Escherichia coli

Escherichia coli (commonly abbreviated E. coli) is a Gram-negative, enteric (in the GI tract), facultatively anaerobic, rod-shaped bacterium of the genus Escherichia that is commonly found in shit. They ferment lactose to produce CO2. The presence of E.coli in water suggests that other pathogens can be present as well.

Most of the 150 strains of E. coli are not infectious and are only opportunistic.

We will focus on the pathogenic strains, which are Enterotoxigenic E. coli (ETEC), Enteroinvasive E. coli (EIEC), and Enterohemorrhagic/pathogenic E. coli (EHEC).

ETEC produces an exotoxin, EIEC will invade cells of the large intestine, and EHEC/EPEC produce shiga toxin after conjugation with Shigella. An example of an EHEC is E. coli 0157:H7.

Infections
Cystitis is an UTI involves urinary bladder more common in females b/c of shorter urethra. E. coli is responsible for 85% of uncomplicated cases of cystitis. #2 cause of uncomplicated cystitis is Proteus, which is also the #1 cause of complicated.

Epidemic Diarrhea: Also called summer diarrhea and infantile diarrhea. Caused by enteropathogenic strain, such as, E. coli 0157:H7. Very easily spread.

Traveler’s Diarrhea: Also called Tourista. Concern in drinking water and raw vegetables. Mostly caused by enterotoxigenic strains. 

Peritonitis: Has to do w/the peritoneum which is the interior lining of the body. E. coli will get in b/c of holes in the intestinal tract. Appendicitis: when becomes blocked by stool, cancer, foreign body.


In addition to the normal gram stain, serology is used to determine the specific strain.

Treatment
Use cephalosporins such as Ceftriaxine, Cefotaxime, or Cefepime for identified E. coli infections.

If you have an uncomplicated UTI that is not identified, doctors may simply prescribe combinations of Sulfamethoxazole and Trimethoprim (Bactrim).