An antibiogram or sensitivity test is used to determine the susceptibility of organisms involved in various infections to antimicrobial drugs when the susceptibility of the organism cannot be predicted on the basis of its identity. Antibiotic susceptibility is sometimes used to monitor hospital infections such as methicillin-resistant Staphylococcus aureus (MRSA) and to evaluate resistance to new antimicrobial drugs.
There are no interpretative criteria for all bacteria. The division into categories of sensitive, moderately sensitive, and resistant is based on the levels of antibiotics achieved in the serum of individuals with normal renal and hepatic function. Antibiotics that accumulate in the urine can be effective for urinary tract infections even when the microbes are classified as resistant. Conversely, medicines that do not penetrate the tissues with poor blood supply may not be effective even when microbes are classified as susceptible.
Depending on their sensitivity to specific antibiotic concentrations, microorganisms are characterized as:
Sensitive: This category implies that the infection caused by the particular microbial strain can be treated with the appropriate dosage of the antimicrobial agent, for this type of infection, with the specific microbial species, unless contraindicated.
Moderately Sensitive: This category includes strains of microbes that are not clearly sensitive.
Resistant: Antimicrobial strains belonging to this class are not inhibited by the usual systemic concentrations of the antimicrobial agent, at the usual dosage and/or specific mechanisms of microbial resistance (e.g., β-lactamases) may be present.
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. The correct interpretation of laboratory results allows a doctor to distinguish "healthy" from "diseased".
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be interpreted in relation to each individual case and family history, clinical findings, and the results of other laboratory tests and information. Your personal physician should explain the importance of your test results.
At Diagnostiki Athinon we answer any questions you may have about the test you perform in our laboratory and we contact your doctor to get the best possible medical care.