The following antibiotics will be tested for resistance on all positive cultures: penicillin, cefazolin, ceftazidime, imipenem, gentamicin, tobramycin, erythromycin, azithromycin, ciprofloxacin, ofloxacin, levofloxacin, gatifloxacin, moxifloxacin, doxycycline, and vancomycin.