Salmonellosis, A world Wide Scourge?

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In my last article on the subject of bacteria (shigella) I described some bacterial terminology in lay man’s terms to help you to understand the scientific terminology. Today I would like to touch a little upon the subject of how we categorize bacteria. There are many species of bacteria and the have evolved in many different ways. Each has found a niche in the evolutionary ladder and they have adapted themselves to be able to live in a vast variety of different conditions. What I want to do is to go through some of the different conditions in which bacteria live and by which bacteria are categorized.

The first three categories I am going to describe relate to different temperature conditions in which bacteria can be found and by which they are categorized for having this quality.

Psicrophilic. Psicro in Greek means low. Psicrophilic bacteria are ones which prefer to function at low temperatures. Normally speaking, low temperatures means below 5 degrees Celsius. The advantage that these bacteria have by utilizing cold conditions is that there are very few other bacteria that can compete with them at this temperature. From a food hygiene perspective these are the bacteria which cause refrigerator spoilage. If you have ever notices a slightly slimy surface to food that is kept at low temperatures this sliminess can be caused by psicrophilic bacteria. Normally these are not considered to be pathogenic bacteria but if you are particularly sensitive eating food that has been affected by psychrophylic bacteria can cause mild to medium stomach upset.

Mesophilic. Mesophilic bacteria are once which prefer to perform their metabolic functions at a moderate temperature range. This means that this category of bacteria is active between temperatures of 10 degrees Celsius to 40 degrees Celsius. many processes in the food industry, particularly the cheese industry, and most fermentation processes occur within this temperature range. This is also the temperature at which the vast majority of pathogenic bacteria function and therefore this presents the need for close control of bacteria action within the cheese and fermentation industries. Mistakes in this area would definitely cost lives. It is also the temperature at which most bacteria attack our bodies.

Thermophilic. Thermophilic bacteria are bacteria which have developed the ability to operate their metabolic functions at high temperatures. Bacteria of this classification can survives in temperatures in excess of 100 degrees Celsius. Some bacteria of this classification are used in the food industry and some are found in nature. In processes of controlled rotting the development of thermophilic bacteria is undesirable because they will break the materials down too much. This can be caused in the manufacture of compost by giving too much food. By giving too much food the temperature rises, the desirable bacteria are killed as well as the worms and the thermophilic bacteria turn the entire compost heap into useless mush.

The next three categories that I would like to discuss refers to the chemical environment in which bacteria live with respect to levels of acidity. Bacteria have developed the ability to survive in a wide range of acidic or non acidic conditions. Many such bacteria by acting in different acidic or non acidic climates become desirable from an industrial point of view. Many industrial processes rely upon bacterial activity for the production of the end product. This is true of the food and non food industries. However, some conditions become the target zone of pathogenic bacteria.

Basophilic. Bacteria which thrive in a basophilic climate are bacteria which prefer to live in a base of alkali environment. The level of which depends upon the specific species of bacteria. Some pathogenic bacteria become pathogenically active in alkali environments particularly bacteria which break down the proteins in meat and fish. They have developed this ability because ammonia is produced in decomposing flesh which is an alkali. In saying that many industrial processes are dependant upon basophilic bacteria.

Normophilic. Normophilic bacteria are ones which perform their metabolic functions at a neutral PH level or there about. Bacteria wich are active within this climate include many types of pathogens. You may remember that we have already talked about the fact that most pathogenic bacteria cannot remain active when acidity levels are raised and PH is lowered. We can therefore state that a great many pathogens function in mesophilic, normophilic conditions. If you think about it this is logical because the acidic conditions within a body are more of less neutral. The bacteria have become suited to the environment in which they are designed to exist.

Acidophile. Bacteria which have developed to survive within an acidophile environment are ones which perform their metabolic function in a strong acid environment. Again, bacteria such as these have evolved in nature to continue the degradation of matter when conditions become too acidic for normophilc bacteria. This category of bacteria is also used extensively throughout industry for a great many purposes. Not many bacteria within this group are pathogens.

The third category of bacteria about which I would like to discuss with you refers to how the bacteria relates to the use of oxygen. by this I mean can the bacteria survive with or without the presence of oxygen. Most pathogenic bacteria exist in an anaerobic environment or can change from an aerobic environment to an anaerobic one depending on the environment in which it is trapped.

Obligate aerobic. An obligate aerobic bacteria is one which must have the presence of free oxygen around it. Many industrial processes rely upon bacteria of this category.

Obligate anaerobic. Obligate anaerobic bacteria are bacteria which for the most part cannot tolerate an oxygen rich environment and perform all their metabolic functions through fermentation. Some bacteria from this category are pathogens.

Facultative anaerobic bacteria are ones which can switch from an oxygen rich environment to an environment devoid of oxygen and back again as the need arises. Many pathogenic bacteria belong to this category. By belonging to this niche facultative anaerobic bacteria have ensured the ability to survive even when conditions change.

Now that you have this information look up different bacterial species on the Internet and see if you can distinguish pathogenic bacteria in several of the different categories stated here.

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You have all heard of the Salmonella food outbreaks and scares that pop up all around this country and in many other places around the world, but how many of you know that “Salmonella” is not a disease as such?  That would be called Salmonellosis.


Salmonella is a genus of Gram-negative, non-spore forming, and motile enterobacteria with flagella which protrude in all directions (peritrihous).  Salmonella gets it’s energy from oxidation and reduction reactions using organic sources.  Most species of Salmonella are facultative anaerobics and are found around the world in  many different locations both  in warm blooded and coldblooded animals alike, and, believe it or not, human beings.  Some of the diseases attributed to Salmonella include typhoid fever, paratyphoid fever, and food borne Salmonellosis.

Samonella infections are all zoonotic.  They can be transmitted from humans to animals and from animals to humans.  Common strains are Salmonella Enterica Subsp., Enterica Serovar Typhi, or Salmonella Typhi.  Enteritis Salmonella can cause diarrhea, and infants, small children, the elderly, and people suffering from suppressed immune systems can become very seriously ill will need antibiotic treatment to rectify the problem.

There are an estimated forty thousand cases of Salmonella infections reported annually within the USA.  Salmonella can survive for weeks outside of a living organism.  Sunlight accelerates their death rate, as does being heated to a temperature of fifty five degrees for a period of one hour, or to sixty degrees for a period of not less than half an hour.  To guard against Salmonella food must be heated to at least seventy five degrees for a minimum of ten minutes.  Freezing does not kill salmonella .

Sources of Salmonella infections can be caused by injestion of unclean foodstuffs especially in institutional kitchens and restaurants, polluted surface water or stagnant water, improperly thawed poultry, or uncooked eggs from Salmonella infested birds.  Suspected foods contaminated by Salmonella outbreaks are taken off shop selves and returned to the manufacturer and should not be ingested.

The Salmonella in peanut butter found inside the products of the Peanut Corporation of America, has become one of the worst food borne Salmonella outbreaks in US food history and has been put down to criminal negligence.
Salmonellosis usually develops within twelve to seventy two hours after the person becomes infected with salmonella and Salmonella infections normally resolve in about seven days with oral liquid treatments.  Antibiotics such as ampricillin, ciproflaxacin, and trimethoprim-sulfamethoxazale are the best treatments for Salmonella infections which spreads to the intestines.  Some Salmonella patients have developed Reiter’s Syndrome which can lead to chronic arthritis and antibiotic treatments tend to have little effect on whether or not the patient develops arthritis from the Salmonella infection.

Beef, pork, milk, poultry, and eggs are the main host carriers of Salmonella, but any  type of food can become contaminated by this bacteria.  Eating raw or undercooked eggs, poultry, or meat can be a good method of contracting a Salmonella infection, as can cross-contamination of foods.  Symptoms of Salmonella infections may include diarrhea, fever, and abdominal cramping.  Laboratory tests are required to determine the presence of Salmonella and its specific strain.

Milk pasteurization, farm animal hygiene, cleaner slaughterhouse regimes, cleaner vegetable and fruit harvesting and packing operations, and better educational training standards of food industry workers in basic food handling and restaurant safety inspection procedures, may all help prevent Salmonella outbreaks from happening.
US Government Departments, such as the Center for Disease Control and Prevention, monitor the frequency of Salmonella infections in the Country, and help local and State Health Departments investigate outbreaks and devise controls and measures to lessen cases from happening.


The Food and Drug Administration inspects imported foods, milk pasteurization plants, promotes better food preparation techniques in restaurants and processing plants, as well as regulates the wrongful use of certain types of antibiotics as food animal growth inducers.  The United States Department of Agriculture monitors the health of food animals, inspects egg manufacturing plants, and the quality of slaughtered and processed meats.  The United States Environmental Protection Agency regulates and monitors drinking water supplies for safety.

The following steps can be taken to help prevent outbreaks of Salmonellosis:  cook poultry, ground beef, and eggs thoroughly at hot temperatures, avoid cooking oversized batches, do not eat or drink raw eggs or unpasteurized milk, wash hands after handling raw meat or poultry, and if foods in restaurants are served undercooked such as meat, eggs, and poultry send them back and have them cooked some more.
Salmonellosis is preventable by adopting correct food hygiene measures.

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