An antibiogram provides information to the doctor so he or she knows which drug to prescribe. This is because the different types of bacteria do not respond equally well to the same antibiotics. Similarly, the drugs are different and attack only a certain type of infectious substance.
But why is it that not all microorganisms can be treated with the same antibiotic? This is a common question and the answer lies in the concept of evolution. This is because microorganisms have evolved to have mechanisms to avoid substances that prevent them from surviving.
We need to know these resistances in advance in order to apply the right treatment to the infected person. For this purpose, the antibiogram reveals the sensitivity of a given bacterium to certain antibiotics.
Resistance to antimicrobials
Bacteria become resistant over time based on their need to survive. Drug resistance, which we can observe in antibiograms, has two categories:
- Congenital mechanisms that a bacterial family has naturally entered into its genetic code (they already had it long before the use of antibiotics).
- Acquired mechanisms as certain bacteria have created methods to resist or combat antibiotics (they went from being sensitive to these drugs to being resistant).
An example of acquired resistance
An example of acquired resistance is what happened after Alexander Fleming’s discovery of penicillin. Penicillin was the main antimicrobial agent in the 1940s, but a bacterium called Staphylococcus aureus quickly developed resistance.
Penicillin is an antibiotic that binds to an enzyme formed by the bacterial wall. In other words , this substance inhibits the synthesis of the bacterial wall, leaving the microorganism unprotected and leading to its death. However, Staphylococcus aureus generated enzymes called penicillinases to break down the penicillin molecule.
Hazards from antimicrobial resistance
The Centers for Disease Control and Prevention (CDC) wrote a report for 2019 on the threat of antibiotic resistance in the United States, showing that the number of resistant bacteria remains high. Currently, there are 2.8 million antibiotic-resistant infections.
Looking at all these data, the threat from antibiotic resistance is disturbing and frightening. According to the World Health Organization (WHO), the use and misuse of antimicrobials has increased the number and types of resistant microorganisms in recent years.
What is an antibiogram?
It is a test that helps us determine the most appropriate antibiotic for specific treatment of the infecting bacterium. A doctor takes a sample from the focal point of the infection to isolate the causative microorganism when a person has an infection.
The microorganism then grows in a controlled medium, a culture, to determine what type of bacterium it is and what family it belongs to. Once this step is completed, laboratory technicians cultivate it in another medium with antibiotic-releasing tablets.
The bacteria grow in this new culture , but the bacteria that are sensitive to antibiotics leave a halo around the tablet. This halo shows that the bacterium could not multiply because the antibiotic prevented it.
Treatment according to an antibiogram
A very serious infection does not give time to wait for the results of an antibiogram. Based on the patient’s characteristics, the focus of the infection, and whether the infection was contracted outside or in the hospital, the patient is treated with broad-spectrum antibiotics.
These broad-spectrum drugs cannot be deliberately used for everyone who has an infection. This is because their indication involves a risk of resistance. Of course, there is no problem if they become resistant, as we would not be able to use the same antibiotic for serious infections.
On the other hand , targeted treatment is the treatment tailored to the bacterium in question. It is determined by the antibiogram, which indicates which antibiotic to use.
Avoid bacterial resistance
It is necessary and crucial for humanity to prevent bacterial resistance. In addition , the therapy will be ineffective and the consequences serious if microorganisms become too resistant.
The most important advice is to take the correct dose of the prescribed antibiotic according to the doctor’s instructions. You must not stop taking the medicine, even if you get better, and you must not change the amount according to your own wishes.
The use of an antibiogram will be the norm if one encounters a resistant bacterium, despite the precautions one may take. It is a powerful biochemical tool for treating severe cases of infection.