CLS05 - Enterobacteriaceae (Brief)

  1. Enterobacteriaciae - general characteristics (micro appearance, spores, ___erobic, biochemical char., colony appearance) + exceptions
    • G- rods or coccobacili (when young)
    • Non spore forming
    • Facultative anaerobes
    • Oxidase - (except Plesiomonas shigelloides)
    • Glucose fermentation +
    • Nitrate -> Nitrite + (except Photorhabdus, Xernohabdus)
    • Motile + (except Klebsiella, Shigella, Yersinia)
    • Catalase + (except Shigella dysentariae type 1)
    • Large moist gray colonies on TSA/BAP
  2. True pathogens vs opportunist genera
    • True Pathogens: Salmonella, Shigella, Yersinia, Pathogenic E. coli
    • Opportunists: Citrobacter, Cronobacter, Edwardsiella, Enterobacter, Escherichia, Hafnia, Klebsiella, Morganella, Pantoea, Plesiomonas, Proteus, Serratia
  3. What Ag assoc w/ most enterobacteriaceae?  Why important?
    • O (somatic) Ag: heat-stabile Ag on cell wall
    • H (flagellar) Ag: heat-labile Ag on surface of flagella
    • K (capsular) Ag: heat-labile polysaccharide assoc w/ encapsulated spp
    • Ag can be detected w/ ELISA and serology
  4. Escherichia sp info (habitat, related to, motility, complications)
    • Very common colon isolate (marker of fecal contamination in water)
    • Related to Shigella (DIFFER IN LAC FERM - E. coli is +)
    • Highly motile via peritrichous flagella
    • 4 toxins
    • a-hemolysin: forms pores in host cells
    • Shiga toxin: inhibits protein synthesis
    • Labile toxin (LT): similar to cholera toxin - much diarrhea
    • Stabile toxin (ST): electrolyte loss - much diarrhea
  5. E. coli imp biochemical
    • TSI: A/A
    • Indole: +
  6. UPEC info (name, habitat, diseases, virulence factors)
    • Uropathogenic E. coli
    • Normal flora of large intestine
    • Cause UTIs, disease in immunocomp
    • Special virulence factors...
    • pili: allow adherance to epithelium during flushing events
    • cytolysins: kill WBCs, inhibit phagocytosis/chemotaxis
    • aerobactin: chelate iron
  7. 5 categories of diarrheagenic E. coli.  Basis of differentiation?
    • Differentiation based on virulence factors, clinical manifestation, epidemiology, O and H serotypes
  8. ETEC info (name, transmission, dose, symptoms)
    • Enterotoxigenic E. coli
    • "traveler's diarrhea"
    • self limiting, fecal/oral trans., high infective dose (10^6 - 10^10)
    • watery diarrhea, nausea, abdominal cramps
    • diagnosis not usually necessary
  9. EIEC info (name, mechanism, symptoms, diagnosis)
    • Enteroinvasive E. coli
    • "dysentary"
    • penetration, invasion, destruction of intestinal mucosa
    • fever, severe cramps, malaise, watery diarrhea (very similar to Shigella)
    • diagnosis must indicate invasin virulence factor (not performed at most clinical labs)
  10. EPEC info (name, disease,  diagnosis, transmission)
    • Enteropathogenic E. coli
    • "infantile diarrhhea"
    • assoc w/ daycare, nurseries, nursing homes
    • low-grade fever, malaise, vomiting, diarrhea, stool contains large amounts of mucous + no blood
    • demonstrate adhesive qualities (fimbriae) not observed in EIEC or ETEC
    • transmission is fecal/oral including fomites
  11. EHEC info (name, disease, symptoms, transmission)
    • Enterohemorrhagic E. coli
    • hemorrhagic diarrhea (painful, lots of blood)
    • colitis (intestinal inflammation)
    • hemolytic uremic syndrome (HUS) (low platelets/kidney failure)
    • watery diarrhea -> bloody diarrhea + cramps
    • low grade or no fever
    • absense of leukocytes in stool distinguishes from dysentery
    • transmission from processed meats, unpasteurized dairy, cider, etc
    • **Includes O157:H7 and STEC
  12. EHEC / O157:H7 & STEC virulence factors and diagnosis
    • Verotoxin I (Shiga toxin - Stx1) is phage encoded (can be passed)
    • Vertoxin II (Stx 2)
    • Diagnosed w/ culture on SMAC, subculture clear colonies
    • MUG assay
    • ELISA or latex aggl. for O157, followed by H7
    • Serolog test for presence of Stx1 and Stx1
  13. EAEC info (name, disease, symptoms, virulence)
    • Enteroadherent E. coli
    • Diarrheal syndromes (pediatric)
    • UTIs (pediatric, preggo)
    • watery diarrhea, vomiting, dehydration for 2+ weeks
    • Adhere to surface of epithelial cells and eachother (stacked brick pattern)
    • *note - must treat fluid loss
  14. Shigella info (subgroups, related, antigens)
    • Subgroups based on O (somatic) antigen groups...
    • A (S. dysenteriae)
    • B (S. flexneri)
    • C (S. boydii)
    • D (S. sonnei)
    • Genetically related to E. coli (non-gas producing biotypes)
    • K antigens (capsular) present for some strains and hide O antigens.  Must be removed (heat) for serotyping
  15. Shigella imp biochemical
    • Anaerogenic (no gas)
    • TSI: K/A
    • Nonmotile
    • *S. dysenteriae is mannitol -
    • *S sonnei is mannitol+, ONGP+, ODC+
  16. Shigella (transmission, reservoir, disease)
    • Fecal/oral, direct, 5Fs (food, feces, flies, fomites, fucking)
    • infective dose <10
    • Humans are reservoir
    • Disease: dysentary
    • presence of blood, pus and much mucus in stool
    • high fever, chills, cramps, tenesmus (straining to try to poop)
    • **mild form assoc w/ S. sonnei and S. boydii
    • **Severe form assoc w/ S. dysenteriae
  17. S. sonnei info (predominant? severity?)
    • predominant in USA
    • short duration, self-limiting, fever, watery diarrhea (not much mucus)
    • often asympt
  18. S. fleneri (predominant? typical target? severity?)
    • endemic shigellosis in 3rd world nations
    • gastroenteritis in gay men (oral/anal)
    • Reiter chronic arthritis syndrome
  19. Shigella dysentery type 1 (severity? symptoms?)
    • More severe symptoms
    • penetration of intestinal mucosa (potential circulation)
    • VERY bloody diarrhea, intense ab pain, rectal prolapse, HUS, ileus (intestinal obstruction), toxic megacolon
  20. Edwardsiella (sp? reservoir? diseases?
    • E. tarda is only pathogen
    • reservoir: water that harbors fish or turtles
    • gastroenteritis, wound infections/bacteremia in immunocomp
  21. Citrobacter (sp? diseases? transmission? imp. biochem?)
    • 3 pathogenic (freundii, koseri, braakii)
    • C. freundii: UTIs, pneumonia, intra-abdominal abceses
    • C. koseri: neonatal meningitis (<2mo)
    • 75% develop brain absesses, survivors usually neuro defects
    • C. braakii: bacteremia, wound infections
    • transmission: person-to-person, nosocomial
    • H2S+ (black colonies)
    • citrate+ 
    • 50% are lac+ (pink color on MAC - resembles E. coli)
  22. Klebsiella (sp, disease, virulence factors, habitat, imp biochem,)
    • K. oxytoca: hemorrhagic colitis, bacteremia
    • K. pneumoniae:  immunocomp wound infections, UTIs, bacteremia
    • community-acquired pyogenic liver abscess
    • encapsulated! (grey, mucoid colonies)
    • normal flora of nasopharynx, GI tract
    • Citrate+
    • H2S-
    • Indole- (K. pneumoniae only)
    • Motility negative
    • **NOTE - string test for K. pneumo (lift colony w/ loop and will come off plate like a string due to capsule)
  23. Morganella (habitat, clinical significance, imp biochem)
    • Ubiquitous in env and GI tract
    • Found in patients with diarrhea
    • Clinical significance not clearly defined
    • Phenylalinine deaminase +
  24. Enterobacter (sp, importance, colonial appearance, imp biochem)
    • E. cloacae and E. aerogenes
    • One of most frequently isolated healthcare-assoc infections (contam. respirators, etc)
    • Isolated from wounds, urine, blood, and CSF
    • mucoid colonies may resemble Klebsiella
    • MR-/VP+
    • Lysine decarboxylase: E. cloacae-, E. aerogenes+
    • Arginine dihydrolase: E. cloacae+, E. aerogenes-
    • "aerogenes is arginine neg"
  25. Cronobacter sazakaii (diseases, imp biochem, treatment)
    • Bacteremia, meningitis, necrotizing colitis in neonates
    • MR-/VP+
    • Ornithine decarboxylase+
    • intrinsically resistant to ampicillin and cephalosporins
  26. Proteus (habitat, sp + differentiation, imp biochem, disease)
    • Commensal flora GI tract
    • P. mirabilis (ODC+, indole-)
    • P. vulgaris (ODC-, indole+)
    • phenylalanine deamination+
    • motile SWARMING on non-selective media
    • 3% of all nosocomial disease
    • ascending UTI -> acute glomerulonephtritis
    • wound infections, ear infections, bacteremia
  27. Serratia (disease, virulence factors, imp biochem, sp + way to ID)
    • assoc w/ nosocomial outbreaks (cystitis, bacteremia, septic arthritis)
    • Highly antibiotic resistant, disinfectant resistant
    • DNase+ (the only entero)
    • Lactose-
    • S. marcescens shows red pigment (could be misleading on MacConkey)
  28. Salmonella taxonomy
    • 2 species S. bongori and S. enterica
    • S. enterica has 6 subspecies based on O, H, and Vi (toxin) Ags
    • *Enterica enterica is most common in warm-blooded animals
    • over 2400 serotypes known
  29. Salmonella (imp biochem, virulence factors
    • H2S+ (S. typhi - weak "button" in TSI broth)
    • Indole-
    • lactose-
    • Fimbriae for adherence, ability to penetrate mucosa, entertoxins
  30. Salmonella Antigenic structures
    • O (somatic) antigen: heat-stable, LPS, different O molecules for different serotypes
    • H (flagellar) antigen: heat-labile, occur in 2 phases
    • 1. specific phase - small # serotypes; agglutinate only w/ homologous antisera
    • 2. nonspecific phase - several serotypes; react w/ heterologous antisera
    • Vi (virulence) antigen: heat labile, polysaccharide capsule ONLY W/ Typhi and Choleraeuis
  31. Salmonella diseases (detailed)
    • Gastroenteritis (food poisoning): S. enterica Enterica
    • Ingestion of bacteria from contam food (poultry, eggs, milk, handling pets)
    • Cooking utensils (knives, cutting boards)
    • 10^5 infective dose (<single colony)
    • Salmonellosis symptoms 8-10 hours after ingestion, self-limiting
    • Enteric (typhoid) fever: S. enterica Enterica serotype typhi, paratyphi, choleraesuis
    • tropical disease, transmitted fecal/oral, direct, or recent fomites
    • symptoms 9-14 days after ingestion: fever, malaise, anorexia, myalgia ->  prolonged fever, bacteremia -> dissemination to multiple organs (moves w/ M0)
    • carrier state after infection
    • Bacteremia: nontyphoidal Salmonella
    • prolonged fever/intermittent bacteremia affects young children
    • transient bacteremia/gastroenteritis and septic arthritis in adults
  32. Yersinia (sp w/ disease, reservoires, transmission)
    • Y. pestis: the plague (pneumonic (BAD) and bubonic (treatable)
    • lacks O antigen (no serotypes)
    • reservoirs - rodents, squirrels
    • transmission from FLEA bites, cat scratches, bites, inhalation of aerosolized organisms
    • Y. enterocolitica: diarrheal illness in young children
    • transmission from undercooked meats (pork), milk, liquids
    • Zoonosis
    • Y. pseudotuberculosis: septicemia, symptoms like appendicitis
    • Zoonosis
    • causes pseudotubercles (swellings)
    • tranmission from close contact w/ infected animals, contaminated food
  33. Yersinia (micro appearance, culture considerations, colony appearance)
    • coccobacillus with bipolar staining ("safety pin")
    • grows slower than other enterics
    • CIN agar (bullseye), YSA agar (rarely used), SBA (fried egg morphology w/ little/no hemolysis)
  34. bubonic plague disease mechanism detailed
    • glandular
    • transmitted by flea bite (Y. pestis)
    • bacteria migrate through blood to lymph nodes, proliferate
    • symptoms 2-5 days after bite,include high fever and buboes
    • Mortality 50-60% if untreated, 15% w/ treatment
  35. Plesiomonas Shigelloides (reservoir, trnsmission, disease, imp biochem)
    • reservoir: fresh water
    • transmitted: ingestion of contaminated water OR break in skin
    • disease: gastroenteritis (food poisoning)
    • oxidase+ (the only enterobac)
Card Set
CLS05 - Enterobacteriaceae (Brief)
CLS05 - Enterobacteriaceae (Brief)