SALMONELLA TYPHI
Salmonella is a genus of gram-negative bacteria enterobakteria shaped rod that causes typhoid, paratifus, and foodborne illness. The species of Salmonella can move freely and produce hydrogen sulfide. Salmonella named for Daniel Edward Salmon, American pathologist, although in fact, his colleague Theobald Smith (famous for its results on anaphylaxis) who first discovered the bacterium in 1885 on the pig's body
Pathogenicity
Salmonella is a major cause of diseases spread through contaminated food (foodborne diseases). In general, the serotypes of Salmonella causing illness in the digestive organs. Diseases caused by Salmonella called salmonellosis. The characteristics of people suffering from salmonellosis are diarrhea, abdominal cramps, and fever within 8-72 hours after eating food contaminated with Salmonella.Other symptoms are fever, headache, nausea and vomiting. The three major serotypes of the species S. S. enterica is typhi, S. typhimurium, and S. enteritidis. S. typhi causes typhoid fever (Typhoid fever), because the invasion of bacteria into the blood vessels and gastroenteritis, caused by food poisoning / intoxication. Symptoms of typhoid fever include fever, nausea, vomiting and death. S. typhi is unique only attack humans, and no other host. Salmonella infection can be fatal to infants, toddlers, pregnant mothers and unborn and the elderly. This is because their immune systems are declining. Salmonella Contamination can be prevented by washing hands and keeping clean of food consumed.
Growth Media
Salmonella can be used to regenerate a variety of media, one of which is media Hektoen enteric agar (HEA). Other media that can be used is SS agar, bismuth sulfite agar, brilliant green agar, and xylose-lisine-deoxycholate (XLD) in order . HEA is a selective-differential media. The media is relatively selective because it consists of bile salts that are useful for inhibiting the growth of gram-positive bacteria and some gram-negative, so it is expected to grow only the Salmonella bacteria. This medium is classified a differential medium because it can distinguish Salmonella bacteria with other bacteria by providing three types of carbohydrates in the media, namely lactose, glucose, and salicin, with the most high-lactose composition. Salmonella can not ferment lactose, so that the acid produced little because it only comes from the fermentation of glucose only. This results in colonies of Salmonella will be bluish-green because it produces acid reacts with an indicator that there is at HEA medium, ie acidic and bromtimol fuksin blue.
Typhoid fever / enteric:
Infection S. typhi leading to the development of typhoid or enteric fever. The disease is characterized by sudden onset of sustained fever and systemic, headache, nausea, and loss of appetite. Other symptoms include constipation or diarrhea, enlarged spleen, the possibility of developing meningitis, and / or general malaise. Cases of untreated typhoid fever produces a mortality rate ranging between 12-30% while allowing the survival of treated cases 99%.
Virulence factors:
S. typhi has a combination of characteristics that make it an effective pathogen. This species contains a typical endotoxin from Gram-negative organisms, as well as the Vi antigen which is thought to increase virulence. It also manufactures and removing proteins known as "invasin" which enables cells to take non-phagocytic bacteria, where it can live intracellularly. It is also able to inhibit the oxidative burst of leukocytes, making the innate immune response is ineffective.
Epidemiology:
Meeting people for S. typhi through fecal-oral route from infected individuals to healthy people. Poor hygiene of patients shedding the organism can cause secondary infections, as well as the consumption of shellfish from polluted water bodies. The most common source of infection, however, is drinking water contaminated by urine and feces of infected individuals. Inoculum size estimates for bacterial infections is 100,000. Typhoid fever is also a laboratory infection the second most frequently reported.
The entry of these species of bacteria into the human body is most often achieved by consumption, with the known importance of aerosol transmission. Once ingested, the organisms multiply in the small intestine over a period of 1-3 weeks, breech the intestinal wall and spread to other organ systems and tissues. Innate host defenses do little to prevent infection due to inhibition of oxidative lysis and the ability to grow intracellularly after retrieval.
Transmission S. typhi only shown to occur by the fecal-oral route, often from asymptomatic individuals. 2-5% of previously infected individuals become chronic carriers who show no signs of disease, but actively shed viable organisms capable of infecting others. A famous example is "Typhus" Mary Mallon, who was a food handler is responsible for infecting at least 78 people, killing five. This highly contagious carriers pose a risk to public health because of lack of disease-related symptoms.
Damage caused by typhoid fever is reversible and limited if treatment begins early in infection. This led to the death rate of less than 1% among individuals treated with antibiotic-susceptible strains of S. typhi, making the results and prognosis for patients who are positive.
Prevention:
The key to avoiding infection by S. typhi is the prevention of fecal contamination in drinking water and food supplies. Because this agent is the only source of human infection, it is possible to control the transmission by proper hygiene, waste management, water purification and treatment of the sick. The steps are achieved in advanced societies, connecting to a low incidence. United States has an average of about 400 infections per year, almost exclusively among people who recently traveled to developing countries.
Transmission S. typhi only shown to occur by the fecal-oral route, often from asymptomatic individuals. 2-5% of previously infected individuals become chronic carriers who show no signs of disease, but actively shed viable organisms capable of infecting others. A famous example is "Typhus" Mary Mallon, who was a food handler is responsible for infecting at least 78 people, killing five. This highly contagious carriers pose a risk to public health because of lack of disease-related symptoms.
Damage caused by typhoid fever is reversible and limited if treatment begins early in infection. This led to the death rate of less than 1% among individuals treated with antibiotic-susceptible strains of S. typhi, making the results and prognosis for patients who are positive.
Prevention:
The key to avoiding infection by S. typhi is the prevention of fecal contamination in drinking water and food supplies. Because this agent is the only source of human infection, it is possible to control the transmission by proper hygiene, waste management, water purification and treatment of the sick. The steps are achieved in advanced societies, connecting to a low incidence. United States has an average of about 400 infections per year, almost exclusively among people who recently traveled to developing countries.
Prevention can also be helped with vaccination for the bacteria, but the effectiveness has been questioned. Moreover, it seems that the size of a large inoculum may overwhelm the immunity developed and lead to disease.
Typhoid fever has played an important role in history. This pathogen thrives in community development or the area where the disaster has compromised sanitation. Although the incidence in the United States is very low, disease outbreaks and substantial remains as possible to travel around the world and ignorance of disease carriers. Development of antibiotic treatment and several vaccines have presented the possibility of eradication worldwide. Until this is achieved, however, S. typhi and typhoid fever characteristics of the company will remain a threat to the epidemic in the future.
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