Salmonella typhi bacteria with all details

Salmonella typhi refered from ananthanarayanan

1. SALMONELLA BY R.REENA

2. INTRODUCTION Gram negative rods About1-3*0.5µm in size They are motile by peritrichous flagella

3. SALMONELLA Causes infectious in humanand vertebrates Typhoid fever(Enteric Fever) Gastroenteritis septicemias

4. CLASSIFICATION &NOMENCULTURE According to the dna hybridisation there are two species in the genus salmonella SPECIES ENTERICA SPECIES BONGORI

5. SPECIES ENTERICA Most human infections are caused by subspecies enterica . Which include : salmonella Typhi – causative agent of typhoid fever Specie s Enterica further classified into six subspecies subspecies enterica Subspecies salamae Subspecies arizonae Subspecies diarizonae Subspecies houtenae Subspecies indica Most human infections are caused by subspecies enterica and rarely by arizonae

6. Salmonella enterica and Salmonella arizonae

7. Clinical Entities Typhoidal Non typhoidal Typhoidal – enteric fever group consist of typhoid and paratyphoid bacilli are exclusively or primarily human Non typhoidal - cause food poisioning

8. ANTIGENIC STRUCTURE H- Flagellar antigen O-somatic antigen Vi – surface antigen H-antigen present on flagella strongly immunogenic o -antigens – forms an integral part of the cell wall like endotoxin Vi surface antigen – originally observes in salmonella typhi It envelopes the o antigen

9. ANTIGENIC VARIATIONS H-O VARIATIONS: variation associated with the loss of flagella . Rarely salmonella may lose their flagella by mutation A non motile mutant of s.typhi is the 901-O strain . Which is widely employed for the preparation of O- agglutinable bacterial suspension

10. P ATHOGENECITY Salmonella are strictly parasites of animals and humans. Minfections caused by salmonella range from asymptomatic conditions to fatal diseases and sometimes zoonotic diseases Broadly salmonellae cause the following clinical syndrome : ENTERIC FEVER SEPTICEMIA WITH OR WITHOUT LOCAL SUPPURATIVE LESION GASTROENTERITIS OR FOOD POISIONING

11. TYPHOID FEVER Salmonella typhi –causes typhoid Salmonella paratyphi A,B,C causes paratyphoid fevers Food poision group Spread from animal –humans Causes gastroenteritis – septicemias,localized infection

12. PATHOGENESIS

13. Typhoid mary Mary Mallon (1869-1938) and the history of typhoid fever The best known typhoid carrier was Mary Mallon a newyork cook over a period of 15 years caused at least seven outbreaks of typhoid affecting over 200 persons

14. CLINICAL FEATURES Patient present with fever associated with abdominal pain Incubation period 10-14 days There is relative bradycardia A soft palpable spleen Hepatomegaly also common Rose spots on the skin during the second or third week

15. LABORATORY DIAGNOSIS Bacteriological diagnosis of enteric fever consist of Isolation of bacilli from the patient Demonstration of antibodies in his serum after first week of infection Blood culture- 90%of cases in the first week of fever Clot culture-clotted blood is added to the bile broth medium containing Clot cultures are more productive in yielding better results in isolation

16. Culturing other specimens Feces enrichment in Tetrathionate broth and selsnite broth Culturing in MacConkey Urine culture-positive in 25% Others: Bone Marrow, bile , CSF/sputum

17. Serology WIDAL TEST This is one of the febrile agglutination test to detect H and O agglutinins for typhoid and paratyphoid fever using S.typhi O and H antigens Antigens used in widal test are TO: Typhi O antigen TH: Typhi H antigen AH: paratyphi A flagellar antigen BH:paratyphi B flagellar antigen Two serum specimens obtained at interval of 6-10 days

18. Prevention Typhoid bacilli are primarily intracellular parasites hence ( Cell Mediated Immunity) Typhoid fever can be effectively controlled by improvements in sanitation and provision of safe water supply

19. vaccines An injectable vaccine typhium vi Contains purified vi polysaccharide antigen from s.typhi strain A single dose subcutaneous route given to children>5 years Immunity last for 2 years

20. Treatment Ciprofloxacin is thr drug of choice in case of resistance ceftriaxone ( 1-2 g/day) In some centers use azithromycin for patient compliance. Other important drugs: Amoxicillin Furazolidine Cotromoxazole A mpicillin