I've been looking for a job in an antibiotic resistance for about 8 months because I'm thinking about exploring MD-PhD. I just ask PIs if they are expecting openings in the near future. That shows initiative and when they do get openings, it saves the PI time of scrolling through 50 applications, give or take, when they do have openings, provided they think you are a match for their lab. I found a PI whose lab is expanding in the field of antibiotic resistance in real soon. This was after 8 months of searching. I was VERY picky because this was the only research field I was interested in for possibly pursuing a thesis. I'm in a type 1 diabetes lab and that made me realize my research interests lie more in microbiology, that's why I was so picky. On the upside, being picky meant I was very interested in this field, so impressing the PI was a cake walk when I finally found one. This guaranteed me a spot as a research assistant in their lab when it expands. You may have an easier time finding a PI if you are not as picky as I was, but you may have a harder time impressing the PI.