IV: Cloxacillin, Cefazolin

PO: Cephalexin, Cloxacillin

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Methicillin (oxacillin)-susceptible staphylococci can be considered susceptible to:

• Beta-lactam combination agents (amoxicillin-clavulanate, ampicillin-sulbactam, piperacillin-tazobactam)

• Oral cephalosporins (cephalexin, cefuroxime)

• Parenteral cephalosporins (cefazolin, cefuroxime, cefoperazone, cefotaxime, ceftriaxone, cefepime, ceftaroline)

• Carbapenems (ertapenem, imipenem, meropenem)

IV: Vancomycin

PO (Combination): Trimethoprim/sulphamethoxazole, Rifampicin, Fusidic Acid

IV: Linezolid, Ceftaroline

PO: Linezolid

• Methicillin (oxacillin)-resistant staphylococci are resistant to all currently available beta-lactam antimicrobial agents, with the exception of ceftaroline.

• MIC tests should be performed to determine the susceptibility to vancomycin of all MRSA isolates.

• Rifampicin should not be used alone for antimicrobial therapy.

IV/PO: Trimethoprim/sulfamethoxazole, Clindamycin

PO: Fusidic acid + Rifampicin

PO: Linezolid, Doxycycline

• Rifampicin should not be used alone for antimicrobial therapy.

Enterococcus faecalis:

Ampicillin

Enterococcus faecium:

Vancomycin

Vancomycin Resistant Enterococcus:

Linezolid

Enterococcus faecalis:

Vancomycin, Linezolid

Enterococcus faecium:

Linezolid

• For Enterococcus spp., cephalosporins, aminoglycosides (except for high-level resistance testing), clindamycin and trimethoprim-sulfamethoxazole may appear active in vitro but are not effective clinically and should NOT be reported as susceptible.

• Ampicillin susceptibility tests should be used to predict the activity of amoxicillin.

• Ampicillin results may be used to predict susceptibility to amoxicillin/clavulanate, ampicillin/sulbactam and piperacillin/tazobactam among non-beta-lactamase-producing enterococci.

• Ampicillin susceptibility can be used to predict imipenem susceptibility for Enterococcus faecalis. 

• Nitrofurantoin can be used for susceptible Enterococcus spp. isolated from urine. 

Penicillin, Ampicillin

Amoxicillin/clavulanate, Ampicillin/sulbactam

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Penicillin

Amoxicillin/clavulanate, Ampicillin/sulbactam, Ceftriaxone, Cefotaxime

For non-meningitis isolates of S. pneumoniae, penicillin susceptible can predict susceptibility to:

• Ampicillin (oral or parenteral), amoxicillin

• Beta-lactam combination agents (amoxicillin-clavulanate, ampicillin-sulbactam)

• Cephalosporins (cefuroxime, ceftriaxone, cefotaxime, cefepime, ceftaroline)

• Carbapenems (ertapenem, imipenem, meropenem)

Penicillin, Amoxicillin-clavulanate, Ampicillin-sulbactam

Ceftriaxone, Cefotaxime

The viridans group of streptococci includes the following five (5) groups, with several species within each group:

• mutans group

• mitis group

• salivarius group

• bovis group

• anginosus group (previously known as S. melleri group). This group includes S. anginosus, S. intermedius and S. constellatus only