Enterobacter Flashcards
Overt Pathogens
4
- Salmonella
- Shigella
- Yersinia
- E. coli
Subtypes of E. Coli
2
- Enterotoxigenic (ETEC)
- Enterohemorrhagic (EHEC)
General Characteristics of Overt Pathogens
Type and virulence
Type: rapid growers, facultative anaerobes
Virulence: lipopolysaccharides
Major Lipopolysaccharides
3
Outermost somatic O polysaccharide: epidemiologic classification of strains within species
Core polysaccharide: commen antigen
Lipid A: endotoxin
Epidemiologic Classification
3
- Somatic O polysaccharide
- Capsular K/Vi antigen: heat labile, interferes with O detection
- Flagellar H antigen: heat labile
Common Virulence Factors
5
- Capsule: protects from phagocytes
- Antimicrobial resistance
- Endotoxin, lipid A
- Antigenic phase variation
- Type III secretion systems: molecular syringe, delivers virulence factors to target cells
Escherichia Coli Basics
Trans, clinical, virulence
Transmission: endogenous, gastroenteritis is from exogenous
Clinical: UTI, extraintestinal, GI tract infections
Virulence: general ones, adhesions, exotoxins
Escherichia Coli (ESCO) Infection: UTI
how does it infect, main symptom, establishment
Most common cause
- Adheres to epi cells, doesn’t wash away when you pee
Symptoms: delirium is a big one
Establishment: catheters, pregnancy, hemolysin promotes cell lysis and forms biofilms, gender (longer urethra)
ESCO Infection: Extraintestinal
2 types
Neonatal meningitis: major cause of CNS infections in infants <1 y/o
- K capsular antigen
- Common GI commensal
Septicemia
- Originate from UTI or GI infection
E. Coli: Enterotoxigenic Infection
Disease, symptoms,treatment
Traveler’s diarrhea: most common cause
- Foodborne outbreaks
- Children at risk
Symptoms: nausea, fever, diarrhea, maybe vomiting
- 3-5 days
Treat with supportive care without antibiotics
E. Coli: Enterhemorrhagic (EHEC) Basics
Trans, clinical, virulence
Transmission: eating undercooked ground beef, raw milk, animal fecal contam.
Clinical: hemorrhagic colitis, hemolytic uremic syndrome
Virulence: toxins like Shiga toxin
E. Coli: Enterohemorrhagic (EHEC) Infection
2 diseases, antibiotics?
Hemorrhagic colitis: stomach cramps, bloody diarrhea
Hemolytic uremic syndrome: kidney damage
Antibiotics don’t always help, can increase HUS risk
E. Coli Enterohemorrhagic Serotypes
Major O serotype: O157
Establishment of GI Infections
4
Anatomic alterations: obstruction of secretion flow, stuff gets stuck
Changes in stomach acidity: shigella and escherichia are acid resistant
Normal flora alterations: broad spectrum antibiotics
Encounter with specific pathogenic agents: infectious dose must be reached
Citrobacter, Enterbacter, Klebsiella, Morganella, Proteus, Serratia: Basics
Where, trans, clinical
Where: normal GI flora
Tranmission: endogenous, person to person
Clinical: opportunistic and nosocomial infections