Microbiology - Spot questions

Question 1

What differentiates EHEC 0157:H7 from other strains of E.coli?

Answer 1

In contrast to most E. coli strains, EHEC 0157:H7 does not ferment sorbitol and does not produce glucoronidase.

Unlike other E. coli, EHEC does not invade the intestinal mucosa, instead it elaborates a Shiga-like toxin which inactivates the 60S ribosomal subunit, thereby causing inhibition of protein synthesis and cell death.

Question 2

Which infectious agent is associated with the production of cold agglutinins?

Answer 2

Mycoplasma pneumoniae

Question 3

What causes “cat-scratch disease”?

What other important condition is caused by this organism?

Answer 3

Bartonella henselae.

Also causes bacillary angiomatosis in immunocompromised patients. These vascular proliferative skin lesions can lead to fatal disease.

Question 4

Neutropenia increases susceptibility to which organisms in particular?

What are ecthyma gangrenosum associated with?

Answer 4

Gram negative sepsis.

Pseudomonas aeruginosa.

Question 5

Most cases of EHEC 0157:H7 are associated with recent consumption of?

Answer 5

Undercooked contaminated ground beef.