Lecture 16 Flashcards
Describe the appearance of Enterobacteriaceae (4)
Gram negative
Short rods
Grey (on blood agar)
Range from small round colonies to colonies swarming the plate
What is the biocontainment level for Yersinia pestis?
3
How do we divide Enterobacteriaceae?
Based on their ability to ferment lactose
Describe the appearance of Escherichia coli on an agar plate (3)
Diverse colony morphology
Irregular smooth grey colonies
Non-Hemolytic & beta hemolytic colonie
Describe the metabolism of Escherichia coli. What type of agar is used to display this? And what does it look like?
Lactose fermenter
MacConkey agar
Pink colouration = acid production
Describe the appearance of Klebsiella pneumoniae on blood agar (4)
Mucoid
Smooth
Glistens
Rounded margins
Describe the appearance of Proteus mirabilis on blood agar
Swarms the entire plate
Where are Enterobacteriaceae found? (4)
Wide distribution
Envr
Intestinal tract
Resp tract
Some organisms have specialized niches & some are generalists
What agar indicates the organism is a lactose fermenter? & what does it look like when it is positive? (2)
Eosin methylene blue - black colonies
XLT4 - H2S produces black colonies
Is E. coli positive or negative for the following tests:
- Indole test
- Citrate test
- Urease test
- -
Is K. pneumoniae positive or negative for the following tests:
- Citrate test
- Urease test
- +
2. +
How does the gelatinous test work?
If proteolytic enzymes are present then they convert the gel media into liquid media (gel = positive)
If it remains gelatinous then it is negative
How is E. coli classified?
Enterotoxigenic E. coli (ETEC) - cause intestinal disease
Extraintestinal pathogenic E. coli (ExPEC) - cause extra-intestinal disease
What disease does enterotoxigenic E. coli cause in ruminants & pigs?
Neonatal colibacillosis
Describe the pathogenesis of neonatal colibacillosis caused by enterotoxigenic E. coli
Related to presence of receptors for bacterial fimbriae in the intestine
Expression of receptors is age related
Bacteria adhere closely to enterocytes
Colonize enterocytes
Bacteria disrupt the brush border & mucosal erosions occur
What toxins do enterotoxigenic E. coli produce? (2)
LT - increase cAMP = increase fluid & electrolyte excretion (heat labile toxin)
ST - interferes with enteric NS (heat stable toxin)
What is the virulence factor for enterotoxigenic E. coli?
eae (enterocyte attaching & efficacy) - encodes intimin (binding PRO) which allows the bacteria to attach to the enterocytes
Does disease does enterotoxigenic E. coli mimics dogs?
Parvo
What spp is susceptible to enterohaemorrhagic E.coli?
humans
What toxin does enterohaemorrhagic E. coli produce? (2) What is its function? What symptoms? (2)
Shiga toxin - integer with PRO syn causing edema & hemorrhage
May also possess eae
What are the virulence factors of septicaemia E. coli? (5)
Fimbriae - adherence & possibly avoidance of phagocytosis
Capsule - prevent phagocytosis
Aerobactin - iron scavenging
Endotoxin - component of gram negative cell wall
Colicin V - serum resistance (interferes with complement)
What disease does uropathogenic E. coli cause in dogs & people?
UTIs
Opportunistic infection ascending from the urethra
What are the virulence factors for uropathogenic E. coli? (4)
Fimbriae - P fimbriae protect against phagocytosis
Flagella - swim from bladder to kidneys
Siderophores - acquisition of iron
Alpha hemolysin - pore-forming cytotoxin
How is piglet diarrhea from E.coli categorized?
Neonatal diarrhea
Young piglet diarrhea (until weaning)
Post-weaning diarrhea
How do you tx diarrhea in piglets from E. coli? (3)
a/bs
fluid therapy
Keeping them warm
How do you prevent piglets from getting diarrhea from E. coli?
Keep barn clean to prevent build up of E. coli
Keep piglets warm & dry
What disease does E. coli cause in cattle?
Coliform Mastitis
Describe the pathogenesis of coliform mastitis in cattle
E. coli is shed in feces & enters the teat from the envr
Multiply in teat
Endotoxin is released from dead cells
Leads to cytokine invasion & systemic inflammation
30-40% of cows become bacteremic
How do you tx coliform mastitis in cows from E. coli?
Systemic & intramammary a/bs
How do you prevent coliform mastitis in cows from E. coli?
Remove organic begging materials that support E. coli growth
What disease does avian E. coli cause in poultry?
colibacillosis
What are the symptoms of colibacillosis in poultry? (4)
Omphalitis - yolk sac infection
Colisepticemia
Swollen head syndrome
Air sacculitis - resp infection
How do chickens get colibacillosis?
E. coli present in the envr from either feces or exploiting eggs travel through the egg via the pores
How does colibacillosis present in poultry? (4)
Dead embryos
Swelling & edema of navel
Distended abdomen
Mushy chicks - body wall overlying the yolk sac degenerates
How do you tx colibacillosis in poultry?
a/bs - highly debatable due to high resistance in poultry barns
How do you manage colibacillosis in poultry? (4)
Keep barn clean - descried floor eggs & eggs which have exploded
Disinfect eggs within 2 hours of laying
Good quality diets
Poss vacc
How do we classify UTIs in dogs due to E. coli? (2)
Simple/uncomplicated - 1st time, no underlying abnormality
Complicated - repeat infection, assoc with underlying condition (ex: atopic ureters, bladder carcinomas etc.)
What pop of dogs do we most commonly see UTIs due to E. coli?
Spayed females
How do you tx UTIs in dogs? (3)
A/bs based on culutre & susceptibility testing
A/b depends on wether it is an upper or lower infection
Address underlying disease
What samples do you collect to test for E. coli for patients with diarrhea? (2)
Feces
Colonic tissue for history
What samples do you collect to test for E. coli for patients with mastitis?
Milk
What samples do you collect to test for E. coli for chickens with omphalitis? (2)
Inner viscera from dead chicks
What samples do you collect to test for E. coli for dogs with UTIs? (2)
urine (cysto preferred)
Does E. coli pose a zoonotic risk?
Yes, food borne transmission possible to transmit enterohemorrhagic E. coli
Poss source of a/b resistance
Animal –> human –> animal –> human transmission (not as well understood as food borne illness)
How can people prevent getting E. coli?
Wash hands
Protective equipment
What a/bs are all Enterobacteriaceae intrinsically resistant to? (6)
Benzylpenicillin
Glycopeptides
Fusidic acid
Macrolide
Lincosamides
Rifampin
How do you tx E. coli?
Susceptibility testing - they are resistant to a lot of things is we need to find out what
