Enterobacteriaceae Part 1

Cards (81)

  • Enterobacteriaceae
    - gram neg bacilli/coccobacilli
    - enterics/coliforms
    - habitants: intestinal tract
    - does not produce cytochrome except: plesiomonas
    - can reduce nitrate to nitrite except: photorhabdus & xenorhabdus
    - all glucose fermenter
    - motile with a presence of peritrichous flagella except:
    • Shigella
    • Klebsiella
    • Yersinia
  • H2S
    • blackening of the colony or medium
    • observed on Triple Sugar Iron Agar (TSI)
    S - Salmonella
    P - Proteus
    A - Arizona
    C - Citrobacter
    E - Edwardsiella
    • observed on Lysine Iron Agar (LIA)
    S - Salmonella
    A - Arizona
    C - Citrobacter
    E - Edwardsiella
  • Urease
    • Rapid urease producers
    P - Proteus
    P - Providencia
    M - Morganella
    • Slow urease produces
    C - Citrobacter
    K - Klebsiella
    E - Enterbacter
    Y - Yersinia
    S - Serratia
  • Deaminase
    P - Proteus
    P - Providencia
    M - Morganella
  • Lysine Decarboxylation
    • Positive
    K - Klebsiella
    E - Escherichia
    E - Edwardsiella
    S - Serratia
    S - Salmonella xpt: paratyphi A
    H - Hafnia
  • Lysine Decarboxylation
    • Negative
    P - Proteus
    P - Providencia
    M - Morganella
    C - Citrobacter
    Y - Yersinia
    E - Enterobacter
    S - Shigella
  • Pathogenic & Spectrum of Diseases
    1. Opportunistic Pathogen
    S - Serratia
    P - Proteus
    E - Enterobacter
    E - E.coli
    C - Citrobacter
    k - Klebsiella
  • Pathogenic & Spectrum of Diseases 
    2. Intestinal Pathogens (Primary pathogens)
    S - Salmonella typhi : typhoid/enteric fever
    S - Shigella : dysentry
  • Virulence and Antigenic Factors
    1. O antigen/Somatic
    • Heat stable
    • located at cell wall
  • Virulence and Antigenic Factors 2. H antigen/Flagella
    • Heat labile
    • located at the surface of flagella
    • responsible for motility
  • Virulence and Antigenic Factors 3. K antigen/Capsullar
    • heat labile
    • located at encapsulated spp.
    • E. coli - K1 antigen
    • S. enterica - V1 antigen
  • Escherichia coli
    • 1885
    • colon/golden bacillus
    • primary marker of fecal contamination in water quality testing
    • motile: fimbriae & sex pili & O,H,K antigen
    • lactose (+): pink colonies on MAC Agar
    • EMB: green metallic sheen
    • most common cause of nosocomial infection
    • UTI, bacteremia, menigitis
  • Uropathogenic Escherichia coli is the most common cause of UTI
  • Gastrointestinal pathogen causes diarrhea
  • Enterotoxigenic E. Coli
    • Diarrhea in adults and esp in children
    • one of the major causes of infant bacterial diarrhea
    • sometimes reffered to as travelers diarrhea
    • MOT: contaminated food/water
    • Achlorhydria(deficiency in HCL acid): high risk factor
    • heat labile enterotoxin
    • no vomiting/ fever
  • Enteropathogenic E. Coli
    • infantile diarrhea
    • Symptoms: low grade fever, vomiting, diarrhea
    • O serogroups - cause of diarrhea
    • H antigenic - intestinal infection
    • Stool: Water with mucus but without blood
  • Enteroinvasive E. coli
    • dysentery with direct penetration, invasion, and destruction of intestinal mucosa
    • similar to shigellosis
    • MOT: person to person via faecaloral route
    • Non lactose fermenter
    • do not decarboxylate lysine
  • Enterohemorrhage E. coli
    • O 157 : H7 - hemorrhagic diarrhea, colitis hemolytic uremic syndrome (HUS) [ low platelet count and kidney failure]
    • Biochemical test: 4 methylumbelliferyl - B - D - glucuronide assay (MUG)[fluorescent]
    • 2 toxins:
    • verotoxin I - identical to shigatoxins (damage to vero cell)
    • verotoxin II - shigatoxin producing
    • does not ferment sorbitol
    • watery diarrhea, bloody with abdominal cramps
  • Opportunistic Pathogens
    • Part of the intestinal microbiota of humans and animals
  • Intestinal pathogens
    • referred to as the primary pathogens
  • Properties of Enterobacteriaceae
    • Fermentation of glucose, lactose, trehalose, and xylose
    • production of indolent from tryptophan
    • does not produce H2S
    • cannot use citrate as a sole carbon source
  • Uropathogenic E. coli
    • most common cause of UTI in humans
    • Usually, these strains that causes UTI allows them to attach to the epithelial urinary mucosa
  • Enteroadherent E. coli
    • Diarrheal syndrome and UTIs - DAEC (diffusely adherent E. coli)
    • EAEC (enteraggregative E. coli) -diarrhea by adhering to the surface of intestinal mucosa
    • Most common causes of septicemia and meningitis among neonates
  • Escherichia hermanii
    • yellow pigmented
    • isolated from CSF, wounds, and blood
  • Escherichia vulneris
    • yellow pigmented
    • isolated from humans with infected wounds
  • Escherichia albertii
    • associated with diarrheal disease in children
  • Klebsiella and Raoutella ( - - + + )
    • most grow on Simmons citrate and in potassium cyanide broth
    • None H2S producing
    • A few hydrolyze urea slowly
    • all (-) in methyl red test
    • all (+) in Voges proskauer test
    • no indole is produced from tryptophan
    • motility is variable
    • associated w/ opportunistic and hospital infections
  • Klebsiella and Raoutella ( - - + + )
    • Klebsiella pneumoniae - most commonly isolated species; large polysaccharide capsule
    • Capsule: provide protection against phagocytosis (responsible for moist and mucoid colonies) (tend to string)
    • Friedlanders bacillus
    • able to cause pneumonia which is very necrotic and hemorrhagic- currant jelly is sputum
  • Klebsiella oxytoca
    • the only indole (+) among Klebsiella spp.
    • Isolated in stool and blood cultures
    • ornithine positive
    • linked to antibiotic associated hemorrhagic colitis
  • Klebsiella pneumoniae subsp. ozaenae
    • highly associated with the presence of plasmid mediated ESBLs
    • isolated from nasal secretions and cerebral abscesses
  • Klebsiella pneumoniae subp. rhinoscleromatis
    • isolated from patients with rhinoscleroma
    • infection in the nasal cavity
    • intense swelling and malformation of the entire face and neck
  • Raoutella (klebsiella) ornithinolytica
    • indole and ornithine decarboxylase positive
  • Raoutella (klebsiella) planticola
    • isolated from urine, RT, and blood
  • Klebsiella variicola
    • isolated from primarily sterile sites
  • Enterobacter, Cronobacter, & Pantoea ( - - + +)
    • motile
    • resembles klebsiella when growing on MAC agar
    • grow on Simmons citrate medium and potassium cyanide broth
    • (-) methyl red test
    • (+) voges proskauer test
    • usually produce ornithine decarboxylase
    • lysine decarboxylase is produced by most spp. but not by E. gergoviae or E. cloacae
    • Considered as slow urease producer except: E. gergoviae
  • Enterobacter taylorae
    • lactose (-)
    • ONPG (+)
  • Enterobacter gergoviae
    • resembles enterobacter aerogenes
    • rapid urease produces (RUP)
    • causes infection of urinary tract and blood
  • Cronobacter sakazakii
    • Biochemically similar to E. cloacae
    • Yellow pigment
    • Pathogen in neonates - meningitis an bacteremia
    • Often coming from powdered infant formula
  • Pantoea agglomerans
    • Triple decarboxylase negative
    • Lysine, ornithine, arginine
    • (+) indole
    • (-) mannitol, raffinose, salicin, sucrose, maltose, xylose
  • Serratia ( - V + + )
    • opportunistic pathogen
    • associated with outbreaks in HC settings
    • Ferment lactose slowly
    • (+) for o -nitrophenyl - B - D - galactopyranoside (ONPG) test except: S. fonticola
    • Ability to produce extracellular DNase
    • S. marcescens, S. rubidaea, S. plymuthica produce a pink to red pigment, prodigiosin especially when incubated at room temperature