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Salmonellosis

S.enteritis causes diarrhoea, stomach cramps and fever. Known as salmonellosis. The classic signs of food poisoning. They can develop within 12 hours up to 3 days and can even last up to 1 week. Most patients that are hospitalised are due to severe dehydration, because of the above symptoms.

Salmonella is a major cause of human bacterial infections in the United States. According to the Centre for Disease Control and Prevention (CDC), Salmonella cause infections of around 1 million Americans every year, leading to 19,000 hospitalisations and 380 deaths. When considering bacteria such as E.coli 0157:H7 where although there are only 2 000 hospitalisations, 60 people die from this disease each year.

Transmission from Animals

You get Salmonella by eating foods that are contaminated by animal faeces. The most common foods that are contaminated with salmonella include animal products such as beef, poultry, milk, and eggs. However, any food is susceptible to contamination including fruits and vegetables.

Salmonella can be contracted directly from pets such as dogs, cats, birds, turtles, and fish. It can be spread from person to person when an infected person’s faeces contaminate food through unwashed hands.

Symptoms

Symptoms of salmonellosis include:

1. stomach cramps
2. bloody stools
3. diarrhoea
4. muscle pains
5. nausea
6. vomiting
7. dizziness
8. fever

How to prevent Salmonellosis

Preventing salmonellosis is a simple procedure:

1. Cooking your foods to an internal temperature of 75º C (167˚F) easily kills the bacteria.
2. Handling your raw meats (especially chicken/eggs) separately from ready to eat foods will greatly minimise this risk.
3. Keep foods properly refrigerated until ready to prepare and cook.
4. Handwashing and personal hygiene are essential in preventing cross-contamination.
5. Avoid eating high-risk foods, including raw or undercooked eggs.
6. Undercooked ground beef or poultry, and unpasteurised milk

Treatment

The  treatment of symptoms relate to dehydration in most cases. This means taking in fluids and replacing electrolytes in your body. Simple antibiotic treat will resolve further complications.

• Anti-diarrheals. Medications such as loperamide (Imodium A-D) can help relieve cramping, but they may also prolong the diarrhoea associated with salmonella infection.
• Antibiotics. If your doctor suspects that salmonella bacteria have entered your bloodstream, or if you have a severe case or a compromised immune system, he or she may prescribe antibiotics to kill the bacteria. Antibiotics are not of benefit in uncomplicated cases. In fact, antibiotics may prolong the period in which you carry the bacteria and can infect others, and they can increase your risk of relapse.

What are the food safety pillars?

• Cleaning & Sanitising
• Personal Hygiene
• Food Storage
• Temperature Control
• Food Handling

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There are two different types of bacteria involved with food.

The first types of bacteria involved with food are known as food spoilage bacteria and the second is known as food poisoning or pathogenic bacteria.

1. Food Spoilage Bacteria

These types of bacteria are easily detectable as they make the food go off (rancidification). We are able to see it, taste it and more commonly able to smell it. These act as warning signs to say do not eat this. They are generally not dangerous to your health, but certainly should not be consumed. These also require very high numbers of colonies to be consumed to be able to cause illness.

2. Pathogenic Bacteria

These types of bacteria involved with food, need very small amounts of bacterial colonies to be able to make you sick. These are the bacteria that we are most concerned with, as you cannot see it taste it or smell these bacteria. There are no indications that these bacteria are present in your food.

Within this broad category, there are specific bacteria that we are concerned with in the kitchen environment. This applies to both the home kitchen and a production kitchen such as restaurants, hotels and food service.

Escherichia coli (E.coli)

E.coli are one of the most commonly known food poisoning bacteria and are what we call an indicator organism. E.coli originates from our gut as well as in other mammals such as cattle. If E.coli originates in the gut, it, therefore, tells us that faecal matter is present, and occurs as a result of unhygienic practices.

E.coli is a gram-negative bacteria that is naturally occurring within the environment. Mostly in soil or in our gut.

Most E.coli strains are not pathogens, in other words, disease-causing bacteria. They do and can exist harmlessly with humans, and is an important part of our internal flora. This means the internal makeup of various bacteria in our gut that allows us to consume our food. These essentially keep bad pathogens at bay.

However, there are strains of E.coli that are dangerous such as E.coli O157:H7. These cause hemorrhagic gastroenteritis and can be severe. In general, E.coli is a bacterium that should be avoided.

E.coli mostly occurs in our gut and is present in raw meats. This bacteria becomes an indicator of unhygienic practices that may have taken place. Two perfect examples of this, are when we do not wash our hands after going to the toilet and when we do not wash our hands after the handling of raw meats.

Staphylococcus aureus (S.aureus)

S.aureus is a gram-positive bacteria that occurs naturally on the skin and nasal passages of humans. Usually, this bacterium is harmless in small numbers but, can cause skin infections if numbers get too high.

In food, S.aureus is concerning because it produces a heat-stable toxin, which can cause severe food poisoning. Heat-stable meaning that the toxin can survive cooking temperatures.

Can you guess why S.aureus is used as an indicator organism in food safety and hygiene?

Because S.aureus occurs in the nasal passages and on the skin, those that are natural carriers (10 to 15% of the world’s population) require antibiotic treatment to keep this bacteria at below infection levels.

This is so that those that work with food, do not cause further infection. Of course, hand-washing and preventing the touching of the nose are key areas in preventing contamination of food.

Finding this bacteria in food and/or on hands of food handlers tells us that there’s been some break in the food safety pillars. The potential for causing food poisoning increases dramatically when these are present.

These bacteria perfect examples of the two, most common causes of food poisoning.

Frequently Asked Questions

Bacteria Involved in Food Spoilage

Common bacteria involved in food spoilage:

1. Lactic acid formation: eg. Lactobacillus
2. Lipolysis: eg. Pseudomonas
3. Pigment formation: eg. Flavobacterium
4. Gas formation: eg. Lactobacillus
5. Slime or rope formation: eg. Enterobacter, Streptococcus

Bacteria Involved in Food Poisoning

Other pathogenic bacteria involved in food poisoning include:

1. Salmonella enteritidis
2. Listeria monocytogenes
3. Clostridium botulinum
4. Campylobacter

What are the food safety pillars?

• Cleaning & Sanitising
• Personal Hygiene
• Food Storage
• Temperature Control
• Food Handling

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What are bacteria?

Before we can understand how bacteria affect your food, we need to understand more about this microorganism.

How do we define bacteria?

Bacteria are single-celled microorganisms which can exist either as independent (free-living) organisms or as parasites (dependent upon another organism for life). They are about 0.5 to 2 micrometres in size. A grain of sand is 2 millimetres in size. This means you could fit 1000 bacterial cells into a single grain of sand. This means we can only see bacterial cells through the microscope.

Other than through the microscope, they form what we call “colonies” which have millions of cells which allow us to easily see them in a medium that is grown in the lab known as agar plates. This is the simplest method used, in order to identify and see bacteria. We use this method to count how many bacterial cells are present in for example a swab of a cutting board. Greater than 300 colonies is considered dirty and contaminated.

These were one of the very first organisms to exist on our planet, so they are very, very old and have co-existed with humans since the beginning. There are millions of different types of bacteria, some good for you and some very dangerous to your health.

So where can you find bacteria?

Bacteria live in water, soil, in plants and in animals. These microorganisms are so prominent on earth that they also live in some of the most extreme environments, such as the deep ocean, hot springs and there is even evidence that bacteria lived on Mars.

Bacteria on a human-associated level grows in your gut, on your skin and in your hair (eye-lashes included). So much so, that recent research has shown that the makeup of the different kinds of bacterial cells in your gut and skin is MORE unique than a fingerprint.

They also grow and survive in the food that we eat, raw meat and vegetables by design must be cooked so that we as humans can consume these foods without getting sick from the pathogens that thrive in these environments.

There are two main distinctions for bacteria which we define as gram-positive and gram-negative.

We use this distinction to group the various types of bacteria by how they look and behave. All commonly occurring bacterial species fall under these two categories. Suffice to say we identify bacterial cells in the lab with a simple test that we use as a broad category to determine which germ we are looking at.  This test is known as a Gram stain. This means that there are two main types of bacteria that look and behave differently from each other. With this method, we are able to see them under the microscope.

This test also helps us see their shape. There are three shapes, bacilli (rod-shaped),  cocci (circular), and spirilla (corkscrew shaped).

 What Do Bacteria Need to Survive?

There are 6 elements in the environment that allow bacteria to grow and survive:

• Temperature
• Moisture Content
• pH
• Nutrient Content
• Oxygen
• Time

Temperature

Bacteria can survive in a very large temperature ranges. They can survive between 0 to 60 °Celsius (32 – 122 °Fahrenheit), however, on a human-associated level they grow at their best between 20 and 45 °Celsius (68 – 113 ° Fahrenheit).

This is because the bacteria that we are concerned with have adapted to our internal bodies, in order to infect and contaminate our bodies. Therefore the absolute best temperature is 37 ° C (98 ° F).

Moisture (Water activity)

Bacteria can grow mostly in moisture rich environments. In food, they love moisture rich conditions. Water activity means how much water is available in a food product. Such an example would be cucumbers, there is a high availability of water in cucumbers, lettuce and celery (95%). When compared to dried spices (5 – 50%). Most bacteria need at least 80% water to survive.

Nutrient content

As we as humans need nutrients to survive, so does bacteria. With nutrient high content, food is a perfect source of nutrients for them to grow. Which is why we need to have very good hygiene standards in the kitchen. Food that we as humans consume is an ideal environment for bacteria. The skin of humans and animals are also an example of a high nutrient source.  Bacteria require sources of carbon, nitrogen, phosphorous, iron and a large number of other minerals.

pH (acidity)

The pH or acidity level also affects how bacteria grow and how effectively they can survive within the environment. Their ideal acidity level in food ranges from a pH of 5 to 8 . This means items such as vinegar is unlikely to allow them to survive.

Lemons are always a popular food when anti-bacterial properties are mentioned. Indeed the pH does discourage the growth of bacteria but is not a major factor when killing bacterial cells that occurs from cross-contamination. Meats, spinach and milk are within the ideal pH range for bacteria. Yogurt has a pH just below the ideal range and is generally considered less risky than milk because of this.

Oxygen

Bacteria can grow in both oxygen rich and poor environments. This means sealed and unsealed products. Therefore, vacuum packed meals and foods are not free from concern. This also means exposing foods to the environment and leaving food uncovered allows them to grow.

Time

The longer bacterial cells are exposed to the above factors in their ideal conditions, the more established the bacterial cells become. These factors are all dependent on time, and bacteria can rapidly multiply within 15 to 45 minutes.

Summary

• We now know that bacteria can survive in temperatures of between 0 – 65ºC (32 – 149ºF)
• Grow best at 20 – 45 ºC (20 – 113ºF).
• They rapidly multiply in 15 – 45 minutes in these ranges.
• Moisture rich environments are favourable.
• Can survive at pH of 3.0 – 7.5
• Can survive in oxygen-rich and poor conditions.

As you can see, bacteria are similar to humans in what they need to survive, hence there are human-associated bacterial cells, and as a result, they that occur in the foods that we consume.

Check out our articles on specific pathogens that will apply your knowledge:

• E.coli
• Staph aureus
• Salmonella
• Listeria monocytogenes
• Clostridium
• Campylobacter

For more information on the food safety pillars check the ebook on Amazon.

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