Notes - Salmonella

Notes - Salmonella - A U.F. student went to a picnic at...

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A U.F. student went to a picnic at some springs on the Santa Fe River. Two days after the picnic, she had a brief period of vomiting followed by severe abdominal cramps and large volume, watery diarrhea. The diarrhea has continued for three days. She had a temperature of 38˚C and a few leukocytes but no RBCs in her stool. She had abdominal tenderness and hyperactive bowel sounds. She ate chicken salad, rare hamburger, and homemade ice cream at the picnic. The student took over the counter anti-diarrheal agents, and the symptoms resolved on the second day of home-treatment, so she did not seek medical help. Salmonella History: Early 1800’s: pathologists document association of human intestinal ulceration (typhoid fever) with bacteria 1885: Salmon and Smith: isolated Bacillus cholerae-suis from swine with hog cholera (now known as S. enterica serovar Choleraesuis) Kauffmann-White scheme: describes >2400 serovars FOODBORNE OUTBREAKS #1 cause of reported foodborne bacterial diseases (maybe #2 behind Campylobacter ) Three major diseases: gastroenteritis typhoid fever (not in US) septicemia (blood infection) TAXONOMY Gram negative rods, facultative anaerobes Family = Enterobacteriaceae 90% DNA identity to E. coli Motility Peritrichous flagella But also nonflagellated Two species: S. enterica, S. bongori S. enterica: 2,400 serovars recognized Phage types Serology
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Agglutination of bacteria by Salmonella-specific antibodies O antigens : lipopolysaccharide (LPS) on outer membrane H antigens : flagella Vi antigen : capsule only in S. typhi , S. paratyphi C, and S. dublin Complete antigenic formula of a Salmonella isolate requires all three. Nontyphoid Gastroenteritis Multiple S. enterica serovars Symptoms: Incubation 6-46 hours (requires growth of bacteria in the intestines before symptoms appear) Symptoms: Abrupt onset, nausea, fever, headache, vomiting, diarrhea, cramps Severe cases can have bloody diarrhea 7-10 days, self-limiting May lead to extra-intestinal invasion or enteric fever, especially in immunocompromised Nontyphoid Gastroenteritis Chronic conditions: Antibiotics prolong carrier state (repress natural flora) Aseptic arthritis, Reiter’s syndrome, ankylosing spondylitis (genetic predisposition at MHC) LPS associated autoimmunity : inserts into host cell membranes, which are then attacked by
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Notes - Salmonella - A U.F. student went to a picnic at...

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