to determine if the idea that individuals who receive antibiotic treatment then develop HUS (Wong et al. 1930).  According to, “The Risk of the Hemolytic–Uremic Syndrome after Antibiotic Treatment of Escherichia coli O157:H7 Infections” article no evidence has been provided supporting this hypothesis.  However, the researchers still do not recommend treatment by antibiotics for this momentary infection (Wong et al. 1930). 

 E. coli 0157:H7 has been linked to meat from multiple animals including cattle, pigs, chicken, sheep, and deer (Keen et al. 780).  The other major transmission of this pathogen is through crops. Lettuce is one of the leading reservoirs for this bacterium and has been responsible for multiple outbreaks.  E. coli bacteria can persist in small numbers in soils and on crops.  On occasion, conditions in the field lead to contamination of the produce.  This is a problem for lettuce and other crops because it is often eaten uncooked.  Poisoning of the produce can occur when the being harvested and processed or before while still growing.  Application of raw manure or contaminated water source are ways that lettuce could be polluted prior to harvest.  The raw manure can come from livestock or wild-animals which is hard to regulate.  Manure is also often applied as a fertilizer but the manure could have not been composted properly leading to contamination of the crop.  Escherichia coli 0157:H7 can subsist in the field a duration of approximately four to eight weeks.  The National Organic Program gives a standard of at least one hundred twenty days between when the manure is applied to the crop and when it is gathered.  The bacterium can have greater longevity of survival when in cool temperatures and clay soils (Cooley et al. 2329).

 Microorganisms are responsible for some reduction of bacterium that are found in the field.  Microorganisms compete with the pathogens thus reducing their prevalence on the produce (Cooley et al. 2329).  Studies have been completed with how the effects of other bacteria effect the growth of E. coli.  Endurance of the 0157:H7 E. coli was increased by Wausteria paucula when the lettuce was grown from vaccinated lettuce seed.  However, Enterobacter asburiae diminished the survival of E. coli 0157:H7 on the leaves of the lettuce (Cooley et al. 2329). 

 With these techniques in mind, the options of how to control E. coli 0157:H7 production on leaf lettuce will be discussed.  The options of water irrigation and its effect on lettuce will be analyzed, and if the idea of E. coli being contracted at industrial plants where the lettuce is packaged and distributed is a concern. 

 Today many foods are prepared in large industrial facilities.  The companies have numerous amounts of product circulating daily.  This is especially true of produce and namely lettuce.  Many gardeners may plant lettuce in their yearly garden but due to small production (one plant only produces one head of iceberg lettuce) most leafy greens are bought in grocery stores.  This mass production of lettuce can lead to contamination of the product by bacterium (Stuart).  E. coli 0157:H7 is a concern for lettuce and must be regulated and observed carefully to ensure products sold to the public are clean and healthy for consumption.  One noteworthy outbreak of E. coli 0157:H7 from a manufacturing setting was an episode with contaminated spinach in 2006 (Stuart).  In general, the packaging companies tend to devote their time to sterilizing the growing environment and not to making the necessary changes in the processing system (Stuart). 

 Many efforts are being made by production facilities to confirm that the produce shipped out to consumers is safe.  Through major outbreaks the concern for food safety has heightened, and new ideas of isolation have sprung forth.  For example, industrial facilities have quality assurance staff who inspect the trailers delivering the produce for mold or bugs.  This is one avenue to prevent bacterium from entering the work environment.  If the inspector identifies any bacterium on the lettuce the produce will not be accepted.  Also, numerous swabs for bacteria are taken daily in most facilities to check for bacteria in the work environment and on the equipment the lettuce and other produce travel on. 

 Another method of protection from bacterium like E. coli from infecting lettuce and other produce is antimicrobial food packaging.  This process is known as active packaging and it works by adding active components into the packaging system.  This process is capable to eliminate pathogenic microorganisms and prevent spoilage of the lettuce.  Antimicrobial packaging works by reducing the growth rate of bacterium and lessening the number of live counts of microbes.  This type of packaging is explicitly designed to increase shelf-life and ensure safety and quality of the product (Ahvenainen, 50).  Treatment for various foods can include antimicrobials like bacteriocins, fungicides, or polymers (Ahvenainen, 54).  However, to treat E. coli on lettuce natural extracts are used; for example, grapefruit seed extract, herb-extract, and silver-zirconium (Ahvenainen, 55).  This is a harmless way to prevent bacterium on lettuce and supply the produce lasting effects. 

 Another way that E. coli 0157:H7 is spread to lettuce is from polluted water irrigation systems and contaminated soil.  These are simple forms of transportation that take place while the crops are still growing.  As has been discussed, Escherichia coli 0157:H7 prospers well in cool wet climates which makes unclean water and soil an excellent reservoir for the bacterium.  This phenomenon was tested by using laser scanning microscopy, fluorescence microscopy, and retrieval of viable cells from the inside tissues of the lettuce plants.  The bacterium moves inside of the plant tissues and are then protected from the sanitizing agents because they can not reach the E. coli.  Through research it has been proven that E. coli comes enter into the lettuce by means of the root system and moves throughout the edible section of the plant.  The soil is contaminated when untreated or improperly treated manure is used (Solomon et al. 397).  According to the article, “Transmission of Escherichia coli O157:H7 from Contaminated Manure and Irrigation Water to Lettuce Plant Tissue and Its Subsequent Internalization” 8.3% of cattle have E. coli 0157:H7 present in their waste.  If this feces is not handled properly it can easily infect the crops.  Even though a time of composting is required for all feces, E. coli 0157:H7 has longevity that may have not been originally expected.  In the event of flooding, the feces have the opportunity to enter the fields of lettuce and contaminate the crop (Solomon et al. 397).  Likewise, if contaminated water enters the irrigation system the same process is able to take place.  Escherichia coli 0157:H7 is able to survive in water for an extended amount of time (Solomon et al. 397).

 When lettuce is taken to a production facility washing of the crop takes place.  However, since the bacterium is not on the surface area the washing step is not fully effective to alleviate the plant of all of the E. coli 0157:H7.  If the bacterium was on the surface the washing would be enough to clean the product.  Chlorine is added to the water as an extra measure of sanitation, but it is only slightly effective for the cells that are below the surface of the leaf (Solomon et al. 397). 

Furthermore, direct contact with the contaminated water or manure is not required for the crop to become infected with bacterium.  The roots of the plant are the only mechanism necessary to infect the lettuce with E. coli.  E. coli is able to go beyond the surface of the lettuce and contaminate the edible portion of the plant making washing alone not enough to ensure safety for consumption (Solomon et al. 400).

There are specific steps the consumers can take to help prevent consumption of the E. coli 0157:H7 on the lettuce they eat.  The main issues that seem to occur when preparing food at home for individuals is the incomplete washing of the lettuce, not properly washing hands when working with food, cross-contamination, and not storing produce at the correct temperature (Cohen and Bruhn, 1287).

When consumers buy produce at the grocery store it is recommended to bag the produce separately from other products, such as meat and poultry.  However, when shoppers were inquired about bagging produce separately to limit microbe contamination few reported they followed these recommendations (Cohen and Bruhn, 1289).

Next, the consumers were asked how they wash their lettuce after getting it home.  The following ways to wash were questioned: “rubbing with hands, washing under running water, scrubbing with a brush, chlorine solution, and soaking the product” (Cohen and Bruhn, 1289).  The results were overwhelming for simply washing the lettuce by rinsing it under running water.   The second most common technique was to the lettuce in a container or the sink.  A small percentage of individuals chose to not wash the lettuce at all (Cohen and Bruhn, 1289).  By not washing the lettuce the chance for contraction contamination by E. coli is increased.

 The means of storage of the product is another form that leads to questioning when concerned with keeping microbe counts limited.  Most consumers keep lettuce on the refrigerator shelf or located in the refrigerator fruit/vegetable drawer (Cohen and Bruhn, 1290).  Proper storage of lettuce in the refrigerator is vital to keeping it fresh and good to eat. 

Hand washing before handling food is a necessary step to keep bacteria off of food.  According to the study, only approximately half of the people wash their hands before handling produce (Cohen and Bruhn, 1289).  Without this important step the likelihood of microbes contaminating the food is increased. 

Cleaning of the refrigerator regularly is another means of keeping microbe levels to a minimum.  If the refrigerator is cleaned and disinfected the number of contaminations on produce and other food would be minimized.  For the majority of people when asked how often they clean their refrigerator responded with once a month or two to three times a year.  It was less often for individuals to report cleaning once a week.  There were a few exceptions of people cleaning yearly or less than one time per year (Cohen and Bruhn, 1291).  

It is also important to clean the preparation area before and after handling fresh produce.  It is also vital to not cross-contaminate preparation areas.  For example, do not cut meat and then chop lettuce with the same knife and same area where the raw meat was prepared.  If there was E. coli on the meat it would then infect the lettuce which is consumed raw.  Most people wash the work station following cutting of lettuce than they do before cutting.  In contrast, most people reported cleaning the sink before preparing fresh produce as opposed to after (Cohen and Bruhn, 1292). 

Overall, consumers need to improve handling of lettuce and other produce while at the store by bagging separately to prevent contact with raw meat.  Lettuce should be stored away from meat in the refrigerator to prevent cross-contamination.  Hand-washing before preparation of food should be conducted routinely.  Food preparation surfaces should be cleaned before and after cutting of lettuce.  Disinfection and cleaning the refrigerator regularly at least once a month is suggested.  If these recommendations are followed the occurrence of E. coli 0157:H7 on lettuce could be limited by these techniques of precaution.

In conclusion, Escherichia coli 0157:H7 is a bacterial pathogen that can be found on lettuce.  Lettuce can become contaminated by raw manure, contaminated water, and manure that has not been composted properly and is being used as a fertilizer.  Another form of contamination is from packaging facilities and industrial plants where lettuce is shipped from.  Bacterium is able to go beyond the surface and will not be washed off with merely chlorinated water.  The bacterium can travel through the roots of the lettuce plant and infect the edible portion of the vegetable without direct contact with the E. coli

When lettuce is prepared at a packaging facility there is chance of contamination by the equipment used in transportation of the food.  Quality assurance technicians swab the areas and test for microbes to ensure that bacterium is not viable.  The technicians also evaluate the product before the facility accepts the lettuce in case of previous contamination or bugs on the lettuce.  Antimicrobial food packaging is an inventive way that companies have discovered to treat lettuce and other produce in order to eliminate microbe growth and give increase longevity of the product. 

Lettuce can become infected by E. coli 0157:H7 by polluted water irrigation and/or contaminated soil.  E. coli is often found in cattle’s feces.  This can be applied to the lettuce as a fertilizer or by flooding of water which spreads it to the fields with the crop.  Also, wild animals travel through the fields of the crop and can drop contaminated waste onto the lettuce.  E. coli is able to move through the root system of lettuce and infect the leaves below the surface level.  Laser scanning, fluorescence microscopy, and viable cell harvesting are laboratory techniques that can be used to test if E. coli has infected tissues inside the plants.  Chlorine is added to the water as a way to ensure cleaning of the lettuce when taken to a processing facility.  However, for the plants infected with E. coli below the surface chorine will only be slightly effective.  The chlorine water will not be able to remove all of the E. coli because it is below the exterior level. 

There are techniques that can be used to minimize the concern of being infected with E. coli by taking precautions with handlings, preparation, and storage of the lettuce.  Proper bagging of the lettuce, washing of the surfaces and knives used to prepare the product, washing hands before handling food, storing the lettuce in the refrigerator away from raw meat, and maintaining clean facilities are all ways to reduce the chance of infection by E. coli 0157:H7 from lettuce.  Eliminating cross-contamination of vegetables and meat will also alleviate a major opportunity for E. coli to be spread. 

Through these techniques and a growing understanding of E. coli 0157:H7 on lettuce the prevalence of infections can be limited. 

Works Cited

  • Ahvenainen, Raija. “Novel Food Packaging Techniques”.  Food Science and Technology. Woodhead Publishing: 2003, pp. 50-60. 11 November 2018.
  • Bell, B.P., et al. “A multistate outbreak of Escherichia coli O157:H7-associated bloody diarrhea and hemolytic uremic syndrome from hamburgers: the Washington experience.” Journal of American Medical Association, 1994, Vol. 272, pp. 1349-1353. 11 November 2018.
  • Cooley, Michael B, Chao, Diana, Mandrell, Robert E. “Escherichia coli O157:H7 Survival and Growth on Lettuce Is Altered by the Presence of Epiphytic Bacteria”. Journal of Food Protection: October 2006, Vol. 69, No. 10, pp. 2329-2335. 11 November 2018.
  • Griffin, Patricia and Tauxe, Robert. “The Epidemiology of Infections Caused by Escherichia coli O157:H7, Other Enterohemorrhagic E. coli, and the Associated Hemolytic Uremic Syndrome”. Epidemiological Review: 1991, Vol. 13, pp. 60-98. 11 November 2018.
  • Keen, J.E., et al., “Shiga-toxigenic Escherichia coli O157 in agricultural fair livestock, United States”. Emerging Infectious Diseases: 2003, Vol. 12, No. 5, pp. 780-86. 11 November 2018.
  • Parmar, Malvinder, S. “Hemolytic-Uremic Syndrome”. Medscape. 16 November 2017. 11 November 2018.
  • Perna, Nicole T, Plunkett, Guy, Blattner, Frederick, R. “Genome Sequence of Enterohaemorrhagic Escherichia coli O157:H7”. International Journal of Science. Nature: 25 January 2001, Vol. 409, pp. 529-533. 11 November 2018.
  • Riley, LW, et al., “Hemorrhagic colitis associated with a rare Escherichia coli serotype,” New England Journal of Medicine: 1983, Vol. 308, No. 12, pp. 681, 684-85. 11 November 2018.
  • Solomon, Ethan B., Yaron, Sima, Matthews, Karl R. “Transmission of Escherichia coli O157:H7 from Contaminated Manure and Irrigation Water to Lettuce Plant Tissue and Its Subsequent Internalization”. Appl. Environ. Microbiol. Jan 2002, 68 (1) 397-400. 11 November 2018.
  • Stuart, Diana. “The Illusion of Control: Industrialized Agriculture, Nature, and Food Safety”. Agriculture and Human Values. Springer Nature: 22 January 2008. 11 November 2018.
  • Tarr, Phillip I., Gordon, Carrie, A., Chandler, Wayne. “Shiga-Toxin-Producing Escherichia coli and Haemolytic Uraemic Syndrome”. Science Direct. The Lancet: March 2005, Vol. 365, Issue 9464, pp. 1073-1086. 11 November 2018.
  • Wong, Craig, S., Watkins, Sandra L., Tarr, Phillip I., et al. “The Risk of the Hemolytic–Uremic Syndrome after Antibiotic Treatment of Escherichia coli O157:H7 Infections”. The New England Journal of Medicine. Massachusetts Medical Society: 29 June 2000, pp. 1930-1936. 11 November 2018.

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