Typhoid Fever, Typhus, and Yellow fever Flashcards
What are the common manifestations of Typhus and Typhoid?
sustained high fever, skin rashes, delirium
What microorganisms cause Typhus and Typhoid fever (enteric fever)
Typhus - Rickettsia
Typhoid - Salmonella
What is the Sx difference between Typhus and Typhoid?
Typhus - rash is much more abundant and DONT BLANCH
Typhoid - rash “rosy spots” are pink and BLANCHES
What demographic dues Typhoid fever usually occur in?
mostly among travelers
What are 4 defining characteristics of Salmonella? (cause of enteric fever)
- Enterobacteriaceae
- Gram negative bacilli
- peritrichous
- facultative anaerobe
How is Salmonella serovars classified?
O, H, K antigens
O antigen = outer membrane
H antigen = flagella antigen
S. Typhi - strain that causes typhoid fever
Wheer are salmonelloses usually localized? who are the usual hosts?
Most are located in GI EXCEPT for enteric fever
Salmonella are zoonotic EXCEPT: S. Typhi, S. Paratyphi
How is typhoid fever transmitted?
Fecal-Oral
Patients and long-term convalescent carriers shed bacteria in FECES and/or URINE
humans = only host
What is the pathophysiology of Typhoid fever?
- Bacteria penetrate PEYER’s PATCHES - replicate in macrophages
- Intestinal lymph nodes ->mesenteric lymph nodes -> thoracic duct = systemic infection
- Multiply in organswith macrophages (liver, spleen, bone, marrow)
What is the most important lymphocyte against Salmonella enterica?
TH1 - produces INF-gamma to enhance the bacteriocidal capacity of macrophages
what is the incubation period of typhoid fever, what are Sx?
Incubates 10-14 days
Sx: first week = flu-like Sx
1. Faint, sparse, blancing, pnik macules on abdomen and chest first few days
- Prolonged fever (4-6 weeks)
- Splenomegaly, hepatomegaly
- Leukopenia in adults
What are complications of typhoid fever?
- intestinal hemorrhage/perforation
- Encephalopathy
- Mycarditis
- Intravascular coagulation
- Osteomyelitis, meningitis, endocarditis
- Chronic carriers usually have CHOLELITHIASIS
How is Typhoid fever diagnosed?
Culture blood, feces, urine:
- Salmonella grows on McConkey agar
- –Salmonella = CANT ferment lactose = WHITE spots
- –e. Coli = ferments lactose = RED spots - TSI tube - salmonella produces H2S = BLACK in tsi tube
- Widal test - detects antiO and antiH
What are some common characteristics of all enterobacteriaceae
- negative for cytochrome C oxidase,
- reduce nitrate to nitrite
- ferment glucose
- facultative
- peritrichous
- immotile, Gram neg bacillus
What 3 microoganisms are lactose fermenters?
Escherichia
Enterobacter
Klebsiella
Which 3 microorganisms are Lactose-non-fermenters
Salmonella
Shigella
Proteus
What substance is produced by e coli?
indole
What substance is produced by Salmonella?
H2S
Which organism is positive for urease?
Protease
What test is used to differentiate between Enterobacteriaceae from other species?
Oxidase test
Enterobes are oxidase negative
What is the treatment and prevention of Typhoid fever?
Tx:
- Fluoroquinolones
- third gen cephalosporins
Why is chlorampenicol good for enteric fever (S. typhi?)
it can diffuse into cells to kill the intracellular bacteria
What family is Yellow fever in?
Flaviviridae
What are 4 characteristics of flaviviridae?
- Enveloped
- icosahedral capsid
- +ve sense ssRNA
- Spread by Aedes aegypti from human to human
