Enterobacteriaceae Diversity of species Ecology Found worldwide in soil, water, vegetation, and microbial flora of animals and humans Some are always associated with disease e.g., Shigella, Salmonella, yersinia pestis Some are normal flora that can become opportunistic pathogens . e.g. E, coll, k. pneumoniae p mirabilis BIOL 533 Lecture
BIOL 533 2 Lecture 12 Enterobacteriaceae • Diversity of species • Ecology – Found worldwide in soil, water, vegetation, and microbial flora of animals and humans – Some are always associated with disease • e.g., Shigella, Salmonella, Yersinia pestis – Some are normal flora that can become opportunistic pathogens • e.g., E. coli, K. pneumoniae, P. mirabilis
Enterobacteriaceae Epidemiology Animal reservoir: most salmonella infections Human carrier:5a/e∥m5hige∥a Endogenous spread in a susceptible patient Can involve all body sites 5% hospitalized patients develop nosocomial infections primarily caused by Enterobacteriaceae such as Escherichia ● Sites of infection BIOL 533 Lecture
BIOL 533 3 Lecture 12 Enterobacteriaceae • Epidemiology – Animal reservoir: most Salmonella infections – Human carrier: Salmonella typhi, Shigella – Endogenous spread in a susceptible patient • Can involve all body sites • 5% hospitalized patients develop nosocomial infections, primarily caused by Enterobacteriaceae such as Escherichia • Sites of infection
Microbial Physiology and structure Cell morphology Moderate-sized gram rods Non-spore-forming Motile(with peritrichous flagella) or non-motile Physiology All are facultative anaerobes Simple nutritional requirements Ferment glucose Reduce nitrates to nitrites BIOL 533 Lecture
BIOL 533 4 Lecture 12 Microbial Physiology and Structure • Cell morphology – Moderate-sized Gram— rods • Non-spore-forming • Motile (with peritrichous flagella) or non-motile – Physiology • All are facultative anaerobes • Simple nutritional requirements: – Ferment glucose – Reduce nitrates to nitrites
Distinguishing Characteristics Oxidase Distinguishes among other fermentative and non- fermentative gram bacilli Lactose fermentation(red colonies on MacConkey agar) Separate Escherichia, Klebsiella, Enterobacter from other lactose Enterobacteriaceae BIOL 533 Lecture
BIOL 533 5 Lecture 12 Distinguishing Characteristics • Oxidase¯: – Distinguishes among other fermentative and non-fermentative Gram— bacilli • Lactose fermentation (red colonies on MacConkey agar) – Separate Escherichia, Klebsiella, Enterobacter from other lactose— Enterobacteriaceae
Distinguishing Characteristics Resistance to bile salts Separate Shige∥ a and sa/me∥ la from normal flora in this group Eosin Methylene Blue(EMB Lactose, eosin, methylene blue; Lact, grow With green sheen BIOL 533 Lecture 12
BIOL 533 6 Lecture 12 Distinguishing Characteristics • Resistance to bile salts – Separate Shigella and Salmonella from normal flora in this group • Eosin Methylene Blue (EMB) – Lactose, eosinY, methylene blue; Lac+; grow with green sheen