Salmonella Pathogenesis PDF

Salmonella and salmonellosis Prof Ruiting Lan [email protected]  Safe exam Browser and testing Safe exam browser download link And Safe browser testing will be set up on the moodle  Learning objectives What is Salmonella? What diseases does Salmonella...

Salmonella and salmonellosis Prof Ruiting Lan [email protected]  Safe exam Browser and testing Safe exam browser download link And Safe browser testing will be set up on the moodle  Learning objectives What is Salmonella? What diseases does Salmonella cause? How does Salmonella cause disease? How do S. Typhimurium and S. Typhi differ in causing disease? Salmonella spp. Morphology Gram negative rods Typing Two major surface antigens  Lipopolysaccharide “O” antigen  Flagellar protein “H” antigen Used to identify different serovars  Salmonella enterica Host range expansion Human Birds & pathogens I (1478) mammals Farm animals VI (12) Genetic distance 0.01 Cold blooded vertebrates II (498) Birds SPI-2 IIIb (327) Usually non- pathogenic IV (69) to humans SPI-1 VII (>2) IIIa (94) V (21) S. bongori  Salmonella naming system Salmonella typhimurium – old name as a species Salmonella enterica serovar Typhimurium Salmonella Typhimurium S. Typhiumurium  Salmonella Infection Broad Clinical Spectrum Enteric fever Systemic infection Carrier state Gastroenteritis Infection solely within gastrointestinal tract Invasive infections Infections of the blood stream  Global burden Typhoid fever – 9.2 million cases and 110,000 deaths per year Non-typhoidal Salmonella (NTS) infections – 93.8 million annual cases with 155,000 deaths  Salmonella infections Causative agents Enteric Fevers Gastroenteritis Causative Salmonella enterica Salmonella enterica agents serovars serovars Typhi Typhinurium Paratyphi A Enteritidis most frequent Human adapted Zoonotic pathogen Salmonella infections Clinical picture Salmonella Typhi Non-typhoidal Salmonella serotypes. Intestinal Not typically diarrheal Typically diarrheal 1/3 patients have diarrhea Self limiting symptoms Intestinal Mononuclear infiltrate Massive neutrophil (PMN) pathology In diarrheal patients infiltration PMN scarce in stool PMN in stools Site of Small intestine, other Terminal ileum and colon infiltrate organs  Salmonella infections Survival and Persistence Feature S. Typhi Non-typhoidal serovars Infection Systemic Localised Colonisation Liver, spleen, bone Intestine sites marrow, intestine, Mesenteric lymph mesenteric lymph nodes nodes Incubation 5-9 days 12-72 hours period Persistence Approx 3 weeks Approx 10 days  Gastroenteritis Symptoms and susceptible hosts Symptoms Susceptible hosts Asymptomatic Children 10% Carrier state Chronic carriage (