Enterobacteriacae Flashcards
What is the major cell wall antigen in Enterobacteriacae
LPS - lipopolysaccharide
What are the three major components in the LPS?
Outer somatic polysaccharide, Core polysaccharide, and Lipid A
What is the common antigen that all Enterobacteriacae possess?
Core polysaccharide (in LPS)
What part of LPS is important for epidemiologic classification of strains within a species?
O polysaccharide
What is the function of Lipid A?
Endotoxin - virulence factor
The serologic classification of Enterobacteriacae are based on what three major antigens?
Somatic O polyssaccharides, K (capsule) antigens, and H (flagellar) antigens
What diseases (two main ones) does E.coli O:157 H:7 cause?
Hemorrhagic colitis and hemolytic uremic syndrome (HUS)
What are the two toxins that ETEC possesses that cause watery diarrhea?
STa and LT-I (heat stable toxin and heat labile toxin)
What is the pathogenesis of EPEC?
Attachment/Effacentment (A/E) – Attachment to intestinal epi cells and destruction of microvilli
EPEC causes what symptoms and primary affects what age of people?
Watery diarrhea; infants
What is the cluster of genes called that causes virulence in EPEC and STEC?
locus of enterocyte effacement (LEE)
What ECOL? Most infections are attributed to the consumption of undercooked ground beef or other meat products, water, unpasteurized milk or fruit juices (e.g., cider made from apples contaminated with feces from cattle), uncooked vegetables such as spinach, and fruits.
STEC
VTEC and EHEC are subgroups of what type of ECOL
STEC
The diagnosis of STEC is made based on the production of what two toxins?
Stx1 and Stx2
What type of ECOL can cause hemorrhagic colitis and hemolytic uremic syndrome?
STEC
What disease causes traveler’s diarrhea; infant diarrhea in developing countries; watery diarrhea, vomiting, cramps, nausea, low-grade fever
ETEC
_____ is essentially identical to the Shiga toxin produced by Shigella dysenteriae
Stx1
True or False: STEC strains with both Shiga toxins and attaching and effacing activity are more pathogenic than strains producing only one Shiga toxin
TRUE
HUS is more closely associated with what Stx toxin?
Stx2
What are the two most common organisms that cause meningitis in infants younger than one month? (1 Enterobacteriaceae and 1 non-Enterobacteriaceae )
ECOL and BHSB
What serovars of Salmonella are adapted to ONLY human hosts?
Salmonella Typhi and Salmonella Paratyphi
Salmonella Typhi causes a febrile illness called____?
Typhoid Fever
What bacteria does this: The bacteria responsible for enteric fever pass through the cells lining the intestines and are engulfed by macrophages. They replicate after being transported to the liver, spleen, and bone marrow
Salmonella Typhi
Shigella _____ strains produce an exotoxin called Shiga toxin
Shigella dysenteriae
What species of Shigella is responsible for most cases in the US?
Shigella sonnei
What species of Shigella predominates in developing countries?
Shigella flexneri
Shigellae cause disease by invading and replicating in cells lining the __________
Colon
_____ is characterized by abdominal cramps, diarrhea, fever, and bloody stools.
Shigellosis
The cardinal feature of ______ is lower abdominal cramps and tenesmus (straining to defecate), with abundant pus and blood in the stool.
shigellosis
What organism can grow at 4C?
Yersinia
What color colonies would STEC, particularly 0157:H7, produce on sorbitol MAC plates?
Colorless
What method is this and what organism is it used to isolate: by mixing the fecal specimen with saline
and then storing the specimen at 4° C for 2 weeks or more before subculturing it to agar media.
Cold Enrichment for Yersinia
Y. pestis grows best at what temperature?
22-25C
This organism mimics appendicitis
Yesinia enterocolitica
Yersinia enterocolitica is urea ___ and indole ____ (pos/neg)
Positive; positive
This organism can grow at 4C
Yersinia enterocolitica
Aeromonas hydrophilia is oxidase ____, ____ (motile/nonmotile), and _____ hemolytic
positive, motile, beta hemolytic
