Vaginal swabs in pregnancy

What can be screened for in vaginal swabs in pregnancy?
Vaginal swabs may be taken in pregnancy for select tests and screens. For each of the tests (numbered below), please list:
e. at what point in pregnancy we perform this test
f. what they are screening for, and why
g. what typical symptoms present with these conditions
you may also feel free to add any tests that are standard in your community or subtract tests that are not standard in your community.
Chlamydia and Gonorrhea
Bacterial Vaginosis
Yeast
Trichomonas
(other)
When collecting any of the vaginal swabs above, do you perform the test, or do you give your clients instructions to self-swab?
In some rare circumstances, swabs to culture sores, cysts, or other wounds in pregnancy may be taken from the chest/breasts, vaginal area, and other spots. What might these swabs/cultures be screening for?