What is group b strep and how can someone get it?

A bacteria. Group b strep is a type of bacteria that grows on the skin and in your vagina. It can cause an infection in the baby so all women are screened for colonization in the third trimester and treated with antibiotics during labor if the screen is positive. You get it from other people who are colonized.
Common germ. Group b strep is a periodic visitor to the digestive tract & at any given time 30% of women may have it show up on a vaginal swab. Except for it's well known nasty habit of hurting newborns & occasionally causing urinary tract infections it can be just a benign hitchhiker in your system. If you have urinary symptoms antibiotic treatment may be helpful, but rarely eliminates this germ permanently.