Salmonella micro biological aspects.pptx

Salmonella

1. Salmonella A Brief Study

2. Table of contents 01 04 02 05 03 06 History Etiology Classification Properties Diseases & Diagnosis Treatment

3. History 01

4. First famous carrier of typhoid fever in US She worked as a cook for charles henry and several private homes. She was a food handler responsible for infecting atleast 78 people, killing 5. She was popularly called “TYPHOID MARY” First discovery by Dr. Daniel E. Salmon, So the Organism is named SALMONELLA History MARY MALLON :

5. Typhoid Mary “Typhoid Mary”, real name Mary Mallon worked as a cook in New York City in the early 1900s. Public health Pioneer Sara Josephine Baker, MD, PhD Tracked her down after discovering that she was the common link among many people who had become ill and typhoid fever. She was traced to typhoid outbreak after which she was sent to jail till death.

6. Etiology 1. Disease is caused by serovars of genus salmonella. 2. Family : Enterobacteriaceae 3. Gram – ve , Motile by peritrichous flagella. 4. Facultative anaerobes.

7. S. T yphi with Flagella

8. Classification NON TYPHOIDAL SALMONELLA : Colonise intestines of animals. Also infects human causing gastroenteritis and septicemia . TYPHOIDAL SALMONELLA : Includes Serotypes S.typhi & S. Para Typhi. Restricted to human hosts causing enteric fever (Typhoid or ParaTyphoid )

9. Can survive at 8 C – 45 C ; Cannot survive > 70 c pH of 4 – 8 71.1 c for 15 sec pasteurization is enough to destroy Salmonella. Can resist dehydration for longer period both in faeces & foods of humans and animal consumption. Can survive for months in brine with 20% salinity ; particularly in products high in protein or fat content such as salted sausages. Can survive for long time in soil and water. PROPERTIES :

10. 7. According to Kuffmann – white scheme salmonella is divided into different serotypes based on –O- Somatic, H – Flagellar , Vi – Capsular antigenn 8 . Phage typing is also useful. 9. Virulance factors include lipopolysacchari de (LPS), Outer wall, Pili , Flagella, Cytotoxin , Enterotoxin . 10. Currently there are 2579 serovars .

11. The classification of Salmonella has been controversial for many years, now it's taxonomic classification depends on the Kauffman – White scheme (1934) in which typing is primarily performed using serological identification of somatic (O), flagella (H) and capsular (K) or (Vi) antigens [13,21]. According to most recent nomenclature, the genus Salmonella consists of two major species ; Salmonella enterica S. bongori Kauffman white scheme classification

12. Subspecies I: S. enterica subspecies enterica: It includes the greatest majority of Salmonella serotypes contain about 1435 serovars which commonly cause disease in man and warm-blooded animal Subspecies II: S. enterica subspecies salamae : Contains about 485 serovars and cause disease in coldblooded animals, while human infections with this Salmonella serotypes have rarely been documented Subspecies III; consists of 94 serovars mainly exists in reptile and birds.based on DNA hybridisation techniques this group has been further divided into; 1.Salmonella enterica

13. 4. Subspecies III a.; S.enterica subspecies arizonae . 5. Subspecies III b; S.enterica subspecies diarizonae ; consists of 321 serovars ,this subdivision correlates with differences in the flagellar antigen and the speed of the lactose fermentation. 6. Subspecies IV; S.enterica subspecies houtenae ; consists of 96 serovars 7 . Subspecies V; S.enterica subspecies indica; consists of 11 serovars

14. 2.Salmonella bongori It occurs more commonly in warm blooded animals and in thee environmnt.17 serovars have been have been and the symbol V is used to differentiate them fro the serovars of S.enterica subspecies enterica .

15. Salmonella can also be divided according to their host prediliction into 3 groups: 1.Salmonella which are primarily adapted to man:S.typhi and S.paratyphi 2.Salmonella which are primarily adapted to a particular species;S.cholerasuis and serovars of S.enteritidis like S.pullorum,S.gallinarum and S.dublin . 3.Salmonella which has not been adapted to a particular host;includes over 2000 serovars of S.enteritidis that effect man and animals.

16. Sets of antigens. Detection by serotyping. Somatic or o antigens contain long-chain polysaccharides comprises of heat stable polysaccharide commonly. Antigens are strongly immunogenic and induce antibody formation rapidly and in high titers following infection or immunisation. The flagellar antigen is of a dual nature occurring in one of the 2 phases. H – Flagellar antigens O – Somatic antigens Vi - surface antigen in some species only. Antigenic Structure of Salmonella

17. H antigen also called flagellar antigen, heat label protein Boiling destroys antigenicity . When mixed with anti serum produces agglutination and fluffy clumps are produced. H antigens are strongly immunogenic induces antibodies rapidly.

18. O antigens form integral part of cell wall like endotoxins, they are unaffected by boiling. When mixed with anti serum produce chalky clumps, take more time reaction, at high temperature 50 to 55 degrees centigrade. O antigens are less immunogenic than H antigens.

19. Vi antigen Many strains in S.typhi covers the O antigens –prevents agglutination. Resembles like K antigens Destroyed after boiling at 60 degree centigrade/1 hour. Acts as virulence factor, protects the bacilli against Phagocytosis and activity of Complement Poorly immunogenic Low titer of antibodies are produced, Not diagnostic.

20. May be phenotypic / Genotypic H to O = Loss of Flagella May be phase variation from I to II V to W Variation S to R Variation Antigenic Variation in Salmonella

21. Host Range & Reservoirs :

22. Animals : Faeco – oral route Contaminated animal feeds Poultry Litter transovarially Humans : Contaminated Food and Water Faeco – Oral Route Direct Contact Vertical and Horizontal transmission Transmission :

23. Pathogenesis After ingestion of non-typhoid Salmonella, it colonize the mucosa of caecum, ileum and colon. Sometimes, Bacilli enter through the pharyngeal mucosa, attach to the epithelial cells of intestinal villi induce their own intake into the cells by process of endocytosis. pass through the cells (transcytosis) and within 24 hours are found in the lamina propria and sub mucosa. they are rapidly phagocytosed by macrophages, if immune status of the host is diminished, it disseminate and multiply within phagocytic cells (mostly macrophages) within phagosomes.

24. Pathogenesis Production of cytotoxic and entrotoxins contribute to gut damage and provocation of inflammatory response, the intestinal mucosal releases prostaglandins which activates Adenylate cyclase and resulting increase in cyclic adenosine monophosphate. It induces secretion of water, bicarbonate and chloride that results in marked fluid increase in intestinal lumen and causes diarrhoea Faeces may contain blood mucus and neutrophils. The intestinal infections may lead to bacteremia or septicemia resulting in death or infection or remain localised in internal organs.

25. Pathogenesis In contrast, S. typhi enter the gastrointestinal tract, invade the local lymphatic tissue, pass via the bloodstream to various organs, Multiply in the liver, gallbladder, inflammation of the intestine can be so intense manifested by lymphoid hyperplasia (as in Peyer's patches) that it causes local necrosis of the tissue, leading to ulceration and perforation of the intestine and hemorrhage

26. S. dublin S. typhi CATTLE : • YOUNG CALVES : septicaemic form is common and characterized by dullness, depression, high fever which may lead to death within 24-48 hrs. • ADULTS: High fever, appearance of blood clots in faeces, followed by profuse diarrhoea (sometimes with mucus & blood), abdominal pain, abortions. Disease in Animals

27. : \ SWINE: 1.Pigs are host to several serotypes and principal reservoir of S.cholerasuis 2.serotypes that attack pig are entertidis,dublin,typhimurium 3.serotypes isolated from intestines and mesentric lymph nodes. 4.pigs of 2-4 months age are more susceptible 5.Swine paratyphoid [ S.cholerasuis ]or necrotic enteritidis occurs in poorly managed herds. 6.Pigs commonly develop chronic enteritis with persistent diarrhoea intermittent fever,and severe emaciation. 7.So pork productsare often a source of infection.

28. : \ SHEEP & GOAT s : Infrequent. • S.typhimurium causes gastroenteritis. • S. abortus ovis causes abortions in last 2 months of pregnancy & gastroenteritis.

29. Disease in Animals HORSES : S. abortus equi • Causes abortions in mares and arthritis in colts. • S.typhimurium causes enteritis sometimes causing high mortality. POULTRY : • PULLORUM DISEASE : Caused by S. pullorum • Bacillary white diarrhoea . • Transmission can be vertical (transovarian) but also occurs via direct or indirect contact with infected birds or contaminated feed, water or litter. • Disease seen in all age groups but

30. DISEASE IN HUMANS : • Incubation period lasts for 6-73 hrs. • Non typhoidal salmonella enteritis is a common food borne disease causes diarrhoea (blood and mucus), abdominal pain, loss of appetite, nausea and sometimes vomiting. • Death rate is higher in infants and older people, immunocompromised. • Typhoid fever include severe flu like symptoms. • Salmonella often go away without treatment unless it does not contain complications.

31. DEHYDRATION : Dry mouth, sunken eyes, dizzy, weak, confused, head ache. SEVERE INVASIVE SALMONELLA INFECTION : Bacteria enter blood stream spread to various organs. Causes meningitis – brain, Osteomyelitis – bone, Septic arthritis – joint, Polynephritis , Peritonitis , Cholecystitis, Endocarditis. REACTIVE ARTHRITIS : After recover from salmonella, infection triggers inflammation in painful joints (especially knees, ankles) Complications

32. Confirmatory diagnosis made by isolation of organism from food, tissue specimens from intestine or other organs. Diagnosis CULTURAL EXAMINATION:

33. EMB, colourless colonies on mac conkey agar, bismuth sulphite medium permits rapid detection of salmonella which form black colonies because of production of H2S. Diagnosis DIFFERENTIAL MEDIUM CULTURES

34. Salmonella-shigella agar, Hektoen enteric agar, XLD or deoxycholate citrate agar which favour growth of salmonella & shigella over enterobacteriaceae . Diagnosis SELECTIVE MEDIUM CULTURES

35. The specimen is put into selenite F or tetrathionate broth or RVS ( Rappaport vassadilis salmonella ) enrichment broth, both of which inhibit replication of normal intestinal bacteria & permit multiplication of salmonella. Diagnosis ENRICHMENT CULTURES

36. Diagnosis Salmonella on XLD agar

37. Diagnosis Salmonella on Mac Conkey’s agar

38. Diagnosis Salmonella on Wilson Blair agar

39. Suspected colonies from solid media are identified by biochemical reaction patterns & slide agglutination tests with specific sera. Diagnosis FINAL IDENTIFICATION

40. • On TSI agar, slant/butt -or + gas, + ve or – ve H2S • S.typhimurium alkali/acid + gas, +H2S • S. typhi alkali/acid –gas, + ve H2S • The black colour in tube indicates the production of H2S. • IMVIC test for salmonella is - + - + Diagnosis BIOCHEMICAL TESTS

41. • In this test known sera and unknown culture are mixed on a slide. • Clumping can be observed within few minutes . • There are commercial kits available to agglutinate and serogroup salmonella by their O antigens : A, B, C1, C2, D & E Serological Examination : Agglutination Test :

42. Serological Examination : Agglutination Test :

43. WIDAL TEST –Tube agglutination Test. In 1896 Widal A professor of pathology and internal medicine at the university of Paris, He developed a procedure for diagnosing typhoid fever based on the fact that antibodies in the blood of an infected individual cause the bacteria to bind together into clumps. Serological Examination : Tube Dilution Test ( Widal ) :

44. WIDAL TEST –Tube agglutination Test. Detects O and H antibodies. Diagnosis of Typhoid and Paratyphoid. Testing of H agglutinins in Dryers tubes, a naroow tube floccules at the bottom Testing fot O agglutinins in Felix tubes, Chalky Incubated at 37o centigrade overnight. Serological Examination : Tube Dilution Test ( Widal ) :

45. • Serum agglutinins rise during the second and third weeks of salmonella infection. • Serial two fold dilutions of unknown serum are tested against antigens from representative salmonellae. • RESULTS : High titer of O (1:160) suggests active infection. High titer of H (1:160) suggests past immunization or past infection. High titer of Vi antigen occurs in some carriers. Serological Examination : Tube Dilution Test ( Widal ) :

46. WIDAL TEST –limitations: It is time consuming and often times when diagnosis is reached it is too late to start an antibiotic regimen. In spite of several limitations many Physicians depend on Widal Test. Serological Examination : Tube Dilution Test ( Widal ) :

47. WIDAL TEST – False Positive and Negative: It should be interpreted in the light of baseline titers in a healthy local population. This is especially important when there is a high local prevalence of non-typhoid salmonellosis. The Widal test may be falsely positive in patients who have had previous vaccinations or infection with S Typhi. Serological Examination : Tube Dilution Test ( Widal ) :

48. WIDAL TEST – False Positive and Negative: Widal titers have also been reported in association with the dysgammaglobulinaemia of chronic active hepatitis and other autoimmune diseases. 64’8’9 false negative results may be associated with early treatment, with hidden organisms in bone and joints and with relapses of typhoid fever Occasionally the infecting strains are poorly immunogenic. Serological Examination : Tube Dilution Test ( Widal ) :

49. PCR : Rapid identification of salmonella serovars in faeces by specific detection of virulence genes, invA and spvC . Pulse Field gel electrophoresis also used to characterize the types of S.enterica isolate. Use of DNA probe based on virulence gene is a sensitive test for screening large number of samples to detect virulent salmonella spp. Molecular Determination :

50. Prevention & Control : GOOD HYGIENE & MANAGEMENT : • Sanitation, plus formaldehyde treatment alone or in combination with heat, at farms, lairage & hatchery is most efficient method. • Carriers should be segregated from healthy ones. • Animal /poultry excreta & waste should be properly disposed.

51. Prevention & Control : PATHOGEN FREE ANIMAL FEEDS : • Animal feeds like meat, fish &bone meals should be irradiated or heat treated. • Pelleting, ionizing radiation & treatment of processed feed with formic acid eliminate salmonella.

52. Prevention & Control : IMMUNIZATION : • Vaccination by live or attenuated salmonella vaccines should be used to protect poultry & other animals. • S. dublin strain 51 – calves • S. choleraesuis - pig • S. abortus equi – equine • S. gallinarum strain 9R (live) – poultry

53. Treatment : Use of antibiotics with or without competitive exclusion of salmonella can be adopted as a control measure.

54. Prevention & Control : IN MAN : Personal hygiene. Proper sewage disposal. Proper handling of foods to prevent cross contamination. Proper heat Treatment of foods. i.e. pasteourization of milk and cooking of foods particularly of animal origin. Supply of potable water. Periodic testing of foods & Pasteurization of milk & cooking of foods particularly of animal origin. Vaccines include : traditional heat killed, Vi subunit & Live oral vaccine, S. typhi Ty21A for Typhoid.

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