When to combine antibiotics?

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Almost all specialists insist that antibiotics should be used only when absolutely necessary and if possible, the amount of antibiotics should be limited to the body. However, in clinical practice, not all cases of using one type of antibiotic can reverse the disease, but a combination antibiotic (combination of 2,3 different drugs) must be used to treat it thoroughly. Clinical antibiotic combination is also necessary in certain cases.

1. Benefits of antibiotic combination

Around us there are many pathogens, types of bacteria that cause many different pathogens can damage the same organ. However, in reality, there is no universal drug that can kill all types of bacteria. Each type will have a certain mechanism of action and pharmacodynamics against certain types of pathogens. In this case, the combination of two antibiotics will be better than using them alone.
Here are 2 main benefits to antibiotic combination:
The combination of antibiotics in treatment can increase the spectrum of action against harmful bacteria. Example: Pneumonia and respiratory infections are usually caused by a group of bacteria like staphylococcus, streptococcus, or sometimes E.coli or Klebsiella bacteria. If only β-lactam antibiotics are used, they are only effective against staphylococci and streptococci. But if combined with aminoglycoside antibiotics, the effect will increase, even with intestinal bacteria. The combination of antibiotics as above is especially effective if we do not have the conditions to accurately identify the type of bacteria causing the disease.
Many cases of antibiotic combination help increase the pharmacodynamic effect of the drug many times. Example:
Sulfamide antibiotics: competitively inhibits PABA, then reduces dihydrofolate synthesis, an important process in DNA synthesis. The antibiotic Trimethoprim: inhibits the enzyme that breaks down dihydrofolate reductase. If these two antibiotics are combined, the pharmacokinetics will increase 100 times.

2. Disadvantages of antibiotic combination

Due to the multi-therapeutic effect, the disadvantages of antibiotic combination in clinical practice are also potentially harmful. In essence, the use of an antibiotic has also caused certain effects to the user. If more than one drug is used at the same time, the harmful effects will increase many times. Example:
Aminoglycoside antibiotics: are drugs that cause bloating, nausea and vomiting. Metronidazole antibiotic: an antibiotic with side effects that makes patients tired. The combination of these two antibiotics can increase these unwanted reactions on the patient's body. Obviously, the combination of drugs in this case is not good and the patient is not healthy enough to follow the correct course of treatment.

The more complicated case is that 2 antibiotics combined have a non-reciprocal mechanism. For example, if penicillin and tetracycline are combined to treat meningitis, be careful. Tetracycline, which is a 30S inhibitor of ribosomes in protein synthesis, is inhibited if penicillin is added. Therefore, we need to master the principle of antibiotic combination in treatment and avoid the combination of two antagonistic antibiotics.

3. When to combine antibiotics?

Currently, all antibiotics are produced with high medicinal properties and broad spectrum of action, so moderate and mild infections may not need to be combined with antibiotics in treatment. However, in more complicated cases, combination antibiotics should be considered:
Patient is hospitalized with severe illness but cannot wait for microbiological test results. Patients with infections during hospital stay with strains of pathogens with high drug resistance (pneumonia, post-operative bacteremia ....) or mixed infections, widespread infections need to combine antibiotics to prevent infection. widen the spectrum of effects. Example of clinical antibiotic combination:
If the patient has severe pulmonary infection, it is recommended to combine 1 ß-lactam antibiotic (such as Co-amoxiclav, Cefotaxime, Cefuroxime, or Ceftriaxone...) with 1 macrolide antibiotic. such as Clarithromycin are recommended because they enhance each other's effects. For patients with intra-abdominal infections due to co-infection of anaerobic and anaerobic bacteria, the antibiotic Metronidazole should be combined with a broad-spectrum antibiotic such as Gentamicin, Cefotaxime, Ciprofloxacin to cover all possible pathogens. disease agent. This is a serious infection that requires good management to avoid complications or death. For patients with endocarditis, the use of combination antibiotics is also often indicated in the first place. In addition, the combination of Penicillin and Gentamicin is also used to treat endocarditis caused by enterococci or staphylococci. This regimen is found to be more effective than penicillin alone. For TB treatment, combining antibiotics in treatment also helps reduce the rate of drug resistance. When using isoniazid antibiotic, the rate of drug-resistant TB is 1/106, when using rifampicin, the rate of drug resistance is 1/108 of pathogens. When combining the two types above, the rate of drug resistance decreased significantly. To successfully treat TB, the treatment regimen usually requires a combination of 2-3 different antibiotics, which seems to be an immutable formula.

Combining antibiotics in treatment also has the effect of increasing drug activity to deal with cases of bacteria with high drug resistance, often applied when treating immunocompromised patients (AIDS). After organ transplantation, long-term immunosuppressive drugs must be used to increase the bactericidal effect or with severe infections in sites that are difficult to absorb antibiotics such as osteomyelitis, meningitis, endocarditis..
Thus, the clinical combination of antibiotics should only be done when it is predicted that the possibility of using single antibiotics is not effective enough. It is not recommended to use combination antibiotics widely because it is easy to encounter adverse interactions due to antagonism...if not careful, unpredictable complications can occur.

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