by jko757

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  • Escherichia coli
  • Shigella
  • Salmonella enterica
  • Yersinia
  • Klebsiella pneumoniae
  • Enterobacter
  • Citrobacter
  • Serratia marcescens
  • Proteus
Enterobacteriaceae characteristics
  • gram -
  • facultative anaerobic bacilli and coccobacilli
  • many are normal flora (colon expecially)
  • some are not- Salmonella, Shigella and Yersinia
Opportunistic pathogens  
normally benign but are able to produce disease in a host whose defenses have been compromised (AIDS, reptured appendix etc)
Antigens on enterobacteriaceae
  • Lipopolysaccharide (O antigens)
  • capsular polysaccharides (K antigen)
  • flagella (H antigen)
Escherichia coli
  • part of normal flora
  • causes UTIs and travelers diarrhea
  • 5 types
  • enterotoxigenic (ETEC)
  • enterohemorrhagenic (EHEC)
  • enterophatogenic (EPEC)
  • enterinvasive (EIEC)
  • enteroaggregative (EAEC)
alpha hemolysin
pore formin toxin; disrupts plasma membranes
e choli
iron siderophore (e coli)
polysaccharide capusle (e. coli)
reduces phagocytosis (K1 capsule associated with meningitis and bacteremia)
E. coli pili
  • important to act as adhesins
  • type 1- binding to the bladder
  • P pilli- binding to the upper urinary tract (pyelonephritis)
heat labile toxin (LT)
  • ETEC
  • A-B toxin
  • similar to cholera toxin
  • stimutes adenylate cyclase (make cAMP) in gut cells
  • plasmid encoded
heat stable toxin (ST)

  • ETEC

  • stimulates guanylate cyclas (cGMP) in gut cells

  • plasmid encoded

bundle forming pili (BFP)
  • EPEC
  • innitial atachemnt to intestinal epithelium
  • EPEC
  • adhesin on the surface of bacteria
type III secretion system
  • directly injects bacterial proteins into cytoplasm of host
  • secretion apparatus brings toxins to exterior of bacterium
  • translocation complex inserts into host membrane and puts toxins in there
  • effector proteins- toxins that have enzymatic activity
  • Tir is in EPEC- receptor for intimin
pathogens with type III secretion system
  • P. aerugionsa
  • Salmonella
  • Shigella
  • Bordetella
  • Yersinia
  • Chlamidia
  • EPEC
type III secretion system image
EPEC type III secretion
  • attachtes to microvilli
  • loss of structgure and formation of pedestal
  • secretes Tir- acts as a receptor for intimin- tight adherence
E coli clinical diseases
  • 90% of bladder and pyelonephritis
  • meningitis in neonates
  • nosocomial infection
Hemolytic-uremic syndrome
  • hemolytic anemia
  • decreased platlets
  • renal failure
  • CNS dysfunction
  • 3-5% mortality
  • dysenteriae
  • flexneri
  • boydii
  • sonnei
  • cause dysentery
  • common cause of diarrhea and 15% of foodborne ilnesses
  • more common in developed countries
  • chickens and turtles are reservoirs
  • salmonella serovar Typhi causes typhoid fever
salmonella pathogenicity island 1 (SPI-1)
  • type III secretion system
  • induces ruffling of enterocytes and internalization of bacteria
  • leads to strong inflammatory response and diarrhea
salmonella pathogenicity island 2 (SPI-2)
  • salmonella can disseminate into the blood using htis type III secretion
  • especially in imm. comp patients
salmonella diseases
  • need a large inoculum- bacteria is killed in stomach
  • diarrhea, nasea- 24-48 hrs
  • half fever
  • 8% bacteremia
typhoid fever
  • prolonged fever
  • bacteremia
  • constipation or diarrhea
  • abdominal pain
  • sometimes rash
  • sometimes in carrier state (no symptoms, but quite contagious)
  • shed in the feces
  • Y. enterocolitica-GI
  • Pseudotuberculosis-GI
  • Y. pestis- causes plague
Y. pestis
  • causes plague
  • very contagious
  • zoonotic
  • concerns about biological warfare
hemin storage locus (hms)
  • allows Y. pestis to colonize the flea forgut
Y. pestis patho
  • blocks flea forgut
  • when animal tries to eat, regurgitates meal with bacteria
  • inoculatedd into host
  • goes to lymph node and causes bubo
  • goes into blood stream- LPS->septic shock
  • eventually gets to macrophages in the lungs- aerosols
Y pestis genes

  • Ail- adhesin

  • type III secretion system (plasmid)

  • secrtes Yerseinia outer proteins E and H

  • Fra1- antiphagocytic- part of capsule

  • Pla- plasminogen activator- dissemnation

Bubonic plague
  • 2-6 day incubation
  • bubo develops near bite of flea (transmission vector)
  • fevers, chills, malaise, arthralgia and headach
  • bubo is large and painful
Penumonic plague
  • spread from human to human (through air)
  • 1-4 day incubation
  • sdden onset of chills, feve,r headach, myalgias (muscle ache), weakness
  • cough with blood sometimes
  • high mortality rate
  • contagious- aerosol
Primary septicemic plague
  • direct contact with infected animal tissue
  • nausea vomiting, diarrhea and abdominal pain (pretty unassuming)
Extended spectrum beta- lactamases (ESBLs)
  • resistance to most beta lactam like agents execpt carbapenems¬†
  • klebsiella and E. coli spp
  • Elebsiella pneumonia carbapenemase (KPC) strains are resistant to all of them now
Enterobacter, Citrobacter, Serratia marcescens
  • nosocomial respiratory infections UTI and abdominal infections
  • resistant to beta lactams
Proteus spp
  • P. mirabilis
  • P. vulgaris
  • "swarming motility"
  • colonies rapidly expend- hundreds of flagella on cells
  • UTI
  • have a urease that splits urea into ammonium hydroxide to raise urine PH
  • Pseudomonas aerugionas
  • fluorenscens, putida and stutzeri rare causes
  • can grow pretty much anywhere with air
exotoxin A
  • aeruginosa
  • acts similar to DT
  • ADP ribosylates EF2
  • P. aeruginosa
  • exopolysaccharid
  • mucoidy phenotype in cycstic fibrosis (this bacteria lives well in patients with CF)
  • antiphagocytic
LasA and LasB
  • P. aeruginosa
  • proteases that degrade elastin
Quorum sensing
  • system by which bacteria determine their numbers
  • want to wait for enough to start producing toxin
  • see lec for good picgture
ecthyma gangrenosum
  • skin lesions caused by P. aerugenosa
Legionella pneumophilla
  • cause Legionairre's Diseas
  • natural and manmade bodies of water are infested
  • lots of serogroups, but 1 is what causes most diseases
coiling phagocytosis
  • L. pneumophila
  • formation of a long, thin pseudopod by the macrophage
  • wraps around the bacterium
  • engulfed as a coiled vesicle
  • does not fuse- blocked
  • ER membrane and ribosomes are recruited to the phagosome
dot locus
  • L. pneumophila
  • defect in organelle trafficking
  • blocks phagolysosome fusion
  • recruits ribosomes
  • type IV secrtion system
Legionairre's disease (server pneumonia)
  • high fever
  • respiratory symptoms also with
  • head ache
  • changs in mental status
  • nausea
  • vomitting
  • diarrhea
  • hyponatremia
  • Livin in salt and freshwater
  • exposure to seawater
  • V. cholerae
  • V. parahemolyticus- gastroenteritis
  • V. vulnificus- gastroenteritius, wound in seawater, bad bacteremia (liver disease/alcoholic)
  • Gram -, slender slightly spiral shaped
  • pylori
  • commonly cause peptic ulcers
urease (H. pylori)
  • breaks down urea to make the environment around the bacteria more alkaline so it can survive
flagella and curved shape (H. pylori)
  • higher motility through mucus that lines the stomach
  • adherence
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