Coliforms & Klebsiella Flashcards
What genera make up Coliforms?
Citrobacter
Eneterobacter
Escherichia
Klebsiella
How do all Coliforms grow on MacConkey agar? How can Citrobacter, Enterobacter, and Klebsiella be differentiated?
lactose fermenters = purple
- Citrobacter = H2S gas and black on TSI
- Enterobacter = CO2 gas and yellow in TSI, urease negative
- Klebsiella = CO2 gas and yellos in TSI, urease positive
What are the main 4 sites of colonization of Coliforms?
4 tubular tracts
1. GI tract
2. respiratory tract
3. urogenital tract
4. mammary glands
What 3 species of Klebsiella are of veterinary importance? What are these members of ESKAPE resistant to?
- K. aerogenes (ESKAPE)
- K. pneumoniae (ESKAPE)
- K. oxytoca
carbapenem
What is the main unique characteristic of Klebsiella when grown on a plate? What are other important characteristics?
highly mucoid colony due to their very thick capsule, making it not accessible to phagocytes and antibiotics
- Gram-negative (LPS)
- lactose fermenter
- non-motile (no flagella/H antigen)
- no H2S gas
- urease positive
What 2 characteristics contribute to the serotype diversity of Klebsiella? What does this lead to?
- LPS —> 8-11 O serotypes
- capsule —> 77-80 K serotypes
- lack flagella = no H serotype
antigenically different —> same vaccine will not work for all strains
What are the 2 types of K. pseudomoniae based on the size of their capsule?
- classical with usual capsule thickness
- hypercapsulated hypervirulent strain (additional virulence factors)
How can an isolated colony of Klebsiella be differentiated from the classical type or hypercapsulated type?
string test - hypermucoviscous phenotype colony will have a long string when gathered by a toothpick/inoculation loop and picked up
(snot = mucoid capsule organized in a glycocalyx)
What 5 cellular structures contribute to Klebsiella’s virulence factors?
- capsule (slime layer) - evades phagocytosis and immune evasion
- lipopolysaccharide (endotoxin) - evade serum killing factors and phagocytosis
- type I fimbriae - adherence to host surfaces and conjugative plasmid exchange
- biofilm formation - survival in harsh environment
- outer membrane proteins - protection from antimicrobials
What 4 Klebsiella products factor into its virulence?
- siderophores - rob iron from host cell
- urease - allow growth in urinary tract
- colibactin toxin - interefere with host cell cycle, induce DNA damage, or cause colorectal cancer
- 5 different plasmids - multidrug resistance
Why is Klebsiells super resistant to diverse antimicrobials?
leading trafficker of multidrug-resistant encoding plasmids:
1. pKPN3
2. pKPN4
3. pKPN5
4. pKPN6
5. pKPN7
(ESKAPE)
Major virulence factors in Klebsiella:
What are the 3 habitats of Klebsiella? In what environment is it especially abundant?
- mouth, skin, vulva, teats, and colon of vertebrates
- bowel and respiratory tract of humans and animals
- feces, soil, water, sewage, plants
dairy farms and cows
What are the 2 modes of transmission of Klebsiella?
- from flora —> causes infection during stress
- oral-fecal route
What 2 species of Klebsiella cause a majority of infections? What signs do each cause?
- K. pneumoniae - pneumonia, mastitis
- K. oxytoca - colitis, sepsis, mastitis
When is it most common for Klebsiella to cause liver abscesses?
(pus formed inside liver)
cattle in feedlots
