Table 1.

Inferred Susceptibility to β-Lactam Agents for Staphylococci Based on Testing of Penicillin and Oxacillin or Cefoxitin

Actual Susceptibility Result
Penicillin	Oxacillin or Cefoxitin	Inferred Susceptibility Result
S	S	S to penicillins (penicillinase-labilea and stableb), β-lactam/β-lactamase inhibitor combinationsc, cephemsd, and carbapenemse
R	S	R to penicillinase-labile penicillins
		S to penicillinase-stable penicillins, β-lactam/β-lactamase inhibitor combinations, antistaphylococcal cephems, and carbapenems
R	R	R to penicillins, β-lactam/β-lactamase inhibitor combinations, cephems, and carbapenems except newer cephalosporins with anti-MRSA activity (when confirmed by standardized testing [eg, ceftaroline])

Abbreviations: MRSA, methicillin-resistant Staphylococcus aureus; R, resistant; S, susceptible.

^aPenicillinase-labile penicillins: amoxicillin, ampicillin, azlocillin, carbenicillin, mezlocillin, penicillin, piperacillin, ticarcillin.

^bPenicillinase-stable penicillins: cloxacillin, dicloxacillin, flucloxacillin, methicillin, nafcillin oxacillin.

^cβ-Lactam/β-lactamase inhibitor combinations: amoxicillin-clavulanic acid, ampicillin-sulbactam, piperacillin-tazobactam, ticarcillin-clavulanic acid.

^dAntistaphylococcal cephems include the oral cephems (cefaclor, cefdinir, cefpodoxime, cefprozil, cefuroxime, loracarbef) and the parenteral cephems (cefamandole, cefazolin, cefepime, cefmetazole, cefonicid, cefoperazone, cefotaxime, cefotetan, ceftizoxime, ceftriaxone, cefuroxime, cephalothin, ceftaroline moxalactam) for indications approved by the US Food and Drug Administration or other regulatory bodies in the country of use.

^eCarbapenems: doripenem, ertapenem, imipenem, meropenem.