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
How does Klebsiella infection cause different signs based on the source of infection?
4 tubular tracts
- ulcerative colitis: abdominal pain, discomfort, diarrhea, bloating, flatulance, constipation, nausea, headaches, peritonitis, joint/muscle pain, fatigue, weakness
- UTI: fever, lower abdominal pain, bloody urine, frequent urination, back pain, vomiting
- pneumonia: high fevers, chills, flu-like symptoms, cough, yellow/bloody mucus, shortness of breath, chest pain
- mastitis
(also: septicemia, liver abscesses, meningitis, soft tissue infections)
When is it most common for Klebsiella to cause liver abscesses?
(pus formed inside liver)
cattle in feedlots
What are the most common diseases caused by classical Klebsiella infections and the hypervirulent strain?
CLASSICAL: bacteremia, pneumonia, surgical site infection, UTI
HYPERVIRULENT: meningitis, endophthalmitis, liver and splenic abscesses, soft tissue infection
What are possible specimen Klebsiella can be isolated from?
- urine (UTI)
- pus (wound infection)
- sputum (respiratory tract infection)
- blood (bacteremia)
- CSF (meningitis)
- sterile body fluids and stool
What biochemical tests can be done to diagnose Klebsiella infection?
- Gram -
- oxidase -
- MacConkey agar lactose fermenter
- TSI CO2 +
- motility -
- urease +
What are the 2 major factors that make Klebsiella super virulent?
- mucoid capsule
- AMR plasmids
