Section: USMLE

58) A 24-year-old woman in her third trimester of pregnancy presents with urinary frequency and burning for the past few days. She denies fever, nausea, vomiting, or chills. She takes no medications besides prenatal vitamins and is generally in good health. Physical examination is remarkable for mild suprapubic tenderness, and a urine dipstick is positive for white blood cells, protein, and a small amount of blood. Culture produces greater than 100,000 colonies of gram-negative bacilli. Which of the following attributes of this uropathogenic organism is most strongly associated with its virulence?

1. Bundle-forming pili
2. GVVPQ fimbriae
3. Heat labile toxins
4. Heat stable toxins
5. P pili
6. Type 1 pili

Urinary tract infections are the most common bacterial infections encountered during pregnancy, and Escherichia coli is the most commonly isolated organism. In the U.S., 70% of cases are caused by P pili-positive strains.

Bundle-forming pili are found in enteroaggregative E. coli (EAEC).

GVVPQ fimbriae are found in EAEC.

Heat labile toxins are pathogenic factors in enterotoxic strains (ETEC).

Heat stable toxins are pathogenic factors in ETEC or EAEC.

Type 1 pili are a major pathogenic factor in ETEC.