Can the docs tell what kind of bacteria u are infected with by just looking at you?

I mean they prescribe antibiotics without a bacteria culture. How can they tell what kind of bacteria u have?

U go to the doc, he looks at u, then he writes a prescription...

pano nya alam na ung antibiotic na na-prescribe nya is effective against ur bacteria? trial and error? if it doesnt work, he prescribes another?