Sidd
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"Sustainable dairy business."
Posted on 22. Dec 2023
The salmonella is small, gram negative, non-spore forming rod. They are widely distributed in nature with humans and animals being their primary reservoirs. Salmonella food poisonings result from indigestion of food containing appropriate strains of this genus in significant numbers.The genus Salmonella are considered to have a two species named Salmonella enterica and Salmonella bongori. Serotyping differentiates the strains and they are referred as to by, for example S. eneterica serotype Typhimurium or as S. Typhimurium (Gracey & Collins, 1992).Epidemiology
The primary habitat of Salmonella species is the intestinal tract of the animals such as farm animals, birds, humans, reptiles, and insects. The primary habitat is intestinal tract.As an intestinal form, the organisms are excreted in faeces from which they may be transmitted by insects and other living creatures to large number of places (Kalpelmecher, 1993).Salmonella can be grouped into Salmonella Typhi and S. Paratyphi which are agents of typhoid and paratyphoid fevers which are the most severe of diseases caused by Salmonella.Pathogenesis
Salmonella often enter the host by ingestion, even with several systems to mediate acid resistance, few survive the stomach and move into the small intestines. Normal flora protects against colonization of administration of oral antibiotics facilitates establishment of infection.Entry of salmonella usually occurs without mucosal damage in systemic infections but enteric infection is characterized by local damage without septicaemia-salmonella infection with M cells in payer’s patches is facilitated by fimbrial adhesions. This is followed by ruffling of the target cell membrane which results in internalization of the bacteria in membrane bound vacuoles (Brayan, 1994).The ruffles facilitate uptake of bacteria in membrane bound vacuoles or vesicles which often coalesce. The organisms replicate in these vesicles and are eventually releases from the cells, which sustains only mild or transient damage. The complex invasion process is mediated by the product of a number of chromosomal genes, whereas growth within a cell depends on the presence of virulence plasmids (Walderhaug, 2007).Symptoms
The incubation period of the salmonella is 12-36 hours. The clinical signs include diarrhoea, which may be watery, greenish and foul smelling. This may be preceded by headache and chills in most cases the symptoms resolve in 2-3 days without any complication (CDC, 2011).The bacteria induce responses in the animal that is infecting which typically causes symptoms, rather than any direct toxin product. Symptoms are usually gastrointestinal, including nausea, vomiting, abdominal cramps and bloody diarrhoea with mucous, headache and fatigue.Symptoms can be severe in young children and elderly. Symptoms last a week generally up to a week and can appear 12-72 hours after ingestion of the bacteria.Detection of pathogens
It can be provided only by isolation of the agent from stool or vomit in human, feed samples in cases of animals, and samples concerned food items like milk and milk products samples. For culture and isolation, the use of selective enrichment media such as Salmonella-shigella agar, or deoxycholate agar after 24 hours is the usual procedure.Selenite enrichment broth or tetrathionate broth can be used to isolate highly selective for salmonella, especially S. enterica serovar Typhi. Agar and plates are incubating at 37°C overnight and growth identified by biochemical tests and slide agglutination tests (Brayan, Mckiley, & Mixon, 1971; Brayan, 1994).Prevention and control
The principal sources of infection are carrier animals and contaminated feeds containing food stuff of animal origin. There is a critical need to develop a method to control the spoilage or poisoning of food by Salmonella ordinary farms by instituting bio-containment practices in addition to enhanced food processing method, preparation and storage practices (Quinn, Markey, Carter, Demelly, & Leonard, 2001).Effective heat processing of food of animal origin, which includes pasteurization of milk and eggs, irradiation of meat and poultry thermal processing, good hygiene practices during production of food, vaccination of food producing animals. Consumers, particularly vulnerable groups should avoid undercooked meat and poultry, raw milk, eggs and foods containing raw and uncleaned vegetables.The control is also based on reducing the risk of exposure to infection. Intensively-reared, food producing animal are more likely to acquire infection and are also major source of human infection.Occurrence is worldwide. Drastic increase in incidence of salmonellosis, particularly due to S. enteritidis, has occurred during the past two decades in Europe, North America and some other countries. In Europe and North America, contaminated eggs and poultry have been the major source of infection.References
- Brayan, F. (1994). Microbiological Food Hazards Based on Epidemiological Information. Food Technology, 28, 52-59.
- Brayan, F., Mckiley, T., & Mixon, B. (1971). Use of Time Temperature in Detecting the Responsible Vehicles and Contributing Factors of Foodborne Disease Outbreaks. Journal of Milk Food Technology, 34, 576-582.
- Gracey, L., & Collins, D. (1992). Food Poisoning: Salmonella Surveillance in Meat Hygiene (9th ed.). London, UK: Bailliere Tindal.
- CDC. (2011). Estimates of Foodborne Illnesses in the United States. New York: Centers of Disease Control.
- Kalpelmecher, K. (1993). The Role of Salmonella in Foodborne Diseases: In Microbiological Quality of Foods. New York: Academic Press.
- Quinlan, J. J. (2013). Foodborne Illness Incidence Rates and Food Safety Risks for Populations of Low Socioeconomic Status and Minority Race/Ethnicity: A Review of the Literature. International Journal of Environmental Research and Public Health, 10, 3634-52.
- Walderhaug, M. (2007). Foodborne Pathogenic Microorganisms and Natural Toxins. Food and Drug Administration, Center for Food Safety and Applied Nutrition, 28, 48-65.
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