Thank you Dr. I forgot to mention that I'm 40 yrs. old so the "pimple" thing is a little weird. I had mild acne as a teenager but it disappeared by the time I was 18.
I guess there's no harm in testing again, but most pimples of the kind you describe are sterile -- have no bacteria. That's why the dermatologist recommended the cyclines, which help acne and similar sterile follicular conditions.
Still, if the cyclines haven't worked, it might be at leats worth considering a course of Keflex of the equivalent, whether or not a culture is positive.
Folliculitis is a very hard condition to have and to treat.
Good luck.
Dr. Rockoff