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
Other Infections: Klebsiella Pneumoniae
Community/nosocomial: pneumonia
- Capsule, adhesins
Other Infections: Proteus spp.
UTI with or without kidney stones
- Biofilm, adhesins, proteases
Other Infections: Citrobacter Koseri
Meningitis, brain abscesses in neonates
Other Infections: Enterobacter/Cronobacter
For both
Enterobacter: various nosocomial like UTI
Cronobacter: meningitis/sepsis in newborns
Other Infections: Serratia, Morganella
Both cause various nosocomial infections
Salmonella Basics
where, trans, clinical
Where: typhi and paratyphi in humans, not normal flora
Transmission: person to person, fecal oral, contaminated food
Clinical: gastroenteritis, typhoid fever
Salmonella Virulence
and pathogenesis
Can traverse intestinal mucosa
Pathogenesis:
- Ingest microbe, absorb into epi cells in intestines
- Penetrates cells and multiply
- Stimulation of cAMP and fluid secretion from host immune response
Salmonella Infections
two, treatment
Gastroenteritis: acid sensitive, vomiting, nausea, diarrhea, can recover without treatment, caused by foods, 4-7 day duration
Enteric fever: typhi or paratyphi, typhoid fever, pain and diarrhea, 4 week duration w some relapse
S. typhi has a vaccine
Shigella: Basics
where, trans, clinical, virulence
Where: human host specific, not normal flora
Transmission: fecal oral
Clinical: diarrhea, pediatric disease
Virulence: traverse intestinal mucosa
- S. dysenteriae has an exotoxin
Shigella: Species
4 and grouping
- S. sonnei, Group D, most common
- S. flexneri, Group B, more severe
- S. boydii, Group C, more severe
- S. dysenteriae, Group A, most serious
Shigella: Infections
symptoms, recovery, risks
Shigellosis
- Short incubation
- Low dose
- Watery diarrhea, becomes bloody/mucus, cramps, fever
- 1 week duration
Recovery: often without treatment, immunocompromised may get antimicrobials
Risk: poor hygiene, child care, janitors, mlm
Yersinia: Basics
3 species, where for each, trans, significance
Y. pestis: rats, rodents, flea vector | ingestion or inhalation of tissue or airborne droplets | bubonic plague, pneumonic plague
Y. enterocolitica: dogs, cats, rodents, rabbits, pigs, cattle | consumptopn of contaminated food, contact with contam. animal | enterocolitis, pseudoappendicitis
Y. psudotuberculosis: birds, deer, rodents: same as above
Yersinia Pestis: Virulence Factors
Plasmids that encounde virulence genes’
- pPCP1: bacteriocin that kills other bacteria and activates plasminogen, degrades complement and prevents opsonization and phagocytic migration - allows for deep tissue invasion
- pMT1: murine toxin that enhances survival in the flea gut, F1 capsular antigen
Yersinia Pestis: Infections
2 of them
Bubonic plague
- 1 wk incubation
- Fever, swelling of lymph node, bacteremia without treatment, 75% mortality
Pneumonic plague
- 2-3 day incubation
- Fever, malaise, pulmonary symptoms
- Person to person spread possible, highly infectious
- Mortality rate 90% without treatment
Other Yersinia Infections
Enterocolitis
- Fever, pain, diarrhea (maybe bloody), vomiting
- Lasts up to 2 weeks
- Meats, oysters, fish, raw milk
Pseudoappendicitis: from abdominal pain of lower right quadrant, thinks its appendix problem
Extraintestinal: arthritis
Plesiomonas Shigelloides: Basics
where, trans, clinical
,Where: soil, freshwater, warm and cold blood animals
Transmission: contaminated food or water, reptile exposure
Clinical: gastroenteritis (watery or secretory diarrhea, can be chronic for months even) or opportunistic sytemic (meningitis, bacteremia)
Salmonella: Serotyping
- Somatic O
- Surface Vi
- Phase 1 or phase 2 flagellar (H antigen)
