Isolation And Characteristics Of Salmonella Species From Frozen Foods
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Isolation And Characteristics Of Salmonella Species From Frozen Foods
ABSTRACT
In August 2000, researchers in Owerri conducted a study to evaluate the prevalence of Salmonella species in frozen foods. A total of 30 food samples were obtained from several markets in 10 different sites throughout Owerri and tested for Salmonella.
Following culture and biochemical tests, three distinct Salmonella species were isolated: Salmonella typhi, Salmonella typhimurium, and Salmonella paratyphi A. Salmonella was identified in 20 of the 30 food samples analysed (66.67%).
Salmonella typhi were recovered with a prevalence rate of 12 (40%) from 30 samples, followed by Salmonella paratyphi A with a prevalence rate of 5 (16.67%) and Salmonella typhimurium with a prevalence rate of 3 (10%).
Chapter one
INTRODUCTION
Foodborne illnesses are one of the most significant economic and health issues in both industrialised and developing countries. In recent years, Salmonella has been one of the most common causes of food-borne illness.
Salmonellosis is an infectious disease that is frequently transmitted by contaminated food, particularly food products of animal origin such as meat, chicken, eggs, animal goods, and occasionally vegetables in the food chain.
Salmonelosis prevalence is difficult to estimate in developing countries due to insufficient surveillance. As a result, several research have been conducted globally, revealing that the prevalence and kind of salmonella serotypes vary by geographical region.
Salmonella entericaserovars Enteritidis and Typhimurium were identified as the two most common serotypes of Salmonella isolated in Iran and other countries. Over the last two decades, the rise of antibiotic-resistant Salmonella has become a major global concern.
The widespread use of antibiotics in the diets of domestic animals has resulted in drug-resistant microorganisms that can be transmitted to humans. Furthermore, in recent years, the problem of resistant strains to multiple medications (MDR) has grown, and most studies in Iran and other countries have demonstrated high resistance of Salmonella strains to various antibiotics.
It belongs to the Emterobacteriaceae family and is a facultative anaerobic gram-negative bacillus that parasitises the intestines of many vertebrate species. It also infects humans, causing enteric fever, gastroenteritis, and septicaemia, a condition known as Salmonellosis infection.
The genus Salmonella is the most complicated of the enterobacteriaceae, with about 2,000 closely related bacteria that cause sickness by reproducing in the digestive tract. (Aora, 2004).
Each salmonella subgroup or serotype shares a common antigen and has its own name, and the Kauffman-White scheme describes the bacteria’s antigenic complexity.
According to this scheme, the terminology used to identify specific protein coats, or serovars, is not well settled, and what were previously thought to be multiple species of the genus Salmonella are now thought to be serovars of only two species by many researchers: Salmonella enterica and Samonella bongori.
However, these classifications are not generally accepted in the scientific literature, therefore commonly termed serovars are still used. The Kauffman-White classification distinguishes about 2, 500 varieties of samonella bacteria based on two basic types of antigens (Somatic O and flagella H).
Initially, Salmonella species were named based on clinical considerations, such as Salmonella typhi-murium (mouse typhoid disease) and S. cholerae-suis (hog cholera).
After it was discovered that host specificity did not exist for many species, new strains (or serovars, short for serological variants) were given species names based on the area where they were originally isolated.
Serovar Typhimurium is quite diverse and may be very old. The majority of the isolates are from a single clonal complex. Isolates are classified as phage types, however not all phage types have a single origin, as established by mutational changes.
Phage type DT104 is diverse and has several sequence variations, with the multidrug-resistant form being the most successful, producing outbreaks in many parts of the world.
Serovar typhi is a younger strain than Typhimurium, perhaps originating between 30,000 and 50,000 years ago. Salmonella serotypes often found in animals and mammals include:
* Salmonella enterica subspecies arizonae is present in cold-blooded animals, birds, and mammals.
* Salmonella enterica serovars (subspecies enterica).
* Salmonella choleraesuis (Bacillus paratyphoid B & C). This is an intestine commensal in pigs; it becomes pathogenic if resistance is low; humans can become infected by consuming ill animals; and the bacteria cause septicaemic salmonellosis in swine.
* Salmonella enteritidis can be found in the intestines of cattle, rats, ducks, and people; it causes calf paratyphoid fever and acute gastroenteritis in humans.
* In central Europe, Salmonella paratyphi B, a human infection, produces paratyphoid fever.
* Salmonella typhi is found in temperate and subtropical zones. It is the human pathogen of typhoid fever; 3-5% of those who become ill are permanent carriers of the infection.
* Salmonella typhimurium causes a variety of infections in birds, including severe systemic paratyphoid disorders. It causes salmonella enteritis (food poisoning) in people.
* Salmonella dublin is one of the bacteria that cause cow salmonellosis.
* Salmonella typhisuis is one of the pathogens that cause hog salmonellosis.
* Salmonella brandenburg causes abortions and enteritis in shepherd cattle.
* Salmonella anatum and Salmonella Montevideo.
Animals absorb Salmonella from the soil or contaminated processed foods, such as feeds. The germs are then excreted alive in infected animals’ excrement.
Humans, on the other hand, consume Salmonella through contact with unsanitary food, especially in institutional kitchens and restaurants.
Excretions from either sick or infected but apparently clinically healthy people and animals (particularly endangered carers and animals)
Polluted surface and standing food (for example, in shower hoses or unused food dispensers)
Unhygienic thawed poultry (the melt food contains many microorganisms).
An affinity with reptiles (pet tortoises and snakes), particularly aquatic turtles, is well documented.
Salmonella bacteria may survive several weeks in a dry environment and several months in food; as a result, they are regularly discovered in polluted foods, with contamination via carrier animal manure being especially important.
Salmonella is spread mostly by aquatic vertebrates, particularly birds and reptiles. Poultry, cattle, and sheep are frequent sources of contamination. Salmonella can be present in foods, especially meats and uncooked eggs.
Salmonella infections other than typhoid fever are known as enteric fever, salmonella food poisoning, and gastroenteritis. These infections are typically less severe than typhoid fever and are caused by one of the numerous Salmonella enteritidis serotypes.
Salmonella enteritidis and Salmonella typhimurium are responsible for the majority of epidemic outbreaks and food poisoning in humans and animals, with Salmonella Dublin and Salmonella Thompson also contributing.
Non-typhodial salmonellosis is more common than typhoid fever and is now stable around 40,000 to 50,000 cases per year. All strains are zoonotic in origin, yet human carriers may exist under certain conditions. The kind of salmonella that affects people typically causes illness, which is characterised by diarrhoea and vomiting.
Diarrhoeal illness appears to be a serious health risk for both humans and animals. Many salmonella grow in their host’s intestines, and once there, salmonella’s wave-long filaments known as flagella move around until they come into contact with an appropriate cell.
The bacteria adhere to the cell and are “swallowed”; tiny “hairs” known as fimbriae play a key role in boosting the host’s immunity.
THE AIM OF THIS STUDY IS:
To isolate Salmonella species from frozen foods in Owerri.
Identify the isolated species.
To determine the market place from which Salmonella was isolated.
To identify the places (or markets) with the highest isolation rates.
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