Food Microbiology Report: E. coli Contamination in Cheese Production

This report provides a comprehensive overview of E. coli, a gram-negative facultative anaerobic bacteria, and its implications in food microbiology, specifically focusing on cheese production. It discusses the sources of E. coli contamination, including raw milk, and the potential for foodborne illnesses. The report highlights the clinical presentation of E. coli infections, including the Shiga toxin-producing strains, and the critical control points in cheese production where contamination can occur. It further explores primary and secondary infection routes, as well as the identification and subtyping methods used to analyze E. coli O157, including MLVA profiling. The report concludes by linking evidence of E. coli contamination in cheese production to potential systemic infections and public health concerns, emphasizing the importance of pasteurization and food safety practices. The report references several studies related to E. coli and its impact on food safety.

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FOOD MICROBIOLOGY

Food Microbiology
Microbiology of E coli
E coli is a gram positive facultative anaerobic bacteria, which is found in the lower
intestine of living organisms. E coli have certain serotypes which causes serious harm in the
hosts and is responsible for food poisoning. E coli contamination has been associated to
products produces in large scale and has led to food recalls due to the contamination already
caused, (Vogit & Dippold, 2005). Normally there are strains of E Coli which are harmless,
they are referred to as normal flora and produce vitamin k2 in their hosts, (Haudault et al,
2001), and is essential in preventing colonization process in the intestines.
The genesis of E Coli is from faecal matter and is expelled from the environment
whereby it causes contamination. The bacteria nourishes well in faecal matter for a period of
3 days, (Russell & Javis, 2001). Thus E coli is attributed to many disease which include
cholecystisis, bacteraemia, urinary tract infections among other diseases.
Clinical presentation of E Coli
E coli being a gram negative anaerobic makes ATP and at the same time switch to
fermentation in the absence of oxygen. They exist in the intestines of humans and animals.
Harmful E Coli are often pathogenic and can cause illness through causing diarrhoea or
illness outside the intestinal path. Diarrhoea causing E coli can be transmitted in water or
food or through contact with animals or people.
The Shiga toxin producing E Coli or Verocytotoxin producing E Coli is the most
common heard type of infection and has been associated with food borne outbreaks. The
toxin referred to shiga causes damages the intestines linings. The bad strain identified as
O157:H7 can make people very sick. It is associated with abdominal; pains, cramps and
blood in the diarrheal flow. At times it is responsible for acute kidney failure among children.
Further it is associated with bleeding, confusion, seizures or bleeding.
Cheese and E coli contamination
Raw milk has been found to contain various germs such as the bacteria, viruses and
paracistes.raw milk has not yet undergone pasteurization that is heated to specific
temperature for set amount of time in order to destroy harmful germs. Thus raw milk is
unpasteurized and can contain harmful germs which include campylobacteria, E Coli, Listeria
and Slamonnela, (Mathews et al., 2006).
Thus cheese can cause E Coli due to the raw product of which is milk which is not
pasteurized. Thus cheese from unpasteurized milk cause the E coli contamination if the
bacteria strains are present in the milk, thus is a risk factor for shiga toxins, (Lejeune et
al.,2001).
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Food Microbiology
Critical control points of cheese production include raw milk obtained from the
animals. The six steps in cheese production include acidification, coagulation, curd and whey,
salting, shaping and ripening. The critical steps which can bring contamination include
acidification and coagulation steps.
Primary and Secondary infections of E Coli
E coli can be contaminated in other substances like water. Contact with water from a
person who has E Coli could affect and have an impact on infection. Further these individuals
could have had contact from one another especially from infected individuals, (Williams et
al, 2005).
Primary infections of E Coli include intake of untreated milk that is if one consume
unpasteurized milk, intake of fruits and vegetables washed using contaminated water,
consumption of her foods and beverages which might be contaminated.
Secondary infection can entail drinking water which is contaminated, contact from
infected persons or contact from animals already contaminated with the bacteria. Other
indirect sources include the use of chopping board that has uncooked meant and contact with
raw foods like salad.
E Coli O157 PT21/28
E Coli O157 is common name which means shared by cattle and it is the main reservoir
of human causing infections. The PT refers to Phage type 21/28 as a subtype of E coli. The
PT refers to the cases upon diagnosis and classification which refers to 21 cases in 28 disease.
It is used to describe the disease further and give a more elaborate meaning.
Identification of E Coli O157, is arrived at using the latex reagents which include O157
antibody coated latex and control latex. The isolation process being undertaken in O157
agglutination is identified through biochemical means of confirmation, (Kruger et al., 2006).
Lab confirmation and determination has to utilise with patients who present diarrhoea.
The stool specimens include whole, stool, swabs. With this approach specimens should be
taken immediately, (Lindstedt et al., 2004).
MLVA profiling of O157
Multi locus variable number tandem repat analysis is an established technique, which is
established under the sub typing and getting the genetic diversity of STEC. It is an
established technique to sub type E Coli O157, MLVA is a PCR based sub type method that
is used to discriminate the strains of different of bacteria based on the tandems, (LLucchesi et
al., 2006).
The modern molecular bacterial sequencing has been utilised under polymorophic
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Food Microbiology
molecular markets such as the Varibelk Number Tandem Repeats or the MLVA in a rapid
and specific way to discriminate on the different serotype using the PCR Amplification tool,
(Murphy et al., 2008).
Linking evidence
The cheese being made in Astone market could be linked to E Colli infection, as it was
observed to be common in the production process. The results obtained shows that E coli
bacteria could have potential systemic infection and contaminate the final products.
This evidence can be supported with the fact that cheese is produced from raw milk
which could be a direct linked for E Colli contamination. Thus is supported with the 26 cases
of same strain being identified among patients.
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Food Microbiology
Reference
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gastrointestinal tract protect germfree mice againstSalmonella typhimuriuminfection.
Gut, 49(1), 47-55.
Krüger, A., Padola, N. L., Parma, A. E., & Lucchesi, P. M. (2006). Intraserotype diversity
among Argentinian verocytotoxigenic Escherichia coli detected by random amplified
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LeJeune, J. T., Besser, T. E., & Hancock, D. D. (2001). Cattle Water Troughs as Reservoirs
ofEscherichia coli O157. Applied and Environmental Microbiology, 67(7), 3053-3057.
Lindstedt B.A., Vardund T., L., Kapperud G. Multiple-locus variable-number tandem-repeats
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Lucchesi, P. M., Krüger, A., & Parma, A. E. (2006). Distribution of saa gene variants in
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Matthews, L., Low, J. C., Gally, D. L., Pearce, M. C., Mellor, D. J., Heesterbeek, J. A. P., ...
& Gunn, G. J. (2006). Heterogeneous shedding of Escherichia coli O157 in cattle and
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Murphy, M., Minihan, D., Buckley, J. F., O'Mahony, M., Whyte, P., & Fanning, S. (2008).
Multiple-locus variable number of tandem repeat analysis (MLVA) of Irish
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dissemination routes. BMC veterinary research, 4(1), 2.
Russell, J. B., & Jarvis, G. N. (2001). Practical mechanisms for interrupting the oral-fecal
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Vogt, R. L., & Dippold, L. (2005). Escherichia coli O157: H7 outbreak associated with
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Williams, A. P., Avery, L. M., Killham, K., & Jones, D. L. (2005). Persistence of Escherichia
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