Aerobic Susceptibility Gram Positive Organism

This test checks how a gram-positive bacterial infection responds to a wide panel of antibiotics, helping doctors figure out which drugs will actually clear the infection instead of relying on guesswork. Once a gram-positive organism, things like Staphylococcus, Streptococcus, or Enterococcus, gets isolated from a patient sample, the lab tests it against dozens of antibiotics individually and reports back whether each one is likely to work, partially work, or fail entirely. Gram-positive bacteria have their own particular resistance quirks, MRSA being probably the most well-known example, which makes this kind of targeted testing especially important rather than optional.

Who should get this test done?

This test is recommended for:

●     Individuals with a confirmed gram-positive bacterial infection requiring tailored antibiotic selection
●     Individuals with suspected MRSA or other resistant staph infections
●     Individuals with skin, soft tissue, or bloodstream infections not improving on initial treatment
●     Individuals with recurrent infections where past antibiotics may no longer be effective
●     Hospitalized or ICU patients where infection severity calls for precise, evidence-based drug choices
Why consider this test?

Gram-positive infections come with their own set of resistance challenges, and treating them with the wrong antibiotic can mean a slower recovery or a worse outcome altogether. This test specifically screens for resistance patterns like methicillin resistance through oxacillin and cefoxitin screening, along with inducible clindamycin resistance, both of which can completely change which antibiotics are actually safe and effective to use. It also checks gentamicin synergy, which matters quite a bit in serious infections like endocarditis, where certain antibiotic combinations work far better together than either drug would alone. Having this level of detail upfront means doctors aren’t left adjusting treatment after the fact once a drug has already failed.

More information

The panel runs through a tiered list of antibiotics, starting with first-line options like penicillin, ampicillin, and azithromycin, moving into a much larger second-line group that includes vancomycin, linezolid, daptomycin, and several others typically reserved for tougher infections. A dedicated screening section checks specifically for resistance markers like MRSA (Methicillin-resistant Staphylococcus aureus) and clindamycin resistance, while a smaller supplemental section covers additional drugs like rifampin for specific clinical situations. Each antibiotic is reported with its own interpretation, giving doctors a full resistance profile in one place rather than ordering multiple separate tests.

Other names

●     Culture and sensitivity, gram positive
●     Gram positive antibiotic susceptibility test
●     C&S, gram positive organism
●     MRSA susceptibility panel
●     Gram positive culture sensitivity panel