It was positive for hydrolysis of gelatin, production of hydrogen sulphide. It was negative for casein, starch hydrolysis, indole, urease, methyl red, Voges-Proskauer test and nitrate reduction. Is Salmonella
Salmonella
Salmonella is a genus of rod-shaped gram-negative bacteria of the family Enterobacteriaceae. The two species of Salmonella are Salmonella enterica and Salmonella bongori. Salmonella enterica is the type species and is further divided into six subspecies that include over 2,500 serot…
Full Answer
What is the clinical importance of Salmonella typhimurium?
Salmonella Typhimurium 1 Clinical importance. Salmonella is a well-known genus of bacteria, mostly because it is a zoonosis causing food poisoning outbreaks, widely reported by the media. 2 Etiology and transmission. ... 3 Associated symptoms. ... 4 Associated lesions. ... 5 Diagnosis. ... 6 Treatment, Prevention and Control. ... 7 References. ...
Is tryptophan deaminase positive or negative in Salmonella?
Phenylalanine and tryptophan deaminase negative. Plasmids in Salmonella may code for antibiotic resistance (resistance plasmids are frequent due to the selective pressure of extensive antibiotic therapy), bacteriocins, metabolic characteristics such as lactose or sucrose fermentation, or antigenic changes of O antigen.
What is the growth pattern of Salmonella typhimurium on Hektoen enteric agar?
Colonial growth pattern displayed by Salmonella Typhimurium cultured on a Hektoen enteric (HE) agar. S. Typhimurium colonies grown on HE agar are blue-green in color indcating that the bacterium does not ferment lactose However it does produce hydrogen sulfide, (H 2 S), as indicated by black deposits in the centers of the colonies.
What are the characteristics of salmonella strains?
Most Salmonella strains are motile with peritrichous flagella, however, nonmotile variants may occur occasionally. Most strains grow on nutrient agar as smooth colonies, 2-4 mm in diameter. Most strains are prototrophs, not requiring any growth factors.
Is Salmonella typhimurium urease positive or negative?
Negative (-ve)Biochemical Test and Identification of Salmonella TyphiCharacteristicsSalmonella TyphiUreaseNegative (-ve)VP (Voges Proskauer)Negative (-ve)Fermentation ofAdonitolNegative (-ve)55 more rows•Jun 13, 2022
Is Salmonella typhimurium catalase positive?
Salmonella enterica, a Gram-negative, non-sporing, catalase-positive, oxidase-negative facultative anaerobic bacilli is a significant cause of morbidity and mortality in humans and animals, with multidrug-resistant S. enterica serovar Typhimurium being an emerging problem (1–4).
Is Salmonella typhimurium citrate positive?
When Simmons Citrate agar is inoculated with Salmonella typhimurium , the medium turns royal blue. This is a positive result for the citrate test.
How is Salmonella typhimurium identified?
They are identified with a combination of serological and biochemical tests. Salmonella Enteritidis and Salmonella Typhimurium are the two most important serotypes of salmonellosis transmitted from animals to humans in most parts of the world.
How does Salmonella typhimurium differ biochemically from S typhi?
The key difference between Salmonella typhi and Salmonella typhimurium is that Salmonella typhi is a bacterial serotype that causes typhoid fever in humans, while Salmonella typhimurium is a bacterial serotype that causes gastroenteritis in humans.
What is the morphology of Salmonella typhimurium?
MICROSCOPIC APPEARANCEGram Stain:Negative.Morphology:Straight rods.Size:0.7-1.5 micrometers by 2.0-5.0 micrometers.Motility:Usually motility by peritrichous flagella, however non-motile mutants do occur, and one type ( Salmonella gallinarum / Salmonella pullorum ) is always non-motile.Capsules:None.1 more row
Is Salmonella typhimurium H2S positive?
Typhimurium, as well as a virulence plasmid in H2S negative Salmonella suggested that H2S negative Salmonella is also a significant public health concern. Such finding warrants the development of an improved method for effective coverage of H2S negative Salmonella.
Which bacteria is citrate positive?
Bacteria citrate positive A positive reaction is indicated by growth with an intense blue color in the slant : Klebsiella, Enterobacter , Citrobacter, Providencia, Proteus, Serratia, vibrio cholerae, Pseudomonas, Salmonella enteritidis and members of the subgenera Salmonella II, III and IV.
Does Salmonella typhimurium ferment sucrose?
Salmonella can ferment glucose but not lactose or sucrose. Lack of lysine decarboxylase production is also characteristic of the genus Salmonella.
What is unique about Salmonella typhimurium?
Salmonella typhimurium, a pathogen that most often causes gastroenteritis in humans, also uses PCD to promote infection. However, unlike S. pneumoniae and C. difficile that use proteins encoded by the bacterium to drive cell lysis, S.
Which test is confirmatory test in Salmonella?
Serological confirmation tests typically use polyvalent antisera for flagellar (H) and somatic (O) antigens. Isolates with a typical biochemical profile, which agglutinate with both H and O antisera are identified as Salmonella spp.
What is Salmonella typhimurium common name?
Initially, each Salmonella "species" was named according to clinical considerations, for example Salmonella typhi-murium (mouse typhoid fever), S. cholerae-suis.
Is Salmonella typhimurium and Salmonella typhi the same?
Salmonella Typhimurium and Salmonella Typhi are closely related. However, there are distinct differences in the type and severity of infectious disease they both cause. This difference in infections is the result of differences in their genetic makeup.
What is the difference between Salmonella typhi and Nontyphoidal Salmonella?
Salmonella typhi and paratyphi cause enteric fever, a syndrome associated with fever and abdominal pain. Non-typhoidal Salmonella cause gastroenteritis.
Are all Salmonella oxidase negative?
Salmonellae are facultative anaerobes and are catalase positive, oxidase negative and ferment glucose, mannitol and sorbotol to produce acid or acid and gas.
Is Salmonella typhimurium aerobic or anaerobic?
Salmonella species are Gram-negative, flagellated facultatively anaerobic bacilli characterized by O, H, and Vi antigens.
What is Gram staining?
Gram staining is used to differentiate bacterial species into two large groups Gram-positive and Gram-negative based on the chemical and physical properties of their cell walls. Gram's stain differentiates between two major cell wall types. Bacterial species with walls containing small amounts of peptidoglycan and lipopolysaccharide, are Gram-negative and bacteria with walls containing relatively large amounts of peptidoglycan and no lipopolysaccharide are Gram-positive.
What is the purpose of Gram stain?
The Gram stain also allows for cell size, shape, and arrangement to be determined. Biochemical testing also helps to identify organisms. One type of biochemical test is fermentation tests. Fermentation is the formation of gas, acid, and other products by the action of bacteria on pyruvic acid. PR Glucose, PR Lactose, and PR Sucrose fermentation detection can be seen as broth color change and the presence or absence of a bubble. Making use of a mannitol salt agar growth can help determine and/or isolate gram positive cocci, interpretations are made by growth and color results.
What media is used for Salmonella?
The most commonly used media selective for Salmonella are SS agar, bismuth sulfite agar, Hektoen enteric (HE) medium, brilliant green agar and xylose-lisine-deoxycholate (XLD) agar. All these media contain both selective and differential ingredients and they are commercially available.
How long does it take for Salmonella to go away?
Most persons infected with Salmonella sp. develop diarrhea, fever, and abdominal cramps 12 - 72 hours after infection. The illness usually lasts 4 - 7 days, and most people recover without treatment. However, in some cases, the diarrhea may be so severe that the patient needs to be hospitalized.
What is the zoonotic bacterium that can infect humans, birds, reptiles, and?
Also known as Salmonella Arizonae , it is a zoonotic bacterium that can infect humans, birds, reptiles, and other animals. (CDC) Table 1. Characteristics shared by most Salmonella strains belonging to subspecies I. Motile, Gram-negative bacteria.
Does Salmonella harbor phages?
Also, Salmonella may harbor temperate phages and plasmids. Plasmids in Salmonella may code for antibiotic resistance (resistance plasmids are frequent due to the selective pressure of extensive antibiotic therapy), bacteriocins, metabolic characteristics such as lactose or sucrose fermentation, or antigenic changes of O antigen.
Is salmonella isolated from plating media?
Isolation and Identification of Salmonella. A number of plating media have been devised for the isolation of Salmonella. Some media are differential and nonselective, i.e., they contain lactose with a pH indicator, but do not contain any inhibitor for non salmonellae (e.g., bromocresol purple lactose agar).
Can a plasmid be transferred to Typhimurium?
The F plasmid can be transferred to Typhimurium, and an Hfr strain of Typhimurium may subsequently be selected. Conjugative chromosomal transfer may occur from Typhimurium Hfr to E. coli or from E. coli Hfr to Typhimurium.
What bacteria produce urease?
It is also useful to identify Cryptococcus spp., Brucella , Helicobacter pylori, and many other bacteria that produce the urease enzyme. Directly, this test is performed on gastric biopsy samples to detect the presence of H. pylori.
What is the purpose of the urease test?
The urease test is used to determine the ability of an organism to split urea, through the production of the enzyme urease.
What is a urea breath test?
Urea breath test is a common non-invasive test to detect Helicobacter pylori also based on urease activity. This is highly sensitive and specific test.
What is the color of the mucosa in a biopsy?
The test is performed at the time of gastroscopy. A biopsy of mucosa is taken from the antrum of the stomach, and is placed into a medium containing urea and an indicator such as phenol red. The urease produced by H. pylori hydrolyzes urea to ammonia, which raises the pH of the medium, and changes the color of the specimen from yellow (NEGATIVE) to red (POSITIVE).
What are the limitations of urea?
Limitations of Urease Test 1 Some organisms rapidly split urea ( Brucella and H. pylori ), while others react slowly. 2 It is recommended that biochemical and/or serological tests be performed on colonies from pure culture for complete identification. 3 To facilitate growth and the urea hydrolysis reaction, do not use inoculum from a broth suspension. 4 After prolonged incubation times a false-positive alkaline reaction may be seen. To rule out this occurrence, check the test with a control (an uninoculated tube of Urea Agar) along with the inoculated tube during prolonged incubation. 5 Do not heat the Urea Agar Slants, as urea decomposes very readily when heated. 6 To detect Proteus species, the Urea Agar, Slants must be examined within 6 hours of inoculation for a reaction. 7 Urea Agar should not be used to determine the quantitative rate of urease activity, as organisms vary in their capability and rate of hydrolysis. 8 Failure to incubate this medium with loose caps may cause erroneous results to occur. 9 Urea is light sensitive and can undergo autohydrolysis. Store at 2 to 8u0001C in the dark.
How many drops of urea agar to inoculate slant?
Streak the surface of a urea agar slant with a portion of a well-isolated colony or inoculate slant with 1 to 2 drops from an overnight brain-heart infusion broth culture.
How long does it take for urease to turn pink?
Rapid urease-positive organisms turn the entire medium pink within 24 hours. Weakly positive organisms may take several days, and negative organisms produce no color change or yellow as a result of acid production.
Clinical Importance
Etiology and Transmission
- Salmonella typhimuriumis a gram negative bacteria that colonizes the intestinal tract of the pig, and more particularly the ileum, caecum and spiral colon, through their Peyer patches. The main route of transmission is feco-oral since the pigs start shedding the bacteria within minutes from infection and can continue to shed up to 5 months after re...
Associated Symptoms
- The main symptom of salmonellosis is a yellowish diarrhea affecting pigs from mid-nursery all the way to market. Dehydration and anorexia are commonly seen among affected pigs. The initial episode does not last much longer than a week, but re-infection is common within the next 3 to 4 weeks. Mortality is rare and the majority of the pigs will completely recover. However, some indi…
Diagnosis
- Definitive diagnosis by clinical symptoms alone is difficult as many pathogens can cause diarrhea in pigs. Lesions found during the necropsy, such as pseudomembranes in the ileum or button ulcers in the spiral colon should be indicative of salmonellosis. Isolation of the bacteria along with clinical signs and lesions is the only way to get a definitive diagnosis. Salmonellacan easily be c…
Treatment, Prevention and Control
- Antimicrobial treatments can be effective in decreasing the severity of the clinical signs and stopping the propagation of the disease among the herd but they are not appropriate for long-term management of the disease. Typically drugs such as apramycin, ceftiofur, trimethoprim-sulfonamide, or gentamicin can be used. Reports of antimicrobial resistance are common; it is r…
References
- National Animal Health Monitoring Survey (NAHMS). 2006 https://www.aphis.usda.gov/animal_health/nahms/swine/downloads/swine2006/Swine2006_dr_…