What is the antibiotic susceptibility test

Antibiogram (MBABG)

The antibiogram is a special examination procedure in the context of so-called "medical microbiology". Microbiology is a special diagnostic discipline that primarily deals with the diagnosis of small organisms (so-called microorganisms) and the diseases caused by them.

Microorganisms can be roughly divided into the following groups:

The bacteria form a special group of microorganisms, because with them there has to be between the

  • normal bacterial flora of man and
  • bacterial infections can be distinguished.

The normal bacterial flora in particular is of great importance for the normal functioning of the human body. Without these bacteria, digestion would not function properly, for example, as large parts of the digestive tract (especially the intestines) need a certain composition of bacterial colonization (so-called "intestinal flora").

Other examples of this normal bacterial flora are also

  • the skin (certain bacteria, the coagulase-negative staphylococci, are responsible for the "protective acid mantle" of the skin),
  • the oral cavity ("pharynx flora"),
  • the vagina (this is where the so-called Döderlein rod bacteria are usually found).

On the other hand, bacteria can also cause diseases:

  • bacterial infectious diseases.

There are a number of laboratory procedures for the diagnostic clarification of these diseases (so-called "bacteriological diagnostics"), whereby a wide variety of test materials are used:

  • Blood,
  • Urine,
  • Chair,
  • Secretions,
  • Cerebrospinal fluid (cerebrospinal fluid),
  • Swabs (from skin, wounds or body cavities),
  • Biopsies, punctures or irrigation from regions deeper in the body.

With regard to bacteriological diagnostics, all of these examination materials are used depending on the medical question, whereby the following detection methods exist:

  • Direct verification procedures - Here the pathogens (in this context the bacteria) are detected directly. These procedures include:
    • microscopic pathogen detection (microscopic examination of unstained [so-called "native preparations"] or colored [e.g. Gram stain] materials),
    • Bacterial culture (growing the bacteria on special culture media),
    • Antibiogram (clarification of any resistance of the bacteria to antibiotics),
    • Detection of bacterial antigens (these are special molecular protein structures of the bacteria) as well
    • Special processes (such as the polymerase chain reaction [PCR]).
  • Indirect detection methods - Here the reaction of the body's immune system to the bacterial infectious disease is examined:
    • As part of this diagnosis, antibodies in the blood (so-called "serology" or "serological diagnostics") as well as in other body fluids are measured. Generally speaking, antibodies are special proteins produced by the body. The main task of antibodies is to protect the body from everything that is foreign to the body.