L4 MHD: Enterobacter I Flashcards
What bacteria cannot ferment glucose?
What bacteria is oxidase negative but CAN ferment glucose?
- Pseudomonas
- ENTEROBACTERIACEAE
(Vibronaceae is oxidase positive)
Characteristics of Enterobacteriaceae:
- Gram + or - ?
- Rod or Bacilli?
- Indigenous flora of _____
- Colonize ______ of what patients?
- Aerobic or anaerobic?
- Gram negative
- Rod
- GI tract
- Respiratory tract of hospitalized patients
- grow rapidly BOTH aerobically & anaerobically
- simple growth requirements
What are the 3 components of the Enterobacteriaceae LPS endotoxn?
- O Antigen
- Core oligosaccharide
- attaches directly to lipid A - LIPID A
- Antibodies are directed to what part of the LPS endotoxin?
- What is the innermost region of LPS that is responsible for toxicity?
- What causes the toxicity of this component?
- O Antigen
- 100-200 serotypes
- outermost domain
- polysaccharide (repeating monosaccharide trimers) - LIPID A
- bacterial cells are lysed by the immune system–> fragments of membrane containing lipid A are released into the circulation, causing fever, diarrhea, and possible fatal endotoxic shock
(also called septic shock).
- _____ located in peritrichous FLAGELLA
(more than 50 serotypes)
- ____ located in the CAPSULE
(80 serotypes)
- H- Antigen
- flagellar = MOTILE - K - Antigen
- K is for german word for capsule **
- prevents phagocytosis of the organism
What is the pneumonic for bacteria that ferment LACTOSE
What are 4 common features of Enterobacter, Serratia, and Klebsiella?
Test with macConKEE’S
agar
C- Citrobacter K - Klebsiella E - Enterobacter E - E.Coli S - Serratia (slowly ferments lactose)
- Multidrug resistant
- All NOCOSOMIAL
- Cause Pneumonia & UTI
- ALL FERMENT LACTOSE
What is the K antigen important for?
important in causing extraintestinal colonization, UTI, and invasive disease.
(reason for neonatal meningitis)
What are 7 virulence factors of Enterobacteriaceae?
(they are described below)
- LPS; causes fever, sepsis, shock & multigrain failure
- Protects from phagocytosis
- Altered expression of K, H antigens which protects from antibody mediated cell death
- Secretion of bacterial virulence factors into host cells
- Sequester growth factors
- Resistance to ____
a)
b)
- Endotoxin
- Capsule
- Antigenic Phase Variation
- Type III secretion system
- Iron Scavengers
- RESISTANCE TO
a) serum killing
b) antimicrobials
What is the structure of
Enterobacteriaceae? Color?
- gram negative RODS
2. PINK on gram stain
What are the 4 most important biochemical characteristics of Enterobacteriaceae?
TEST!!!
- Facultative Gram-Neg rods
- Ferment glucose
- Reduce nitrate to NITRITE
- Oxidase negative*
What are the bacteria that ferment lactose?
What agar is used to detect this?
What color are the lactose fermenters?
What are the 4 NON-lactose fermenters that are gram neg?
1. macConKEE'S agar 1. Citrobacter 2.Klebsiella 3.Enterobacter 4.E.Coli 5.Serratia
- MacConkey Agar
(only for gram neg.) - PURPLE/PINK!
- ENTERIC PATHOGENS
(all lactose negative)
a) Salmonella
b) Shigella
c) Proteus
d) Yersinia
- What are the 7 tribes?
2. What tribe does shigella fall under?
- Tribe I – Escherichieae
- Tribe II –Edwardsielleae
- Tribe III – Salmonelleae
- Tribe IV – Citrobactereae
- Tribe V – Klebsielleae
- Tribe VI – Proteeae
- Tribe VII – Yersinieae
- Tribe I – Escherichieae
- What tribe is E.COli in
- What is its habitat?
- What is the usually infection and how does it occur?
- Does it ferment lactose?
- Tribe I - Escherichieae
- INTESTINES of humans & animals
- exists in human & animal feces
- presence in water is indicator of fecal contamination
3. UTI from our own flora
4. YES - ferments lactose
What are the 6 clinical symptoms of EColi?
- It is 80% of community acquired ____
- gram negative SEPSIS
- UTI
- Wound infections
- Pneumonia in IC hospitalized patients*
- Meningitis in neonates
- GASTROENTERITIS
- UTI -– 80% of community acquired UTIs are due to E.COli
What organism of E.Coli is described by the following:
- Elaboration of secretory toxins (LT, ST) that do not damage the mucosal epithelium
- Secretory diarrhea (Traveler’s Diarrhea) similar to V. cholerae.
- PROFUSE water diarrhea
- Produce Heat Labile (cAmp) and Heat Stabile (cGmp) ENTEROTOXINS
- No inflammation or Invasion
Enterotoxigenic
E. coli (ETEC)
- Often accompanied by mild abdominal cramps.
- Dehydration and vomiting occur in some cases
T = traveler’s
What organism of E.Coli is described by the following:
- Adhere to EPITHELIAL cells in localized microcolonies and cause attaching and effacing lesions
- Usually occurs in INFANTS** (TEST)
- No GROSS BLOOD**
- Characterized by low-grade fever, malaise, vomiting, and diarrhea, with a prominent amount of MUCUS
Enteropathogenic
E. coli (EPEC)
P = pediatrics
- no toxin produced
- adheres to apical surface
- flattens villi & prevents absorption