5.5 Gram Negative Lactose Fermenting Aerobic Rods Flashcards
what are the 3 types of lactose fermenters
escherichia, klebsiella, enterobacter
what are the 3 types of non-lactose fermenters
salmonella, proteus, yersinia
how do we identify gram negative aerobic rods (what medium and why)
MacConkey agar (it tells apart lactose fermenters from non-lactose fermenters and contains stuff that inhibits G+ and fungal growth - bile salts and crystal violet)
where do gram negative lactose fermenting rods live and what do we call them
intestine; aerobes or facultative anerobes
what is the MOST IMPORTANT LF and NLF gram-negative rod
LF: Escherichia coli
NLF: Salmonella enterica
fill in the following:
ESKapE
E: Enterococci
S: Staphylococcus
K: Klebsiella
E: Enterobacter
T/F Escherichia coli is zoonotic and reportable
F: zoonotic but not reportable
what is the dominant aerobe in the intestine
Escherichia coli (dominant anaerobe = Clostridium)
Where is E. coli primarily located
large intestine
what is the nature of E. coli in the intestine
most are non-pathogenic commensals but some strains are extremely pathogenic
what are the following antigens that make up the serotypes of E. coli:
O:
K:
H:
F:
O: LPS
K: capsule
H: flagellum
F: fimbriae/pilli
what is serotyping useful for and what is the caveat
useful to identify strains/clones of bacteria; need to have the antiserum against the antigen to use it
how does genotyping work
uses PCR and whole genome sequencing to find virulence genes to characterize pathotypes of bacteria
what are the TWO main branches of E. coli
enteric pathogenic and extra-intestinal pathogenic
describe the branching of the types of enteric pathogenic E. coli
can be broken broadly into: ETEC, EPEC, STEC
STEC divides into EHEC and pig ED
ETEC contains ________ adhesins and __________ whereas EPEC contains _______ adhesins and _________
pilli; enterotoxin; intimin; A/E protein
what is the difference between the two strains of STEC
EHEC: causes diarrhea and systemic disease (kidney shit); Shiga toxin, pili, intimin
Porcine STEC (ED): causes diarrhea and edema
what are clinical signs of ETEC
post-weaning diarrhea, dehydration
what are the histologic lesions of ETEC
none
how do we diagnose ETEC
PCR, agglutination test
T/F ETEC is zoonotic and reportable
F to both
T/F ETEC is very host specific
T
where is ETEC
small intestine
how does ETEC develop
viruses/diet predispose to it; pili attach to the epithelial cell villi; produces enterotoxins (STI, STII, LT); diarrhea and death
what are the 3 enterotoxins produced by ETEC
STI, STII, LT
what is the general mechanism of all 3 ETEC enterotoxins
they secrete or inhibit uptake of electrolytes, which fluid follows, resulting in diarrhea and dehydration
what type of diarrhea (2) does ETEC cause
post-weaning diarrhea in piglets and neonatal diarrhea in piglets and calves
how do we treat ETEC and what is an important consideration
supportive care (ex. rehydration) and antibiotics; the antibiotics won’t work until the epithelial cells regenerate
why do we care about EHEC
because cows are asymptomatic carriers and influence the development of the disease in humans through contact and consumption of products
T/F EHEC is zoonotic and reportable
F; zoonotic, not reportable
where does EHEC live
large intestine
what type of lesions does EHEC cause
inflammatory lesions
what is the pathogenesis of EHEC
ingestion -> bypasses stomach and small intestine -> in large intestine attaches and damages microvilli -> produces Shiga toxin -> bloody diarrhea -> goes septic to the kidney -> hemorrhagic uremic syndrome
EHEC causes _______ and _______ lesions to the ________ of the _______
attaching; effacing; microvilli; colon
how do we diagnose EHEC in humans
hemorrhagic diarrhea, HUS, PCR in lab
how do we treat EHEC in humans
supportive care
what is the strain of EHEC that is important in humans (O___:H____)
O157:H7
how can we prevent EHEC infections in humans
vaccination of cattle before slaughter; slaughter hygiene; food hygiene
what does the colon of a pig with STEC look like
edematous in the mesentery
T/F EPEC is zoonotic and reportable
F: neither
what species is most prone to EPEC
rabbits
describe the pathogenesis of EPEC
injested -> bypasses stomach and small intestine -> attaches to microvilli in the colon -> diarrhea
how can we diagnose coliform mastitis caused by extraintestinal E. coli
assessing milk, SCC, agglutination, PCR
T/F ExPEC is zoonotic and reportable
F; zoonotic but not reportable
what are some diseases caused by UPEC
ascending UTIs, coliform mastitis, endotoxemia
UPEC has _______ adhesins and secretes _____
pili; LPS
UPEC is unique because it causes _________ infections, mainly in what species
ascending; dogs and cats
T/F APEC is zoonotic and reportable
F; zoonotic but not reportable
what diseases does APEC cause and in what species
septicemia and cellulitis in birds
what is a predisposing factor to APEC
hypo or agammaglobulinemia
T/F ExPEC are resistant to complement
T
how do ExPEC compete for iron
siderophores
what are the 2 Klebsiella spp of interest to vetmed
Klebsiella pneumoniae and Klebsiella oxytoca
what type of pathogen is Klebsiella pneumoniae
opportunistic; major cause of hospital-acquired infections in humans
what does Klebsiella oxytoca cause
antibiotic-associated haemorrhagic enterocolitis
what type of pathogen is enterobacter
opportunist; causes hospital-acquired infections in humans and animals (like K. pneumoniae)
how does Enterobacter look (2 characteristics of the bacteria)
mucoid and encapsulated
