Salmonella is a genus of rod-shaped, Gram-negative, non-spore forming, predominantly motile enterobacteria with diameters around 0.7 to 1.5 µm, lengths from 2 to 5 µm, and flagella which project in all directions (i.e. peritrichous). They are chemoorganotrophs, obtaining their energy from oxidation and reduction reactions using organic sources and are facultative anaerobes; most species produce hydrogen sulfide,[1] which can readily be detected by growing them on media containing ferrous sulfate, such as TSI. Most isolates exist in two phases; phase I is the motile phase and phase II the non-motile phase. Cultures that are non-motile upon primary culture may be swithched to the motile phase using a Craigie tube.
Salmonella are closely related to the Escherichia genus and are found worldwide in warm- and cold-blooded animals, in humans, and in nonliving habitats. They cause illnesses in humans and many animals, such as typhoid fever, paratyphoid fever, and the foodborne illness salmonellosis.[2]
Salmonella is named for pathologist D.E. Salmon.
Contents
1 Salmonella as disease-causing agent
2 History
3 Salmonella nomenclature
4 Genetics
5 Sources of infection
6 Deaths
7 Medically relevant representatives
8 See also
9 References
Salmonella as disease-causing agent
Salmonella infections are zoonotic; they can be transmitted by humans to animals and vice versa. Infection via food is also possible. A distinction is made between enteritis salmonella and typhoid/paratyphoid salmonella, whereby the latter because of a special virulence factor and a capsule protein (virulence antigen) can cause serious illness, such as Salmonella enterica subsp. enterica Serovar Typhi, or Salmonella typhi). Salmonella typhi is adapted to humans and does not occur in animals.
Enteritis Salmonella (e.g., Salmonella enterica subsp. enterica serovar Enteritidis) can cause diarrhoea, which usually does not require antibiotic treatment. However, people at risk such as infants, small children, the elderly, HIV patients and those with suppressed immunity can become seriously ill. Children with sickle cell anemia who are infected with salmonella may develop osteomyelitis.
In Germany, Salmonella infections must be reported (§ 6 and § 7 of the German law on infectious disease prevention, Infektionsschutzgesetz). Between 1990 and 2005 the number of officially recorded cases decreased from approximately 200,000 cases to approximately 50,000. It is estimated that every fifth person in Germany is a carrier of Salmonella. In the USA, there are approximately 40,000 cases of Salmonella infection reported each year.[3] According to the World Health Organization, over 16 million people worldwide are infected with typhoid fever each year, with 500,000 to 600,000 of these cases proving to be fatal.
Salmonella can survive for weeks outside a living body. They have been found in dried excrement after over 2.5 years. Ultraviolet radiation and heat accelerate their demise; they perish after being heated to 55 °C (131 °F) for one hour, or to 60 °C (140 °F) for half an hour.[citation needed] To protect against Salmonella infection, it is recommended that food be heated for at least ten minutes at 75 °C (167 °F) so that the center of the food reaches this temperature. Salmonella is not destroyed by freezing.
History
The genus Salmonella was named after Daniel Elmer Salmon, an American veterinary pathologist. While Theobald Smith was the actual discoverer of the type bacterium (Salmonella enterica var. Choleraesuis) in 1885, Dr. Salmon was the administrator of the USDA research program, and thus the organism was named after him.[4] Smith and Salmon had been searching for the cause of common hog cholera and proposed this organism as the causal agent. Later research, however, would show that this organism (now known as Salmonella enterica) rarely causes enteric symptoms in pigs,[5] and was thus not the agent they were seeking (which was eventually shown to be a virus). However, related bacteria in the genus Salmonella were eventually shown to cause other important infectious diseases.
Salmonella nomenclature
Salmonella nomenclature is complicated. Initially each Salmonella species was named according to clinical considerations,[6] e.g., Salmonella typhi-murium (mouse typhoid fever), S. cholerae-suis (hog cholera). After it was recognized that host specificity did not exist for many species, new strains (or serovar, short for serological variants) received species names according to the location at which the new strain was isolated. Later, molecular findings led to the hypothesis that Salmonella consisted of only one species,[7] S. enteric, and the serovar were classified into six groups,[8] two of which are medically relevant. But as this now formalized nomenclature[9][10] is not in harmony with the traditional usage familiar to specialists in microbiology and infectologists, the traditional nomenclature is common. Currently, there are two recognized species: S. enterica and S. bongori, with six main subspecies: enterica (I), salamae (II), arizonae (IIIa), diarizonae (IIIb), houtenae (IV), and indica (VI).[11] Historically, serotype (V) was bongori, which is now considered its own species.
Genetics
Serovar Typhimurium has considerable diversity and may be very old. The majority of the isolates belong to a single clonal complex. Isolates are divided into phage types, but some phage types do not have a single origin as determined using mutational changes. Phage type DT104 is heterogeneous and represented in multiple sequence types, with its multidrug-resistant variant being the most successful and causing epidemics in many parts of the world.
Serovar Typhi is relatively young compared to Typhimurium, and probably originated approximately 30,000-50,000 years ago.
Sources of infection
Unclean food, particularly in institutional kitchens and restaurants,
Excretions from either sick or infected but apparently clinically healthy people and animals (especially endangered are caregivers and animals),and is of considerable girth
Polluted surface water and standing water (such as in shower hoses or unused water dispensers),
Unhygienically thawed fowl (the meltwater contains many bacteria),
An association with reptiles (pet tortoises and snakes) is well described.[12]
Deaths
About 142,000 Americans are infected each year with Salmonella enteritidis from chicken eggs and about 30 die.[13]
Medically relevant representatives
S. enterica ssp. arizonae, in cold-blooded animals, poultry, mammals
S. choleraesuis (Bacillus paratyphoid B and C), intestinal commensalists in pigs, pathogenic if resistance is weak; humans can be infected by ingesting sick animals; the bacteria cause hog cholera
S. enteritidis, in the intestines of cattle, rodents, ducks (and their eggs) and humans; causes calf paratyphoid fever and acute gastroenteritis in humans
S. paratyphi
S. paratyphi A, solely a human pathogen, causes paratyphoid A, transmission by contact and infected food or water
S. paratyphi B, in central Europe usually a human pathogen, causes paratyphoid B; transmission by contact and infected food, water or fly excrement
S. typhi, occurs in temperate and subtropical zones, the human pathogen of typhus abdominalis; transmission by contact and infected food, water or fly excrement; 3–5 % of all persons falling ill remain permanent carriers of the pathogen
S. typhimurium, causes a usually fatal, feverish intestinal infection in birds and mammals; conveyed by contaminated foodstuffs; causes Salmonella enteritis ("food poisoning") in humans
S. dublin, one of the pathogens causing cattle salmonellosis
S. typhisuis, one of the pathogens causing hog salmonellosis
Aug 20, 2009
Disease
In many cases, the terms disease, disorder, morbidity and illness are used interchangeably. In some situations, specific terms are considered preferable.
Infection
This term broadly refers to any abnormal condition that impairs normal function. Commonly, this term is used to refer specifically to infectious diseases, which are clinically evident diseases that result from the presence of pathogenic microbial agents, including viruses, bacteria, fungi, protozoa, multicellular parasites, and aberrant proteins known as prions. An infection that does not produce clinically evident impairment of normal functioning is not considered a disease. Non-infectious diseases are all other diseases, including most forms of cancer, heart disease, and genetic disease.
Illness
Illness and sickness are generally used as synonyms for disease. However, this term is occasionally used to refer specifically to the patient’s personal experience of his or her disease.In this model, it is possible for a person to be diseased without being ill, (to have an objectively definable, but asymptomatic, medical condition), and to be ill without being diseased (such as when a person perceives a normal experience as a medical condition, or medicalizes a non-disease situation in his or her life). Illness is often not due to infection but a collection of evolved responses, sickness behavior, by the body aids the clearing of infection. Such aspects of illness can include lethargy, depression,anorexia, sleepiness, hyperalgesia, and inability to concentrate.
Disorder
In medicine, a disorder is a functional abnormality or disturbance. Medical disorders can be categorized into mental disorders, physical disorders, genetic disorders, emotional and behavioral disorders, and functional disorders.
The term disorder is often considered more value-neutral and less stigmatizing than the terms disease or illness, and therefore is preferred terminology in some circumstances. In mental health, the term mental disorder is used as a way of acknowledging the complex interaction ofbiological, social, and psychological factors in psychiatric conditions. However, the term disorder is also used in many other areas of medicine, primarily to identify physical disorders that are not caused by infectious organisms, such as organic brain syndrome.
Medical condition
A medical condition is a broad term that includes all diseases and disorders, but also includes normal situations, such as pregnancy, that might benefit from medical assistance or have implications for medical treatments. As it is more value-neutral than terms like disease, it is sometimes preferred by people with these conditions. On the other hand, by emphasizing the medical nature of the condition, this term is sometimes rejected, such as by proponents of the autism rights movement. The term medical condition is used as a synonym for medical state, where it describes a patient’s current state, as seen from a medical standpoint. This usage is seen in statements that describe a patient as being “in critical condition”, for example.
Morbidity
Morbidity (from Latin morbidus: sick, unhealthy) refers to a diseased state, disability, or poor health due to any cause. The term may be used to refer to the existence of any form of disease, or to the degree that the health condition affects the patient. Among severely ill patients, the level of morbidity is often measured by ICU scoring systems.
Comorbidity is the simultaneous presence of two medical conditions, such as a person with schizophrenia and substance abuse.
In epidemiology and actuarial science, the term morbidity rate can refer to either the incidence rate, or the prevalence of a disease or medical condition. This measure of sickness is contrasted with the mortality rate of a condition, which is the proportion of people dying during a given time interval
Infection
This term broadly refers to any abnormal condition that impairs normal function. Commonly, this term is used to refer specifically to infectious diseases, which are clinically evident diseases that result from the presence of pathogenic microbial agents, including viruses, bacteria, fungi, protozoa, multicellular parasites, and aberrant proteins known as prions. An infection that does not produce clinically evident impairment of normal functioning is not considered a disease. Non-infectious diseases are all other diseases, including most forms of cancer, heart disease, and genetic disease.
Illness
Illness and sickness are generally used as synonyms for disease. However, this term is occasionally used to refer specifically to the patient’s personal experience of his or her disease.In this model, it is possible for a person to be diseased without being ill, (to have an objectively definable, but asymptomatic, medical condition), and to be ill without being diseased (such as when a person perceives a normal experience as a medical condition, or medicalizes a non-disease situation in his or her life). Illness is often not due to infection but a collection of evolved responses, sickness behavior, by the body aids the clearing of infection. Such aspects of illness can include lethargy, depression,anorexia, sleepiness, hyperalgesia, and inability to concentrate.
Disorder
In medicine, a disorder is a functional abnormality or disturbance. Medical disorders can be categorized into mental disorders, physical disorders, genetic disorders, emotional and behavioral disorders, and functional disorders.
The term disorder is often considered more value-neutral and less stigmatizing than the terms disease or illness, and therefore is preferred terminology in some circumstances. In mental health, the term mental disorder is used as a way of acknowledging the complex interaction ofbiological, social, and psychological factors in psychiatric conditions. However, the term disorder is also used in many other areas of medicine, primarily to identify physical disorders that are not caused by infectious organisms, such as organic brain syndrome.
Medical condition
A medical condition is a broad term that includes all diseases and disorders, but also includes normal situations, such as pregnancy, that might benefit from medical assistance or have implications for medical treatments. As it is more value-neutral than terms like disease, it is sometimes preferred by people with these conditions. On the other hand, by emphasizing the medical nature of the condition, this term is sometimes rejected, such as by proponents of the autism rights movement. The term medical condition is used as a synonym for medical state, where it describes a patient’s current state, as seen from a medical standpoint. This usage is seen in statements that describe a patient as being “in critical condition”, for example.
Morbidity
Morbidity (from Latin morbidus: sick, unhealthy) refers to a diseased state, disability, or poor health due to any cause. The term may be used to refer to the existence of any form of disease, or to the degree that the health condition affects the patient. Among severely ill patients, the level of morbidity is often measured by ICU scoring systems.
Comorbidity is the simultaneous presence of two medical conditions, such as a person with schizophrenia and substance abuse.
In epidemiology and actuarial science, the term morbidity rate can refer to either the incidence rate, or the prevalence of a disease or medical condition. This measure of sickness is contrasted with the mortality rate of a condition, which is the proportion of people dying during a given time interval
Aug 19, 2009
H1N1 (SWINE FLU)
H1N1Flu (Swine Flu)
Also called: Swine flu
Swine flu is an infection caused by a virus. It’s named for a virus that pigs can get. People do not normally get swine flu, but human infections can and do happen. The virus is contagious and can spread from human to human. Symptoms of swine flu in people are similar to the symptoms of regular human flu and include fever, cough, sore throat, body aches, headache, chills and fatigue.
There are antiviral medicines you can take to prevent or treat swine flu. There is no vaccine available right now to protect against swine flu. You can help prevent the spread of germs that cause respiratory illnesses like influenza by
•Covering your nose and mouth with a tissue when you cough or sneeze. Throw the tissue in the trash after you use it.
•Washing your hands often with soap and water, especially after you cough or sneeze. You can also use alcohol-based hand cleaners.
•Avoiding touching your eyes, nose or mouth. Germs spread this way.
•Trying to avoid close contact with sick people.
•Staying home from work or school if you are sick
Also called: Swine flu
Swine flu is an infection caused by a virus. It’s named for a virus that pigs can get. People do not normally get swine flu, but human infections can and do happen. The virus is contagious and can spread from human to human. Symptoms of swine flu in people are similar to the symptoms of regular human flu and include fever, cough, sore throat, body aches, headache, chills and fatigue.
There are antiviral medicines you can take to prevent or treat swine flu. There is no vaccine available right now to protect against swine flu. You can help prevent the spread of germs that cause respiratory illnesses like influenza by
•Covering your nose and mouth with a tissue when you cough or sneeze. Throw the tissue in the trash after you use it.
•Washing your hands often with soap and water, especially after you cough or sneeze. You can also use alcohol-based hand cleaners.
•Avoiding touching your eyes, nose or mouth. Germs spread this way.
•Trying to avoid close contact with sick people.
•Staying home from work or school if you are sick
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