Enterobacter & Citrobacter Flashcards
What are the 2 Enterobacter species of veterinary importance?
- E. cloacae - AMR (ESKAPE)
- E. sakazakii - contaminates infant powder formula, causing enterocolitis, sepsis, and meningitis
What are the 3 major characteristics of Enterobacter?
- lactose fermenter
- urease negative
- motile by peritrichous flagella
What 2 culture media are best for Enterobacter isolation and differentiation?
- MacConkey agar - lactose fermenter = purple
- blood agar - fecal odor
What are the 4 most common habitats of Enterobacter?
- digestive tract, vulva, and oral cavity of animal hosts
- clinical/hospital environments (patients, health care staff, equipment)
- home and industrial environments
- food, water, sewage, soil, plants, feces
What 7 virulence factors affect Enterobacter’s pathogenicity?
- flagella - motility, biofilm formation, protein export, adhesion
- LPS - endotoxin
- type 3 secretion system
- α-hemolysins
- thiol-activated pore-forming cytotoxins
- siderophores - iron robbing from host cells
- multi-drug resistance plasmids
What 2 genes are present in Enterobacter cloacae that is causing the emergence of multi-drug resistance?
- ESBL - confer resistance to most β-lactams
- bla(KPC) - resistance to last-resort carbapenems
(ESKAPE)
Under what conditions will Enterobacter cause disease? What 5 diseases are most common?
in immunocompromised patients
- UTI
- intra-abdominal infection
- pneumonia
- bacteremia/septicemia
- wound infection
What biochemical tests are used to identify Enterobacter after isolation?
- Gram -
- oxidase -
- MacConkey agar lactose fermenter
- TSI CO2 gas
- motility +
- urease -
What 3 species of Citrobacter are of veterinary importance?
- C. freundii
- C. koseri
- C. diversus
What are 5 important characteristics of Citrobacter?
- Gram-negative rod
- motile via peritrichous flagella (H antigen)
- SLOW lactose fermenter (coliform)
- produce black H2S on TSI agar
- urease positive
What is the sole source of carbon used by Citrobacter?
citrate
What can Citrobacter be used as an indicator of?
continually excreted with feces from humans and animals - fecal material contamination in the environment, water, and feed/food
(liker Enterococcus and Proteus)
What is the main habitat of Enterobacter?
digestive tract, vulva, and oral cavity of vertebrates and invertebrates
What are 6 major virulence factors that affect the pathogenicity of Citrobacter?
- adhesins
- motility
- biofilm formation
- immunoavoidance
- toxins
- nutrient/iron acquisition
- type 3 secretion system - intimate attachment to manipulated epithelial surface
What are the 3 major host ranges of Citrobacter?
- humans (zoonotic)
- animals
- aquatic species and reptiles (catfish, rainbow trout, turtles)
Citrobacter are rare opportunistic nosocomial bacteria. What are 7 common diseases it causes?
- enteritis and intra-abdominal sepsis
- UTI
- endocarditis
- pneumonia
- brain abscesses
- septicemia in neonatal infections with aggressive meningitis, sepsis, and multiple abscesses in the brian and joints
- wound infections
(colonize 4 tubular organs)
What is a rare presentation of Citrobacter infection?
bulla formation (large air-filled spaces)
What are 5 specific signs of Citrobacter infection in reptiles?
- septicemic cutaneous ulcerative disease in turtles
- petechiae on carapace/shell and skin
- anorexia
- lethargy
- liver necrosis
Citrobacter, septicemic cutaneous ulcerative disease:
Citrobacter, subcutaneous abscesses:
What is a common sign of Citrobacter infection in fish?
ulcerative disease with rotten and necrotic muscle
In what environment is Citrobacter infections most common?
- aquacultures
- reptile breeding facilities
major problem in aquatic animals (fish) and reptiles
What biochemical tests can be done to differentiate Citrobacter after isolation?
- Gram -
- oxidase -
- MacConkey agar lactose fermenter
- TSI H2S gas
- motility +
- urease +
How does Citrobacter infection generally present in humans and fishes/reptiles?
bulla formation
ulcerative dermatitis
