Percentage of total AU contributed by the 4 most commonly used agents in each level of neonatal patient care. a All other agents as follows: level III NICUs: amikacin, amoxicillin, amoxicillin and/or clavulanate, amphotericin B, amphotericin B liposomal, ampicillin and/or sulbactam, anidulafungin, azithromycin, aztreonam, cefazolin, cefdinir, cefepime, cefixime, cefotaxime, cefotetan, cefoxitin, ceftaroline, ceftazidime, ceftriaxone, cefuroxime, cephalexin, ciprofloxacin, clindamycin, colistimethate, daptomycin, doxycycline, ertapenem, erythromycin, fidaxomicin, fluconazole, levofloxacin, linezolid, meropenem, metronidazole, micafungin, nafcillin, nitrofurantoin, oseltamivir, oxacillin, penicillin G, penicillin V, posaconazole, rifampin, sulfamethoxazole and/or trimethoprim, tobramycin, voriconazole; level II-III NICUs: amikacin, amoxicillin, amoxicillin and/or clavulanate, amphotericin B, amphotericin B liposomal, ampicillin and/or sulbactam, azithromycin, aztreonam, caspofungin, cefazolin, cefdinir, cefepime, cefotaxime, cefotetan, cefoxitin, ceftaroline, ceftazidime, ceftriaxone, cefuroxime, cephalexin, ciprofloxacin, clindamycin, daptomycin, doxycycline, erythromycin, imipenem and/or cilastatin, levofloxacin, linezolid, meropenem, metronidazole, micafungin, nafcillin, nitrofurantoin, oseltamivir, oxacillin, penicillin G, penicillin V, piperacillin and/or tazobactam, rifampin, sulfamethoxazole and/or trimethoprim, tobramycin; level II special care nurseries: amoxicillin and/or clavulanate, azithromycin, cefazolin, cefdinir, cefepime, cefixime, ceftaroline, ceftazidime, ceftriaxone, cefuroxime, cephalexin, clindamycin, erythromycin, fluconazole, linezolid, meropenem, metronidazole, nafcillin, nitrofurantoin, oseltamivir, oxacillin, penicillin G, penicillin V, piperacillin and/or tazobactam, rifampin, sulfamethoxazole/trimethoprim, vancomycin; level I well newborn nurseries: azithromycin, cefazolin, cefepime, cefotaxime, cefoxitin, ceftazidime, ceftriaxone, cephalexin, clindamycin, erythromycin, fluconazole, levofloxacin, metronidazole, nafcillin, oseltamivir, oxacillin, piperacillin and/or tazobactam, vancomycin.