E. Coli Flashcards
Causes mild dehydration and Causes enteritis
ETEC
has Clinical syndrome similar to Shigella dysentery
EIEC
Dysentery-like diarrhea with fever
EIEC
Elicits mucosal inflammation, epithelial necrosis, and ulceration
EIEC
primary cause of hemorrhagic colitis or bloody diarrhea
EHEC
2 Syndromes CAUSED by EHEC
Hemolytic Uremic Syndrome
Thrombotic Thrombocytopenic Purpura
Causes mucoid diarrhea and is often persistent
EAggEC
Starts with watery diarrhea and abdominal pain
EAggEC
Increases mucus secretion, which forms a layer overlying the epithelium of the small intestine
EAggEC
Bfp, Intimin
EPEC
STa, LT-I, EtpA, P Pili, Dr fimbriae
ETEC
No toxins; damages intestinal wall by Mechanical Cell destruction
EIEC
Shiga-like toxins; Intimin-Tir mediated attachment and effacement
EHEC
Bundle forming fimbriae, ST enterotoxins: EAST (Enteroaggregative Stable Enterotoxins) and SHET (Shigella Enterotoxins), Dispersins, Hemolysins,
EAggEC
Contaminated food, water, fomites
EPEC
Contaminated water, improperly treated drinking water, water
ETEC
Contaminated food and water
EIEC
EAggEC
Ingestion of contaminated food; person-person transmission
EHEC
Infectious dose of 10^6
EPEC
ID of 10^8 (elderly are susceptible to low doses)
ETEC
ID of 10^6 to 10^10
EIEC
low ID; 10 organisms by ingestion
EHEC
10^10 organisms (ID)
EAggEC
IP of 6-49 hours
EPEC
IP of 14-30 hours
ETEC
IP of 2-8 days
EHEC
IP of 2-48 hours
EIEC
IP of 8-18 hours
EAggEC
E. Coli in sorbitol MacConkey Agar
Colorless colonies
E. Coli in Eosin Methylene Blue Agar
Blue-black colonies with metallic green sheen
Identification for EPEC
Polymerase Chain Reaction
DNA hybridization methods (detection of EAF and gene encoding bfp)
Fluorescent Actin Staining
Presence of LT in E.Coli detected thru:
Rabbit Ileal Loop Method Adult Rabbit skin Method Tissue Culture Tests Serological Tests Genetic Probes
Presence of ST in isolates:
Infant Mouse Test
Genetic Probes
Detection of ETEC:
Non-radioactively labeled oligonucleotides DNA probes
PCR
EIEC detection:
Sereny Test
Cell Culture Test
VMA enzyme-linked immunosorbent assay
Identification of EHEC strains
Cytotoxic effects of VERO and HELA cells
DNA Probes
Detection of EAggEC
Agglutination tests w/ specific antisera H
Type of gastroenteritis that infect the large intestine and produce shiga toxin that causes bloody diarrhea
Hemorrhagic Colitis
IP of hemorrhagic colitis:
1-6 days
Symptoms include: marked edema on portions of colon and absence of pathogens in stool
Hemorrhagic Colitis
Results from abnormal premature destruction of RBC
HUS (Hemolytic Uremic Syndrome)
Decreased output of urine
oliguria
Paleness of skin
Pallor
Symptoms include: Oliguria Pallor Edema thrombocytopenia microangiopathic hemolytic anemia
HUS
reduced delivery of oxygen to the tissues
Microangiopathic Hemolytic Anemia
Deficiency of platelets in the blood
Thrombocytopenia
Characterized by clotting in small blood vessels in the body; less prominent neurological manifestations; Purpura; fatigue; tachycardia
TTP
Purple-colored spots
Purpura
May decrease the amount of diarrhea
Bismuth Subsalicylate
Alternative drug for Trimethoprim/Sulfamethoxazole
Clotrimoxazole
Reduces duration of diarrhea; for children
Trimethoprim/sulfamethoxazole
Strictly for Adults; disrupt the enzyme topoisomerase II, a DBA gyrase that is necessary for the replication of the microorganism
Ciprofloxacin
Drug for EPEC
Oral Neomycin
Genus of E. Coli
Escherichia
Family of E. Coli
Enterobacteriaceae
Acute, profuse, watery diarrhea w/c rarely becomes persistent
Stools are not bloody, mucoid, or dysenteric
EPEC
Diarrhea without fever
ETEC
Abrupt onset of watery diarrhea that is nondysenteric
ETEC
found on the cell wall of E. Coli
LPS (Lipopolysaccharide)
How to distinguish E. Coli from other families:
- Ability to ferment lactose and other sugars
* Indole from tryptophan
Parts of an E. Coli:
- Flagella
- F or sex pilus
- Common Pili / Type 1 fimbriae
- Capsule
- Cell Wall
- Plasma Membrane
- Periplasmic space
- Cytoplasm
- Ribosomes
Part for surface adherence to epithelial cells of the GI tract; protects from phagocytic engulfment
Common Pilus or Type 1 Fimbriae
Part composed of Colonic acid; protects bacteria from perennial effects of drying: Digestion/Killing
- serve as reserve of nutrients; protection against dessication
Capsule
Part essential for the viability; contains ligands for adherence as well as receptor sites
Cell Wall
Part that prevents osmotic lysis; confers rigidity and shape
Peptidoglycan
Enzyme for assembly of cell wall; contains sensing proteins for chemotaxis
Periplasmic Space
Antigenic types of e. coli
Serotypes
Somatic antigen; encoded by the rfb gene cluster
O Antigen
Flagellar Antigen; specified by flagellin
H Antigen
Capsular antigen; proteinaceous organelles for colonization
K Antigen
Serotypes responsible for diarrhea in animals and CFA
K88 and K99
Fimbrial Antigen; heat labile proteins
F Antigen
Strain of EHEC
0155:H7
where is the 0155:H7 derived?
EHEC strain 055:H7
Adhere to the epithelium of gut tightly
055:H7
Strain of e. coli that is unable to ferment sorbitol and Beta-glucuronidase activity
EHEC 0155:H7
Environment where the harmless commensal e.coli resides
- Large/Small intestine
* External Environments
Virulence Factors of E. Coli:
- Fimbriae
- Endotoxin
- Capsule
- Growth Factors
- Adhesins
- Exotoxins
Virulence factor that promotes virulence
Fimbriae
2 Types of Fimbriae
- Encoded by chromosomes
* Encoded by plasmids
Type of fimbriae that is most common and is not related to virulence
Encoded by Chromosomes
Type of fimbriae that is small in number and is closely related to virulence
Encoded by Plasmids
Virulence factor that plays an important role in the pathogenesis of UTI caused by E. Coli
Fimbriae
Responsible for the systemic manifestations of Gram negative bacteria
Endotoxin
Virulence factor that protects bacillus from phagocytosis and bactericidal effects of compliment
Endotoxin
Is the capsule hydrophilic or hydrophobic?
Hydrophilic
Virulence factors that protect the E. Coli from phagocytosis
Capsule
Virulence factor that interferes with antibody binding; but is not effective in the presence of Antibody to O or K Antigen
Capsule
Capability to compete for nutrients in the host cells
Growth Factors
Facilitates adsorption of Iron
Iron-Chelating Compounds
Lyse host cell erythrocytes thereby releasing iron compounds for use of bacteria
Hemolysins
Virulence factor that facilitates firm adhesion of the E. Coli to the mucosa of the GIT
Adhesins
Enumerate the Adhesins:
- CFA (Colonization Factor Antigen)
- AAF (Aggregative Adherence Fimbriae)
- Bundle forming Pili (Bfp)
- P Pili
- IPA - Invasion Plasmid Antigen
- Dr Fimbriae
- Intimin
Adhesin that mediates the attachment to the small intestine mucosa
CFA
Adhesin that produces an inflammatory response to the epithelial cells with EAggEC; contradicts Dispersin
AAF
For the adherence of EPEC to the epithelial cells
Bfp
binds to P blood group antigens
P Pilus
Invade tissue cells
IPA
bind to Dr blood group antigens
Dr Fimbriae
Disrupts intestinal epithelium by attaching and destroying the microvilli and effacing lessions
Intimin
Virulence factors secreted by EHEC and EPEC
Tir
Two types of exotoxins:
- Hemolysins
* Enterotoxins
Important in the pathogenesis of disease caused by uropathogenic strains of E. Coli
Hemolysins
3 Recognized Enterotoxins of E. Coli:
- Shiga Toxins
- Heat Stable Toxins
- Heat Labile Toxins
Similar to the Shigella dysenteriae type I toxin
Shiga Toxins
Type of Shiga toxin not neutralized by antibodies for Stx
Stx-2
Type of shiga toxin that is neutralized by antibodies agains Stx
Stx-1
Type of Shiga-like toxin that is similar to the ABS Shiga Toxin by shigella dysenteriae bacteria
Verotoxin
Virulence factor that causes hemorrhagic colitis and hemolytic uremic syndrome; damages glomerulus and vascular endothelium
Verotoxin
Strain of E. Coli that produces Verotoxin
EHEC
Toxic to the Vero Cell line; identical to Shiga Toxins
VT-I
Toxins that are low-molecular weight proteins
Heat Stable Toxins (ST)
Heat stable toxins in humans; small, methanol soluble, monomeric toxin
STa
Binds to guanylate cyclase to increase the level of cGMP and thus increases the fluid secretions (Sodium)
STa
Type of heat stable toxin that is not soluble in methanol and is not associated to human disease
STb
Similar to the cholera toxin; responsible for the secretion of Prostaglandin and production of inflammatory cytokines
LT-I
Increases the secretion of Chloride and decreases the absorption of sodium that results to a watery diarrhea
A Subunit of LT-I
LEE genes
Locus of Enterocytes Effacement genes
Encodes intimin protein
gene espE
Induces signal transduction
gene espB
secreted serine protease
espP
Virulence factor responsible to induce hemorrhagic colitis and the lysis of RBS
Enterohemolysin protein
Protect bacteria agains reactive oxygen species
Catalase Peroxidase
bunds to tips of flagella; adherence to intestinal cells
EtpA
Responsible for the degradation of immune cells
Cytolysins
Limiting aggregation of strains; contradicts AAF
Dispersin
Synonyms of EPEC
Intestinal Pathogenic E. Coli
EPEC invasive or non-invasive?
Non-Invasive
Synonyms of EIEC
Shigella-like E. Coli
EIEC Invasive or Non-Invasive?
Invasive
Synonyms of EHEC
Verotoxigenic E. Coli
ETEC Invasive or Non-invasive?
Non-Invasive
EHEC Invasive or Non-invasive
Invasive
EAggEC Invasive or Non-Invasive?
Non-Invasive
Does not invade stomach tissues directly; release toxins from bacteria; causes disruption of secretory process; watery stool
Non-Invasive Bacteria
invades stromach tissues directly and causes tissue destruction and bloody stool
invasive bacteria
Affects infants; adheres to small bowel and includes polymerization of actin filaments
EPEC
Attachment and effacing phenomenon thus forming attaching and effacing lesions
EPEC
leading cause of infantile diarrhea (Type of EPEC)
Typical
Non motile e. coli that does not produce decarboxylate lysine; does not ferment lactose and does not produce gas
EIEC
Closely related to shigella species
EIEC
Causes HUS; has Shiga-like Toxins
EHEC
Typical Stacked brick or glass Hep-2 cells; increases mucus secretion and produces layer overlying the epithelium
EAggEC
Common in neonates and young children
EPEC
Common cause of traveler’s diarrhea (Belly Delhi)
ETEC
Children below 5 y/o in developing countries
EIEC
Common cause of GI Infections in developed countries in children below 5 y/o
EHEC
Common during the summer months
EHEC
Acute and persisting pediatric diarrhea in developed and underdeveloped countries; secretory diarrhea
EAggEC
