5.6 Gram Negative Non-Lactose Fermenting Aerobic Rods Flashcards
how does diarrhea from Salmonellosis differ from E. coli
Salmonellosis causes mucoid, necrotic, watery, bloody diarrhea whereas E. coli causes watery, sometimes haemorrhagic diarrhea
how would you culture a bacteria from diarrhea to differentiate E. coli from Salmonella
1) selective media (ex. MacConkey agar)
2) enrichment culture
3) lactose fermentation test
what laboratory testing would you order to diagnose salmonellosis
- PCR
- serology
- typing of isolates
how do the intestines of an animal infected with salmonellosis look (3)
- inflammed mucosa
- fibrin
- pseudomembranes
what is the main species of Salmonella in veterinary medicine? How many subspecies? What subspecies causes the most clinical infections?
Salmonella enterica; 6 subspecies; Salmonella enterica subsp. enterica
where does salmonella live in animals? is this normal or not?
colon; should NOT normally be there (not normal flora except in reptiles)
what is unique about the multiplication of salmonella
can multiply not only in the host but also in the environment and in food
how do we further classify the subspecies of S. enterica
into serovars (over 2500) via serotyping using slide agglutination for O and H antigens
what is unique about the flagella of salmonella
biphasic
how can we FURTHER classify serovars of salmonella
into subtypes (phage types, pulsotypes, sequence types, etc.)
T/F animals can be carriers of salmonella
T
what are the 2 major types of disease caused by salmonella enterica
diarrhea (severe and inflammatory) and septicemia (shock, abortion, death)
what are the 2 broad categories of salmonella serotypes and how do they differ in the type of disease caused
host-adapted: cause systemic infection and septicemia
non host-adapted: cause gastroenteritis +/- septicemia if predisposed
what two serovars of Salmonella are non host-adapted
Salmonella enterica subsp. enterica serovar Indiana and Salmonella enterica subsp. enterica serovar Enteritidis
T/F Salmonella enterica is zoonotic
T
what are pathogenicity islands and what bacteria are they involved with
involved with Salmonella enterica; two types (SPI-1 and SPI-2) that are involved in the invasiveness of Salmonella
what is the difference between SPI-1 and SPI-2 (in regards to salmonella); what is the similarity between them?
SPI-1: involved in uptake by enterocytes, apoptosis, inflammation, diarrhea
SPI-2: involved in survival in macrophages
Both SPI-1 and SPI-2 use a Type III secretion system
(host-adapted/non host-adapted) S. enterica contain virulence _________ that contain ______ genes
host-adapted; plasmids; spv
what are spv genes involved in
intracellular multiplication and survival, resistance, fimbriae
what does LPS on salmonella do
causes inflammatory enteritis with secretory diarrhea
how does Salmonella enterica cause septicemia
migrates through the intestines and survives in macrophages, where it is then systemically distributed
how are neutrophils involved in salmonella enterica gastroenteritis
when salmonella invades epithelial cells (via SPI-1) it promotes recruitment and diapedesis of a large number of neutrophils; this in turn causes an increase in vascular permeability; neutrophils induce tissue injury, causing fluid accumulation; eventually a large number of neutrophils and fluid fill the intestinal lumen, creating pseudomembranes and diarrhea
if you were to look at the intestines of an animal that died from salmonellosis histologically, what would you see?
tons of neutrophils in the intestinal lumen
what are some factors that influence whether or not salmonellosis will develop
1) dose
2) virulence
3) host (genetics, age, immunity, nutrition)
4) gastric acidity
5) environment (infectious load, hygeine)
